![]() ![]() 10 The location of the aneurysm was recorded according to the classification of segments described by Lister et al, 13 including: 1) anterior medullary, 2) lateral medullary, 3) tonsillomedullary, 4) telovelotonsillar, and 5) cortical segments. In all patients, a complete diagnostic angiogram was obtained before endovascular treatment to define the details of the vascular anatomy of the posterior fossa and assess underlying vascular disease.ĭissection was diagnosed if the lesion demonstrated irregular fusiform dilation with or without associated narrowing of the PICA. Three-dimensional rotational angiography was performed in 4 patients. All angiography and endovascular procedures were performed in a neuroangiography suite equipped with digital subtraction angiography (BN 3000 Philips Medical Systems, Best, the Netherlands) under general anesthesia. 12 The time to treatment ranged from 1 day to 10 days (mean, 3.5 days). Pretreatment clinical status in those patients who presented with SAH was recorded according to the Hunt and Hess classification. The mean age of the patients (4 women, 2 men) was 57.9 years, ranging from 28 to 80 years old. All typical saccular aneurysms at the PICA origin and PICA aneurysms with associated findings of irregular fusiform shape and narrowing of the vertebral artery, suggesting that the aneurysm was likely from extension of a vertebral artery dissection, were excluded. Six were dissecting aneurysms of the distal PICA segment. 5, 10, 11įrom the database of all patients who underwent diagnostic angiography or endovascular treatment for intracranial vascular lesions at a single center, from November 1996 until December 2008, 25 angiographically confirmed PICA aneurysms were identified. However, Cellerini et al 11 and others reported coil treatment of the dissecting aneurysm sacs without parent artery occlusion, claiming it would prevent any chance of PICA territory infarct. 7 – 9 The endovascular approach in most cases occluded the parent artery near or at the level of the dissecting aneurysm. Endovascular treatment decreases the risks associated with manipulating the brain stem and cranial nerves during surgery. 6 More recently, several small series or case reports have been published that illustrate successful endovascular management. Most reported cases have been treated by surgery, with direct clipping, wrapping, or trapping with or without bypass. Treatment decisions were based on the individual clinician's experience, without a standardized approach to treatment. ![]() The anatomy of the PICA and the location of the dissection are variable among the individual patients.Īll of the publications that we know of on dissecting PICA aneurysms include only a small number of cases. SAH was the most common initial clinical presentation (74%), with ischemia accounting for the remaining cases. Tawk et al 5 reviewed all published cases of isolated dissecting PICA aneurysms and reported only 27 cases from 1966 to 2001. 3 An isolated dissection of the distal segment of the PICA with aneurysm formation is a very rare occurrence, accounting for only 0.5%–0.7% of all intracranial aneurysms. Intracranial dissections causing SAH occur more often in the vertebrobasilar system compared with the carotid arteries. Only a small percentage of dissections of the brachiocephalic arteries involve the intracranial arteries, resulting in spiral segmental stenosis or intracranial hemorrhage. The dissections recognized in clinical practice usually present with more serious symptoms, such as severe neck pain or a thromboembolic event. Many of these dissections likely go unrecognized, and thus the true incidence is not well documented. 1, 2 Most spontaneous dissections involve the extracranial carotid and vertebral arteries, often causing pain in the neck or skull base at onset, but otherwise they demonstrate few clinically significant symptoms. Abbreviations PICA posterior inferior cerebellar artery SAH subarachnoid hemorrhageĭissections and dissecting aneurysms of the cerebrovascular system are now more frequently diagnosed, due to a better understanding of the underlying pathophysiology, as well as to advances in neuroimaging, specifically MR imaging and MR angiography. ![]()
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