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Biomedical subjects

B A Bell

Publications and source records attributed to B A Bell.

90 records · Page 5Linked to original sources
PubMed1985

Fifty years of experience with chordomas in southeast Scotland.

We report the clinical presentation and management of 34 patients with a histologically proven chordoma, treated in the neurosurgical departments in Edinburgh and Dundee, over the past 50 years. Although these tumors are commonly regarded as being locally invasive with a variable, but generally slow growth rate, they can metastasize, and this may precede surgical intervention, as in one of our patients. Our cases are compared to those in previously published series, and a comprehensive review of the treatment modalities for tumors at various sites is presented. The optimal treatment to be recommended from our own experience, and that of others, is aggressive operation and radiotherapy. A combination of hyperthermia and chemotherapy has shown some promise, but remains untested, and highlights the need for a multicenter trial with long follow-up to allow the evaluation of new therapeutic approaches.

Adolescent↗
PubMed1985

Effect of experimental common carotid arteriotomy on cerebral blood flow in rats.

Cerebral blood flow (CBF) and its reactivity to alterations in arterial carbon dioxide tension were measured in 52 rats. Measurements were made in four groups of rats: 15 were controls, 14 had one carotid artery clamped, 11 had microvascular common carotid arteriotomies, and 12 had sham arteriotomies. Before carotid operation, a flow change of 1 ml/100 g of brain per minute per torr change in CO2 tension was demonstrated in the rats, a value for reactivity similar to that found in normal humans. After unilateral common carotid ligation, CBF was not significantly disturbed in either hemisphere, and reactivity was preserved. In rats subjected to arteriotomy, CBF fell by 30% from the control level in both hemispheres, and carbon dioxide reactivity was reduced by 80%. Very similar reductions in flow (38%) and reactivity (76%) were produced after sham arteriotomy, in which the common carotid artery was isolated between temporary clamps for 30 minutes, but the arteriotomy incision was not made. The observed flow reduction and carbon dioxide reactivity impairment must result from the reperfusion of the brain through the traumatized carotid artery, inasmuch as no impairment of either flow or reactivity followed extravascular dissection and permanent ligation of the vessel. These changes may be mediated by damage to the sympathetic plexus or the innervation of the carotid body chemoreceptors or by the release of histamine, prostaglandins, or other vasoactive substances from the incised vessel wall. If this finding is applicable to humans, it suggests that the entire cerebral circulation in patients with respiratory impairment may be precarious for some hours after a carotid endarterectomy and confirms the danger of hypercapnia during anesthesia for carotid surgery.

Animals↗
PubMed1985

CBF and time thresholds for the formation of ischemic cerebral edema, and effect of reperfusion in baboons.

Ischemic cerebral edema has been studied in 41 baboons, with regional cerebral blood flow (CBF) determined by hydrogen clearance, and edema measured by microgravimetry. A threshold of ischemia has been identified for baboon cortex and subcortical white matter, which has to be crossed before edema formation begins. This threshold is 40.5% of normal CBF in cortex, and 34.4% of normal flow in subcortical white matter. A time threshold has also been determined, and the baboon brain can withstand 30 minutes of ischemia of the middle cerebral artery without significant edema formation. Reperfusion of ischemic brain has no effect on tissue water if the ischemic flow and time thresholds have not been crossed. Reperfusion of cortex, where water has begun to accumulate, exacerbates the water accumulation in proportion to the extent of the reperfusion. If these results are applicable to man, restoration of flow should not be attempted after an ischemic insult that reduces flow to less than 40% of normal unless it can be accomplished within 30 minutes of the insult. Provided CBF can be restored to above the 40% threshold within 30 minutes, reversal of the neurological deficit and prevention of ischemic edema can be expected.

Animals↗
PubMed1985

Effect of naloxone on deficits after aneurysmal subarachnoid hemorrhage.

The opiate antagonist naloxone was suggested for the amelioration of cerebral ischemia after subarachnoid hemorrhage (SAH) following the 1981 report of clinical improvement of ischemic deficits in 2 patients. The deficit in 1 patient was exacerbated by morphine, suggesting that analgesics acting on opiate receptors should be avoided after SAH, and this would include codeine phosphate and dihydrocodeine, both widely used for post-SAH headache. We studied 21 consecutive patients with aneurysmal SAH whose condition was worse than Grade 1 on the Hunt and Hess scale. A single observer graded them to avoid interobserver error, and they were also given a score on the Glasgow coma scale. Each patient was then given an intravenous injection of 0.9% saline as placebo or 0.4 mg (7 patients) or 2.0 mg (14 patients) of naloxone. Five minutes later, the same observer regraded the patient. After 30 minutes, a second injection of placebo or naloxone was given, and the patient was regraded a third time. Each patient received placebo in one injection and naloxone in the other, but the order was randomized and unknown to the observer. There was no beneficial effect of 0.4 mg of naloxone after aneurysmal SAH, and we did not find an elevated level of the endogenous opiate beta-endorphin in the cerebrospinal fluid in the majority (6 of 8 of the patients in whom it was assayed). Five of the patients given 2.0 mg of naloxone did improve transiently, and none deteriorated after the drug, suggesting that naloxone in a high dose may have a place in the management of some post-SAH deficits.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Rebound thymic hyperplasia in a child with cancer.

A case of biopsy-proven thymic hyperplasia is described in a child with group I paratesticular rhabdosarcoma while on chemotherapy. Other cases of children with cancer reported with this phenomenon are reviewed. Tissue diagnosis is important to differentiate metastatic tumor and to rule out second malignancies in these patients. The initial evaluations are facilitated by CT scanning of the chest and upper extremity venography.

Adolescent↗
PubMed1984

Dundee chordomas.

All patients with chordomas that have been treated in the Dundee neurosurgical unit are reviewed. Five intracranial and two sacral chordomas have presented since the unit opened in 1966. Survival has ranged from one to fifteen years following treatment. The difficulties in diagnosis and in assessing treatment of these rare slow growing neoplasms are discussed.

Adult↗
PubMed1983

A neurosurgical Munchausen tale.

The travels of a young man feigning subarachnoid haemorrhage in London and Scotland, over the past year, are documented. The origins of the Munchausen Tales are reviewed.

Adult↗
PubMed1983

A history of the study of cerebral edema.

A brief review of the historical concepts underlying our present knowledge of cerebral edema is presented, together with the evolution of attempts to measure the edema.

Brain Edema↗
PubMed1980

Computed tomography in aneurysmal subarachnoid haemorrhage.

The initial CT scans of 76 patients with aneurysmal subarachnoid haemorrhage were reviewed, and the amount of blood visible in the basal CSF cisterns was quantified. The outcome of surgery was found to correlate significantly with the quantity of blood seen on the scan, as did the pre-operative grade of the patient, a history of pre-existing hypertension, and the presence of angiographic vasospasm.

Adolescent↗
PubMed1979

Smoking and subarachnoid haemorrhage.

A retrospective study of 208 patients with ruptured cerebral aneurysms showed a highly significant excess of cigarette smokers among both men and women compared with the expected incidence. Results suggested that continued smoking increases the risk of suffering a subarachnoid haemorrhage (SAH) by a factor of 3.9 for men and 3.7 for women. Other factors besides smoking must affect the genesis of aneurysmal SAH since it is found in non-smokers, but continued cigarette smoking appears to increase substantially the risk of aneurysmal SAH occurring.

Adolescent↗
PubMed1978

Angiographically occult arteriovenous malformations of the brain.

Six patients with cerebral arteriovenous malformations which did not show any pathological circulation at angiography are described. Computed tomogram appearances of such lesions may be difficult to distinguish from tumours. The need for surgical exploration in localised high attenuation lesions of uncertain nature is stressed, and the literature is reviewed.

Adult↗
PubMed1978

Hydradenitis suppurativa.

The surgical treatment of a group of 24 patients with hydradenitis suppurativa is described and the clinical features, aetiological factors and other methods of treatment are reviewed. An abnormally high incidence of atopy is noted within the group.

Adult↗