Modified "Extended" Suboccipital Subtonsillar Clipping of a Ruptured Proximal Pica Aneurysm: Technical Note with Relevant Anatomical Demonstration.

Background and Importance: Lesions located lateral to the lower brainstem, such as proximal posterior inferior cerebellar artery (PICA) aneurysms, are surgically challenging. We report a case of a patient with a left proximal PICA aneurysm that was successfully clipped via a so-called "extended" suboccipital subtonsillar approach, which allowed us to obtain proper vascular control without removal of the atlas. The anatomy relevant for this approach has been studied.
Methods: Three adult cadaveric heads were studied. The relevant neurovascular anatomy related to this approach was exposed. Hence, this technique was applied on the patient herewith reported.
Case Presentation: A 60-year-old man with sudden onset of severe headache, nausea, and vomiting was admitted to our hospital. Computed tomography of the brain showed diffuse subarachnoid hemorrhage, mainly distributed at the level of the perimesencephalic cisterns. Cerebral angiography revealed a 3-mm aneurysm arising at the origin of the left PICA. The aneurysm was considered unsuitable for coil embolization, so it was treated via a "modified" posterolateral suboccipital subtonsillar route. The modification consisted of accomplishing proper proximal vascular control at the extracranial segment of the vertebral artery (V3), without the need of further removal of the posterior portion of the atlas. The patient was discharged neurologically intact.
Conclusions: The technique we suggested allowed no unnecessary removal of bone, with no need to drill the occipital condyle or remove the atlas, offered proper proximal vascular control in the early stage of the surgical procedure, and limited the quantity of temporary vascular clips inside the intracranial surgical field.
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