History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors for AVMs include associated familial syndromes and genetic factors. Key risk factors for haemorrhage include previous haemorrhages and drug misuse.
sudden-onset focal neurological deficit
If progressing over minutes to hours, suggests an intracerebral haemorrhage (ICH). Such progression is uncommon in ischaemic stroke and subarachnoid haemorrhage.
In drug users, although uncommon, sudden-onset focal neurological deficit may occur immediately following drug misuse. In this case, it should alert to possibility of ICH secondary to a vascular lesion.[38]
seizures
Generalised seizures, or simple or complex partial seizures ± secondary generalisation.
reduced conscious level
May be secondary to a seizure or reflect the size and mass effect of an intracerebral haemorrhage (ICH). ICH volume and Glasgow Coma Scale score are strong predictors of death within 30 days.[45]
Other diagnostic factors
common
sudden-onset headache
More common with haemorrhagic than with ischaemic stroke but not a key diagnostic factor, as with subarachnoid haemorrhage.
In drug users, although uncommon, sudden-onset headache may occur immediately following drug misuse. In this case, it should alert to possibility of intracerebral haemorrhage secondary to a vascular lesion.[38]
nausea
Common with intracerebral haemorrhage.
vomiting
More common with intracerebral haemorrhage than with ischaemic stroke or subarachnoid haemorrhage.
confusion
Common with intracerebral haemorrhage.
gradual-onset headaches
There is controversy as to whether unruptured AVMs cause headaches, or if their relationship is coincidental. Reported headaches tend to be unilateral, ipsilateral to the AVM, and atypical in nature.[2]
hypertension
Patients are often hypertensive during and immediately following an intracerebral haemorrhage. This does not necessarily reflect established hypertension and may be an autoregulation response to raised intracranial pressure.
coma
Common with intracerebral haemorrhage.
uncommon
gradual-onset focal neurological deficit
Focal neurological symptoms that are not related to haemorrhagic events tend to be of gradual onset and may be transient, persistent, or progressive.[2] Between 5% and 15% of AVMs present with progressive neurological deficits unrelated to haemorrhage.[46] The theoretical explanation is the 'vascular steal phenomenon', which remains controversial.[54]
cognitive dysfunction
Generally, IQs are similar in patients with AVMs and the normal population.[53] Prevalence of cognitive disturbance among those with AVMs is not known. Any cognitive problems seem to develop after starting school and often cannot be directly attributed to the location of the AVM.
Risk factors
strong
familial (malformation)
Familial AVMs are extremely rare. More common in females and supratentorial, but incidence is not high enough to establish an association with a particular genetic factor instrumental in angiogenesis.[32]
Familial syndromes such as ataxia telangiectasia, Wyburn-Mason syndrome, hereditary haemorrhagic telangiectasia (HHT; also called Rendu-Osler-Weber syndrome), and Sturge-Weber syndrome have been associated with AVMs. Approximately 10% of patients with HHT have AVMs.[33]
previous haemorrhages (risk of haemorrhage)
Overall annual risk of haemorrhage is 2% to 4%. Risk is increased during the first 5 years following haemorrhage, being highest in the first year with reported rates of >30%.[31][34][35] However, haemorrhage risk seems to be overestimated in those without haemorrhagic presentation, where rates of <1% have been shown. In these patients, risks of treatment may outweigh risk of rupture.[22][36]
drug abuse (risk of haemorrhage)
Illicit drug abuse is the most common risk factor for stroke in young adults.[37] This occurs by a variety of pathophysiological mechanisms, but these patients frequently have underlying vascular lesions, including AVMs. The hypertensive effects of drugs such as amphetamines, cocaine, and ecstasy increase the risk of rupture.[38]
weak
abnormal venous drainage (risk of haemorrhage)
Factors that increase intracranial venous pressure may increase risk of rupture. Deep venous drainage, a single draining vein, venous stenosis, and high feeding arterial pressure have consistently been shown to be associated with AVM haemorrhage in retrospective studies. The association with venous reflux is less consistent.[2]
small AVMs (risk of haemorrhage)
Hospital series of patients with a haemorrhage from AVMs have shown a higher frequency of small, rather than large, AVMs.[4][27][39][40] This may reflect that small AVMs are less likely to present with seizures or neurological symptoms, or that small AVMs (both symptomatic and asymptomatic) are simply more common. However, they have higher feeding arterial pressures and resistance than larger lesions, and are thought to be at greater risk of rupture.[40] Nevertheless, a long-term follow-up study suggests that large AVM size is an independent risk factor for further haemorrhage.[34]
posterior fossa and deep AVMs (risk of haemorrhage)
co-existing aneurysms (risk of haemorrhage)
pregnancy (risk of haemorrhage)
Evidence is inadequate to determine whether pregnancy influences risk of AVM rupture. Studies of women of child-bearing age have reported contradictory findings.[43][44] While there is no evidence that the mode of delivery influences risk of haemorrhage, patients with an untreated AVM would normally be advised to have an elective caesarean section.
hypertension (risk of haemorrhage)
Hypertension is a major risk factor for intracerebral haemorrhage (ICH). It is often considered to be the primary cause, and generally increases the risk of ICH.[45] With underlying AVM, hypertension possibly increases risk of bleeding, by increasing the feeding arterial pressure. However, retrospective studies have shown no clear association.[2]
Use of this content is subject to our disclaimer