Spinal subarachnoid bleeding of unknown etiology. Case reports.

Spinal subarachnoid bleeding of unknown etiology is extremely rare. It has been suggested that these lesions have to be divided into two subtypes with different behaviour and prognosis according to their location around the spinal cord. The dorsally located bleeding would invariably cause severe spinal cord compression while the ventral lesions would have a very benign course in the absence of remarkable neurological deficit. We observed two patients with spontaneous spinal subarachnoid bleeding of unknown etiology. In both cases the disease was revealed by the sudden onset of severe back pain without subsequent signs of spinal cord compression. In one case the bleeding was ventral to the spinal cord while in the other it was located dorsally. The patients were evaluated with panspinal MRI and selective spinal angiography. They were treated conservatively and follow-up examinations at 18 and 24 months show they are neurologically intact in the absence of rebleeding episodes. We think the diagnosis of spontaneous subarachnoid bleeding of unknown etiology cannot be achieved without a panspinal MRI and a selective angiography have ruled out any other causes. We suggest their incidence is more prevalent than reported due to the difficulty/reluctance to employ MR in the presence of only minor symptoms. Our cases also show that these lesions may have a benign course independently from their location around the spinal cord.