OBJECTIVE: In patients with non-traumatic subarachnoid hemorrhage (SAH) and no evidence for a cerebral aneurysm on angiography, a frequent cause of the hemorrhage is perimesencephalic hemorrhage or other cerebral vascular pathology. In some patients no cause is found. The exact incidence of a spinal vascular malformation (SVM) as the origin for the SAH is not known. We assessed the occurrence of SVM in angiogram-negative, non-perimesencephalic subarachnoid hemorrhage (NPSAH).
METHODS: 47 patients (from a consecutive cohort of 632) were identified with an angiogramnegative, non-perimesencephalic subarachnoid hemorrhage and 42 of these were analyzed by performing MR-imaging of the complete spinal neuraxis with additional spinal angiography on indication.
RESULTS: In four patients a spinal vascular malformation was identified as the cause of the SAH, indicating an incidence of 9 % of SVM in NPSAH, and an incidence of 1 % of SVM in all patients with SAH.
INTERPRETATION: Systematic analysis of angiogram-negative, non-perimesencephalic subarachnoid hemorrhage by MR imaging of the complete spinal neuraxis yields a higher incidence of SVM than previously documented. We recommend MR imaging of the complete spinal neuraxis in patients with a non-perimesencephalic subarachnoid hemorrhage in whom no cause for the hemorrhage has been found.