Low-profile mechanical thrombectomy devices for large vessel occlusion in pediatric ischemic stroke.

BACKGROUND: Mechanical thrombectomy (MT) is a well-established treatment modality for large vessel occlusion (LVO) in adults, but there are limited data in the pediatric population. The rarity of the condition makes prospective trial design difficult, and therefore evaluation of MT devices and outcomes is sparse. In pediatric LVO cases, some newer devices may be appropriate for use in revascularization procedures. Furthermore, illustrative specific device-access combinations have rarely been presented in young patients under the age of 5 years. METHODS: This was a single institution experience in intracranial MT procedures for pediatric acute ischemic stroke (AIS). A given procedure was included if there was an attempt at MT between 2015 and 2023. RESULTS: Sixteen endovascular procedures were performed in 15 patients with AIS, with a mean age of 7.4 years; eight patients were <5 years of age. MT was attempted in 15/16 (93.7%) procedures, including 11 (73.3%) in the anterior circulation and four (26.7%) in the posterior circulation; one case recanalized after medical treatment. The most common MT techniques were combined aspiration with a stentriever (n=10, 66.7%) and aspiration alone (n=3, 20%). Traditional stentrievers (4-6 mm) were used in seven cases and low-profile stentrievers in four cases. Improved reperfusion was achieved in all low-profile stentriever cases. Reperfusion of modified Thrombolysis in Cerebral Infaction ≥2b was obtained in 73.3% of cases, including 72.7% of those in which a stentriever was used. CONCLUSIONS: Low-profile thrombectomy devices may achieve similar revascularization results to other approaches in challenging clinical scenarios observed in younger children.

Infantile dural arteriovenous fistula: a reconsideration.

BACKGROUND: Infantile-type dural arteriovenous shunts (IDAVS) are rare and heterogeneous vascular lesions, complicating their classification and management. The current tripartite classification of pediatric dural arteriovenous shunts (DAVS) into dural sinus malformation, infantile-type, and adult-type, does not stand up to scrutiny, given the variable presentations of the latter two types in children. We estimate the prevalence of IDAVS and evaluate the long term outcomes after endovascular treatment (EVT). METHODS: A retrospective review of a pediatric cerebrovascular database between 2006 and 2023 was conducted. Clinical and radiographic data were analyzed to evaluate the presentation and long term outcomes of IDAVS. RESULTS: IDAVS were identified in 8 (0.5%) of 1463 patients, with mean age at diagnosis of 34.7 months; male infants comprised 62.5%. The most common clinical presentations included macrocephaly (37.5%), seizures (25%), and dilated scalp veins (25%). EVT was performed in 87.5% of cases, averaging 5.8 procedures per patient. Radiographic obliteration was observed in 28.6%. Good clinical outcomes (modified Rankin Scale score of ≤2) were achieved in 85.7%. Our findings showcased discrepancies and limitations in the current classification of pediatric DAVS, prompting a re-evaluation. CONCLUSION: IDAVS accounted for a small proportion of pediatric cerebrovascular pathologies, with markedly heterogeneous presentations. Stepwise selective embolization was associated with favorable outcomes, and is recommended over an aggressive approach with the goal of complete angiographic obliteration. Our proposed revised classification system bifurcates pediatric DAVS into dural sinus malformations and all other DAVS that are manifest in children, thereby enhancing diagnostic clarity and therapeutic approaches.

Lower Cranial Nerve Schwannomas: Cohort Study and Systematic Review.

BACKGROUND AND OBJECTIVES: Schwannomas originating from the lower cranial nerves (LCNS) are rare and pose a significant surgical challenge. Resection is the mainstay treatment; however, risk of treatment morbidity is considerable, and the available literature regarding differential treatment outcomes in this vulnerable population is sparse. METHODS: A single-institution cohort study and systematic literature review of LCNS were performed. RESULTS: Fifty-eight patients were included: 34 underwent surgical resection and 24 underwent stereotactic radiosurgery (SRS). The median age at diagnosis was 48 years (range 17-74). Presenting symptoms were dysphagia (63%), dysarthria/hypophonia (47%), imbalance (33%), and hearing loss/tinnitus (30%). Tumor size was associated with surgical resection, as compared with initial SRS (4.1 cm vs 1.5 cm, P = .0001). Gross total resection was obtained in 52%, with tumor remnants predominantly localized to the jugular foramen (62%). Post-treatment worsening of symptoms occurred in 68% of surgical and 29% of SRS patients ( P = .003). Postoperative symptoms were mostly commonly hypophonia/hoarseness (63%) and dysphagia (59%). Seven patients (29%) had new neurological issues after SRS treatment, but symptoms were overall milder. The median follow-up was 60 months (range 12-252); 98% demonstrated meaningful clinical improvement. Eighteen surgical patients (53%) underwent adjuvant radiation at a median of 5 months after resection (range 2-32). At follow-up, tumor control was 97% in the surgical cohort and 96% among SRS patients. CONCLUSION: Although LCNS resection is potentially morbid, most postoperative deficits are transient, and patients achieve excellent tumor control-particularly when paired with adjuvant SRS. For minimally symptomatic patients undergoing surgical intervention, we advise maximally safe resection with intracapsular dissection to preserve nerve integrity where possible. For residual or as a primary treatment modality, SRS is associated with low morbidity and high rates of long-term tumor control.

Endovascular revascularization of chronically occluded common carotid artery for symptomatic cerebral hypoperfusion.

Endovascular recanalization is increasingly being utilized in symptomatic patients with chronically occluded carotid arteries.1 In carefully selected patients, endovascular recanalization has shown to lower the risk of ischemic events when compared to medical management alone.1 However, successful endovascular revascularization is technically challenging and not without risk.1, 2 In this video, we demonstrate a case of a 64-year-old woman who presented with recurrent transient ischemic attacks. On imaging she was found to have a chronic total occlusion of the common carotid artery from the arch. After obtaining informed consent, the patient underwent a successful endovascular recanalization and stenting of a chronically occluded left common carotid artery with aid from an intravascular guided re-entry catheter. Post operatively the patient developed a neck hematoma which improved and she returned to her neurological baseline. She reported no further symptoms on her three month follow up.

Revascularization of a Complex Case of Vertebrobasilar Insufficiency with Occipital Artery-Anterior Inferior Cerebellar Artery Bypass.

Atherosclerotic disease is the most common etiology in causing posterior circulation strokes and can be found within the intracranial vertebrobasilar system.1 Endovascular and surgical approaches to treat this disease have been defined with both advantages and disadvantages.2,3 We present a case of surgical revascularization of a complex case of vertebrobasilar insufficiency with occipital artery (OA)-anterior inferior cerebellar artery (AICA) bypass (Video 1). A 56-year-old gentleman presented with severe, disabling, and progressive symptoms of vertebrobasilar insufficiency refractory to maximal medical management. Symptom onset was 2 years prior after suffering a left lateral medullary stroke due to a left vertebral artery (VA) occlusion. Angiography showed left VA occlusion after the origin of the posterior inferior cerebellar artery (PICA) and a hypoplastic right VA mostly ending in a PICA with a small and critically stenosed branch to the basilar artery. An initial attempt to revascularize the chronic totally occluded left VA using a combination of anterograde and retrograde (via PComm) approaches was unsuccessful. The decision was made to proceed with an OA-AICA bypass. The end-to-side anastomosis was conducted in the right cerebellopontine cistern and was uncomplicated. Postoperative angiography demonstrated a patent bypass with brisk OA-to-AICA flow with retrograde filling of the basilar artery and its branches. No perioperative strokes. The patient remained free of recurrent symptoms of vertebrobasilar insufficiency at 6 months' follow-up.

Use of intravascular optical coherence tomography to confirm the diagnosis of a carotid web in a patient with recurrent ipsilateral embolic strokes and evaluate the response to stenting.

A Carotid web (CaW) is defined as a focal shelf-like projection of non-atheromatous, fibrous tissue along the posterior wall of the carotid bulb. CaW are rare and commonly overlooked lesions increasingly recognized as a cause of stroke in otherwise healthy patients. Intravascular imaging modalities such as intravascular ultrasound and optical coherence tomography (OCT) have been proposed as an adjunct to digital subtraction angiography for the evaluation of CaW. However, the use of OCT in CaW has yet to be described. This report investigated the utility of OCT as an adjunct imaging modality in the evaluation of CaW morphology in a young patient with recurrent ischemic strokes.

Combined deconstructive and reconstructive treatment of a giant vertebrobasilar fenestration aneurysm.

Aneurysms associated with a vertebrobasilar fenestration are rare lesions and can grow to a giant size, presenting significant therapeutic challenges. Endovascular treatment of these aneurysms has traditionally been with coiling; however, flow diverter placement within the fenestration arms has recently proven to be a viable treatment strategy. The authors present a case of a giant vertebrobasilar fenestration aneurysm in a patient presenting with a cranial nerve VI palsy. The lesion was treated by using a combination of flow diverter placement and vertebral artery sacrifice. The nuances of flow diversion therapy for these aneurysms and the management of intra- and postoperative complications are discussed. The video can be found here: https://stream.cadmore.media/r10.3171/2022.7.FOCVID2256.

Natural history and management of posterior cerebral artery aneurysms: a systematic review and meta-analysis of individual patient data.

We conducted a comprehensive review and meta-analysis to investigate clinical, radiographic characteristics, and treatment outcomes of posterior cerebral artery aneurysms (PCAA). We systematically reviewed English-language articles investigating available treatments (parent artery occlusion (PAO), microsurgery, reconstructive endovascular (rEVT), and conservative treatments) for PCAA and analyzed the based on aneurysm morphology and rupture status. Six-hundred-eighty-five patients with 698 PCAA were identified from 59 studies. Overall, 371 (54.2%) aneurysms were ruptured, 325 (49%) were saccular, and 342 (51%) were non-saccular aneurysms. The mean age of the saccular was lower (40 years) than non-saccular aneurysm group (50 years) (P < .05). In ruptured PCAA, favorable clinical outcomes were comparable between the treatment groups except for patients treated conservatively, which had lower rates of favorable clinical outcomes (35.6%) and higher mortality (55.7%) (P < .0001). Ruptured aneurysms treated with rEVT (22.6%) had the highest recanalization rates compared to PAO (9.2%, P = 0.0001) and microsurgery (3.8%, P = 0.005). In unruptured PCAA, clinical outcomes were similar; higher complication rates were noted in microsurgery (40.4%, P = 0.026) and PAO (21.5%, P = 0.015) compared to rEVT (13.2%), which had higher recanalization rates (15.6%, P < .0001). The rates of subsequent stroke following PAO were 21.8% for unruptured and 32.3% for ruptured PCAA (P = 0.078). Ruptured PCAA portend worse prognosis and typically require an intervention to achieve better outcome whereas the benefit of an intervention in unruptured PCAA is much less clear. rEVT is promising for PCAA management with a good clinical and safety profile but more recurrence compared to PAO and microsurgery.

Combined CSF-venous Fistula and middle meningeal artery embolization for treatment of spontaneous intracranial hypotension.

Transvenous Onyx embolization was recently described as an effective treatment of spontaneous intracranial hypotension caused by CSF-venous fistulas. Patients with CSF-venous fistulas can present with a wide spectrum of clinical and imaging findings, sometimes including spontaneous subdural hematomas, subdural hygromas, or a combination of both. Here, we describe four patients with spontaneous intracranial hypotension complicated by subdural fluid collections caused by CSF-venous fistulas. The patients were treated with transvenous Onyx embolization of their CSF-venous fistulas and transarterial particle embolization of the bilateral middle meningeal arteries, with both procedures performed in a single treatment session. All four patients had clinical improvement and decreased size or resolution of their subdural fluid collections. Based on our findings, we believe that middle meningeal embolization could be a useful adjunct to CSF-venous fistula embolization. A case-control study comparing patients who did or did not undergo middle meningeal embolization will be necessary to validate this supposition.

Delayed recurrence of pediatric arteriovenous malformations after radiologically confirmed obliteration.

OBJECTIVE: Arteriovenous malformations (AVMs) are a major cause of intracerebral hemorrhage in children, resulting in significant morbidity and mortality. Moreover, the rate of AVM recurrence in children is significantly higher than in adults. The aim of this study was to define the risk of delayed pediatric AVM (pAVM) recurrence following confirmed radiological obliteration. Further understanding of this risk could inform the role of long-term radiological surveillance. METHODS: The authors conducted a retrospective review of ruptured and unruptured pAVM cases treated at a single tertiary care referral center between 1994 and 2019. Demographics, clinical characteristics, treatment modalities, and AVM recurrence were analyzed. RESULTS: A total of 102 pediatric patients with intracranial AVMs, including 52 (51%) ruptured cases, were identified. The mean patient age at presentation was 11.2 ± 4.4 years, and 51 (50%) patients were female. The mean nidus size was 2.66 ± 1.44 cm. The most common Spetzler-Martin grades were III (32%) and II (31%). Stereotactic radiosurgery was performed in 69.6% of patients. AVM obliteration was radiologically confirmed in 68 (72.3%) of 94 patients with follow-up imaging, on angiography in 50 (73.5%) patients and on magnetic resonance imaging in 18 (26.5%). AVM recurrence was identified in 1 (2.3%) of 43 patients with long-term surveillance imaging over a mean follow-up of 54.7 ± 38.9 months (range 2-153 months). This recurrence was identified in a boy who had presented with a ruptured AVM and had been surgically treated at 5 years of age. The AVM recurred 54 months after confirmed obliteration on surveillance digital subtraction angiography. Two other cases of presumed AVM recurrence following resection in young children were excluded from recurrence analysis because of incomplete sets of imaging available for review. CONCLUSIONS: AVM recurrence following confirmed obliteration on imaging is a rare phenomenon, though it occurs more frequently in the pediatric population. Regular long-term follow-up with dedicated surveillance angiography is recommended even after obliteration following resection.

Contemporary Management of Cranial Dural Arteriovenous Fistulas.

Cranial dural arteriovenous fistulas (dAVFs) are rare acquired neurovascular disorders that have the potential to profoundly alter the local and global cerebral venous drainage. Factors such as location, angioarchitecture, degree of shunting, and mode of presentation all appear to have some bearing on the natural history of dAVFs, which can vary from almost entirely benign to life-threatening. Accurate and evidence-based risk stratification is, therefore, key to informing important management decisions. The treatment strategies are nuanced and, for an already rare entity, can vary tremendously from 1 fistula to another. It is only through a thorough understanding of their behavior and the treatment options available that we will be able to deliver tailored treatment to the correct dAVF and the correct patient. We aimed to provide an up-to-date summary of the reported data on the natural history and predictors of aggressive behavior for cranial dAVFs in general, followed by site-specific management considerations.

Extra-Intimal Carotid Endarterectomy: Two-Dimensional Microsurgical Approach.

Carotid endarterectomy is a standard treatment for patients with symptomatic carotid artery stenosis.1 Surgical techniques require a full-thickness incision (longitudinal, diagonal, or transverse) through the carotid wall. This incision results in significant plaque disruption and precludes harvesting of intact specimens for research. The video demonstrates an endarterectomy technique for removal of intact plaques using an extra-intimal approach. A 70-year-old man presented to our service with a history of aphasia. Neuroimaging showed the presence of an 80%-90% calcified stenosis of the left internal carotid artery. Brain magnetic resonance imaging revealed multiple acute and subacute left hemispheric strokes. The decision was made to proceed with extra-intimal carotid endarterectomy of the left internal carotid artery after obtaining informed consent. To this end, after appropriate exposure of the carotid artery bifurcation, the adventitia and the tunica media were transected longitudinally followed by the creation of a circumferential dissection plane between the tunica media and the intima (i.e., extra-intimal). After sharply transecting the intimal inlets and outlet of the atheroma, the arteriotomy was repaired in usual fashion (Video 1). The patient was discharged home the next day without complications and remained asymptomatic at 1-year follow-up. To date, this technique has been successfully used in 55 consecutive patients with no intraoperative or postoperative complications. This technique is fast, reproducible, and effective even in highly calcified lesions that are otherwise hard to cut. The approach requires minimal arterial wall and atheroma manipulation and procures intact specimens for high-quality research.

Repeat Catheter Angiography in Patients with Aneurysmal-Pattern Angiographically Negative Subarachnoid Hemorrhage.

BACKGROUND: A significant proportion of patients with subarachnoid hemorrhage have a normal cerebral angiogram. Patients with angiographically negative subarachnoid hemorrhage (anSAH) with either perimesencephalic- (panSAH) or aneurysmal-pattern hemorrhage (aanSAH, also known as diffuse anSAH) have an excellent prognosis, but only if underlying vascular abnormalities are completely excluded. The rate of occult aneurysms in patients with aanSAH varies widely across studies. The purpose of this study was to quantify the value of repeat DSA in these patients. METHODS: We reviewed the records of all patients initially diagnosed with aanSAH after a screening DSA at a single tertiary neurovascular referral center from January 2006-April 2018. Patients with panSAH and traumatic SAH were excluded. We also performed a systematic review and meta-analysis of positive second DSAs in previously published case series of patients with aanSAH who underwent two serial DSAs. For meta-analysis, PubMed Central, MEDLINE and Cochrane Library databases were searched for pertinent studies up to November 2019. The rate of aneurysm detection on repeat angiography was extracted from each study. Pooled rates for positive second angiogram were calculated as untransformed proportions in a binary random-effects model meta-analysis. Inter-study heterogeneity was calculated using an I2 statistic. RESULTS: Three of 27 patients (11.1%) with aanSAH and at least two DSAs were subsequently found to have a cerebral aneurysm in our institutional dataset. Twenty-six studies in our systematic review met inclusion criteria, and the pooled rate of positive second angiogram was 10.4% (95% CI 7.3%-13.5%, P < 0.001). Substantial inter-study heterogeneity was observed in the meta-analysis (I2 = 61.7%, P < 0.001). CONCLUSIONS: One in 10 patients with aanSAH has an occult ruptured aneurysm. A second-look DSA should be strongly considered in these cases.

Transvenous embolization of a cerebrospinal fluid-venous fistula for the treatment of spontaneous intracranial hypotension.

Cerebrospinal fluid-venous fistula is an increasingly recognized cause of spontaneous intracranial hypotension.1 The site of the leak is between the dural sleeve around a spinal nerve root and the surrounding foraminal veins. In appropriately investigated patients, transvenous embolization of the draining foraminal and paraspinal veins has been shown to be an effective way of treating the disease, with low periprocedural morbidity, improvement in symptoms and radiological appearances.2 Video 1 shows the technique employed in a typical case using Onyx (Medtronic, Minnesota, USA) to embolize a CSF-venous fistula at the right T10 neural foramen. neurintsurg;14/9/948/V1F1V1Video 1Video showing the technique for trans-venous embolization of a right T10 CSF-venous fistula for the treatment of spontaneous intracranial hypotension. The first section covers patient selection and work up, before then focusing on the technical aspects of navigating through the azygos system to the target foramen and completely occluding the pathway for CSF outflow.

Venous Causes of Pulsatile Tinnitus: Clinical Presentation, Clinical and Radiographic Evaluation, Pathogenesis, and Endovascular Treatments: A Literature Review.

Tinnitus is an abnormal perception of a sound without external stimulation. Venous pulsatile tinnitus (VPT) is a specific form of tinnitus characterized by an objective and often subjective bruit that occurs as a result of localized venous abnormalities. Clinical evaluation relies on sound quality, duration, and precipitating factors. Idiopathic intracranial hypertension (IIH) and transverse sinus stenosis (TSS) are among the most common causes of VPT. Other causes include sigmoid sinus wall abnormalities (SSWAs), jugular vein anomalies (JVAs), and emissary veins anomalies. These anomalies can be detected on magnetic resonance imaging, magnetic resonance angiography/magnetic resonance venography, and high-resolution temporal bone computed tomography. The pathogenesis behind the VPT includes turbulent blood flow as a result of luminal stenosis or abnormal dilation, amplification of internal sound due to temporal bone defects, and abnormal position of the venous sinus system structures adjacent to the bony structures of the auditive apparatus. Based on these theories, different interventional treatment modalities can be applied to treat the underlying causes. Endovascular treatments have shown high efficacy and safety among those treatments which include stenting of the lateral sinus stenosis in IIH and TSS, coiling of the SSWA and JVA, and embolization of emissary veins anomalies. Further studies are needed to understand the natural history of these anomalies and the efficacy of treatments of VPT, which-unlike other types of tinnitus-can be cured with proper treatment.

Intracranial Hypotensive Crisis From an Insidious Spinal Cerebrospinal Fluid-Venous Fistula: A Case Report.

BACKGROUND AND IMPORTANCE: Progressive episodic spells of altered levels of consciousness, often advancing to include paroxysmal autonomic instability, may be indicative of a diencephalic dysfunction underlying spontaneous intracranial hypotension (SIH). A rare, and often indolent, etiology may be spinal cerebrospinal fluid (CSF) leak-an elusive diagnosis, especially in cases of CSF-venous fistula (CVF) that are often missed on routine computed tomography (CT) myelography and magnetic resonance imaging (MRI). CLINICAL PRESENTATION: We report an unusual case of a 50-yr-old woman who presented with rapidly progressive cyclical, self-resolving episodes of altered mentation and decreased arousal later in the day. Scrutiny of serial brain MRIs led to a diagnosis of SIH, with severe downward diencephalic and brain stem displacement-resulting in cerebral aqueduct occlusion with obstructive hydrocephalus. Initial clinical improvement occurred with CSF diversion, but the patient quickly deteriorated-developing diencephalic spells, including extensor posturing and severely depressed levels of consciousness. Clinical improvement was seen with stopping CSF diversion and Trendelenburg-positioning. After intensive spinal imaging, dynamic CT myelography identified a left T10 nerve root diverticula and CSF-venous fistula. Surgical obliteration resulted in rapid, profound neurological improvement, and ultimately full neurological recovery by 1 yr. CONCLUSION: In our patient, worsening episodes of confusion, postural headaches, and autonomic instability developed due to SIH, which induced profound downward displacement and compression of the diencephalon and brain stem, and accompanied by subsequent obstructive hydrocephalus. Diagnostic persistence identified the CVF, which had caused the complex multifold pathophysiology and clinical presentation. If suspicion remains high for CVF, persistent spinal imaging, particularly with dynamic myelography, may be crucial.

A Comprehensive Study of Spindle Cell Oncocytoma of the Pituitary Gland: Series of 6 Cases and Meta-Analysis of 85 Cases.

OBJECTIVE: To discuss optimal treatment strategy for spindle cell oncocytoma (SCO) of the pituitary gland. METHODS: Institutional cases were retrospectively reviewed. A systematic literature search and subsequent quantitative synthesis were performed for further analysis. The detailed features were summarized and the tumor control rate (TCR) was calculated. RESULTS: Eighty-five patients (6 institutional and 79 literature) were included. The annual incidence was approximately 0.01-0.03/100,000. The mean age was 56 years. Vision loss was present in 60%. Seventy-three percent showed hormonal abnormalities. On magnetic resonance imaging, tumor was avidly enhancing, and the normal gland was commonly displaced anterosuperiorly. Evidence of hypervascularity was seen in 77%. Gross total resection (GTR) was achieved in only 24% because of its hypervascular, fibrous, and adhesive nature. The mean postoperative follow-up was 3.3 years for institutional cases and 2.3 years for the integrated cohort. The TCR was significantly better after GTR (5-year TCR, 75%; P = 0.012) and marginally better after non-GTR + upfront radiotherapy (5-year TCR, 76%; P = 0.103) than after non-GTR alone (5-year TCR, 24%). The TCRs for those with low Ki-67 index (≤5%) were marginally better than those with higher Ki-67 index (5-year rate, 57% vs. 23%; P = 0.110). CONCLUSIONS: Frequent endocrine-related symptoms, hypervascular signs, and anterosuperior displacement of the gland support preoperative diagnosis of SCO. GTR seems to have better long-term tumor control, whereas the fibrous, hypervascular, and adhesive nature of SCO makes it difficult to achieve GTR. In patients with non-GTR, radiotherapy may help decrease tumor progression.

Long-term clinical and mid-term radiographic follow-up of pure arterial malformations.

BACKGROUND: Pure arterial malformations (PAMs) are rare vascular lesions characterized by dilated, tortuous arterial loops without venous shunting. The natural history of PAMs remains unclear. We report the mid-term radiological and longer-term clinical outcomes of the largest series of patients with PAM. METHODS: Retrospective review at a tertiary academic referral center for patients with a PAM. Follow-up clinical and radiological data were collected and analyzed for clinical symptoms and radiographic changes. RESULTS: Twenty-five patients met the inclusion criteria. The mean age at presentation was 30.9 ± 14 years. Nineteen (76%) patients were female, and six (23.1%) were male. Eleven (44%) patients had ≥1 symptom at presentation, of which only 3 (12%) could be linked to PAM. The most common symptom was headache (n=8). PAMs involved a single vessel in 16 (64%) cases and ≥2 vessels in 9 cases (36%). Fifteen (60%) lesions were isolated to the anterior circulation compared to 6 (24%) in the posterior circulation. The most frequently involved vessel was the supraclinoid internal cerebral artery (36%). An associated saccular aneurysm was present in 32% of patients. Ten lesions were partially calcified. The mean radiographic and clinical follow-up was 21.9 ± 26.5 months and 44.6 ± 34.8 months, respectively. None of the patients developed new symptoms related to their lesion or radiographic progression over the duration of follow-up. CONCLUSIONS: PAMs are found most frequently in young, asymptomatic females. PAMs have a benign natural history and are best managed conservatively with serial imaging.