Spinal subarachnoid hematomas: clue to a source of bleeding in traumatic lumbar puncture.

Although damage to the veins of Batson's epidural plexus is usually considered the origin of bleeding in traumatic lumbar puncture, a lesion of these veins would not explain the cases in which postmortem examination shows blood confined to the subdural and subarachnoid spaces. In two patients who had lumbar punctures a few days before death, there was subarachnoid hematoma of the cauda equina at autopsy. In one of these cases, the radicular vessels were shown to be the source of bleeding. Spinal subarachnoid and subdural hemorrhages after lumbar puncture may be due to laceration of radicular vessels by the spinal needle.