Traumatic subarachnoid haemorrhage: an alternative source.

Traumatic subarachnoid haemorrhage is known on many occasions to result from a blow on the neck rupturing the vertebral artery within the cervical spine. On some occasions, however, no such damage to the artery in the neck can be found to account for the haemorrhage. Some cases are described in which the source of haemorrhage was rupture of the vertebral artery within the skull close to the basilar artery. The reason why rupture should occur at this site is discussed.