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Biomedical subjects

B Weir

Publications and source records attributed to B Weir.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effect of reserpine-kanamycin treatment on chronic vasospasm after platelet-enriched subarachnoid hemorrhage in primates.

A model of chronic cerebral vasospasm (VSP) analogous to the clinical situation was established by inducing subarachnoid hemorrhage (SAH) in monkeys. Platelets harvested from 4 ml of blood were added to autologous blood in an attempt to accentuate any effect that vasoactive substances such as serotonin, contained in platelets, might have on producing cerebral VSP. Antiserotonin medications were administered in an attempt to reduce the frequency or severity of angiographically proven VSP. Animals were divided into small (1 ml/kg) and large (1.2 to 1.5 ml/kg) hemorrhage groups and later were randomized equally to receive either saline placebo or reserpine (0.013 mg/kg i.m.) and kanamycin (50 mg/kg p.o.) administered 3 hours after SAH and daily thereafter to Day 7. In both the small and the large hemorrhage groups of treated animals, there was a significant reduction in serotonin levels (P less than 0.01 and P less than 0.05, respectively) compared to base line levels. In the groups of nontreated monkeys with small and large hemorrhages, serotonin levels were not statistically different from control values. Despite reduction of serotonin levels to 19 and 26% of the control values in the small and large hemorrhage, treated groups, there was no apparent difference in the frequency or severity of angiographically proven VSP. This study found no evidence that reserpine and kanamycin have a beneficial effect on preventing VSP when treatment is begun after SAH.

Animals↗
PubMed1984

A randomized placebo-controlled double-blind trial of nimodipine after SAH in monkeys. Part 1: Clinical and radiological findings.

The authors have developed a method to induce chronic cerebral vasospasm after subarachnoid hemorrhage (SAH) in monkeys. With microsurgical techniques, 33 monkeys had a frontotemporal craniectomy and unilateral opening of the subarachnoid cisterns. Cerebrospinal fluid was drained and a fresh hematoma, obtained from an average of 7 ml of autologous blood, was carefully placed against the major arteries of the anterior circulation on one side. The 30 monkeys studied for 7 to 14 days after the SAH were allocated randomly to two treatment groups of 15: one group received placebo and the other nimodipine, 1 mg/kg every 8 hours. Indices monitored before and after SAH included neurological status, cerebral blood flow, computerized tomography, and angiographic vessel caliber. In the placebo group, delayed ischemic neurological deficit developed in one monkey 4 days after clot placement and was present at sacrifice on Day 14. No such deficit occurred in the nimodipine group. The effect of nimodipine on vessel caliber at this dosage was equivocal. Significant vasospasm (31% to 100% reduction in vessel caliber) developed in 87% (26 of 30) of the animals. Overall, vasospasm was slightly more common in the placebo group: in this group, on Days 7 and 14, the incidence of vasospasm was significantly higher (p less than 0.05) than in the nimodipine group. However, the average percentage reduction in vessel caliber of the maximally constricted vessel in each monkey was not significantly different between the two groups.

Animals↗
PubMed1984

A randomized placebo-controlled double-blind trial of nimodipine after SAH in monkeys. Part 2: Pathological findings.

Chronic cerebral vasospasm was induced in monkeys by placement of an autologous blood clot after the basal cisterns had been opened over the arteries of the circle of Willis on one side. The experimental protocol was detailed in Part 1 of this paper. Twenty of the 30 monkeys studied from both groups (one receiving placebo and the other nimodipine) underwent cerebral fixation (Day 14) at controlled pressure by intra-arterial perfusion. The arteries at the base of the brain were studied by light microscopy and scanning (SEM) and transmission electron microscopy (TEM). Cerebral angiography on Day 7 showed that vasospasm was significantly more common (p less than 0.0001) and more severe (p less than 0.01) on the clot side compared to the control or non-clot side. Vasospasm was less severe on Day 14, just before sacrifice. On SEM, 80% of the 20 middle cerebral artery (MCA) specimens that had been in spasm (Day 7) showed marked corrugation , and in some the endothelium had a fish-scale appearance. All of the 10 MCA's on the clot side examined by TEM that had been in spasm (Day 7) showed marked changes such as endothelial swelling, subendothelial proliferation, corrugation of the elastic lamina, and myonecrosis. With few exceptions, none of the basilar arteries or MCA's on the non-clot (control) side showed any abnormalities. The pathological findings of vessels in spasm were considered to be slightly less severe in the nimodipine group; however, the trial drug (1 mg/kg/8 hrs) did not prevent such abnormalities from occurring. The ultrastructural changes in the arterial walls of specimens from both placebo and nimodipine groups in vasospasm are described. Since dramatic changes are present in the vessel walls even after radiologically visible vasospasm has almost completely abated, we believe that vasospasm is due to long-lasting smooth-muscle constriction and not to vessel wall thickening caused by a cellular or subcellular infiltrate.

Animals↗
PubMed1983

Factors affecting coagulation: fibrinolysis in chronic subdural fluid collections.

Plasminogen, alpha2-antiplasmin, fibrinogen, fibrin degradation products (FDP's), and hemoglobin were measured in the supernatant fluid of 25 chronic subdural hematomas and five chronic subdural hygromas. The 30 patients underwent pre- and postoperative computerized tomography. The hematomas were characterized by low fibrinogen and high fibrin degradation product concentrations. The hemoglobin content varied directly with the alpha2-antiplasmin, and inversely with the plasminogen. Four patients underwent reoperation for recurrences. The initial fluid from these cases was characterized by relatively high plasminogen and low alpha2-antiplasmin. The hygromas had no hemoglobin, and low fibrinogen, high FDP's, low alpha2-antiplasmin, and variable plasminogen levels. It is possible that those cases having the greatest capacity to produce plasmin (high plasminogen and low alpha2-antiplasmin) can produce more FDP's which in turn causes more rebleeding and an increased risk of reaccumulation of chronic subdural hematomas.

Chronic Disease↗
PubMed1983

Intraventricular hemorrhage from ruptured aneurysm. Retrospective analysis of 91 cases.

Intraventricular hemorrhage (IVH) from aneurysm rupture is generally considered to be of grave prognostic significance. Ninety-one cases have been studied retrospectively from seven medical centers. The overall mortality rate was 64%. The dramatically poor condition of these patients leads to their rapid admission to the hospital. Eighty-seven percent were admitted on Day 0 or 1, and more than half were classified neurologically as Grade 4 or 5. A multiple regression analysis explained 56% of the variance in survival, using the variables of ventriculocranial ratio (VCR), day of admission, diastolic blood pressure, location of aneurysm, associated intracerebral hematoma, age, grade on admission, sex, and systolic blood pressure. No patient with a VCR of more than 0.25, as calculated from the initial computerized tomography (CT) scan, survived. No patient whose smallest VCR was 0.23 or more survived. This ratio can be simply measured with a millimeter ruler from the CT scan. Patients with IVH usually had enlarged ventricles, even initially. The overall results suggest that early management of intracranial hypertension should be more generally considered, although even when this was done the prognosis was still guarded. The timing of surgery was not an important determinant of outcome, although a significant number of patients died awaiting surgery.

Adolescent↗
PubMed1982

Management and postoperative mortality related to time of clipping for supratentorial aneurysms: a personal series.

An analysis of all 197 consecutive cases of intracranial aneurysms treated by one of us (B. W.) was carried out. 82% were ruptured anterior circle aneurysms. 144 cases were analyzed with respect to post-operative and management mortality where patients were eligible for definitive clipping. Grade-time interactions on transfer to the neurosurgeon were considered. Early operation was not associated with significantly higher post-operative and management mortality. 116 cases clipped and discharged from hospital had longer follow-ups to see if earlier operation was associated with a poorer neurological and social outcome. This was not the case. We therefore believe that since the prime rationale for surgery following subarachnoid haemorrhage is the prevention of rebleeding and since this is more common immediately following the initial haemorrhage, early surgery is indicated whenever this is technically feasible. Since 1978, with a deliberate policy of trying to operate early, for all grades there has been a post-operative mortality of 3%, a case management mortality of 20% and 87% of patients operated upon have been able to go home.

Constriction↗
PubMed1982

Chronic cerebral vasospasm after large subarachnoid hemorrhage in monkeys.

The authors have developed a model of chronic cerebral vasospasm analogous to the clinical situation, by inducing a large subarachnoid hemorrhage (SAH) in monkeys. With this model, the size of the SAH apparent on the first computerized tomography (CT) scan was correlated with the incidence and severity of cerebral vasospasm that developed. Indices monitored for up to 21 days after SAH included cranial CT scan, cerebral blood flow, vessel caliber, and neurological status. The 18 monkeys studied for 48 hours or more were divided into two groups according to the size of the SAH on CT scan. Vasospasm was more common in the group with large SAH. In this group, on Days 0, 7, and 14, the incidence of vasospasm was significantly higher than at other times (p less than 0.001, p less than 0.01, and p less than 0.05, respectively), and the percentage reduction in vessel caliber was significantly greater than in the group with small/medium SAH (Day 7, p less than 0.02; Days 0 and 14, p less than 0.05). Delayed neurological deficit developed in two monkeys with large SHA. Apathy was noted from Day 17 to Day 21 in one, and unsteadiness and drowsiness were noted on Days 4 and 5 in the other. Overall, the incidence, degree, and time course of vasospasm reflected the size of the hemorrhage.

Animals↗
PubMed1981

Effect of therapy on cerebral blood flow following aneurysm surgery.

The authors report on a patient with a ruptured anterior communicating aneurysm treated surgically on the day following her subarachnoid hemorrhage (SAH). Repeated measurements of cerebral blood flow (rCBF) were carried out using the inhalational Xenon 133 method. Dramatic acute increases in rCBF occurred, coincident with clinical improvement, following mannitol, CSF drainage and dopamine. Later, further elevation to normal levels occurred following ventriculoperitoneal shunting.

Adult↗
PubMed1981

Lumbar stenosis: analysis of factors affecting outcome in 81 surgical cases.

The authors report on a retrospective analysis of 81 patients undergoing laminectomy for the clinico-radiological diagnosis of lumbar stenosis. One hundred and eighty-five variables were considered and a computer system was used in their evaluation. The most frequent site of involvement was at L4-5. Follow-up time ranged from 3 months to 12 years. 95% good results were obtained, and the re-operation rate was 7%. The complication rate was 11%. There was no mortality. No significant correlation between factors investigated and the outcome was found. This is in contrast to our series of lumbosacral disc protrusions in which factors such as duration of symptoms and the presence of compensation indicated a poor outcome. Results are compared with other series.

Adult↗
PubMed1981

Ventricular size and cerebral blood flow following subarachnoid hemorrhage.

The relationship among ventricular size on computed tomography (CT), the clinical status of the patient, and cerebral blood flow alterations in subarachnoid hemorrhage is examined. Fifty patients with subarachnoid hemorrhage underwent a total of 71 cerebral blood flow measurements and 115 CT scans. Flow was measured noninvasively using 133Xe inhalation. It is demonstrated that increasing ventricular size is accompanied by clinical deterioration and also by a reduced flow. The effects of the various lesions (as demonstrated by CT) on cerebral perfusion are examined. Of the 23 patients scanned 5 days or less after hemorrhage, 12 had subarachnoid blood visible on the scan. These 12 had flows that averaged 20% lower than the other 11 when examined 6 to 17 days after the hemorrhage. Ventricular enlargement is more prevalent in the first week after the hemorrhage than in the second. Also, blood flow is maximally reduced at the end of the first week following hemorrhage.

Adult↗
PubMed1981

Management mortality and the timing of surgery for supratentorial aneurysm.

A retrospective analysis of 224 patients with a ruptured supratentorial aneurysm, admitted to the care of one of six neurosurgeons on the day or or the day following their subarachnoid hemorrhage, was carried out. Both postoperative and management mortality rates were calculated by the grade of the patient on admission. There were no statistically significant differences in postoperative and management mortality rates when patients were categorized by time of operation, except for the increased management mortality for Grade 3 and 4 patients who were operated on late.

Humans↗
PubMed1981

Dermatofibrosarcoma protruberans of the scalp treated by radical excision, immediate cranioplasty, and free groin flap: case report.

The authors describe a case of dermatofibrosarcoma protruberans of the frontal region in a young girl. The condition was treated by radical excision of the scalp, frontal bone, and sinuses, and immediate reconstruction with an acrylic cranioplasty and microsurgical transfer of a free groin flap. Pathological examination revealed the margins of the excised specimen were clear of tumor. The initial flap failed, but a second graft was immediately transferred successfully, with a good cosmetic result.

Adolescent↗