Intracranial extension of extracranial vertebral artery dissections. A review of 16 cases

Introduction. Vertebral artery (VA) dissections can involve both the extracranial and intracranial portions of the VA. Intradural extension explains the occurrence of subarachnoid hemorrage (SAH). We have studied the rate of this extension, the risk of associated SAH and the therapeutic repercussions at the acute stage. Methods. From 1985 to 2001, 42 patients with a recent extracranial VA dissection were admitted to our department of neurology. When the diagnosis of extracranial VA dissection (involving the first, second or third segment of the VA) was established, we looked for an ipsilateral intracranial extension (involving the fourth segment of the VA and/or the basilar artery). VA dissections strictly located at the intracranial level were excluded. Results. Among 42 patients with angiographically diagnosed extracranial VA dissections, 16 patients (38 percent) had an ipsilateral intradural extension. Two of them developed an inaugural and spontaneous SAH. After a mean follow-up of 4 months under antithrombotic treatment, none of the patients has developed SAH or recurrent SAH. Conclusions. Because of the potential risk for spontaneous SAH at the acute stage, it seems important to exclude an intracranial extension. Lumbar puncture should be undertaken to exclude SAH before consideration of antithrombotic therapy.