Search PubMed⌕ Search

Biomedical subjects

B A Bell

Publications and source records attributed to B A Bell.

At least 73 records · Page 4Linked to original sources
PubMed1991

Improved access to lesions of the central skull base by mobilization of the zygoma: experience with 54 cases.

Improved access to lesions at the medial end of the sphenoid wing or in the interpeduncular cistern after mobilization of the zygoma has been a subject of growing interest in recent years. This study describes the operative technique we have adopted and records our experience with 55 operations in 54 patients who underwent the procedure in the past 3 years. Seven patients had vascular lesions, 44 had tumors, and 3 had miscellaneous lesions. The majority of the tumors were medial meningiomas, and particular note is made of those arising from the cavernous sinus with respect to their resectability. Sixteen of these tumors were encountered, and total excision was possible in 11 cases. Access to the infratemporal fossa is facilitated, and in 2 cases we were able to excise completely trigeminal neuromas that had extended there. The extra maneuver adds little to the overall operating time, and complications relating to it are uncommon, mild in degree, and usually self-limiting. We conclude that the operation is extremely valuable in appropriate circumstances.

Adolescent↗
PubMed1991

Postoperative radiotherapy in the management of spinal cord ependymoma.

Fifty-eight patients with histologically verified spinal cord ependymomas were treated at the Royal Marsden Hospital and Atkinson Morley's Hospital between 1950 and 1987. The median age in this series was 40 years (range 1 to 79 years) and the male:female ratio was 1.8:1. Ten patients had tumors in the cervical cord and 10 in the thoracic cord; 14 tumors involved the conus medullaris and 24 the cauda equina. Forty ependymomas were grade I and 13 were grades II to IV (in five patients there was insufficient material for grading). Eleven patients underwent biopsy only, 33 had partial or subtotal resection, and 14 had complete resection. Forty-three patients received postoperative radiotherapy. The median follow-up period was 70 months (range 3 to 408 months). Cause-specific survival rates were 74% and 68% at 5 and 10 years, respectively. On univariate analysis, age, histological grade, postoperative neurological function, and era of treatment were significant prognostic factors for survival. The histological grade was the only significant independent prognostic factor. The relative risk of death from ependymoma was 9.0 for patients with tumor grades II to IV compared to grade I (p less than 0.005, 95% confidence interval 2.7 to 30). The survival rates of patients following complete excision were significantly better compared to those after incomplete surgery (p less than 0.025). The majority of completely resected neoplasms were low-grade cauda equina tumors. Despite incomplete surgery, 5- and 10-year progression-free survival rates following radical radiotherapy were both 59%, and cause-specific survival rates were 69% at 5 years and 62% at 10 years. This suggests that radiotherapy may achieve long-term tumor control in over half of those patients with residual spinal ependymoma.

Adolescent↗
PubMed1990

Effect of calcitonin-gene-related peptide on postoperative neurological deficits after subarachnoid haemorrhage.

An infusion of calcitonin-gene-related peptide (CGRP) at progressively increased concentrations was given to 15 patients with neurological deficits after intracranial aneurysm surgery for subarachnoid haemorrhage. In 9 of the patients the deficits, quantified by a modified Glasgow coma scale, improved with no adverse effects; after a placebo infusion only 2 of the 15 patients showed improvement. If CGRP can reverse cerebral ischaemia after early intracranial aneurysm surgery, its use may improve the safety of such early surgery, remove the need for late surgery with its increased risk of death from rebleeding, and reduce overall morbidity and mortality of aneurysmal subarachnoid haemorrhage.

Adult↗
PubMed1990

Craniocervical stabilization using Luque/Hartshill rectangles.

Untreated craniocervical instability is associated with a high morbidity and a significant mortality. Existing methods using bone grafts, interlaminar wires, or acrylic eventually produce stability but require prolonged periods of immobility and have a high failure rate. The ideal method of fixation should provide for permanent correction of deformity and relief of symptoms, with immediate stabilization, at a single procedure. Posterior fixation of the occiput to a stable part of the cervical spine with a molded metal rectangle held in place by interlaminar wires was used to accomplish this. We report 20 patients treated consecutively who have undergone craniocervical fusion by this method using Luque/Hartshill rectangles. Fourteen patients had preexisting atlantoaxial instability and 6 had cord compression, but would become unstable after decompression. All operations were performed under general anesthesia; 9 patients (40%) were awake for intubation/positioning, and 7 patients had a simultaneous decompression. Sixteen patients made an uncomplicated recovery and became mobile 3 days postoperatively. Symptomatic and neurological improvement occurred in 70% of all patients. Neurological complications occurred in 4 patients (20%), reflecting the serious nature of the condition; 2 patients (10%) showed no change. Scrutiny of their presentations and operations failed to identify avoidable risk factors, except faulty wiring techniques. In all patients, permanent stabilization was achieved immediately, facilitating early mobilization with a real chance of improvement, which indicates that the method merits wider application.

Adolescent↗
PubMed1990

A scale for neurosurgical audit.

A neurosurgical audit scale has been devised to provide a measure of disability and outcome. The audit scale was tested for observer variation and sensitivity against the Karnofsky scale, the Rosser disability scale and the Rosser distress scale. The highest ratio of observer concurrence compared with chance was noted for the neurosurgical audit scale, and the lowest ratio for the Rosser distress score. Sensitivity was almost identical for each of the scales. The neurosurgical audit scale lends itself to audit based on a computer database for which the input is the discharge summary. This achieves audit without additional work for either medical or secretarial staff.

Disability Evaluation↗
PubMed1990

Maintenance of normal platelet mass in anemic Belgrade rats and their response to iron.

The Belgrade (b/b) rat has severe hypochromic, microcytic anemia accompanied by mild thrombocytopenia and a 49% reduction in megakaryocytes (MKs). The platelet counts are decreased only 34%, but relative platelet size measured by two independent methods averages 50% greater than controls. Thus, the platelet mass of the b/b rat is within the normal range. The marrow MK progenitors (MK colony-forming units, CFU-MK) respond linearly to increased colony-stimulating activity in vitro, but they are reduced 68% and form smaller colonies than normal. Flow cytometric analysis of MK ploidy indicates that significantly more MKs are distributed into the low and high ploidy classes compared with the normal, and the mean ploidy is similar. The b/b rat maintains effective thrombocytopoiesis in spite of a severe reduction in MK progenitors, primarily by an increased rate of maturation of the endomitotic compartment. Iron treatment partially arrests the b/b anemia and is associated with a significant increase in CFU-MK, a normalized MK ploidy distribution, and a significant decrease in platelet size. The favorable response to iron therapy suggests that the megakaryocytopenia is secondary to the severe anemia and results from stem cell commitment to the erythroid lineage.

Anemia↗
PubMed1989

A low cost system for performing CT stereotaxic brain biopsy.

The cost of commercially available CT-compatible frames for stereotaxic brain biopsy has limited their availability in the U.K. Our adaptation to a pre-CT stereotaxic frame that had been in use at Atkinson Morley's Hospital for 12 years, and the availability of a GE 9800 CT scanner has allowed us to carry out accurate CT-directed stereotaxic biopsy at minimal cost. The system has the additional advantage of speed and ease of use in inexperienced neurosurgical hands. Biopsies in 100 patients have been performed by 12 different surgeons (80% by registrars) who mastered the technique without difficulty. The rates of permanent morbidity (4%) and mortality (2%) are low, the two mortalities occurring in patients with high grade astrocytomas. They compare very favourably with rates for freehand burr-hole biopsy, and our overall diagnostic success rate of 83% for the initial biopsies, rising to 90% as a result of re-biopsy in 10 of the patients, is similar to that achieved with much more costly commercial systems. Benign lesions were found in 7% of patients who would otherwise have been assumed to have malignant tumours, and this finding emphasises the value of achieving a histological diagnosis in every lesion of the brain.

Biopsy↗
PubMed1989

Measurement of changes in brain water in man by magnetic resonance imaging.

John Hunter was undoubtedly aware of the water content of normal brain tissue, and described cerebral oedema. The advent of nuclear magnetic resonance (NMR) shed new light on brain water, and the derivation of spatial information and hence images from NMR signals, has permitted studies of regional brain water in man in vivo. The initial study described here tested whether NMR longitudinal relaxation time (T1) correlates with brain water content in the cerebral cortex and white matter in man, and significant relationships have been demonstrated in cortex (r = 0.65, P less than 0.002) and white matter (r = 0.94, P less than 0.0001), the latter having narrow 95% confidence limits. The residual variance allows the prediction of water content from the T1 of white matter, measured from the image of a single patient, with an accuracy of +/- 4% of total tissue water with 95% confidence. In the further study described, the effects of dexamethasone and an infusion of 20% mannitol on brain water content has been assessed in patients with intrinsic cerebral tumours. Dexamethasone had no significant effect on the T1 of normal brain, oedematous peritumoural white matter, or tumour tissue. It must be concluded that the water content of these tissues is not changed by dexamethasone and that the clinical improvement seen in patients with cerebral tumours immediately after dexamethasone has to be explained by some mechanism other than a reduction in cerebral oedema. Mannitol did reduce the T1 of oedematous peritumoural white matter, and the T1 of tumour tissue, but did not change the T1 of normal brain significantly. Thirty minutes after starting the mannitol infusion,water content of the oedematous white matter had been reduced by 1.4%. John Hunter studied the structure and social habits of the honeybee extensively for almost 40 years before he eventually published his findings. Steroids and osmotic agents have been used to treat brain oedema for over 40 years, but their precise mechanisms of action still require further elucidation. Magnetic resonance will hopefully continue to shed further light on this clinically important area.

Adult↗
PubMed1987

Brain water measured by magnetic resonance imaging. Correlation with direct estimation and changes after mannitol and dexamethasone.

Brain water content was measured in tissue samples taken at operation from 19 patients with intrinsic cerebral tumours imaged preoperatively by magnetic resonance. A high correlation (r = 0.94, p less than 0.0001) between white matter water content and the longitudinal relaxation time (T1) enabled water content to be estimated from T1 to within 4%. 11 patients received dexamethasone and improved clinically but their T1, and thus brain water content, was unchanged an average of 6 days later. Intravenous infusion of 20% mannitol in 11 patients significantly reduced T1 in oedematous white matter and tumour within 15 min of administration, and by 30 min the T1 of oedematous white matter had fallen to a mean of 32.4 (SEM 7.1) ms, corresponding to a reduction in water content of 1.4 (0.3)%.

Adult↗
PubMed1987

Hodgkin's disease following Wilms' tumor: a case report.

A patient is described who developed Hodgkin's disease 16 years after treatment of Wilms' tumor with radiation and actinomycin D. The issues relating to Hodgkin's disease as a second malignancy are reviewed. The need for long-term surveillance of patients with malignant disease for late effects of the cancer and its treatment is emphasized.

Adolescent↗
PubMed1987

Correction factors for gravimetric measurement of peritumoural oedema in man.

The water content of samples of normal and oedematous brain in lobectomy specimens from 16 patients with cerebral tumours has been measured by gravimetry and by wet and dry weighing. Uncorrected gravimetry underestimated the water content of oedematous peritumoural cortex by a mean of 1.17%, and of oedematous peritumoural white matter by a mean of 2.52%. Gravimetric correction equations calculated theoretically and from an animal model of serum infusion white matter oedema overestimate peritumoural white matter oedema in man, and empirical gravimetric error correction factors for oedematous peritumoural human white matter and cortex have therefore been derived. These enable gravimetry to be used to accurately determine peritumoural oedema in man.

Adult↗
PubMed1986

Delay in the diagnosis of pediatric brain tumors.

The interval from the onset of symptoms to the diagnosis in 79 children with primary brain tumors was compared with that in 45 children with Wilms' tumor and 123 children with acute leukemia. The patients with brain tumors had a significant delay from symptom onset to diagnosis. Only 38% of primary brain tumors were diagnosed within the first month after the onset of symptoms. In contrast, 84% of Wilms' tumors and 80% of cases of acute leukemia were diagnosed within one month of the onset of symptoms. Early detection of brain tumors is important as it may have a significant bearing on clinical outcome.

Acute Disease↗
PubMed1986

Chemotherapy of childhood acute lymphoblastic leukemia.

This article reviews current chemotherapy of childhood acute lymphoblastic leukemia, with particular emphasis on the pharmacology of the drugs used. In the perspective of the overall treatment plan, the use, mode of action, toxicity and pharmacology of prednisone, vincristine, L-asparaginase, cyclophosphamide, 6-mercaptopurine, methotrexate and cytosine arabinoside are reviewed. Issues relating to central nervous system prophylaxis, drug compliance, drug resistance, and treatment failure are considered.

Antineoplastic Agents↗
PubMed1986

Correlation of human NMR T1 values measured in vivo and brain water content.

A relationship has been demonstrated between nuclear magnetic resonance (NMR) longitudinal relaxation times (T1 values) obtained in vivo in both normal and oedematous (peritumoral) brain tissue, and measurements of brain water obtained by gravimetric analysis of operative samples. Significant correlations were found in seven patients in both cortex (r = 0.97, P less than 0.001) and white matter (r = 0.92, P less than 0.001). These findings suggest that NMR may prove a useful technique for monitoring brain oedema.

Body Water↗