Subarachnoid hemorrhage following posterior spinal artery aneurysm. A case report and review of the literature

Abstract

Isolated posterior spinal artery aneurysms are rare vascular lesions. We describe the case of a 43-year-old man presenting with spinal subarachnoid hemorrhage after a minor trauma who was found to have a dissecting aneurysm of a posterior spinal artery originating from the right T4 level. Endovascular treatment was not contemplated because of the small size of the feeding artery, whereas surgical resection was deemed more appropriate because of the posterolateral perimedullary location that was well appreciated on CT angiography. After surgical resection of the aneurysm the patient had a complete neurological recovery. In comparison to anterior spinal artery aneurysms whose pathogenesis is diverse, posterior spinal aneurysms are most often secondary to a dissection and represent false or spurious aneurysms. Although the definite diagnosis still requires spinal angiography, MRI and CT may better delineate the relationship of the aneurysm to the spinal cord in order to determine the best treatment method. Prompt treatment is recommended as they have high rebleeding and mortality rates.

Figure 1

Sagittal T2W(A), T1W(B) and T1W post Gd (C) MR of the spine demonstrating T1 hyperintensities around the cord from T1 to T4 levels, representing spinal SAH. A circumscribed area of T2 hypointensity at the dorsolateral aspect of the cord at T3 level is noted, with nodular enhancement following contrast administration. CT angiography in coronal reformatted (D) and axial (E) views reveals the exact location of the aneurysm at the right dorsolateral aspect of the cord.

Figure 2

Right supreme intercostal spinal DSA in arterial (A) and late venous (B) phases revealing a fusiform lesion, which shows slow filling and stagnation of the contrast to the venous phase, originating from a dorsolateral radiculopial artery from the right T4 segmental artery compatible with a false aneurysm. Oblique view (C) better demonstrates the small radiculopial artery supplying the aneurysm. Faint filling of the aneurysm after injection into the anterior spinal artery system from the contralateral side (D) via the vasocorona collaterals is observed.

Figure 3

Intraoperative view after right T3 hemilaminectomy (A) revealing the fusiform aneurysm at the dorsolateral aspect of the cord. Post operative angiogram of the right supreme intercostal artery (B) demonstrating disappearance of the previously seen aneurysm.

Figure 4

Microscopic overview (A) of a part of the endoluminal thrombus (asterisk) covered by bundles of collagen fibers (Elastica-van Gieson stain, x50). Focal remnants of an arterial wall are seen (B and C). The elastic lamina (black) stops at the arrows where a pad of intimal thickening is seen (Elastica-van Gieson stain, x200).