[Extracranial vertebral artery aneurysm complicating Klippel-Feil syndrome: case report].

The Klippel-Feil syndrome is one of the spinal malformations characterized by fusion of the cervical vertebrae. It is well known that the malformation can cause some neurologic disorders. However, an aneurysm in the vertebral artery associated with the Klippel-Feil syndrome is extremely rare, with only one case having been reported in the literature. We present a 39-year-old female with a sudden onset of disturbed consciousness. Lateral cervical x-ray films showed the Klippel-Feil syndrome and hypermobility between C1 and C2. MRI showed multiple infarctions in the posterior circulation, including bilateral thalami. Right vertebral angiogram identified the extracranial vertebral artery aneurysm as the source of the emboli. The patient gradually recovered with conservative therapy. The aneurysm was thought to be produced by chronic arterial trauma secondary to excessive movement between C1 and C2. We conclude that an extracranial vertebral artery aneurysm is a serious complication in a patient with the Klippel-Feil syndrome.