Spontaneous resolution of superficial temporal artery pseudoaneurysm
- 1 Otolaryngology - Head and Neck Surgery, Oakland University William Beaumont School of Medicine, Rochester, Michigan, USA
- 2 Otolaryngology - Head and Neck Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA
- Correspondence to Dr Matthew Kun Lee; matthew.lee@cshs.org
Abstract
Superficial temporal artery (STA) pseudoaneurysms are rare vascular lesions that typically present after traumatic head injury. Currently, surgery is the recommended treatment as spontaneous resolution has not been previously reported. Our study aims to present a review of the literature on STA pseudoaneurysms and report a case of spontaneous resolution of a traumatic STA pseudoaneurysm without the need for direct intervention.
Background
The superficial temporal artery (STA) is the terminal branch of the external carotid artery and a rare site for pseudoaneurysm formation after blunt head trauma. The superficial location of the STA, running within the temporoparietal fascia, makes it vulnerable to arterial wall injury and subsequent pseudoaneurysm formation.1 Currently, proximal and distal control of the pseudoaneurysm via surgical ligation and en bloc excision is considered the gold standard treatment.2 Observation without surgical intervention is not a standard recommendation at this time, as there are presently no reported cases of spontaneous resolution of STA pseudoaneurysms. In the current report, we describe a patient who presented with a large STA pseudoaneurysm after blunt trauma and had spontaneous pseudoaneurysm resolution within 9 months of injury.
Case presentation
A woman in her 80s presented to the emergency department initially for head trauma suffered during a ground-level fall. A medical history was significant for atrial fibrillation, for which the patient was being anticoagulated with rivaroxaban. On examination, a fluctuant 2.5 cm left frontotemporal scalp mass was noted. CT imaging confirmed a diagnosis of a haematoma, with no evidence of skull fracture or intracranial bleeding. Incision and drainage were not performed at that time, in favour of management by observation and close follow-up.
Over a period of 6 months, the frontotemporal scalp mass failed to resolve, at which point the patient presented to the otolaryngology—head and neck surgery service (figure 1). Examination revealed a persistent frontotemporal scalp mass measuring 2.5 cm, noted to be palpably and visibly pulsatile in nature. A diagnosis of traumatic pseudoaneurysm formation was suspected based on the clinical history of blunt head trauma and examination findings.
Pulsatile mass at 6 months after initial blunt trauma.
Investigations
At the time of the initial presentation in the emergency department, a CT head had been performed, which confirmed a diagnosis of a scalp haematoma. At first evaluation by otolaryngology 6 months after this injury, the haematoma had transitioned into a firm, pulsatile mass, suspicious for development into a traumatic pseudoaneurysm. As such, a Doppler ultrasound was performed. This demonstrated a vascularised complex mass measuring 2.2 cm × 2.0 cm × 1.4 cm. A ‘to and fro’ Doppler waveform was detected adjacent to and within this mass, consistent with a partially thrombosed pseudoaneurysm (figure 2).
Top: Doppler US showing flow from the superficial temporal artery (STA) into the pseudoaneurysm. Bottom: Schematic representation of the STA pseudoaneurysm. Illustration created by KP. US, ultrasound.
Treatment
The patient was counselled on surgical ligation of the STA pseudoaneurysm to prevent progressive enlargement and rupture, as is considered the gold standard treatment for this disease pathology. Given the patient’s advanced age and comorbidities, she elected against surgery in favour of observation and close follow-up with serial examination, with intervention to be reconsidered if any evidence of clinical progression was noted.
Outcome and follow-up
Over the ensuing months, the patient noted on self-examination that the mass was gradually reducing in size. No associated symptoms other than cosmetic deformity were noted during this period. The patient was re-evaluated in the clinic at 9 months after the initial injury, and a repeat examination revealed a complete resolution of the STA pseudoaneurysm (figure 3). A mild soft-tissue contour deformity and postinflammatory hyperpigmentary changes were noted, but there was no residual mass present on examination. The patient was evaluated again 18 months after the initial injury, confirming no evidence of recurrence or residual symptoms.
Complete STA pseudoaneurysm resolution 9 months after initial blunt trauma. STA, superficial temporal artery.
Discussion
The STA is one of the most common locations for pseudoaneurysm formation in the head and neck after blunt trauma. Arterial pseudoaneurysms form when blood vessels are damaged and leaking blood through one arterial point accumulates in the adjacent tissues. The blood is contained within a weak fibrin and platelet wall that is formed via activation of the clotting cascade.3 Since the collection of blood is not surrounded by true vessel walls, it is known as a pseudoaneurysm. A pseudoaneurysm is differentiated from a haematoma by the presence of a communicating neck to the feeding artery that allows blood to flow in and out of the fluid collection. A Doppler ultrasound will show a pathognomonic ‘to and fro’ pattern in the neck of the pseudoaneurysm, which will help differentiate it from a haematoma.4 Unlike a haematoma, a pseudoaneurysm demonstrates ongoing vascular inflow and outflow, and therefore, has not been known to resolve without surgical intervention.
Numerous anatomic factors account for the high incidence of STA pseudoaneurysms in this region, including the superficial location of the STA within the temporoparietal fascia, relative lack of soft tissue cushioning where the artery crosses from the temporalis to the frontalis muscle, and the tethering effect of the fascia at this level, which limits any lateral displacement of the artery in response to tangential forces.5
Trauma-related STA pseudoaneurysms typically present with a pulsatile mass that is reported several weeks after initial blunt force trauma. Symptoms related to this condition can vary based on the adjacent anatomic structures surrounding the pseudoaneurysm and will often include headaches, pulsations, ear discomfort or facial pain.6 Diagnosis of an STA pseudoaneurysm is often suspected based on the clinical history and physical examination alone, particularly when the patient presents with a distinct traumatic event preceding the onset of the pseudoaneurysm. However, it is recommended that the diagnosis be confirmed via ultrasonography or CT angiography.7 The benefit of using CT angiography is the added knowledge about the true size, degree of thrombus, amount of opacification present in the pseudoaneurysm, as well as the anatomic landmarks in the area.6 8 This anatomical information can aid physicians in assessing the severity of the pseudoaneurysm and considering the risks of monitoring the vessel or sending the patient for neurosurgery.
Various treatment options for STA pseudoaneurysms have been proposed, though the gold standard of treatment remains proximal and distal surgical ligation of the vessel.7 Generally, with meticulous surgical technique and a proper understanding of the anatomy, this is considered to be a safe procedure with low operative risks. The potential complications associated with STA pseudoaneurysm excision include infection, haematoma and damage to the facial nerve.9 Specifically, if the pseudoaneurysm is located in the frontal (anterior temporal) branch of the STA, there is an elevated risk of inadvertent injury to the temporal branch of the facial nerve as it lies close to this arterial branch. As the course of the temporal branch of the facial nerve can be estimated using Pitanguy’s line (starting 0.5 cm below the tragus and coursing to 1.5 cm above the lateral eyebrow), excisions performed within this line may warrant additional counselling regarding the potential risk of facial nerve injury.9
Non-surgical treatment modalities include endovascular interventions, manual compression, percutaneous thrombin injection or endovascular approaches.7 Observation alone has not been recommended due to the purported risk of aneurysm rupture and delay in aneurysm control.10 This is exemplified in a report by Ndlovu et al, in which lack of intervention resulted in pseudoaneurysm rupture necessitating an anastomotic repair.11
While the STA is a common site for traumatic pseudoaneurysms in the head and neck, it is overall quite a rare entity. The largest study published to date (a systematic review of the Cochrane and MEDLINE databases) included 166 patients from the years 1861–2010.12 In this review, all patients with an STA pseudoaneurysm underwent intervention with the vast majority treated by surgical resection, and a small percentage treated by manual compression, percutaneous thrombin injection or endovascular intervention. However, there are no reported cases of STA pseudoaneurysms that had spontaneous resolution without intervention. This is not surprising, as in all described reports surgical intervention is stated to be the gold standard therapy, likely due to the fear of progressive enlargement with eventual rupture.
In our report, the STA pseudoaneurysm was observed without intervention and achieved full resolution of their pseudoaneurysm within 9 months, with no evidence of recurrence at 18 months follow-up. There was no pseudoaneurysm haemorrhage or any other related complication. While surgical treatment remains the current standard of care for STA pseudoaneurysms, the patient in our report has demonstrated that surgical intervention may not always be necessary, and close observation is a safe alternative to direct intervention.
Learning points
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The superficial temporal artery (STA) is the terminal branch of the external carotid artery and a potential site for pseudoaneurysm formation after blunt head trauma. The superficial location of the STA, running within the temporoparietal fascia, makes it vulnerable to arterial wall injury and subsequent pseudoaneurysm formation.
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Proximal and distal control of the pseudoaneurysm via surgical ligation and en bloc excision is considered the gold standard treatment. Yet, our report supports observation with serial monitoring as an appropriate alternative for the management of trauma-related STA pseudoaneurysms.
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Our patient with an STA pseudoaneurysm was observed without intervention and achieved full resolution of their pseudoaneurysms within 9 months of onset, with no related complications. This supports observation with close surveillance as a safe and viable option for management.
Ethics statements
Patient consent for publication
Footnotes
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Contributors MKL significantly contributed to: conception and design of study, acquisition and interpretation of data, drafting the article and revising it critically for important intellectual content, final approval of the version published. JR significant contributed to, acquisition and interpretation of data, drafting the article and revising it critically for important intellectual content, final approval of the version published. KP significantly contributed to, creation of educational illustrations used in manuscript, revising the article critically for important intellectual content, final approval of the version published.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.
References
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