D.J. Thomas

Multi-infarct dementia

Abstract Fifty-two patients presenting with dementia were divided into a group in whom clinical features suggested an ischaemic basis (multi-infarct dementia) and a group in whom a primary degenerative process seemed more likely. Focal EEG changes and angiographic evidence of ischeamic areas and atheromatous disease of intracranial vessels were more common in the “ischaemic” than in the primary degenerative group. CBF was significantly reduced in the former but the regional pattern was equally distorted in the two groups. These findings strengthen the belief that the ischaemic score can identify those patients whose dementia is associated with vascular disease.

Cerebral haemodynamic changes after extracranial-intracranial bypass surgery.

Regional cerebral blood flow, oxygen utilisation, fractional oxygen extraction, and cerebral blood volume were measured by positron emission tomography in twelve patients with carotid artery occlusion. Follow-up studies were carried out at a mean interval of eleven weeks after extracranial-intracranial bypass surgery. Clinical improvement was observed in three patients who had presented with frequent transient ischaemic attacks. One patient with multiple vascular occlusions suffered a stroke at the time of surgery. Follow-up studies showed an increase of regional cerebral blood flow in only two of the twelve patients. In the group as a whole, there was no significant change of cerebral blood flow, oxygen consumption or fractional oxygen extraction after bypass surgery. The most consistent post-operative change, observed in eleven of the twelve patients, was a fall of cerebral blood volume in the cortical territory of the bypassed carotid artery (p less than 0.01). This effect was most marked in patients with bilateral carotid occlusion, in whom there was often an accompanying fall of blood volume in the contralateral hemisphere. The post-operative findings were consistent with an increase of regional cerebral perfusion pressure as a result of the bypass procedure. Although this effect is potentially of value, those patients with most to gain from bypass surgery may also run the highest risk of peri-operative cerebral ischaemia.

EFFECT OF HIGH HÆMATOCRIT ON ALERTNESS

Patients with high-normal or above-normal haematocrit were found to have impaired alertness when compared with a control group matched for age and occupation. On retesting the controls had improved alertness scores attributable to a practice effect; but the patients, when retested after reduction of haematocrit by venesection, had improved significantly more than the controls. Improvement in alertness correlated very well with the increase in cerebral blood flow which followed venesection. Levels of venous haematocrit that are generally accepted as normal may not necessarily be optimum.

An intravenous 133xenon clearance technique for measuring cerebral blood flow.

An intravenous 133Xe clearance technique for measuring cerebral blood flow (CBF) is described. Results obtained compared well with those using the intracarotid 133Xe technique. The reproducibility of the method was checked by repeating measurements within a few hours in 14 patients, when no significant overall change occurred, and after some days in 23 patients when a mean fall in flow of 8% was observed. CBF was measured in 52 control subjects. The mean fast component flow (Ff) was 68.6 ml/100 g/min (SD 11.3). No difference between the two hemispheres was found. Flow was confirmed to be higher anteriorly in the cerebral hemispheres. A significant inverse correlation was found between CBF and age.

Comparison of Angiographic and CT Findings between Patients with Multi-Infarct Dementia and Those with Dementia Due to Primary Neuronal Degeneration

The CT and angiographic appearances in multi-infarct dementia have been compared with those of primary neuronal degeneration. It was possible to make a CT or angiographic diagnosis of multi-infarct dementia in about 40% of patients diagnosed by the ischaemic scoring method of Hachinski et al. [1].

Cerebral blood flow after surgery for recent subarachnoid haemorrhage

243 measurements of cerebral blood flow by a noninvasive 133Xe clearance technique have been made in 45 patients undergoing surgery for a recently ruptured cerebral aneurysm. Two groups of patients have been defined by the presence or absence of a postoperative rise in cerebral blood flow which showed a significant correlation with level of consciousness after operation.

Haematocrit, hypertension and smoking in patients with transient ischaemic attacks and in age and sex matched controls.

The blood pressure, smoking habit and haemotocrit of 154 patients with transient ischaemic attacks and 191 age-and sex-matched neurological controls were studied. Regression analysis revealed that the haematocrit value was related to both systolic and diastolic blood pressure, and to smoking. Smoking elevated the haematocrit by 1.9 +/- 0.59 in males and by 2.18 +/- 0.68 in females. When these associations were allowed for there was still evidence of a higher haematocrit in patients with transient ischaemic attacks (plus 1.44 +/- 0.56 in males and 0.75 +/- 0.75 in females p less than 0.02). The role of an elevated haematocrit in the pathogenesis of cerebrovascular disease and its management are briefly discussed.

Effect of tinofedrine (Homburg D8955) on cerebral blood flow in multi-infarct dementia.

Tinofedrine, a new derivative of l-norephedrine, was examined for cerebral vasodilator activity in man. Ten patients with reduced cerebral blood flow (CBF) and multi-infarct dementia were given the drug intravenously. Cerebral blood flow increased significantly by 28% from a mean of 43.3 to 55.5 ml/100 g/min.

Ocular Ischaemic Syndrome Secondary to Occult Giant Cell Arteritis

A 74–year-old man presented with a three day history of a red right eye and decreased vision. He had no past ophthalmic history. His only past medical history was that he had had a cerebrovascular accident (CVA) one month previously from which he had made a full recovery. A CT scan of his brain at the time revealed multiple small vessel infarcts in the region sub-served by the posterior cerebral circulation. Cardiac ECHO and carotid Doppler ultrasound scans were performed and were normal. He lived alone and was previously a heavy smoker of 40 per day although he had stopped smoking since his CVA. He was taking simvastatin 40 mg once per day and oral aspirin 75 mg once per day, both of which were commenced after his CVA. He denied any systemic symptoms such as occur in association with giant cell arteritis (GCA).