Subdural haematoma (SDH) can be a neurosurgical emergency that, if left untreated, can lead to haematoma expansion, increased intracranial pressure (ICP) or brain herniation. Acute SDH carries a high mortality risk.[4]Servadei F, Nasi MT, Giuliani G, et al. CT prognostic factors in acute subdural haematomas: the value of the 'worst' CT scan. Br J Neurosurg. 2000 Apr;14(2):110-6.
http://www.ncbi.nlm.nih.gov/pubmed/10889882?tool=bestpractice.com
[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
Supportive care for an acute trauma-related SDH includes an airway, breathing, circulation, disability (ABCD) approach to assessment.
Neurosurgeons and neurointensivists use many different strategies for managing acute and chronic SDHs. Generally, the most important criteria for determining management of acute SDHs are neurological signs/symptoms and radiographic appearance. Subacute haematomas can be treated in the same way as chronic haematomas; acute-on-chronic haematomas are usually treated in the same way as acute SDHs.
Acute SDH
If a patient has an acute SDH following a traumatic brain injury (TBI), an ABCD approach should be used to ensure rapid assessment of airway, breathing, circulation, and disability.
All patients with Glasgow Coma Scale (GCS) score <9 need to have ICP monitoring with ventriculostomy, subarachnoid bolt, or intraparenchymal monitor.[55]Bullock MR, Chesnut R, Ghajar J, et al; Surgical Management of Traumatic Brain Injury Author Group. Surgical management of acute subdural hematomas. Neurosurgery. 2006 Mar;58(suppl 3):S16-24;discussion Si-iv.
http://www.ncbi.nlm.nih.gov/pubmed/16710968?tool=bestpractice.com
[72]Caniano DA, Nugent SK, Rogers MC, et al. Intracranial pressure monitoring in the management of the pediatric trauma patient. J Pediatr Surg. 1980 Aug;15(4):537-42.
http://www.ncbi.nlm.nih.gov/pubmed/6774080?tool=bestpractice.com
[73]Crutchfield JS, Narayan RK, Robertson CS, et al. Evaluation of a fiberoptic intracranial pressure monitor. J Neurosurg. 1990 Mar;72(3):482-7.
http://www.ncbi.nlm.nih.gov/pubmed/2303881?tool=bestpractice.com
Other physiological parameters can be measured which help guide therapy, including brain oxygenation through monitoring of partial pressures of oxygen in focal brain tissue areas or global cerebral oxygenation with intraparenchymal oximetry monitors, near-infrared spectroscopy, and continuous electroencephalographic (EEG) monitoring for seizures. An epileptologist can be consulted for interpretation of EEG recordings.[74]Procaccio F, Polo A, Lanteri P, et al. Electrophysiologic monitoring in neurointensive care. Curr Opin Crit Care. 2001 Apr;7(2):74-80.
http://www.ncbi.nlm.nih.gov/pubmed/11373514?tool=bestpractice.com
[75]Mayberg TS, Lam AM. Jugular bulb oximetry for the monitoring of cerebral blood flow and metabolism. Neurosurg Clin N Am. 1996 Oct;7(4):755-65.
http://www.ncbi.nlm.nih.gov/pubmed/8905787?tool=bestpractice.com
[76]Hoelper BM, Alessandri B, Heimann A, et al. Brain oxygen monitoring: in-vitro accuracy, long-term drift and response-time of Licox- and Neurotrend sensors. Acta Neurochir (Wien). 2005 Jul;147(7):767-74;discussion 774.
http://www.ncbi.nlm.nih.gov/pubmed/15889319?tool=bestpractice.com
Brain Trauma Foundation guidelines recommend emergency surgical evacuation of the haematoma for patients with any one or more of:[77]Carney N, Totten AM, O'Reilly C, et al. Guidelines for the management of severe traumatic brain injury, Fourth Edition. Neurosurgery. 2017 Jan 1;80(1):6-15.
https://journals.lww.com/neurosurgery/fulltext/2017/01000/guidelines_for_the_management_of_severe_traumatic.3.aspx
http://www.ncbi.nlm.nih.gov/pubmed/27654000?tool=bestpractice.com
[78]Ono J, Yamaura A, Kubota M, et al. Outcome prediction in severe head injury: analyses of clinical prognostic factors. J Clin Neurosci. 2001 Mar;8(2):120-3.
http://www.ncbi.nlm.nih.gov/pubmed/11484659?tool=bestpractice.com
SDH of >10 mm or a midline shift >5 mm (regardless of GCS score). These features are significant predictors of a poor prognosis and are therefore key factors informing the decision on whether surgical intervention is indicated.
A GCS score <9 that has dropped ≥2 points between injury and emergency room (regardless of haematoma width or extent of midline shift).
A GCS score <9 and one or both of: fixed or asymmetric pupils and/or ICP >22 mmHg (regardless of haematoma width or extent of midline shift).
Conservative management with ongoing monitoring is generally considered appropriate for patients who have none of the above features.
However, the evidence to underpin the above criteria for surgical versus conservative management is weak. In practice, there is a consensus that surgical intervention is indicated for any patient with an acute SDH who is comatose whereas there is substantial variation between neurosurgical centres in the thresholds applied for acute surgical evacuation in non-comatose patients with similar clinical presentations.[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
The CENTER-TBI study analysis of 1407 patients with trauma-related acute SDH treated in 65 centres in Europe and Israel found there was no clear superiority in functional outcomes (based on GCS scores at 6 months) for centres that tended to prefer acute surgery over initial conservative treatment (with the option for delayed surgery if indicated by ongoing monitoring).[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
Across all 65 centres, 24% of the patients had acute surgical evacuation but this ranged from 5.6% to 51.5% in individual centres, with a twofold higher probability of receiving acute surgery for a clinically similar patient in one centre versus another centre selected at random. Among the 76% who were initially managed conservatively, delayed surgery was needed in 11%.[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
The authors concluded that while the benefit of immediate surgery is well established for a patient with acute SDH who is comatose (i.e., GCS score < 9), it is less clear for patients with a GCS score ≥ 9 and initial conservative treatment can be considered for this group unless a neurosurgeon sees a clear and specific indication for acute surgery.[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
The decision depends on balancing the potential complications of surgery with the risk of irreversible deterioration or death following initial conservative treatment.
There is also ongoing debate about the benefits versus risks of immediate surgery for acute SDH in older individuals, with studies reaching conflicting conclusions.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
[79]Manivannan S, Spencer R, Marei O, et al. Acute subdural haematoma in the elderly: to operate or not to operate? a systematic review and meta-analysis of outcomes following surgery. BMJ Open. 2021 Dec 3;11(12):e050786.
https://bmjopen.bmj.com/content/11/12/e050786.long
http://www.ncbi.nlm.nih.gov/pubmed/34862284?tool=bestpractice.com
An evidence review for the UK National Institute for Health and Care Excellence (NICE) guideline on head injury stated that, in practice, neurosurgical intervention is less likely to be offered to adults aged ≥75 years due to risks outweighing benefits.[63]National Institute for Health and Care Excellence. Head injury: assessment and early management. May 2023 [internet publication].
https://www.nice.org.uk/guidance/ng232
One meta-analysis of outcomes following surgical evacuation for acute SDH in patients aged >60 years found that the pooled estimated mortality was 39.8% (95% CI 32.7% to 47.1%) at discharge, based on 10 studies of 739 patients, and 49.3% (95% CI 42.0% to 56.6%) at mean follow-up of 7.1 months, based on 10 studies of 555 patients.[79]Manivannan S, Spencer R, Marei O, et al. Acute subdural haematoma in the elderly: to operate or not to operate? a systematic review and meta-analysis of outcomes following surgery. BMJ Open. 2021 Dec 3;11(12):e050786.
https://bmjopen.bmj.com/content/11/12/e050786.long
http://www.ncbi.nlm.nih.gov/pubmed/34862284?tool=bestpractice.com
Severe disability was common among survivors; only 18.8% (95% CI 13.8% to 24.4%) had a GCS score of 4 or 5 at discharge.[79]Manivannan S, Spencer R, Marei O, et al. Acute subdural haematoma in the elderly: to operate or not to operate? a systematic review and meta-analysis of outcomes following surgery. BMJ Open. 2021 Dec 3;11(12):e050786.
https://bmjopen.bmj.com/content/11/12/e050786.long
http://www.ncbi.nlm.nih.gov/pubmed/34862284?tool=bestpractice.com
In one retrospective review, poor outcome for acute SDH surgery (e.g., discharge GCS; recurrence; readmission) was predicted by age over 85 years, but death and complications were not. Those aged greater than 90 years with presentation GCS score <10 all had poor outcomes.[80]Whitehouse KJ, Jeyaretna DS, Enki DG, et al. Head injury in the elderly: what are the outcomes of neurosurgical care? World Neurosurg. 2016 Oct;94:493-500.
http://www.ncbi.nlm.nih.gov/pubmed/27465419?tool=bestpractice.com
However, the CENTER-TBI study reported a non-significant suggestion of benefit from acute surgery versus initial conservative management in patients aged >65 years (adjusted OR 1.18, 95% CI 0.65% to 2.24%).[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
Late (72 hours to 10 days) ICP elevations >25 mmHg.
Management of antithrombotic therapy
When a patient is diagnosed with acute or chronic SDH, it is essential to establish whether they are taking any anticoagulation or antiplatelet agents. Tailored management (including possible reversal) of antithrombotic therapy is a key element of initial care for all patients with SDH and of peri-operative optimisation for those who need neurosurgical intervention.[32]Stubbs DJ, Davies BM, Dixon-Woods M, et al. Protocol for the development of a multidisciplinary clinical practice guideline for the care of patients with chronic subdural haematoma. Wellcome Open Res. 2023;8:390.
https://wellcomeopenresearch.org/articles/8-390/v1
http://www.ncbi.nlm.nih.gov/pubmed/38434734?tool=bestpractice.com
[81]Subramanian M, Kaplan LJ, Cannon JW. Thromboelastography-guided resuscitation of the trauma patient. JAMA Surg. 2019 Dec 1;154(12):1152-3.
http://www.ncbi.nlm.nih.gov/pubmed/31596452?tool=bestpractice.com
Many patients with severe head injury present with coagulopathy and require normalisation of their coagulation profile.[82]Cortiana M, Zagara G, Fava S, et al. Coagulation abnormalities in patients with head injury. J Neurosurg Sci. 1986 Jul-Sep;30(3):133-8.
http://www.ncbi.nlm.nih.gov/pubmed/3783267?tool=bestpractice.com
[83]Goodnight SH, Kenoyer G, Rapaport SI, et al. Defibrination after brain-tissue destruction: A serious complication of head injury. N Engl J Med. 1974 May 9;290(19):1043-7.
http://www.ncbi.nlm.nih.gov/pubmed/4821906?tool=bestpractice.com
[84]Harhangi BS, Kompanje EJ, Leebeek FW, et al. Coagulation disorders after traumatic brain injury. Acta Neurochir (Wien). 2008 Feb;150(2):165-75;discussion 175.
http://www.ncbi.nlm.nih.gov/pubmed/18166989?tool=bestpractice.com
Drug-specific reversal therapy should be initiated for those requiring urgent surgery for life-threatening bleeding.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Most patients will need suspension of (and in some cases reversal of) their antithrombotic therapy, although these decisions must be based on judicious weighing of the individual patient’s relative risks of bleeding versus thrombosis.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
[85]Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for reversal of antithrombotics in intracranial hemorrhage: a statement for healthcare professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016 Feb;24(1):6-46.
http://www.ncbi.nlm.nih.gov/pubmed/26714677?tool=bestpractice.com
Immediate reversal of anticoagulation is generally recommended if active bleeding is present.[86]National Institute for Health and Care Excellence. Blood transfusion. Nov 2015 [internet publication].
https://www.nice.org.uk/guidance/ng24
Specific anticoagulant reversal recommendations for patients with life-threatening bleeding (all aetiologies) are published by the Neurocritical Care Society/Society of Critical Care Medicine, American Heart Association (AHA), and American Society of Hematology.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
[85]Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for reversal of antithrombotics in intracranial hemorrhage: a statement for healthcare professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016 Feb;24(1):6-46.
http://www.ncbi.nlm.nih.gov/pubmed/26714677?tool=bestpractice.com
[87]Raval AN, Cigarroa JE, Chung MK, et al. Management of patients on non-vitamin K antagonist oral anticoagulants in the acute care and periprocedural setting: a scientific statement from the American Heart Association. Circulation. 2017 Mar 7;135(10):e604-33.
https://www.ahajournals.org/doi/10.1161/CIR.0000000000000477
http://www.ncbi.nlm.nih.gov/pubmed/28167634?tool=bestpractice.com
[88]Witt DM, Nieuwlaat R, Clark NP, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: optimal management of anticoagulation therapy. Blood Adv. 2018 Nov 27;2(22):3257-91.
https://ashpublications.org/bloodadvances/article/2/22/3257/16107/American-Society-of-Hematology-2018-guidelines-for
http://www.ncbi.nlm.nih.gov/pubmed/30482765?tool=bestpractice.com
Antithrombotic therapy is a risk factor for acute and chronic SDH.[11]Connolly BJ, Pearce LA, Hart RG. Vitamin K antagonists and risk of subdural hematoma: meta-analysis of randomized clinical trials. Stroke. 2014 Jun;45(6):1672-8.
http://stroke.ahajournals.org/content/45/6/1672.long
http://www.ncbi.nlm.nih.gov/pubmed/24876259?tool=bestpractice.com
[15]Baechli H, Nordmann A, Bucher HC, et al. Demographics and prevalent risk factors of chronic subdural haematoma: results of a large single-center cohort study. Neurosurg Rev. 2004 Oct;27(4):263-6.
http://www.ncbi.nlm.nih.gov/pubmed/15148652?tool=bestpractice.com
[16]Gaist D, García Rodríguez LA, Hellfritzsch M, et al. Association of antithrombotic drug use with subdural hematoma risk. JAMA. 2017 Feb 28;317(8):836-46.
https://jamanetwork.com/journals/jama/fullarticle/2605799
http://www.ncbi.nlm.nih.gov/pubmed/28245322?tool=bestpractice.com
[34]Hylek EM, Singer DE. Risk factors for intracranial hemorrhage in outpatients taking warfarin. Ann Intern Med. 1994 Jun 1;120(11):897-902.
http://www.ncbi.nlm.nih.gov/pubmed/8172435?tool=bestpractice.com
[35]Komatsu Y, Uemura K, Yasuda S, et al. Acute subdural hemorrhage of arterial origin: report of three cases [in Japanese]. No Shinkei Geka. 1997 Sep;25(9):841-5.
http://www.ncbi.nlm.nih.gov/pubmed/9300455?tool=bestpractice.com
Patients on oral anticoagulation therapy are estimated to have a 4- to 15-fold increased risk for SDH, leading to a higher likelihood of haematoma expansion, an increased risk of death, and a worse functional outcome unless anticoagulation is quickly reversed.[36]Al-Mufti F, Mayer SA. Neurocritical care of acute subdural hemorrhage. Neurosurg Clin N Am. 2017 Apr;28(2):267-78.
http://www.ncbi.nlm.nih.gov/pubmed/28325461?tool=bestpractice.com
[89]Yang J, Jing J, Chen S, et al. Reversal and resumption of anticoagulants in patients with anticoagulant-associated intracerebral hemorrhage. Eur J Med Res. 2024 Apr 24;29(1):252.
https://eurjmedres.biomedcentral.com/articles/10.1186/s40001-024-01816-5
http://www.ncbi.nlm.nih.gov/pubmed/38659079?tool=bestpractice.com
Use of antithrombotic therapy is particularly common among older patients who present with chronic SDH, in whom there are often indications for anticoagulation and/or antiplatelet agents (e.g., atrial fibrillation, mechanical heart valves).[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
Evidence is scarce to inform decisions around the cessation of antithrombotic therapy and reversal of anticoagulation in patients with intracranial bleeding.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
Decisions around the cessation or reversal of anticoagulation should be individualised.
The risks as well as the benefits of vitamin K antagonist (e.g., warfarin) reversal should be considered in patients with concurrent symptomatic or life-threatening thrombosis, ischaemia, heparin-induced thrombocytopenia, or disseminated intravascular coagulation.[85]Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for reversal of antithrombotics in intracranial hemorrhage: a statement for healthcare professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016 Feb;24(1):6-46.
http://www.ncbi.nlm.nih.gov/pubmed/26714677?tool=bestpractice.com
Providers managing SDHs should also be aware of the use of direct oral anticoagulants (DOACs) which target either thrombin or factor Xa. Examples of these drugs include dabigatran, rivaroxaban, apixaban, and edoxaban. DOACs have several advantages over warfarin, including less risk of life-threatening haemorrhages, which is why their use is increasing.[85]Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for reversal of antithrombotics in intracranial hemorrhage: a statement for healthcare professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016 Feb;24(1):6-46.
http://www.ncbi.nlm.nih.gov/pubmed/26714677?tool=bestpractice.com
When treating SDHs in patients on DOACs, providers are encouraged to consult with their haematology colleagues for potential reversal options.[85]Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for reversal of antithrombotics in intracranial hemorrhage: a statement for healthcare professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016 Feb;24(1):6-46.
http://www.ncbi.nlm.nih.gov/pubmed/26714677?tool=bestpractice.com
[90]Morais J, De Caterina R. Stroke prevention in atrial fibrillation: a clinical perspective on trials of the novel oral anticoagulants. Cardiovasc Drugs Ther. 2016 Apr;30(2):201-14.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4858545
http://www.ncbi.nlm.nih.gov/pubmed/26780749?tool=bestpractice.com
[91]Brem E, Koyfman A, Foran M. Review of recently approved alternatives to anticoagulation with warfarin for emergency clinicians. J Emerg Med. 2013 Jul;45(1):143-9.
http://www.ncbi.nlm.nih.gov/pubmed/23375217?tool=bestpractice.com
Current guidelines suggest that all patients discontinue antiplatelet agents in the acute period post injury when intracranial haemorrhage (ICH) is present or suspected.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
[85]Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for reversal of antithrombotics in intracranial hemorrhage: a statement for healthcare professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016 Feb;24(1):6-46.
http://www.ncbi.nlm.nih.gov/pubmed/26714677?tool=bestpractice.com
The reversal of antiplatelet agent effects in patients with traumatic intracranial haemorrhage remains controversial.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
The American College of Surgeons (ACS) states that for patients with normal platelet function or documented resistance, reversal therapies are not recommended and routine platelet transfusion is not recommended for use in reversing antiplatelet agent effects.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Clinical judgment should be used to determine if patients with TBI on antiplatelet agents who are undergoing surgery or invasive procedures with low platelet counts need platelet transfusions to achieve haemostasis.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
However, the risk-benefit decision is often particularly complex in patients who are taking dual antiplatelet therapy.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
Evidence suggesting a significant risk of thrombosis associated with cessation of dual antiplatelet therapy in specific subgroups of patients (e.g., those who have undergone recent placement of drug-eluting stents).[92]Major J, Reed MJ. A retrospective review of patients with head injury with coexistent anticoagulant and antiplatelet use admitted from a UK emergency department. Emerg Med J. 2009 Dec;26(12):871-6.
http://www.ncbi.nlm.nih.gov/pubmed/19934132?tool=bestpractice.com
[93]Généreux P, Rutledge DR, Palmerini T, et al. Stent thrombosis and dual antiplatelet therapy interruption with everolimus-eluting stents: insights from the xience V coronary stent system trials. Circ Cardiovasc Interv. 2015 May;8(5):e001362.
https://www.ahajournals.org/doi/10.1161/CIRCINTERVENTIONS.114.001362
http://www.ncbi.nlm.nih.gov/pubmed/25940520?tool=bestpractice.com
In such patients, continuation of aspirin monotherapy may be advisable to minimise the risk of cardiac ischaemic events.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
In the specific instance of SDH, practice varies between centres. Advice should be sought from haematology or cardiology colleagues to enable a detailed, personalised risk assessment.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
For patients with chronic SDH without acute bleeding, there are very few data available to guide the decision on whether to suspend or continue anticoagulation.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
In practice, if a patient with a chronic SDH has no signs of raised ICP and will be managed conservatively, the risk-benefit balance may sometimes be in favour of continuing anticoagulation therapy, depending on the strength of the specific indication for its use. Specialist advice is needed to make these nuanced decisions.
All patients with acute SDH who are on antithrombotic therapy require serial prothrombin time, partial thromboplastin time, international normalised ratio (INR), and platelet and fibrinogen levels followed. Although anti-Xa assays are available, the AHA notes that these are not widely accessible and often are not able to be run quickly enough in an urgent setting.[94]Greenberg SM, Ziai WC, Cordonnier C, et al. 2022 guideline for the management of patients with spontaneous intracerebral hemorrhage: a guideline from the American Heart Association/American Stroke Association. Stroke. 2022 Jul;53(7):e282-361.
https://www.ahajournals.org/doi/full/10.1161/STR.0000000000000407?rfr_dat=cr_pub++0pubmed&url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org
http://www.ncbi.nlm.nih.gov/pubmed/35579034?tool=bestpractice.com
Evidence from 2019 suggests that targeted reversal utilising viscoelastic assays, including thromboelastography or rotational thromboelastometry, may provide an overall survival benefit and decrease in recurrent bleeding in the first 6 hours following trauma.[81]Subramanian M, Kaplan LJ, Cannon JW. Thromboelastography-guided resuscitation of the trauma patient. JAMA Surg. 2019 Dec 1;154(12):1152-3.
http://www.ncbi.nlm.nih.gov/pubmed/31596452?tool=bestpractice.com
Reversal therapy should not be delayed while waiting for laboratory results in urgent situations when the patient is at high risk for bleeding.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Correction of coagulopathy can include vitamin K (useful in patients with warfarin-related prolongation of INR), fresh frozen plasma, platelets (goal platelet count is >100 x 10⁹/L; >100,000/microlitre), cryoprecipitate (used in patients with low fibrinogen levels), protamine (used for patients on heparin), recombinant coagulation factor Xa (andexanet alfa) for patients on apixaban or rivaroxaban, and activated factor VIIa.[95]Narayan RK, Wilberger JE, Povlishock JT. Neurotrauma. New York, NY: McGraw Hill Health Professions Division; 1996.
Restarting antithrombotic therapy
The ACS recommends restarting anticoagulation no later than 14-90 days after TBI, depending on patient-specific risk for thrombosis and bleeding.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Clinical practice varies significantly but most clinicians consider it safe to restart anticoagulation in the majority of patients after a 2-week break, although it may need to be sooner in individuals with a very strong indication for anticoagulation (e.g., a recent venous thromboembolism or a metallic heart valve).[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
[59]Stubbs DJ, Davies BM, Menon DK. Chronic subdural haematoma: the role of peri-operative medicine in a common form of reversible brain injury. Anaesthesia. 2022 Jan;77 Suppl 1:21-33.
https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/anae.15583
http://www.ncbi.nlm.nih.gov/pubmed/35001374?tool=bestpractice.com
[96]Xu Y, Shoamanesh A, Schulman S, et al. Oral anticoagulant re-initiation following intracerebral hemorrhage in non-valvular atrial fibrillation: Global survey of the practices of neurologists, neurosurgeons and thrombosis experts. PLoS One. 2018;13(1):e0191137.
https://pmc.ncbi.nlm.nih.gov/articles/PMC5784940
http://www.ncbi.nlm.nih.gov/pubmed/29370183?tool=bestpractice.com
Safe restart of anticoagulant therapy may also occur significantly sooner if traumatic intracranial bleeding is less significant and/or stable on repeat CT imaging.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
[88]Witt DM, Nieuwlaat R, Clark NP, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: optimal management of anticoagulation therapy. Blood Adv. 2018 Nov 27;2(22):3257-91.
https://ashpublications.org/bloodadvances/article/2/22/3257/16107/American-Society-of-Hematology-2018-guidelines-for
http://www.ncbi.nlm.nih.gov/pubmed/30482765?tool=bestpractice.com
Antiplatelet agents may be restarted as early as 4 days after injury, based on assessment of patient-specific risk for thrombosis and bleeding.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Risks for acute and delayed ICH after restarting antiplatelet agents must be weighed against the morbidity of thrombotic complications that can have significant clinical consequences.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Management of raised intracranial pressure
In patients with increased ICP, a standard protocol is used for management. It is important to follow traditional traumatic brain injury principles, including maintaining a cerebral perfusion pressure of 60-70 mmHg.[77]Carney N, Totten AM, O'Reilly C, et al. Guidelines for the management of severe traumatic brain injury, Fourth Edition. Neurosurgery. 2017 Jan 1;80(1):6-15.
https://journals.lww.com/neurosurgery/fulltext/2017/01000/guidelines_for_the_management_of_severe_traumatic.3.aspx
http://www.ncbi.nlm.nih.gov/pubmed/27654000?tool=bestpractice.com
An ICP of 22 mmHg (in adults) is a useful initial threshold for treatment.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
An ICP of 22 mmHg is a useful initial threshold for treatment. However, ongoing research suggests this threshold is dependent upon individual patient factors such as injury type and severity.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
When the risk/benefit of advancing treatment becomes a concern, such as for therapy with significant hazards (e.g., decompressive craniectomy), a treatment range of 20-25 mmHg should be considered.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Primary options that can be used to lower ICP include raising the head of the bed to 30°, using the reverse Trendelenberg position if spinal instability or injury is present.[97]Feldman Z, Kanter MJ, Robertson CS, et al. Effect of head elevation on intracranial pressure, cerebral perfusion pressure, and cerebral blood flow in head-injured patients. J Neurosurg. 1992 Feb;76(2):207-11.
http://www.ncbi.nlm.nih.gov/pubmed/1730949?tool=bestpractice.com
Analgesics and sedation can be useful, as pain and agitation can increase the ICP.[98]Kelly DF, Goodale DB, Williams J, et al. Propofol in the treatment of moderate and severe head injury: a randomized, prospective double-blinded pilot trial. J Neurosurg. 1999 Jun;90(6):1042-52.
http://www.ncbi.nlm.nih.gov/pubmed/10350250?tool=bestpractice.com
Using paralytics in intubated patients can help to attenuate the effects of suctioning.[99]Kerr ME, Sereika SM, Orndoff P, et al. Effect of neuromuscular blockers and opiates on the cerebrovascular response to endotracheal suctioning in adults with severe head injuries. Am J Crit Care. 1998 May;7(3):205-17.
http://www.ncbi.nlm.nih.gov/pubmed/9579247?tool=bestpractice.com
Hyperventilation to a goal pCO₂ of 30 to 35 mmHg (monitored with serial arterial blood gases) can be beneficial in reducing ICP, but is only recommended as a temporary measure as prolonged use can be associated with cerebral vessel constriction and decreased blood flow.[100]Kinoshita K. Traumatic brain injury: pathophysiology for neurocritical care. J Intensive Care. 2016 Apr 27;4:29.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4847183
http://www.ncbi.nlm.nih.gov/pubmed/27123305?tool=bestpractice.com
[101]Oertel M, Kelly DF, Lee JH, et al. Efficacy of hyperventilation, blood pressure elevation, and metabolic suppression therapy in controlling intracranial pressure after head injury. J Neurosurg. 2002 Nov;97(5):1045-53.
http://www.ncbi.nlm.nih.gov/pubmed/12450025?tool=bestpractice.com
Secondary treatment options to lower ICP include hyperosmolar therapy with hypertonic saline in concentrations between 3.0% and 23.4%, and a dosing limit based on an upper serum sodium limit of 155 mmol/L.[7]Fisher B, Thomas D, Peterson B. Hypertonic saline lowers raised intracranial pressure in children after head trauma. J Neurosurg Anesthesiol. 1992 Jan;4(1):4-10.
http://www.ncbi.nlm.nih.gov/pubmed/15815431?tool=bestpractice.com
[102]Qureshi AI, Suarez JI, Bhardwaj A, et al. Use of hypertonic (3%) saline/acetate infusion in the treatment of cerebral edema: Effect on intracranial pressure and lateral displacement of the brain. Crit Care Med. 1998 Mar;26(3):440-6.
http://www.ncbi.nlm.nih.gov/pubmed/9504569?tool=bestpractice.com
[103]Munar F, Ferrer AM, de Nadal M, et al. Cerebral hemodynamic effects of 7.2% hypertonic saline in patients with head injury and raised intracranial pressure. J Neurotrauma. 2000 Jan;17(1):41-51.
http://www.ncbi.nlm.nih.gov/pubmed/10674757?tool=bestpractice.com
[104]Rangel-Castilla L, Gopinath S, Robertson CS. Management of intracranial hypertension. Neurol Clin. 2008 May;26(2):521-41.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2452989
http://www.ncbi.nlm.nih.gov/pubmed/18514825?tool=bestpractice.com
[105]Ragland J, Lee K. Critical care management and monitoring of intracranial pressure. J Neurocrit Care. 2016 Dec 28; 9(2):105-12.
https://www.e-jnc.org/journal/view.php?number=245
[106]Lewandowski-Belfer JJ, Patel AV, Darracott RM, et al. Safety and efficacy of repeated doses of 14.6 or 23.4% hypertonic saline for refractory intracranial hypertension. Neurocrit Care. 2014 Jun;20(3):436-42.
http://www.ncbi.nlm.nih.gov/pubmed/24026522?tool=bestpractice.com
There is insufficient evidence to recommend one osmotic agent over another.[77]Carney N, Totten AM, O'Reilly C, et al. Guidelines for the management of severe traumatic brain injury, Fourth Edition. Neurosurgery. 2017 Jan 1;80(1):6-15.
https://journals.lww.com/neurosurgery/fulltext/2017/01000/guidelines_for_the_management_of_severe_traumatic.3.aspx
http://www.ncbi.nlm.nih.gov/pubmed/27654000?tool=bestpractice.com
[107]Chen H, Song Z, Dennis JA. Hypertonic saline versus other intracranial pressure-lowering agents for people with acute traumatic brain injury. Cochrane Database Syst Rev. 2020 Jan 17;1(1):CD010904.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010904.pub3/full
http://www.ncbi.nlm.nih.gov/pubmed/31978260?tool=bestpractice.com
Osmotic diuretics such as mannitol can also be used, but should be avoided if the serum osmolar gap exceeds 18 mOsm/kg to 20 mOsm/kg.[108]Erstad B. Critical care pharmacotherapy. Lenexa, KS: American College of Clinical Pharmacy; 2016. Use of hypertonics (saline) or hyperosmolar therapy (mannitol) may be counterproductive due to the risk of expansive haematoma volume, and are used only as a temporising measure until urgent surgical interventions can be implemented.[109]Fomchenko EI, Gilmore EJ, Matouk CC, et al. Management of subdural hematomas: part I. Medical management of subdural hematomas. Curr Treat Options Neurol. 2018 Jun 23;20(8):28.
http://www.ncbi.nlm.nih.gov/pubmed/29936548?tool=bestpractice.com
External ventricular drainage of cerebrospinal fluid can also be considered.[110]Solomou G, Sunny J, Mohan M, et al. Decompressive craniectomy in trauma: what you need to know. J Trauma Acute Care Surg. 2024 Oct 1;97(4):490-6.
https://journals.lww.com/jtrauma/fulltext/2024/10000/decompressive_craniectomy_in_trauma__what_you_need.2.aspx
http://www.ncbi.nlm.nih.gov/pubmed/39137371?tool=bestpractice.com
Treatment options for refractory elevated intracranial pressure include maintaining the patient in a pentobarbital coma (requires continuous EEG monitoring), inducing hypothermia by intravascular cooling or topical cooling blankets, and decompressive hemicraniectomy.[111]Eisenberg HM, Frankowski RF, Contant CF, et al. High-dose barbiturate control of elevated intracranial pressure in patients with severe head injury. J Neurosurg. 1988 Jul;69(1):15-23.
http://www.ncbi.nlm.nih.gov/pubmed/3288723?tool=bestpractice.com
[112]Tokutomi T, Morimoto K, Miyagi T, et al. Optimal temperature for the management of severe traumatic brain injury: effect of hypothermia on intracranial pressure, systemic and intracranial hemodynamics, and metabolism. Neurosurgery. 2003 Jan;52(1):102-11;discussion 111-2.
http://www.ncbi.nlm.nih.gov/pubmed/12493106?tool=bestpractice.com
[113]Polderman KH, Tjong Tjin Joe R, Peerdeman SM, et al. Effects of therapeutic hypothermia on intracranial pressure and outcome in patients with severe head injury. Intensive Care Med. 2002 Nov;28(11):1563-73.
http://www.ncbi.nlm.nih.gov/pubmed/12415442?tool=bestpractice.com
[114]Clifton GL, Coffey CS, Fourwinds S, et al. Early induction of hypothermia for evacuated intracranial hematomas: a post hoc analysis of two clinical trials. J Neurosurg. 2012 Oct;117(4):714-20.
http://www.ncbi.nlm.nih.gov/pubmed/22839656?tool=bestpractice.com
[115]Timofeev I, Czosnyka M, Nortje J, et al. Effect of decompressive craniectomy on intracranial pressure and cerebrospinal compensation following traumatic brain injury. J Neurosurg. 2008 Jan;108(1):66-73.
http://www.ncbi.nlm.nih.gov/pubmed/18173312?tool=bestpractice.com
[116]Chibbaro S, Tacconi L. Role of decompressive craniectomy in the management of severe head injury with refractory cerebral edema and intractable intracranial pressure. Our experience with 48 cases. Surg Neurol. 2007 Dec;68(6):632-8.
http://www.ncbi.nlm.nih.gov/pubmed/17765952?tool=bestpractice.com
Surgical technique for acute SDH
The decision of what type of surgery to perform depends on the radiographic appearance of the haematoma and the surgeon's preference.[117]Huang Q, Dai WM, Wu TH, et al. Comparison of standard large trauma craniotomy with routine craniotomy in treatment of acute subdural hematoma. Chin J Traumatol. 2003 Oct;6(5):305-8.
http://www.ncbi.nlm.nih.gov/pubmed/14514370?tool=bestpractice.com
Surgical intervention for acute SDH can be a standard trauma craniotomy or a hemicraniectomy and duraplasty if there is significant cerebral swelling or associated contusions. Data from 2023 suggest that patients who underwent standard craniotomy versus decompressive hemicraniectomy for acute SDH had similar functional outcomes and that those with severe, coexisting parenchymal injury may benefit from craniectomy.[118]Hutchinson PJ, Adams H, Mohan M, et al. Decompressive craniectomy versus craniotomy for acute subdural hematoma. N Engl J Med. 2023 Jun 15;388(24):2219-29.
http://www.ncbi.nlm.nih.gov/pubmed/37092792?tool=bestpractice.com
Evidence suggests similar functional outcomes for craniotomy and primary decompressive craniectomy.[110]Solomou G, Sunny J, Mohan M, et al. Decompressive craniectomy in trauma: what you need to know. J Trauma Acute Care Surg. 2024 Oct 1;97(4):490-6.
https://journals.lww.com/jtrauma/fulltext/2024/10000/decompressive_craniectomy_in_trauma__what_you_need.2.aspx
http://www.ncbi.nlm.nih.gov/pubmed/39137371?tool=bestpractice.com
The RESCUE-ASDH trial of 450 patients with acute SDH in 11 countries involved intraoperative randomisation to craniotomy or decompressive craniectomy. Results published in 2023 showed similar disability and quality-of-life outcomes at 6- and-12 month follow-up.[119]Ibrahim I, Maarrawi J, Jouanneau E, et al. Evacuation of chronic subdural hematomas with the Twist-Drill technique: results of a randomized prospective study comparing 48-h and 96-h drainage duration [in French]. Neurochirurgie. 2010 Feb;56(1):23-7.
http://www.ncbi.nlm.nih.gov/pubmed/20053413?tool=bestpractice.com
Those undergoing craniotomy were significantly more likely to require further cranial surgery within 2 weeks (14.6% vs. 6.9% of the craniectomy group) but wound complications were threefold more common in those who had craniectomy (12.2% vs. 3.9% of the craniotomy group).[119]Ibrahim I, Maarrawi J, Jouanneau E, et al. Evacuation of chronic subdural hematomas with the Twist-Drill technique: results of a randomized prospective study comparing 48-h and 96-h drainage duration [in French]. Neurochirurgie. 2010 Feb;56(1):23-7.
http://www.ncbi.nlm.nih.gov/pubmed/20053413?tool=bestpractice.com
Observational cohort data from the multi-centre CENTER-TBI study, covering 336 patients with acute SDH requiring surgical evacuation, also concluded that there were no significant differences in functional outcomes between centres that preferred primary decompressive craniectomy versus those that favoured craniotomy.[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
The leaders of both studies concluded that primary decompressive craniectomy should be reserved for patients in whom immediate replacement of the bone flap is not possible due to intraoperative swelling and should not be used pre-emptively for acute SDH.[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
[119]Ibrahim I, Maarrawi J, Jouanneau E, et al. Evacuation of chronic subdural hematomas with the Twist-Drill technique: results of a randomized prospective study comparing 48-h and 96-h drainage duration [in French]. Neurochirurgie. 2010 Feb;56(1):23-7.
http://www.ncbi.nlm.nih.gov/pubmed/20053413?tool=bestpractice.com
Secondary decompressive craniectomy
A small proportion of patients will have refractory intracranial hypertension following craniotomy for surgical evacuation of an acute SDH.[110]Solomou G, Sunny J, Mohan M, et al. Decompressive craniectomy in trauma: what you need to know. J Trauma Acute Care Surg. 2024 Oct 1;97(4):490-6.
https://journals.lww.com/jtrauma/fulltext/2024/10000/decompressive_craniectomy_in_trauma__what_you_need.2.aspx
http://www.ncbi.nlm.nih.gov/pubmed/39137371?tool=bestpractice.com
Secondary decompression involves the removal of the bone flap later in the patient's course - typically to treat the elevation of ICP refractory to other treatments.[120]Hawryluk GWJ, Rubiano AM, Totten AM, et al. Guidelines for the management of severe traumatic brain injury: 2020 update of the decompressive craniectomy recommendations. Neurosurgery. 2020 Sep 1;87(3):427-34.
https://journals.lww.com/neurosurgery/fulltext/2020/09000/guidelines_for_the_management_of_severe_traumatic.1.aspx
http://www.ncbi.nlm.nih.gov/pubmed/32761068?tool=bestpractice.com
In this scenario, the evidence base is complex and the decision to proceed with secondary decompressive craniectomy versus ongoing medical management must be individualised based on the patient’s potential for benefits versus risk of complications.[110]Solomou G, Sunny J, Mohan M, et al. Decompressive craniectomy in trauma: what you need to know. J Trauma Acute Care Surg. 2024 Oct 1;97(4):490-6.
https://journals.lww.com/jtrauma/fulltext/2024/10000/decompressive_craniectomy_in_trauma__what_you_need.2.aspx
http://www.ncbi.nlm.nih.gov/pubmed/39137371?tool=bestpractice.com
In practice, the presence of pre-existing comorbidities is a significant factor determining the most appropriate treatment for older people with acute SDH, since this is a major driver of poor outcomes even with surgery.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
[37]van Essen TA, Lingsma HF, Pisică D, et al. Surgery versus conservative treatment for traumatic acute subdural haematoma: a prospective, multicentre, observational, comparative effectiveness study. Lancet Neurol. 2022 Jul;21(7):620-31.
http://www.ncbi.nlm.nih.gov/pubmed/35526554?tool=bestpractice.com
Brain Trauma Foundation guidelines recommend consideration of secondary decompressive craniectomy for late (within 10 days of admission) refractory ICP elevation to improve mortality and favourable outcomes.[120]Hawryluk GWJ, Rubiano AM, Totten AM, et al. Guidelines for the management of severe traumatic brain injury: 2020 update of the decompressive craniectomy recommendations. Neurosurgery. 2020 Sep 1;87(3):427-34.
https://journals.lww.com/neurosurgery/fulltext/2020/09000/guidelines_for_the_management_of_severe_traumatic.1.aspx
http://www.ncbi.nlm.nih.gov/pubmed/32761068?tool=bestpractice.com
[121]Hutchinson PJ, Kolias AG, Timofeev IS, et al. Trial of decompressive craniectomy for traumatic intracranial hypertension. N Engl J Med. 2016 Sep 22;375(12):1119-30.
https://www.nejm.org/doi/10.1056/NEJMoa1605215
http://www.ncbi.nlm.nih.gov/pubmed/27602507?tool=bestpractice.com
Secondary decompressive craniectomy performed for early (within the first 72 hours of care) refractory ICP elevation is not recommended to improve favourable outcomes and medical management is advised instead.[120]Hawryluk GWJ, Rubiano AM, Totten AM, et al. Guidelines for the management of severe traumatic brain injury: 2020 update of the decompressive craniectomy recommendations. Neurosurgery. 2020 Sep 1;87(3):427-34.
https://journals.lww.com/neurosurgery/fulltext/2020/09000/guidelines_for_the_management_of_severe_traumatic.1.aspx
http://www.ncbi.nlm.nih.gov/pubmed/32761068?tool=bestpractice.com
[122]Cooper DJ, Rosenfeld JV, Murray L, et al. Patient outcomes at twelve months after early decompressive craniectomy for diffuse traumatic brain injury in the randomized DECRA clinical trial. J Neurotrauma. 2020 Mar 1;37(5):810-6.
https://www.liebertpub.com/doi/10.1089/neu.2019.6869
http://www.ncbi.nlm.nih.gov/pubmed/32027212?tool=bestpractice.com
This recommendation was based on findings from two high-quality studies:[120]Hawryluk GWJ, Rubiano AM, Totten AM, et al. Guidelines for the management of severe traumatic brain injury: 2020 update of the decompressive craniectomy recommendations. Neurosurgery. 2020 Sep 1;87(3):427-34.
https://journals.lww.com/neurosurgery/fulltext/2020/09000/guidelines_for_the_management_of_severe_traumatic.1.aspx
http://www.ncbi.nlm.nih.gov/pubmed/32761068?tool=bestpractice.com
The DECRA trial randomised 155 patients with severe, diffuse TBI and early refractory intracranial hypertension (within the first 72 hours of care) to either decompressive craniectomy or intensive medical therapy. It found that decompressive craniectomy did not improve survival or neurological outcomes compared with medical management but it did increase the risk of vegetative survival.[122]Cooper DJ, Rosenfeld JV, Murray L, et al. Patient outcomes at twelve months after early decompressive craniectomy for diffuse traumatic brain injury in the randomized DECRA clinical trial. J Neurotrauma. 2020 Mar 1;37(5):810-6.
https://www.liebertpub.com/doi/10.1089/neu.2019.6869
http://www.ncbi.nlm.nih.gov/pubmed/32027212?tool=bestpractice.com
The RESCUEicp trial randomised 408 patients with TBI and late refractory intracranial hypertension (within 10 days) to secondary decompressive craniectomy or ongoing medical care. It found that decompressive craniectomy was associated with a significant mortality reduction.[121]Hutchinson PJ, Kolias AG, Timofeev IS, et al. Trial of decompressive craniectomy for traumatic intracranial hypertension. N Engl J Med. 2016 Sep 22;375(12):1119-30.
https://www.nejm.org/doi/10.1056/NEJMoa1605215
http://www.ncbi.nlm.nih.gov/pubmed/27602507?tool=bestpractice.com
Two-year follow-up data also showed better functional improvement over 6 to 24 months for the group who had decompressive craniectomy compared with those who have standard medical management.[123]Kolias AG, Adams H, Timofeev IS, et al. Evaluation of outcomes among patients with traumatic intracranial hypertension treated with decompressive craniectomy vs standard medical care at 24 months: a secondary analysis of the RESCUEicp randomized clinical trial. JAMA Neurol. 2022 Jul 1;79(7):664-71.
https://jamanetwork.com/journals/jamaneurology/fullarticle/2792806
http://www.ncbi.nlm.nih.gov/pubmed/35666526?tool=bestpractice.com
Chronic SDH
The choice between conservative management or surgery for chronic SDH is typically based on haematoma size, extent of midline shift, severity of neurological dysfunction, and degree of raised intracranial pressure. The degree of surgical risk and potential for recovery may also be considered.
Chronic SDHs may be surgically managed in a variety of ways. There is no high-quality evidence available to show whether one technique is superior to others.[59]Stubbs DJ, Davies BM, Menon DK. Chronic subdural haematoma: the role of peri-operative medicine in a common form of reversible brain injury. Anaesthesia. 2022 Jan;77 Suppl 1:21-33.
https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/anae.15583
http://www.ncbi.nlm.nih.gov/pubmed/35001374?tool=bestpractice.com
Surgical management may be frontotemporoparietal craniotomy, burr hole craniotomy with irrigation, or twist-drill craniotomy with drain placement.[119]Ibrahim I, Maarrawi J, Jouanneau E, et al. Evacuation of chronic subdural hematomas with the Twist-Drill technique: results of a randomized prospective study comparing 48-h and 96-h drainage duration [in French]. Neurochirurgie. 2010 Feb;56(1):23-7.
http://www.ncbi.nlm.nih.gov/pubmed/20053413?tool=bestpractice.com
[124]Liu W, Bakker NA, Groen RJ. Chronic subdural hematoma: a systematic review and meta-analysis of surgical procedures. J Neurosurg. 2014 Sep;121(3):665-73.
http://thejns.org/doi/full/10.3171/2014.5.JNS132715
http://www.ncbi.nlm.nih.gov/pubmed/24995782?tool=bestpractice.com
Newer methods of evacuation include subdural evacuating port systems.[125]Hoffman H, Ziechmann R, Beutler T, et al. First-line management of chronic subdural hematoma with the subdural evacuating port system: institutional experience and predictors of outcomes. J Clin Neurosci. 2018 Apr;50:221-5.
http://www.ncbi.nlm.nih.gov/pubmed/29428265?tool=bestpractice.com
Recurrent SDHs that have a fluid consistency may be treated with a subdural-peritoneal shunt.
The use of a subdural drain or subdural evacuation port system (SEPS) decreases recurrence rates and mortality without increasing complications.[124]Liu W, Bakker NA, Groen RJ. Chronic subdural hematoma: a systematic review and meta-analysis of surgical procedures. J Neurosurg. 2014 Sep;121(3):665-73.
http://thejns.org/doi/full/10.3171/2014.5.JNS132715
http://www.ncbi.nlm.nih.gov/pubmed/24995782?tool=bestpractice.com
[126]Santarius T, Kirkpatrick PJ, Ganesan D, et al. Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet. 2009 Sep 26;374(9695):1067-73.
http://www.ncbi.nlm.nih.gov/pubmed/19782872?tool=bestpractice.com
[127]Peng D, Zhu Y. External drains versus no drains after burr-hole evacuation for the treatment of chronic subdural haematoma in adults. Cochrane Database Syst Rev. 2016 Aug 31;2016(8):CD011402.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011402.pub2/full
http://www.ncbi.nlm.nih.gov/pubmed/27578263?tool=bestpractice.com
[
]
How do external drains compare with no drains after burr-hole evacuation for chronic subdural hematoma?/cca.html?targetUrl=https://cochranelibrary.com/cca/doi/10.1002/cca.1986/fullShow me the answer[Evidence B]87be13b5-330f-47e4-88fa-84c295b473f2ccaBHow do external drains compare with no drains after burr‐hole evacuation for chronic subdural haematoma? Trials have shown that SEPS placement in combination with middle meningeal artery embolisation reduces size, decreases length of stay, decreases seizure burden, and has minimal peri-operative morbidity.[128]Saway BF, Roth W, Salvador CD, et al. Subdural evacuation port system and middle meningeal artery embolization for chronic subdural hematoma: a multicenter experience. J Neurosurg. 2023 Jul 1;139(1):131-8.
http://www.ncbi.nlm.nih.gov/pubmed/36681990?tool=bestpractice.com
[129]Golub D, Ashayeri K, Dogra S, et al. Benefits of the Subdural Evacuating Port System (SEPS) procedure over traditional craniotomy for subdural hematoma evacuation. Neurohospitalist. 2020 Oct;10(4):257-65.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7495698
http://www.ncbi.nlm.nih.gov/pubmed/32983343?tool=bestpractice.com
See Emerging treatments.
Acute-on-chronic haematomas, or haematomas that fail to evacuate after drain placement, are treated with either burr hole craniotomy with irrigation or standard frontotemporoparietal craniotomy with or without intraoperative drain placement. Drain placement has been shown to lower recurrence rates.[126]Santarius T, Kirkpatrick PJ, Ganesan D, et al. Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet. 2009 Sep 26;374(9695):1067-73.
http://www.ncbi.nlm.nih.gov/pubmed/19782872?tool=bestpractice.com
[127]Peng D, Zhu Y. External drains versus no drains after burr-hole evacuation for the treatment of chronic subdural haematoma in adults. Cochrane Database Syst Rev. 2016 Aug 31;2016(8):CD011402.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011402.pub2/full
http://www.ncbi.nlm.nih.gov/pubmed/27578263?tool=bestpractice.com
[
]
How do external drains compare with no drains after burr-hole evacuation for chronic subdural hematoma?/cca.html?targetUrl=https://cochranelibrary.com/cca/doi/10.1002/cca.1986/fullShow me the answer[Evidence B]87be13b5-330f-47e4-88fa-84c295b473f2ccaBHow do external drains compare with no drains after burr‐hole evacuation for chronic subdural haematoma?
Bilateral SDHs
Treatment of bilateral SDHs is more complex than treatment of unilateral SDHs, and there is a significantly higher recurrence rate associated with treatment of chronic bilateral SDHs.[130]Fomchenko EI, Gilmore EJ, Matouk CC, et al. Management of subdural hematomas: part II. Surgical management of subdural hematomas. Curr Treat Options Neurol. 2018 Jul 18;20(8):34.
http://www.ncbi.nlm.nih.gov/pubmed/30019165?tool=bestpractice.com
Decision-making is complicated if significant differences in SDH size/thickness or lateralisation of symptoms are present, suggesting that one SDH is asymptomatic.[130]Fomchenko EI, Gilmore EJ, Matouk CC, et al. Management of subdural hematomas: part II. Surgical management of subdural hematomas. Curr Treat Options Neurol. 2018 Jul 18;20(8):34.
http://www.ncbi.nlm.nih.gov/pubmed/30019165?tool=bestpractice.com
In general, there is no established paradigm for treatment. When the two haematomas are equal in size many neurosurgeons treat both sides simultaneously; when the two haematomas are asymmetric many neurosurgeons will treat only the larger or symptomatic one.
One study compared patients with bilateral SDHs who were treated either with unilateral surgery or with bilateral surgery. The recurrence rate among patients treated with a unilateral approach was nearly twice as high as that for patients treated with a bilateral approach (21.6% vs. 11.5%); the absence of post-operative drainage and mixed density SDH were independent predictors for re-treatment.[68]Andersen-Ranberg NC, Poulsen FR, Bergholt B, et al. Bilateral chronic subdural hematoma: unilateral or bilateral drainage? J Neurosurg. 2017 Jun;126(6):1905-11.
http://thejns.org/doi/full/10.3171/2016.4.JNS152642
http://www.ncbi.nlm.nih.gov/pubmed/27392267?tool=bestpractice.com
One study utilising bilateral middle meningeal artery embolisation in combination with bilateral burr hole drainage showed potential for decreased recurrence.[131]Wei Q, Fan G, Li Z, et al. Middle meningeal artery embolization for the treatment of bilateral chronic subdural hematoma. Front Neurol. 2021 Oct 28;12:651362.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8582486
http://www.ncbi.nlm.nih.gov/pubmed/34777190?tool=bestpractice.com
While this would suggest using a more aggressive approach to treat bilateral SDHs, additional studies are required before any guidelines can be established.
Unilateral SDH with contralateral epidural haematoma
When treating acute SDHs associated with trauma, it is important to recognise the potential for an epidural haematoma on the contralateral side. Although rare, this is a potentially life-threatening situation. A small epidural haematoma contralateral to an acute SDH can rapidly expand when the compressive force of the SDH is relieved by surgical evacuation.[69]Su TM, Lee TH, Chen WF, et al. Contralateral acute epidural hematoma after decompressive surgery of acute subdural hematoma: clinical features and outcome. J Trauma. 2008 Dec;65(6):1298-302.
http://www.ncbi.nlm.nih.gov/pubmed/19077617?tool=bestpractice.com
[70]Mohindra S, Mukherjee KK, Gupta R, et al. Decompressive surgery for acute subdural haematoma leading to contralateral extradural haematoma: a report of two cases and review of literature. Br J Neurosurg. 2005 Dec;19(6):490-4.
http://www.ncbi.nlm.nih.gov/pubmed/16574562?tool=bestpractice.com
If it has not been initially recognised, expansion of the epidural haematoma may not be noticed until after surgery, when the surgical drapes are removed and the patient is found to have a blown pupil on the side of the epidural haematoma.
The best approach for treating this situation is initial recognition of a small epidural haematoma contralateral to an acute SDH. Most epidural haematomas are associated with skull fractures coursing through the foramen spinosum where the middle meningeal artery is injured.[57]Schweitzer AD, Niogi SN, Whitlow CT, et al. Traumatic brain injury: imaging patterns and complications. Radiographics. 2019 Oct;39(6):1571-95.
https://pubs.rsna.org/doi/10.1148/rg.2019190076?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
http://www.ncbi.nlm.nih.gov/pubmed/31589576?tool=bestpractice.com
Any skull fracture involving the foramen spinosum should warn the operating neurosurgeon of this possible situation.
When an epidural haematoma is present with a contralateral acute SDH, consideration should be given to the possibility that the epidural haematoma may expand after evacuating the SDH. In this situation the patient can be positioned so that a craniotomy on the contralateral side can quickly be performed.
SDH with associated ventriculoperitoneal shunt
SDHs can occur in patients with a ventriculoperitoneal shunt, often due to 'over shunting' - removal of too much cerebrospinal fluid (CSF) and thereby creating a physiological pulling force into the subdural space.[43]Berger A, Constantini S, Ram Z, et al. Acute subdural hematomas in shunted normal-pressure hydrocephalus patients - management options and literature review: a case-based series. Surg Neurol Int. 2018 Nov 28;9:238.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6287333
http://www.ncbi.nlm.nih.gov/pubmed/30595959?tool=bestpractice.com
[44]Sundström N, Lagebrant M, Eklund A, et al. Subdural hematomas in 1846 patients with shunted idiopathic normal pressure hydrocephalus: treatment and long-term survival. J Neurosurg. 2018 Sep;129(3):797-804.
https://thejns.org/view/journals/j-neurosurg/129/3/article-p797.xml?tab_body=fulltext
http://www.ncbi.nlm.nih.gov/pubmed/29076787?tool=bestpractice.com
In this situation, expansion of the SDH increases pressure inside the brain, which is subsequently relieved through additional shunting of CSF from the ventricular system. With additional CSF drainage, the ventricular system becomes smaller and the SDH continues to expand.
Treatment in this situation is initially focused on obstructing additional drainage from the ventriculoperitoneal shunt. If the shunt is a programmable shunt, it is recommended that the shunt be adjusted to the highest setting.[132]Zemack G, Romner B. Adjustable valves in normal-pressure hydrocephalus: a retrospective study of 218 patients. Neurosurgery. 2002 Dec;51(6):1392-400;discussion 1400-2.
http://www.ncbi.nlm.nih.gov/pubmed/12445344?tool=bestpractice.com
[133]Hayes J, Roguski M, Riesenburger RI. Rapid resolution of an acute subdural hematoma by increasing the shunt valve pressure in a 63-year-old man with normal-pressure hydrocephalus with a ventriculoperitoneal shunt: a case report and literature review. J Med Case Rep. 2012 Nov 22;6:393.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3537755
http://www.ncbi.nlm.nih.gov/pubmed/23174021?tool=bestpractice.com
If this setting is not high enough to stop additional drainage or if the shunt is not programmable, the distal end of the shunt can be externalised and connected to a bedside collection system where there is greater control over drainage, including the option to obstruct flow completely.
Prophylactic anticonvulsants
The routine use of prophylactic anticonvulsants for patients with acute SDH is controversial and high-quality evidence from randomised controlled trials (RCTs) is needed. Local protocol or the neurology team should be consulted for advice.
Patients with trauma-induced and non-trauma-related SDH are at increased risk of seizures.[134]Pruitt P, Naidech A, Van Ornam J, et al. Seizure frequency in patients with isolated subdural hematoma and preserved consciousness. Brain Inj. 2019;33(8):1059-63.
http://www.ncbi.nlm.nih.gov/pubmed/31007086?tool=bestpractice.com
Some guidelines recommend prophylactic anticonvulsants for patients with acute traumatic SDHs for up to 7 days after presentation (in the absence of indication to continue).[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Seizure prophylaxis may be continued beyond 7 days if seizure activity (clinical or EEG) occurs beyond 24 hours or if the patient was previously receiving drug treatment for a known seizure disorder.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
Anticonvulsant prophylaxis has been shown to decrease the occurrence of early, post-traumatic seizures.[135]Temkin NR, Dikmen SS, Wilensky AJ, et al. A randomized, double-blind study of phenytoin for the prevention of post-traumatic seizures. N Engl J Med. 1990 Aug 23;323(8):497-502.
https://www.nejm.org/doi/10.1056/NEJM199008233230801?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200www.ncbi.nlm.nih.gov
http://www.ncbi.nlm.nih.gov/pubmed/2115976?tool=bestpractice.com
[136]Sabo RA, Hanigan WC, Aldag JC. Chronic subdural hematomas and seizures: the role of prophylactic anticonvulsive medication. Surg Neurol. 1995 Jun;43(6):579-82.
http://www.ncbi.nlm.nih.gov/pubmed/7482238?tool=bestpractice.com
[137]Radic JA, Chou SH, Du R, et al. Levetiracetam versus phenytoin: a comparison of efficacy of seizure prophylaxis and adverse event risk following acute or subacute subdural hematoma diagnosis. Neurocrit Care. 2014 Oct;21(2):228-37.
http://www.ncbi.nlm.nih.gov/pubmed/24549935?tool=bestpractice.com
Levetiracetam and phenytoin are similarly efficacious, and recommended in guidelines.[49]American College of Surgeons. Best practice guidelines: the management of traumatic brain injury. 2024 [internet publication].
https://www.facs.org/media/vgfgjpfk/best-practices-guidelines-traumatic-brain-injury.pdf
[138]Wilson CD, Burks JD, Rodgers RB, et al. Early and late posttraumatic epilepsy in the setting of traumatic brain injury: a meta-analysis and review of antiepileptic management. World Neurosurg. 2018 Feb;110:e901-6.
http://www.ncbi.nlm.nih.gov/pubmed/29196247?tool=bestpractice.com
[138]Wilson CD, Burks JD, Rodgers RB, et al. Early and late posttraumatic epilepsy in the setting of traumatic brain injury: a meta-analysis and review of antiepileptic management. World Neurosurg. 2018 Feb;110:e901-6.
http://www.ncbi.nlm.nih.gov/pubmed/29196247?tool=bestpractice.com
However, anticonvulsants carry a notable adverse effect profile and subsequent systematic review data and observational studies have not shown any significant reduction in seizure frequency from their use in patients with SDH.[134]Pruitt P, Naidech A, Van Ornam J, et al. Seizure frequency in patients with isolated subdural hematoma and preserved consciousness. Brain Inj. 2019;33(8):1059-63.
http://www.ncbi.nlm.nih.gov/pubmed/31007086?tool=bestpractice.com
[139]Nachiappan DS, Garg K. Role of prophylactic antiepileptic drugs in chronic subdural hematoma-a systematic review and meta-analysis. Neurosurg Rev. 2021 Aug;44(4):2069-77.
http://www.ncbi.nlm.nih.gov/pubmed/32910368?tool=bestpractice.com
[140]Lavergne P, Labidi M, Brunet MC, et al. Efficacy of antiseizure prophylaxis in chronic subdural hematoma: a cohort study on routinely collected health data. J Neurosurg. 2020 Jan 1;132(1):284-8.
https://thejns.org/view/journals/j-neurosurg/132/1/article-p284.xml
http://www.ncbi.nlm.nih.gov/pubmed/30660118?tool=bestpractice.com
[141]Khor D, Wu J, Hong Q, et al. Early seizure prophylaxis in traumatic brain injuries revisited: a prospective observational study. World J Surg. 2018 Jun;42(6):1727-32.
http://www.ncbi.nlm.nih.gov/pubmed/29159600?tool=bestpractice.com
On this basis, other commentators argue that there is insufficient evidence to support routine prophylactic use in either acute or chronic SDH and instead recommend limiting the use of anticonvulsants to SDH patients who have clinical or EEG-based evidence of seizure activity.[30]Rickard F, Gale J, Williams A, et al. New horizons in subdural haematoma. Age Ageing. 2023 Dec 1;52(12):afad240.
http://www.ncbi.nlm.nih.gov/pubmed/38167695?tool=bestpractice.com
In patients with late post-traumatic epilepsy (beyond the first 7 days after injury) or seizures despite anticonvulsant administration, consultation with a neurologist is recommended. Late post-traumatic epilepsy occurs most commonly in patients with a history of acute SDH and coma for >7 days.[142]Haltiner AM, Temkin NR, Dikmen SS. Risk of seizure recurrence after the first late posttraumatic seizure. Arch Phys Med Rehabil. 1997 Aug;78(8):835-40.
http://www.ncbi.nlm.nih.gov/pubmed/9344302?tool=bestpractice.com
[143]Temkin NR, Dikmen SS, Winn HR. Management of head injury. Posttraumatic seizures. Neurosurg Clin N Am. 1991 Apr;2(2):425-35.
http://www.ncbi.nlm.nih.gov/pubmed/1821751?tool=bestpractice.com
For chronic subdural haemorrhages, the rate of new onset seizures has been reported as between 3% and 23%; however, the data on benefit of using prophylactic anticonvulsants in this patient group are controversial, and no clear evidence exists to support routine prophylactic use of anticonvulsants in this setting.[144]Branco PM, Ratilal BO, Costa J, et al. Antiepileptic drugs for preventing seizures in patients with chronic subdural hematoma. Curr Pharm Des. 2017;23(42):6442-5.
http://www.ncbi.nlm.nih.gov/pubmed/29076415?tool=bestpractice.com
Anticonvulsants are indicated in patients with acute-on-chronic SDH or with a chronic SDH and history of seizures.[145]Won SY, Dubinski D, Freiman T, et al. Acute-on-chronic subdural hematoma: a new entity for prophylactic anti-epileptic treatment? Eur J Trauma Emerg Surg. 2022 Apr;48(2):933-42.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9001543
http://www.ncbi.nlm.nih.gov/pubmed/32986132?tool=bestpractice.com
A specialist should be consulted for advice on further management and treatment choice. Some have advocated using anticonvulsant prophylaxis post-operatively after removing chronic SDHs, although there are no RCTs concerning the use of routine prophylactic anticonvulsants in patients presenting with chronic SDHs.[146]Chen CW, Kuo JR, Lin HJ, et al. Early post-operative seizures after burr-hole drainage for chronic subdural hematoma: correlation with brain CT findings. J Clin Neurosci. 2004 Sep;11(7):706-9.
http://www.ncbi.nlm.nih.gov/pubmed/15337129?tool=bestpractice.com
[147]Ratilal BO, Pappamikail L, Costa J, et al. Anticonvulsants for preventing seizures in patients with chronic subdural haematoma. Cochrane Database Syst Rev. 2013 Jun 6;2013(6):CD004893.
http://cochranelibrary-wiley.com/doi/10.1002/14651858.CD004893.pub3/full
http://www.ncbi.nlm.nih.gov/pubmed/23744552?tool=bestpractice.com