Vasomotor reactivity is exhausted in transient ischaemic attacks with limb shaking.

OBJECTIVES To investigate cerebral vasomotor reactivity in five patients with limb shaking transient ischaemic attacks by using transcranial Doppler sonography. METHOD Attacks with transient limb shaking were unilateral in four patients and bilateral in one. Internal carotid arteries on the side opposite the abnormal limb movements showed three 90-95% stenoses and three occlusions as assessed by cerebral angiography in three and magnetic resonance angiography and ultrasound in one case each. Reactivity of cerebral resistance vessels was studied by measuring peak mean velocities in the middle cerebral artery (MCA) before and after the application of CO2 enriched air. Reference values were obtained from 25 normal subjects. RESULTS During hypercapnia peak mean velocities slightly decreased in five MCAs (steal phenomenon) and remained unchanged in one MCA opposite the abnormal movements, whereas the other MCAs showed normal reactivities. CONCLUSION The delineation of an exhausted cerebral vasoreactivity in all hemispheres opposite the involuntary limb movements suggests that haemodynamic failure is the cause of transient ischaemic attacks with limb shaking.