Surgical Treatment of a Ruptured Isolated Spinal Artery Aneurysm with Negative Angiography Findings: A Case Report

Isolated spinal artery aneurysms are rare vascular lesions of the spinal cord. Due to their rarity, the natural disease course and treatment guidelines have not been clearly defined. Here, we report a case of an angiography-negative isolated spinal aneurysm in the thoracic spine surgically that was treated without neurological compromise using indocyanine green (ICG) and intraoperative neurophysiological monitoring (IONM). A 52-year-old man without any prior medical history presented to the ER with acute lower back and bilateral leg pain accompanied by worsening voiding and difficulty defecating. Magnetic resonance imaging (MRI) of the lumbar spine showed a diffuse subarachnoid hemorrhage in the lumbar spine. The patient was initially treated conservatively with painkillers, but experienced a rapid recurrence of symptoms. A follow-up MRI scan showed subacute transformation and expansion of the subarachnoid hematoma, as well as a non-enhancing, intradural, extramedullary lesion at the T12/L1 level. Angiography did not show any remarkable findings, and surgical exploration revealed a thrombosed aneurysmal lesion. The lesion did not show ICG uptake, and temporary clipping of the caudal end of the lesion did not lead to changes in motor-evoked potential signals. A pathological examination revealed a capillary vascular structure in granulation tissue with organizing thrombi, favoring a thrombosed, granulated lesion over a vascular neoplasm. Rup-tured, isolated spinal aneurysms can be especially difficult to diagnose and treat when angiography findings are negative. We report that a spinal artery aneurysm can be safely excised using intraoperative ICG and IONM.