Cerebral blood flow in migraine accompaniments and vertebrobasilar ischemia.

BACKGROUND AND PURPOSE Transient neurological symptoms of brain stem or occipital lobe origin may be caused by transient ischemic attack in the vertebrobasilar territory (VB-TIA) or late-onset (or late-life) migraine accompaniment (LOMA). It is often clinically difficult to distinguish between VB-TIA and LOMA. METHODS Cerebral blood flow of 23 patients with VB-TIA, 24 with LOMA, and 28 age-matched control subjects was measured using the 133Xe inhalation regional cerebral blood flow (rCBF) technique. RESULTS After adjusting for differences in baseline variables such as blood pressure, hematocrit, and PCO2, patients with VB-TIA had (1) lower mean rCBF than control subjects (P < .003) as measured by the initial slope index method; (2) more frequent anterior rCBF asymmetries than control subjects and patients with LOMA (P < .03 for both comparisons); and (3) higher mean interhemispheric rCBF differences compared with patients with LOMA (P = .08) and control subjects (P < .02). CONCLUSIONS Regional CBF patterns in patients with VB-TIA and LOMA differ, with lower rCBF and more asymmetry of the anterior blood flows in patients with VB-TIA, probably reflecting the effects of stroke risk factors on the cerebral circulation. Patients with LOMA have rCBF patterns more closely resembling those of age-matched healthy subjects. rCBF measurements may assist in the clinical diagnosis of VB-TIA and late-onset migrainous events.