Surgical correction and SPECT imaging of vertebrobasilar insufficiency due to unilateral vertebral artery stenosis.

Abstract

Incapacitating vertebrobasilar insufficiency is generally associated with bilateral vertebral artery disease, whereas unilateral vertebral artery stenosis usually is clinically silent. Regional brain perfusion has not been part of the routine evaluation of patients with vertebrobasilar insufficiency. This report describes two patients who had isolated unilateral vertebral artery stenosis operatively corrected to eliminate their incapacitating vertebrobasilar insufficiency. Hindbrain hypoperfusion was identified preoperatively and evaluated postoperatively, then correlated with patient presentation and response to revascularization. Two patients with incapacitating vertebrobasilar insufficiency presented with isolated unilateral vertebral artery stenosis with patent, nonstenotic internal carotid arteries. Hindbrain hypoperfusion was demonstrated by iodine-123-iodoamphetamine single-photon emission computed tomography preoperatively and demonstrated significant improvement following vertebral-carotid reimplantation. The patients' symptoms resolved following revascularization. Although unusual, unilateral vertebral artery stenosis can cause incapacitating vertebrobasilar insufficiency. These cases demonstrate the value of imaging with single-photon emission computed tomography to evaluate regional brain hypoperfusion and to evaluate objectively the results of therapy.