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Biomedical subjects

G Neil-Dwyer

Publications and source records attributed to G Neil-Dwyer.

At least 91 records · Page 5Linked to original sources
PubMed1981

The clinical importance of lipid solubility in beta blockers.

The comparative effects of three lipophilic beta blocking agents--propranolol (80 mg b.i.d.) metoprolol (200 mg/d) and oxprenolol (160 mg/d) and one hydrophilic agent, atenolol (100 mg/d), were studied in patients undergoing neurosurgery. The respective penetration of these compounds into brain tissue and CSF was measured and correlated with plasma levels. The brain concentration of the three lipophilic beta blockers was high--propranolol some 20 times and oxprenolol and metoprolol some 10 times greater than the concentration of the hydrophilic, atenolol. The clinical relevance of this may be important in reducing the severity of centrally-mediated side effects, such as hallucinations and sleeplessness, by using a beta blocker less likely to penetrate the blood/brain barrier.

Adrenergic beta-Antagonists↗
PubMed1980

beta-Adrenoreceptor-blocking agents and the blood-brain barrier.

1. Sixteen neurosurgical patients received (oral) beta-adrenoreceptor-blocking agents (beta-receptor blockers) for 3-22 days. 2. Lipophilic beta-receptor blockers (propranolol) and metoprolol appeared in cerebrospinal fluid at concentrations similar to the free drug plasma concentration. 3. Cerebrospinal fluid concentrations of beta-receptor blockers were poor predictors of brain concentrations. 4. Both lipophilic beta-receptor blockers appeared in high concentrations in the brain: the brain/plasma ratio was approximately 15:1. 5. Hydrophilic atenolol appeared at low concentrations in brain tissue (about 20 times lower than the lipophilic beta-receptor blockers): the brain/plasma ratio was approximately 0.1:1. 6. Central nervous system-related side effects associated mainly with lipophilic beta-receptor blockers possibly result from high brain tissue concentrations.

Atenolol↗
PubMed1980

Plasma renin activity in patients after a subarachnoid hemorrhage--a possible predictor of outcome.

Plasma renin activity (PRA) was estimated in 23 patients during the 1st week after a subarachnoid hemorrhage (SAH) and in a control group of 6 postlaminectomy patients. Patients with altered levels of consciousness and neurological deficits had significantly higher levels of PRA than did patients who were alert and neurologically intact. The SAH patients were divided into three groups: (a) low renin (13 patients with a PRA of less than 1.77 pmol/ml/hour), (b) normal renin (2 patients with normal renin levels), and (c) high renin (8 patients with a PRA of greater than 2.5 pmol/ml/hour). Patients with high renin levels had a significantly higher incidence of morbidity and mortality than did those with low renin levels. There were also higher levels of urinary catecholamines in the high renin group of patients. The combination of altered consciousness, high levels of urinary catecholamines, particularly adrenaline; and a high PRA in the 1st week after a SAH indicates a poor prognosis.

Adult↗
PubMed1980

A clinicopathological study of patients following a subarachnoid hemorrhage.

The hypothalamus and myocardium of 54 patients (27 males and 27 females, age range 12 to 73 years) who died after subarachnoid hemorrhage (SAH) were examined histologically. In 42 patients, hypothalamic and myocardial lesions were found; in seven, hypothalamic lesions only; and in five, no hypothalamic nor myocardial lesions. A similar examination was performed on a control group of 25 patients (12 males and 13 females, age range 17 to 70 years) who had died from a variety of causes, all producing raised intracranial pressure. In these, no lesions were found in either the hypothalamus or the myocardium. The age of the patient, the site of the vascular pathology, and whether an operation was performed appeared to have no effect on the occurrence of hypothalamic and heart lesions; however, there was a correlation between these lesions, progressive neurological deterioration, and varying pulse rates and blood pressures. This study produces further evidence of the involvement of the autonomic nervous system in some of the deleterious effects of SAH, and a suggestion is made as to possible treatment.

Adolescent↗
PubMed1979

The role of computerized tomography in the care of the injured.

The records of 377 patients with head injuries admitted to the South East Thames Regional Neurosurgical Unit in the two years following the introduction of the EMI scanner (computerized tomography) were examined. Each patient was assessed on the reason for transfer, the necessity for transfer, the safety of transfer and whether immediate access to a scanner would have altered management. The results show that the majority of patients were referred because of a possible intracranial haematoma. Thirty per cent of the patients required operation, in 6 per cent transfer was unnecessary and 10 per cent arrived with inadequate resuscitation. It is suggested that with a wider deployment of head-dedicated scanners to some accident centres, the number of patients with head injuries at present being transferred to special units for assessment would be reduced substantially, with improvement of patient care.

Craniocerebral Trauma↗
PubMed1978

Effect of propranolol and phentolamine on myocardial necrosis after subarachnoid haemorrhage.

A study was set up to assess the effect on the clinical course of subarachnoid haemorrhage (SAH) of giving propranolol 80 mg eight-hourly plus phentolamine 20 mg three-hourly by mouth for three weeks. Out of the 90 patients studied, 14 died. Two of the deaths occurred in an open pilot study of 10 patients, the remaining 12 deaths occurring in patients in a randomised double-blind placebo-controlled study. Postmortem examination was carried out on 12 of the patients, six of whom had been receiving placebo and six propranolol plus phentolamine. Necrotic myocardial lesions were present in the hearts of all six patients (age range 30-59 years) who died while taking placebo (all had had abnormal electrocardiograms (ECGs). In contrast, no necrotic lesions were found in the hearts of the six patients (age range 28-59) who died while receiving the drugs (all had previously had normal ECGs). We conclude that the necrotic myocardial lesions were induced by catecholamines and that propranolol had a cardioprotective effect. While death from a further haemorrhage in cases of SAH is not affected by propranolol and phentolamine, propranolol may have a beneficial effect in other potentially lethal stresses.

Adult↗
PubMed1978

A clinical study of the EMI scanner: implications for provision of neuroradiological services.

The records of the first 571 patients to be examined with an EMI brain scanner were assessed. The patients were divided into diagnostic categories according to their clinical presentation. The intracranial investigations that would have been performed had the scanner not been available were compared with the investigations that were actually performed. As expected, the number of contrast investigations fell, but the reduction surpassed expectation. If the full clinical impact of the scanner is to be realised the patient's illness must be defined in detail and strict attention paid to radiographic detail. By reducing the number of special contrast investigations use of the scanner enables existing contrast facilities to serve a wider population; and use of the brain scanner in district general hospitals would improve the service to patients, especially those with head injuries.

Angiography↗
PubMed1978

Evaluating cost-effectiveness of diagnostic equipment: the brain scanner case.

An approach to evaluating the cost-effectiveness of high-technology diagnostic equipment has been devised, using the introduction of computerised axial tomography (CAT) as a model. With the advent of CAT scanning, angiography and air encephalography have a reduced, though important, role in investigating intracranial disease, and the efficient use of conventional equipment requires the centralisation of neuroradiological services, which would result in major cash savings. In contrast, the pattern of demand for CAT scanning, in addition to the acknowledged clinical efficiency of the scanner and its unique role in the head-injured patient, ephasies the need for improved access to scanners. In the interest of the patients the pattern of service must change.

Brain↗
PubMed1977

Hypothalamic and myocardial lesions after subarachnoid haemorrhage.

The hypothalamus and myocardium of 12 patients who had died after a subarachnoid haemorrhage, and of six patients who had died from other intracranial pathology were examined. Only in the patients who had died from subarachnoid haemorrhage were histological lesions found in both the hypothalamus and myocardium. The possible significance of these findings is discussed with particular reference to the sympathetic nervous system.

Adult↗
PubMed1975

Delay in diagnosis of optic nerve and chiasmal compression presenting with unilateral failing vision.

Out of 29 patients who presented with failing vision in one eye due to optic nerve or chiasmal compression, compression was initially diagnosed in only five. The errors in diagnosis and lack of ophthalmological follow-up led to delays of up to many years with serious deterioration in acuity before referral for intracranial investigation. The chief causes of error were lack of charting of the visual fields, too ready acceptance of the diagnosis of the neuritis in the absence of essential features, and the infrequent use of skull radiographs.

Adolescent↗