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Biomedical subjects

M J Harrison

Publications and source records attributed to M J Harrison.

At least 199 records · Page 11Linked to original sources
PubMed1988

The variable clinical and CT findings after carotid occlusion: the role of collateral blood supply.

A retrospective review of 61 cases of angiographically confirmed occlusion of one or both carotid arteries was carried out to look at the evidence that the presence of collateral blood supply influenced the extent and type of cerebral infarction. Forty six patients had bilateral angiography from which it was possible to assess collateral filling of the internal carotid and middle cerebral arteries. As expected, patients with no CT scan evidence of infarction more frequently had transient ischaemic attacks or retinal infarcts than did those with visible cerebral infarcts. Patients with small cortical ischaemic lesions usually had appropriate neuropsychological or neurological deficits. Three patients with cortical watershed infarcts had a fluctuating deficit. Of the patients with bilateral angiograms 67% showed some filling via collaterals of the middle cerebral artery, and 43% of the internal carotid artery in the siphon. Those with collateral filling were mostly found to have normal CT scans or evidence of peripheral cortical lesions. By contrast most watershed and full territory infarcts were found in individuals whose angiograms showed no collateral filling. It is suggested that in many cases infarction occurs despite collateral flow and is due to distal embolism and that this may be relevant to the recently reported failure of the EC/IC bypass operation.

Carotid Artery Thrombosis↗
PubMed1988

HIV and the nervous system.

Neurological manifestations are common in HIV-infected individuals. Autopsy data suggest that the brain may be affected in as many as 80 per cent of cases. While opportunistic infections represent a major cause of neurological morbidity and mortality, there is growing evidence that HIV is itself neurotropic and can directly affect the nervous system.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Changes in anal sphincter tone at induction of anaesthesia.

Changes in anal pressure have been monitored during the induction of anaesthesia. Falls in pressure accompany loss of consciousness following bolus doses of commonly used intravenous and inhalational anaesthetic agents. Subsequent rises in pressure towards pre-anaesthetic levels are usually associated with the time taken to correct responses and initial recovery. Premedication, including anticholinergic drugs in conventional dosage, does not affect anal pressure.

Alfaxalone Alfadolone Mixture↗
PubMed1987

The effect of increased blood pressure on hemispheric lactate and water content during acute cerebral ischaemia in the rat and gerbil.

Infusions of metaraminol and angiotensin were used to test the effect of increased perfusion pressure on tissue metabolism and oedema after induction of regional cerebral ischaemia in the rat and the gerbil. An increase of mean arterial blood pressure of 30-40 mm Hg in the rat over the first 2 hours after diathermy of the middle cerebral artery prevented the 100% rise in hemisphere lactate seen in normotensive control animals. Angiotensin infusion also prevented early hemispheric oedema in this model. In the gerbil, 4 hours after placing a clip on one carotid artery, metaraminol-induced increases in blood pressure had no such protective effect on the metabolic changes or on oedema. When the clip was removed after 3 hours to permit 1 hour of reperfusion, lactate levels returned to normal but the degree of oedema was unchanged. Hypertension in this reperfusion model caused a slight but not statistically significant increase in oedema. The evidence suggests that moderate increases in blood pressure may be protective against the early metabolic sequelae of focal cerebral ischaemia, but there are potential problems with oedema formation. It is argued that a clinical trial should study the potentially beneficial effects of a brief early increase in blood pressure in the acute aftermath of ischaemic stroke.

Acute Disease↗
PubMed1987

Occult cerebral arteriovenous malformations.

Angiographically occult arteriovenous malformations in the brain are rare but cause considerable diagnostic difficulty. Four personal cases are presented in which CT scans showed hypodense lesions with minimal or no enhancement, and angiograms showed only an avascular mass. Gliomas, a dermoid and an infarct were suspected before histological examination of biopsies or excised specimens. The patients had presented in early adult life with epilepsy and focal deficits.

Adult↗
PubMed1987

Surgery for stroke.

The failure of medical management to make dramatic progress in the prevention and treatment of ischaemic stroke led to the development of surgical approaches. This article discusses the rationale and the track record of the two major procedures currently in use.

Acute Disease↗
PubMed1986

Cerebral consequences of cardiopulmonary bypass.

55 patients undergoing coronary-artery bypass surgery (CABS) and a comparison group of 20 patients having thoracic or major vascular surgery were investigated preoperatively and 8 days and 8 weeks postoperatively for changes in neuropsychological status, psychiatric state, cerebral blood flow, and neurological signs, this last being assessed also at 24 h. Major persisting neurological changes were rare, but minor abnormalities were significantly more common after CABS than after thoracic or vascular surgery. Neuropsychological deficits were common at 8 days in both CABS and comparison groups, and in about a third of all patients persisted at 8 weeks. Cerebral blood flow was reduced at 8 days in some CABS patients, but this was not significant for the group. Pre-existing cerebrovascular disease was not predictive, but low perfusion pressure and long bypass time were associated with postoperative deficits.

Adult↗
PubMed1986

PEEP and CPAP.

Explore the source record for details and available documents.

Humans↗
PubMed1986

Physiological data display during anaesthesia.

It is difficult to chart more than three or four physiological parameters on one graph without causing confusion because of multiple symbols, crossing lines or different scales. A method of charting multiple parameters simultaneously is described which minimises this confusion and can, at a glance, inform the user of the acceptability of the results.

Anesthesia↗
PubMed1986

EEG changes in subcortical dementia: a study of 22 patients with Steele-Richardson-Olszewski (SRO) syndrome.

To assess the value of EEG in distinguishing between cortical and subcortical dementia, we compared the EEGs of 22 patients with SRO syndrome with those of 22 patients who had a comparable degree of dementia due to cortical atrophy. EEG records from patients with SRO syndrome were of low voltage, but with preserved alpha rhythm at 8-10 Hz and were within normal limits in 12/22. In 8 there was an abnormal excess of theta activity and one had additional lateralizing asymmetries. One had frontal intermittent rhythmic slow wave activity. Comparison with records of 22 patients, with cortical atrophy due to Alzheimer's disease but with only mild to moderate dementia, showed a similar low frequency of non-specific abnormalities.

Cerebral Cortex↗
PubMed1986

Remote monitoring using an induction loop.

An electromagnetic induction loop is used to transmit signals from a pulse and respiration monitor to a standard National Health Service hearing aid to facilitate remote monitoring.

Anesthesiology↗