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Concept: Anterior inferior cerebellar artery

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PURPOSE OF REVIEW: The aim of this study is to review the recent findings on the prevalence, clinical features, and diagnosis of vertigo from brainstem and cerebellar strokes. RECENT FINDINGS: Patients with isolated vertigo are at higher risk for stroke than the general population. Strokes involving the brainstem and cerebellum may manifest as acute vestibular syndrome, and acute isolated audiovestibular loss may herald impending infarction in the territory of the anterior inferior cerebellar artery. Appropriate bedside evaluation is superior to MRI for detecting central vestibular syndromes. Recording of vestibular-evoked myogenic potentials is useful for evaluation of the central otolithic pathways in brainstem and cerebellar strokes. SUMMARY: Accurate identification of isolated vascular vertigo is very important since misdiagnosis of acute stroke may result in significant morbidity and mortality, whereas overdiagnosis of vascular vertigo would lead to unnecessary costly work-ups and medication.

Concepts: Stroke, Cerebellum, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery, Metencephalon, Inferior cerebellar veins, Pons, Vestibular nuclei

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BACKGROUND:: Anatomic diversity among cerebellar arteriovenous malformations (AVMs) calls for a classification that is intuitive and surgically informative. Selection tools like the Spetzler-Martin grading system are designed to work best with cerebral AVMs but have shortcomings with cerebellar AVMs. OBJECTIVE:: To define subtypes of cerebellar AVMs that clarify anatomy and surgical management, to determine results according to subtypes, and to compare predictive accuracies of the Spetzler-Martin and supplementary systems. METHODS:: From a consecutive surgical series of 500 patients, 60 had cerebellar AVMs, 39 had brainstem AVMs and were excluded, and 401 had cerebral AVMs. RESULTS:: Cerebellar AVM subtypes were as follows: 18 vermian, 13 suboccipital, 12 tentorial, 12 petrosal, and 5 tonsillar. Patients with tonsillar and tentorial AVMs fared best. Cerebellar AVMs presented with hemorrhage more than cerebral AVMs (P < .001). Cerebellar AVMs were more likely to drain deep (P = .04) and less likely to be eloquent (P < .001). The predictive accuracy of the supplementary grade was better than that of the Spetzler-Martin grade with cerebellar AVMs (areas under the receiver-operating characteristic curve, 0.74 and 0.59, respectively). The predictive accuracy of the supplementary system was consistent for cerebral and cerebellar AVMs, whereas that of the Spetzler-Martin system was greater with cerebral AVMs. CONCLUSION:: Patients with cerebellar AVMs present with hemorrhage more often than patients with cerebral AVMs, justifying an aggressive treatment posture. The supplementary system is better than the Spetzler-Martin system at predicting outcomes after cerebellar AVM resection. Key components of the Spetzler-Martin system such as venous drainage and eloquence are distorted by cerebellar anatomy in ways that components of the supplementary system are not. ABBREVIATIONS:: AICA, anterior inferior cerebellar artery;AVM, arteriovenous malformationmRS, modified Rankin ScalePICA, posterior inferior cerebellar arteryROC, receiver-operating characteristicSCA, superior cerebellar artery.

Concepts: Cerebral cortex, Cerebellum, Anterior inferior cerebellar artery, Arteries of the head and neck, Arteriovenous malformation, Basilar artery, Superior cerebellar artery, Inferior cerebellar veins

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This report presents a fully thrombosed giant aneurysm of the posterior inferior cerebellar artery (PICA) mimicking an intracranial tumour in a 9-year-old paediatric patient. Surgical clipping and aneurysmectomy were performed. Postoperative imaging studies confirmed the removal of the lesion and the patient was discharged with no neurological deficits. Our case shows that giant thrombosed aneurysms involving the PICA could be potentially misdiagnosed as neoplasms in children and great care must be exercised when managing such cases.

Concepts: Medicine, Atherosclerosis, Hypertension, Stroke, Thrombus, Cerebral aneurysm, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery

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BACKGROUND: Cerebellar infarction is easily misdiagnosed or underdiagnosed. In this study, we investigated factors leading to misdiagnosis of cerebellar infarction in patients with acute ischemic stroke. METHODS: Data on neurological and radiological findings from 114 consecutive patients with acute cerebellar infarction were analyzed. We investigated factors associated with misdiagnosis from the data on clinical findings. RESULTS: Thirty-two (28%) patients were misdiagnosed on admission. Misdiagnosis was significantly more frequent in patients below 60 years of age and in patients with vertebral artery dissection, and significantly less frequent in patients with dysarthria. It tended to be more frequent in patients with the medial branch of posterior inferior cerebellar artery territory infarction, and infrequent in patients with the medial branch of the superior cerebellar artery territory infarction. Thirty out of 32 (94%) misdiagnosed patients were seen by physicians that were not neurologists at the first visit. Twenty-four of 32 (75%) misdiagnosed patients were screened only by brain CT. However, patients were not checked by brain MRI or follow-up CT until their conditions worsened. CONCLUSIONS: Patients below 60 years of age and patients with vertebral artery dissection are more likely to have a cerebellar infarction misdiagnosed by physicians other than neurologists.

Concepts: Central nervous system, Medicine, Brain, Stroke, Cerebellum, Posterior inferior cerebellar artery, Vertebral artery dissection, Anterior inferior cerebellar artery

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Posterior inferior cerebellar artery (PICA) is one of the cerebellar arteries which originates from the vertebral artery and has the most complex and variable course. The PICA usually originates from the vertebral artery intracranially as a single trunk, however, absent, double trunk, extracranial, and extradural PICA may also exist. In a collection of 50 cerebellar specimens (100 hemispheres) injected with colored gelatin, one case of bilaterally absent PICA was encountered, male aged 59 (causes of the death was not taken into consideration).

Concepts: Artery, Cerebellum, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery, Inferior cerebellar veins

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BACKGROUND AND PURPOSE: Unruptured anterior inferior cerebellar artery (AICA) aneurysms are rare but potentially lethal cerebellopontine angle (CPA) lesions that may be misdiagnosed as vestibular schwannomas when they present with vestibulo-cochlear symptoms. METHODS: We report two cases of unruptured but symptomatic AICA aneurysms initially referred to us as atypical vestibular schwannomas requiring surgery. Two discriminant MR features are described. RESULTS: One patient refused treatment. The other was successfully treated by coil occlusion. CONCLUSIONS: Caution is advised before suspecting a CPA mass to be a purely extra-canalicular schwannoma, given its extreme rarity. Deafness and cerebellar ischemia may be prevented if AICA aneurysms are correctly identified preoperatively. In the absence of specific arterial imaging, two MR features may distinguish them from vestibular schwannomas: (1) the absence of internal auditory canal enlargement and (2) the “blurry dot sign,” representing blood flow artefacts on pre- and postcontrast studies.

Concepts: Blood, Atherosclerosis, Stroke, Cerebellum, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery, Vestibular schwannoma, Vestibular nuclei

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We describe the case of a 44-year old man with a ruptured wide-necked non-origin aneurysm of the posterior inferior cerebellar artery successfully treated with placement of a low porosity stent. To our knowledge, there are no cases in the literature of a non-origin posterior inferior cerebellar artery aneurysm treated with a flow-diverter stent.

Concepts: Case, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery

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Posterior circulation aneurysms are commonly treated with endovascular techniques. In select cases, microsurgery remains an essential tool for treating these lesions. We present a case of a ruptured posterior inferior cerebellar artery (PICA) aneurysm approached via a craniotomy. Given the labyrinth of neurovascular bundles present in the posterior fossa, surgical exposure of PICA aneurysms can be challenging. This video demonstrates the steps of the craniotomy, subarachnoid dissection, mobilization of the vertebral artery and lower cranial nerves, and clipping of the aneurysm. The video can be found here: http://youtu.be/fQSxQj7oL0U .

Concepts: Atherosclerosis, Stroke, Cranial nerves, Cerebral aneurysm, Aortic dissection, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery, Pseudoaneurysm

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The pipeline embolization device (PED) is frequently used in the treatment of anterior circulation aneurysms, especially around the carotid siphon, with generally excellent results. However, treatment of posterior inferior cerebellar artery (PICA) aneurysms with flow diversion (FD) has not been specifically described or discussed. While there are reports of treating PICA aneurysms using placement of FD stents in the vertebral artery, there are no reports of treating these lesions by placement of flow diverting stents in the PICA vessel itself. Due to the unique anatomy and morphology of these aneurysms, it requires special attention. We assessed our multi-institutional experience treating these lesions, including the first reported cases of the PED placed within the PICA.

Concepts: Blood vessel, Diversion, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery, Arteries of the head and neck

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Aneurysms of the proximal posterior inferior cerebellar artery (PICA) are rare. The management of proximal PICA aneurysms is challenging with either surgical or endovascular treatment. We report our successful experience of treating PICA aneurysms with a multimodal approach.

Concepts: Atherosclerosis, Cerebellum, Posterior inferior cerebellar artery, Anterior inferior cerebellar artery