Primary orthostatic cerebral ischaemia.

four patients with "primary orthostatic cerebral ischaemia" are described. They complained of dizziness, light-headedness or syncope on standing. None had a significant fall in his systemic blood pressure on assuming the erect posture. Each had bruits over the major neck vessels or absent pulses. Angiography showed widespread narrowing or occlusion of the cervical blood vessels which supply the brain. Carotid endarterectomy relieved the patients' symptoms and also reduced the fall in retinal artery pressures on standing noted preoperatively. The clinician who is not aware of the poorly documented syndrome of "primary orthostatic cerebral ischaemia" may fail to recognise that a patient's complaints are due to cerebrovascular disease for they are strikingly different from those of classical transient ischaemic attacks.