Adhesion between an extruded coil and the oculomotor nerve: Unexpected interference due to coil extrusion

BACKGROUND: When direct clipping is performed for a recurrent aneurysm after coil embolization, there are sometimes findings of the coil adhering to the surrounding tissue, after it has been extruded from inside the aneurysm into the subarachnoid space and brain parenchyma. However, there have only been few previous reports on extruded coils adhering to the cranial nerves, preventing aneurysm dissection and clip application. CASE DESCRIPTION: We performed the coil embolization of a ruptured aneurysm originating from the bifurcation of basilar artery and superior cerebellar artery in a 36-year-old male patient. Recurrence was confirmed 5 years after embolization and direct clipping was performed. The intraoperative finding was that part of the coil was strongly adhering to or encircling the oculomotor nerve, making it difficult to achieve sufficient mobility of the cerebral aneurysm. CONCLUSION: When direct clipping is performed after coil embolization of an intracranial aneurysm, part of the coil may be extruded from the aneurysm and then adhere strongly to the cranial nerve.