Lateral Spinal Artery Aneurysm Causing Subarachnoid Hemorrhage: Literature Review and Case Report

Abstract

Ruptured aneurysms of the lateral spinal artery (LSA) causing subarachnoid hemorrhage (SAH) are exceptionally rare. Unlike common aneurysms in the circle of Willis, LSA aneurysms present unique diagnostic and therapeutic challenges due to their complex anatomy. We reviewed the literature, examining case reports detailing LSA aneurysm occurrences, diagnoses, treatments, and complications, and our subsequent analysis highlights the clinical presentations, imaging findings, treatment methods, and anatomical features of the LSA. We identified 10 patients from 7 case reports of LSA aneurysm presenting with SAH, and combined with the present case, this comprised a total of 11 patients. An initial CT angiography identified LSA aneurysm in only 2 of 11 patients, while 5 cases were detected in transfemoral cerebral angiography. Seven patients had stenosis or occlusion of nearby arteries. Among the 10 patients treated, 7 underwent microsurgical clipping, and 3 had endovascular treatment; complications included PICA infarction and subdural hematoma. LSA aneurysms, though rare, should be considered in differential diagnoses of posterior fossa SAH. An accurate diagnosis often requires repeated imaging. It is proposed to individualize treatment strategies based on the unique anatomical structure and hemodynamic conditions of each patient, utilizing both endovascular and surgical approaches. Understanding the vascular anatomy and collateral pathways of the LSA is crucial for improving diagnostic accuracy and treatment outcomes.

Keywords: cerebral angiography; lateral spinal artery aneurysm; posterior spinal artery; subarachnoid hemorrhage.

Figure 1

(A) Initial CT scan displays SAH (arrow) in the posterior fossa and around the midbrain. CT angiography reveals a tiny suspected aneurysm (arrow) at the right cerebellomedullary cistern in axial (B) and coronal views (C).

Figure 2

(A) Cerebral angiography reveals a small irregular branch exhibiting multifocal severe stenoses and dilatations (arrow) in routine AP and lateral views. (B) Bilateral PICAs originate from the contralateral VA.

Figure 3

(A) The microcatheter (arrow) was carefully advanced to the proximal dissection point, and a coil was cautiously inserted (arrowhead), focusing on the proximal dissection point in oblique view. (B) Delayed angiograms showed progressive flow reduction, and the final angiogram confirmed no flow through the dissection segment at the coiling site.

Figure 4

The classification was simplified based on the relationship between the PICA, LSA, and PSA. (A) Origin and branching patterns of PICA and PSA: PICA originating from V4 segment of VA and PSA splitting into descending posterolateral and ascending branches merging with PICA. (B) Segmental connections and cranial anastomosis of LSA: LSA is the outermost cervical spinal artery connecting with VA from C1 to C4 and anastomosing with PICA. Abbreviations: 1 = basilar artery; 2 = vertebral artery; 3 = posterior inferior cerebellar artery; 4 = posterior spinal artery; 5 = lateral spinal artery; 6 = anterior spinal artery.