Treatment of a Basilar Trunk Perforator Aneurysm With the Pipeline Embolization Device: Case Report BACKGROUND AND IMPORTANCE: Basilar trunk perforator (BTP) aneurysms are rare lesions that pose significant challenges to microsurgical clipping and endovascular coiling. We present the intriguing case of a ruptured BTP aneurysm that was success- fully treated with the Pipeline Embolization Device (PED). CLINICAL PRESENTATION: An elderly woman presenting with subarachnoid hemor- rhage was found to have a 1.5-mm aneurysm arising from the proximal portion of a thin midbasilar perforator. The decision was made to treat this aneurysm with flow diversion in an attempt to preserve the patency of the perforator and to avoid the hazards associated with parent vessel trapping. A 3 · 12-mm PED was successfully deployed in the basilar trunk across the neck of the aneurysm, causing stasis in the aneurysm, with continuous flow through the parent vessel. The procedure and postoperative course were uneventful. A follow-up angiogram 2 weeks later showed complete disappearance of the aneurysm with preservation of the patency of the perforator. At the 6-month follow-up, the patient was asymptomatic and remained neurologically intact. CONCLUSION: We present the first case of a BTP aneurysm treated with the PED. The aneurysm was successfully occluded, and the patency of the feeding vessel was pre- served. In light of the limitations of coiling and the hazards associated with microsur- gery and parent vessel trapping, the PED may be a valuable option for BTP aneurysms. KEY WORDS: Aneurysm, Basilar perforator, Flow diversion, Pipeline Embolization Device Neurosurgery 74:E697–E701, 2014 DOI: 10.1227/NEU.0000000000000308 www.neurosurgery-online.com B asilar trunk perforator (BTP) aneurysms are rare lesions that present with subarach- noid hemorrhage (SAH), usually perime- sencephalic in pattern. 1,2 It is a formidable challenge for the neurosurgeon to treat these lesions with either microsurgery or traditional embolization strategies. Flow diversion has emerged as a promising treatment strategy for several types of aneurysms at various intracranial locations. 3-10 The Pipeline Embolization Device (PED; eV3, Irvine, California) is a dedicated flow diverter that received US Food and Drug Administration approval in 2011 for large and giant wide-necked aneurysms arising from the cavernous segment to the superior hypophyseal segment of the internal carotid artery. We present the intriguing case of a rup- tured BTP aneurysm that was successfully treated with the PED. This is the first description of a BTP aneurysm treated with a flow diverter. CLINICAL PRESENTATION An elderly woman presented to an outside institution with the worst headache of her life. A head computed tomography showed extensive SAH predominantly in the basal cisterns with some associated intraventricular hemorrhage (Figure 1). A computed tomographic angiography showed a questionable tiny aneurysm adjacent to the basilar trunk (Figure 2). The patient was transferred to our institution for further evaluation and management. On admission, the patient was noted to be neurologically intact. An angiogram performed on post-SAH day 1 failed to identify a clear aneurysm but showed a blush of contrast next to the basilar trunk. The patient was taken for a second angiogram Nohra Chalouhi, MD Pascal Jabbour, MD Robert M. Starke, MD Mario Zanaty, MD Stavropoula Tjoumakaris, MD Robert H. Rosenwasser, MD L. Fernando Gonzalez, MD Department of Neurosurgery, Thomas Jefferson University and Jefferson Hos- pital for Neuroscience, Philadelphia, Pennsylvania Correspondence: L Fernando Gonzalez, MD, Associate Professor, Department of Neurological Surgery, Division of Neurovascular Surgery and Endovascular Neurosurgery, Thomas Jefferson University Hospital, 901 Walnut St, 3rd Floor, Philadelphia, PA 19107. E-mail: fernando.gonzalez@jefferson.edu Received, December 16, 2013. Accepted, January 20, 2014. Published Online, January 31, 2014. Copyright © 2014 by the Congress of Neurological Surgeons. ABBREVIATIONS: BTP, basilar trunk perforator; PED, Pipeline Embolization Device CASE REPORT TOPIC CASE REPORT NEUROSURGERY VOLUME 74 | NUMBER 6 | JUNE 2014 | E697 Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited.