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Biomedical subjects

F D Brown

Publications and source records attributed to F D Brown.

At least 19 recordsLinked to original sources
PubMed1992

Epidural lipomatosis in steroid-treated patients.

Epidural lipomatosis is a condition in which excess adipose tissue is deposited circumferentially about the spinal cord in the epidural space. It is most frequently seen in patients on chronic steroid treatment for a variety of medical problems and can present as nonspecific back pain, radiculopathy, or frank spinal cord compression. Diagnosis and treatment have generally relied on multi-level decompressive laminectomy after myelography and computed tomography. The immunocompromised state and the reported postoperative mortality (22%) of these patients, however, suggests that nonoperative therapy may be preferable whenever possible. Five cases of epidural lipomatosis are reported, and previous literature is reviewed for presentation, evaluation, and treatment of this condition.

Adult↗
PubMed1990

Cerebral blood flow during the acute therapy of severe hypertension with oral clonidine.

A major risk associated with the acute treatment of severe hypertension is a reduction in cerebral blood flow (CBF) with ischemic injury to the central nervous system. The authors studied CBF before and after the acute treatment of severe hypertension (diastolic blood pressure greater than 115 mm Hg) with clonidine in 13 patients. One patient did not reach goal blood pressure (diastolic blood pressure 105 mm Hg or a decrease by 30 mm Hg) after clonidine alone. In the remaining 12 patients, oral clonidine reduced supine blood pressure from 201.7 +/- 5.0/126.3 +/- 2.1 mm Hg to 149.4 +/- 5.3/96.8 +/- 1.7 mm Hg over an average time period of 85 +/- 7 minutes. Although mean CBF for the group did not change (72.6 +/- 4.2 v 73.7 +/- 3.5 mL/100 mg/min), a significant (greater than 10%) change occurred in 9 of the 12 patients (5 increases and 4 reductions). The magnitude and direction of the change were dependent upon initial CBF (r = -0.65, P less than .05); patients with low pretreatment CBF experienced an increase, whereas those with high initial flow exhibited a decrease. No significant adverse effects were observed. These data confirm previous reports that clonidine is effective in the acute treatment of severe hypertension and demonstrate that its effects on CBF are determined by the pretreatment levels of flow.

Administration, Oral↗
PubMed1989

Superior sagittal sinus infection with Petriellidium boydii: case report.

A case of infection of the superior sagittal sinus with Petriellidium boydii is reported. This relatively common fungal pathogen rarely invades the central nervous system. Immunological compromise and poor personal hygiene seem to be common attributes shared by this patient and the 4 previous patients reported to have suffered invasion of the central nervous system by this organism. This report is unique in that it is the first demonstrating apparent hematogenous dissemination of this organism to the central nervous system.

Brain Diseases↗
PubMed1988

The effect of fetal hypothalamus grafts on weight gain resulting from lesions of the ventromedial hypothalamus.

Bilateral ventromedial hypothalamic lesions in female adult rats which resulted in hyperphagia and rapid weight gain were followed by placement of fetal brain tissue in the anterior third ventricle. The treatment group received fetal hypothalamus grafts, and fetal cortical tissue of identical age was grafted into the control group. A significant reduction in average daily weight gain was noted from 4 to 12 weeks following transplantation in the treatment group. At 12 weeks posttransplantation, the animals were sacrificed for histological analysis. Examination of the hypothalamus grafts revealed neurons, ependymal clusters, and axonal processes which appeared to infiltrate the surrounding hypothalamic parenchyma.

Animals↗
PubMed1979

Detailed monitoring of the effects of mannitol following experimental head injury.

The experimental model of a cerebral missile injury developed by Crockard was used in three groups of Rhesus monkeys treated with mannitol. One group received mannitol 15 minutes after being injured with a BB pellet at 90 m/sec impact. Another group was wounded identically, but mannitol treatment was delayed until 1 hour after injury. The last group was wounded with the missile traveling at 180 m/sec, and mannitol was started 15 minutes after trauma. The data were contrasted with the results from the original model. After receiving mannitol, all groups showed marked improvement in mean blood pressure, cerebral perfusion pressure, cerebral blood flow, and cerebral metabolic rate of oxygen consumption out of proportion to the degree of reduction in intracranial pressure (ICP). The authors conclude that the therapeutic value of mannitol may, in some injuries, be directly related to its effects on blood flow and metabolism, as well as to its better known effects upon ICP.

Animals↗
PubMed1979

Hyperemic and ischemic problems of surgical treatment of arteriovenous malformations.

Three patients with arteriovenous malformations are described who showed signs of massive hyperemia in the vascular territory of the normal brain proximal to arterial ligation. One additional patient had evidence of ischemia of the brain in the territory distal to ligation (steal), and in another both mechanisms were considered as operative hazards.

Adolescent↗
PubMed1978

Treatment of aneurysmal hemiplegia with dopamine and mannitol.

Three patients with severe postoperative hemiplegia and one with hemiplegia following a subarachnoid hemorrhage are presented. None had hematomas. All were treated with dopamine-induced hypertension, mannitol, and large quantities of intravascular fluids. All showed a remarkable degree of clinical improvement, presumably secondary to an increase in cerebral blood flow.

Adult↗
PubMed1977

An experimental cerebral missile injury model in primates.

An experimental model of cerebal missile injury in rhesus monkey is described. The main objective was to create a "clean" wound devoid of bleeding from major vessels and complications due to bone fragments. There was a correlation between the wounding energy and the physiological signs, although we underestimated the actual energy level. After the right parietooccipital to right frontal injury, there was bradycardia, changes in blood pressure, and, in high-energy wounds, a marked alternation in resperation. This suggests that the missile's energy produces direct brain-stem damage, the extent of which can be related to the wounding energy.

Animals↗
PubMed1977

Physiological consequences of experimental cerebral missile injury and use of data analysis to predict survival.

The authors describe cerebrovascular and cerebral metabolic changes in monkeys, subjected to cerebral missile injury. After injury with BB pellet at 90 m/sec, there is a rapid rise in intracranial pressure (ICP), which reaches a peak 2 to 5 minutes posttrauma, and then falls to about 20 to 30 mm Hg. This, with a fall in mean blood pressure (MBP), results in a 50% reduction in cerebral perfusion pressure (CPP), Cerebral blood flow (CBF) is also reduced, although acutely there is no close relationship with (CPP). Cerebrovascular resistance falls initially and then at 30 minutes rises to very high values. Cerebral metabolic rates (CMR's) for oxygen fall after injury and remain low for the rest of the animal's life; CMR's for lactate rise immediately after injury and persists for 5 hours, then fall. After injury with a faster missile (180 m/sec), the ICP rises higher and faster, and the peak is shorter. The CCP is reduced in this injury to approximately 30 mm Hg, and only one animal survived more than 1 hour. With the conventional forms of data analysis, the length of survival after injury correlates well with MBP, ICP, and CBF, but separately they were completely unsatisfactory for prediction of an individuals prognosis. With the technique of multiple linear regression analysis, the survival of individual animals could be predicted with great accuracy. This is possible also when two postinjury parameters,CBF and MBP, are used.

Animals↗
PubMed1977

Somatosensory evoked potentials, cerebral blood flow and metabolism following cerebral missile trauma in monkeys.

Somato sensory evoked potentials (SEP), cerebral blood flow and cerebral metabolism were studied in seven rhesus monkeys before and after a right occipito-frontal missile injury with an air rifle. The sensory evoked potential was present shortly after injury though markedly altered in shape. There was a very close correlation (r2 equal to 0.83) between SEP and cerebral blood flow on the uninjured side five minutes after injury. On the injured side, this was also noted but the amplitude of the SEP was much smaller, perhaps due to direct injury. If the flow in either hemisphere fell below 15-20 mls/100 gm/min, the evoked response disappeared, but in several animals a subsequent increase in flow was associated with a return of electrical activity. There was no correlation with cerebral perfusion pressure or cerebral metabolic rates for oxygen or lactate production, though it is likely that this is not due to physiological reasons but rather methodological. It might be inferred from these results that adequate flow is vital for the preservation and return of electrical activity following brain injury.

Animals↗
PubMed1977

Effect of sodium nitroprusside on cerebral blood flow in conscious human beings.

Hemispheric cerebral blood flow was measured in 14 patients prior to and after the injection of sodium nitroprusside. The intracarotid method of Xenon was utilized, and flow was calculated by the flow initial technique. With a small reduction in blood pressure during the administration of sodium nitroprusside, the cerebral blood flow fell significantly by 15.9+/- 5.6%.

Adult↗
PubMed1976

Effects of trimethaphan and sodium nitroprusside on cerebral blood flow in rhesus monkeys.

In tranquilised spontaneously breathing rhesus monkeys we have found that trimethaphan can reduce systemic blood pressure by 20% with little or no change in CBF. This was in marked contrast to those given nitroprusside which showed signs of loss of autoregulation at a 5% MBP reduction. It is our opinion that the divergence of these results from other work might be explained in part by differing anaesthetic techniques and species variations. On this experience we would be hesitant to use sodium nitroprusside or a hypotensive agent in any patient where cerebral blood flow might be already compromised.

Animals↗