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Biomedical subjects

R A Solomon

Publications and source records attributed to R A Solomon.

At least 91 records · Page 5Linked to original sources
PubMed1991

Stereotactic craniotomy in the resection of small arteriovenous malformations.

Surgical resection of 10 obscure arteriovenous malformations (AVM's) was accomplished with craniotomy guided by computerized tomography (CT) or angiography and the use of the Brown-Roberts-Wells stereotactic frame. Stereotactic craniotomy was invaluable for resection of the following types of AVM's: 1) AVM's with a nidus less than 2 cm in diameter, 2) AVM's located in an eloquent area of the brain, and 3) AVM's located deep in the brain. Stereotactic localization of these AVM's on preoperative radiological studies provides a precise route to the nidus, often avoiding important areas of the brain. This series included six male and four female patients with a mean age of 32 years. All patients presented with an intracerebral hemorrhage, from which eight made a complete neurological recovery prior to surgery. Two AVM's were located on the cortex, three were found subcortically, and five were situated near the ventricles or in the deep white matter. As a guide, angiography was used in six cases and CT in four cases. In each instance, the study providing the best image of the AVM nidus was employed. Postoperatively, no neurological deficits were found in eight patients and, in the two patients with preoperative deficits, neurological improvement was observed after recovery from surgery. Postoperative studies revealed complete removal of the AVM in all patients, and all lesions were confirmed histologically. The authors conclude that stereotactic craniotomy provides the optimum operative approach for the localization and microsurgical resection of AVM's that are either obscure or located deep in the brain.

Adolescent↗
PubMed1991

Relationship between the timing of aneurysm surgery and the development of delayed cerebral ischemia.

A consecutive series of 145 patients with acute aneurysmal subarachnoid hemorrhage (SAH) were operated on within 7 days of SAH and were prospectively evaluated over a 4-year period to determine if the timing of aneurysm surgery influenced the development of delayed cerebral ischemia. All patients were managed with a standardized policy of urgent surgical clipping and treatment with aggressive prophylactic postoperative volume expansion. Patients with delayed ischemic symptoms were additionally treated with induced hypertension. Forty-nine patients underwent surgery on Day 0 or 1 (Group 1) post-SAH, 60 patients on Day 2 or 3 (Group 2), and 36 patients on Days 4 through 7 (Group 3). Postoperative delayed cerebral ischemia developed in 16% of (Group 1) patients, in 22% of Group 2 patients, and in 28% of Group 3 patients. Cerebral infarction resulting from delayed cerebral ischemia developed in only 4% of Group 1 patients, 10% of Group 2 patients, and 11% of Group 3 patients. A bad clinical outcome as a result of delayed cerebral ischemia occurred in one Group 1 patient (2%), two Group 2 patients (3%), and one Group 3 patient (3%). Preoperative grade was not significantly correlated with the incidence or severity of delayed cerebral ischemia at any time interval except that patients in modified Hunt and Hess Grade I or II who underwent surgery on Day 0 or 1 after SAH had no strokes or bad outcomes from delayed cerebral ischemia. This study demonstrates that there is no rationale for delaying aneurysm surgery based on the time interval between SAH and patient evaluation.

Brain Ischemia↗
PubMed1990

Dose-related effects of selective 5-HT2 receptor antagonists on slow wave sleep in humans.

The effects of the selective 5-HT2 receptor antagonists, ritanserin (1, 5 and 10 mg) and ICI 169.369 (50 and 100 mg), were studied on the sleep EEG of healthy volunteers using home-based Medilog 9000 cassette monitoring. Ritanserin (5 and 10 mg) produced a significant increase in slow wave sleep (SWS) while ICI 169,369 also increased SWS but only at a dose of 100 mg. These findings are consistent with the proposal that selective 5-HT2 receptor blockade increases SWS in humans; however, the data cannot exclude involvement of the closely related 5-HT1c receptor in this effect.

Adult↗
PubMed1990

Slow wave sleep and 5-HT2 receptor sensitivity during maintenance tricyclic antidepressant treatment.

The 5-HT2 receptor antagonist cyproheptadine significantly increased slow wave sleep in 12 healthy control subjects but not in 12 patients with a history of major depression, maintained on tricyclic antidepressant treatment. Cyproheptadine produced a similar reduction in REM sleep in both groups of subjects. The results are consistent with the hypothesis that tricyclic antidepressant treatment alters brain 5-HT2 receptor sensitivity, but a primary abnormality in slow wave sleep regulation in depressed patients cannot be excluded.

Adult↗
PubMed1990

Sleep stability with home sleep recording and automatic sleep stage analysis.

Three home sleep recordings were conducted in 12 normal subjects using the Oxford Medilog 9000 system with automatic sleep stage analysis (SS90III). Each night was separated by 1 week. No significant differences were noted for any sleep parameter, with the mean intraindividual variation less than 20% for most parameters. This indicates that sleep patterns are stable over time.

Adult↗
PubMed1990

The effect of arteriovenous malformation resection on cerebrovascular reactivity to carbon dioxide.

To investigate the cerebral hemodynamic changes associated with obliteration of arteriovenous malformations (AVMs), we studied 26 patients undergoing total microsurgical AVM resection during isoflurane and N2/O2 anesthesia. Detectors were placed 5 to 6 cm from the margin of the lesion and in a homologous contralateral position. Cerebral blood flow (CBF) was measured using the intravenous xenon-133 technique before and after AVM resection, during both hypocapnia and normocapnia at each stage. Intraoperative changes in CBF were related to a risk score system based on the patient's history and preoperative angiograms. Seven otherwise healthy patients undergoing spinal surgery were studied to control for anesthetic effects. Patient demographic and clinical data for the AVM group conformed to the expected strata of a large AVM population. The CBF increased after excision (22 +/- 1 ml/100 g/min before excision to 30 +/- 2 ml/100 g/min after excision; mean +/- SE, n = 25, P less than 0.002) without a hemispheric difference. CO2 reactivity increased slightly after excision (4.2 +/- 0.3% change/mm Hg before excision to 4.7 +/- 0.3% change/mm Hg after excision; n = 14, P less than 0.02). The baseline CBF and CO2 reactivity were not different from the control group. There was a weak correlation between the risk score and the percentage of change in the ipsilateral CBF, with a trend for the patients with the lowest risk to have the lowest CBF changes after resection. There was no relationship between CO2 reactivity and risk grade. None of the patients awoke from anesthesia with unexpected neurological deficits. The highest CBF increases were associated with postoperative brain swelling in one patient and fatal intracerebral hemorrhage in another. Both patients had normal CO2 reactivity before excision. One patient suffered postoperative intracerebral hemorrhage, attributable to technical problems, and had no increase in CBF. We conclude that, with an acute increase in the arteriovenous pressure gradient (and cerebral perfusion pressure) that results from shunt obliteration, there is an immediate global effect of AVM resection to increase CBF. Cerebrovascular reactivity to CO2 remains intact both before and after excision.

Adult↗
PubMed1990

Transcranial Doppler ultrasonographic changes after treatment for arteriovenous malformations.

We performed transcranial Doppler ultrasonography on 15 patients with arteriovenous malformations before and after embolization or surgical resection to compare quantitatively the hemodynamic effects of these two treatments. Changes in mean blood velocity and pulsatility index were analyzed in 19 treated feeding arteries. Blood velocity decreased by a mean of 38.1% or 46.5 cm/sec (p less than 0.0001, two-tailed paired t test); decreases were greater for surgically resected arteries (46.2% or 55.9 cm/sec, p less than 0.003) than for embolized arteries (30.8% or 38.0 cm/sec, p less than 0.0003). Pulsatility index increased by a mean of 54.7% or 0.25 (p = 0.0001); increases were greater for surgically resected arteries (65.8% or 0.29, p = 0.0045) than for embolized arteries (44.8% or 0.20, p less than 0.001). The differences in the changes in blood velocity and pulsatility index between treatment groups were not significant. These data demonstrate that embolization results in hemodynamic changes that are qualitatively similar to those occurring after surgical resection of arteriovenous malformations. Transcranial Doppler ultrasonography is a reliable and convenient noninvasive method for monitoring hemodynamic effects of treatments for arteriovenous malformations.

Adolescent↗
PubMed1990

Chronic cerebral blood flow changes following experimental subarachnoid hemorrhage in rats.

Experimental subarachnoid hemorrhage was induced in 52 adult male Wistar rats by microsurgical transclival basilar artery puncture. Telencephalic blood flow measured in 24 rats with subarachnoid hemorrhage was compared with that in 23 sham-operated rats and 10 unoperated control rats using the [14C]butanol indicator fractionation technique. Telencephalic blood flow was significantly less in the rats with subarachnoid hemorrhage than in the sham-operated rats 3 (78.7 +/- 6.9 [n = 7] and 112.0 +/- 8.5 [n = 8] ml/100 g/min, respectively; p less than 0.01), 7 (74.9 +/- 5.1 [n = 9] and 112.6 +/- 4.6 [n = 8] ml/100 g/min, p less than 0.001), and 14 (81.9 +/- 6.0 [n = 8] and 104.1 +/- 5.4 [n = 7] ml/100 g/min, p less than 0.01) days after surgery. Telencephalic blood flow in unoperated controls (114.7 +/- 4.9 ml/100 g/min) did not differ significantly from sham-operated rats. Clinically, the 52 rats with subarachnoid hemorrhage were indistinguishable from 32 sham-operated rats. Postmortem examinations in 10 rats used in a preliminary investigation demonstrated significant blood clot in the basal cisterns 2 hours after basilar artery puncture. Intracranial pressure was slightly elevated (2.3 mm Hg over baseline) 30 minutes after the hemorrhage (n = 7), but when measured 3 (n = 3) or 7 (n = 3) days after surgery it had returned to baseline. Histologic examination of the brains from 10 rats subjected to subarachnoid hemorrhage 7 (n = 5) or 14 (n = 5) days before sacrifice revealed no evidence of cerebral ischemia or vasculopathic changes in the cerebral arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The effects of norepinephrine depletion on cerebral blood flow in the rat.

Cerebral blood flow (CBF) was measured by [14C]butanol indicator fractionation in 10 rats given intraventricular injections of 6-hydroxydopamine (6-OHDA) compared to 8 saline-injected controls. Rats treated with 6-OHDA displayed an 83% reduction in cortical norepinephrine (NE) levels. CBF was significantly increased in 6-OHDA-treated rats compared to controls (average whole brain blood flow of 126.0 +/- 8.3 and 97.1 +/- 10.6 ml.min-1.10(-2)g-1 respectively, P less than 0.05). These studies suggest that noradrenergic innervation of the brain and cerebral microvasculature exerts a moderating effect on resting CBF.

Animals↗
PubMed1989

Cerebral revascularization: a review.

A review of the development and current methods of surgical revascularization of the cerebral circulation is presented. In addition to the conventional superficial temporal artery to middle cerebral artery (STA-MCA) bypass, the techniques of interposition vein grafting and vertebrobasilar revascularization are discussed. The results and implications of the International Cooperative Study are reviewed. Extracranial-intracranial (EC-IC) bypass grafting remains an essential procedure in the treatment of many cerebrovascular conditions, including Moya Moya disease and giant intracranial aneurysms. The efficacy of interposition vein grafts, as well as the EC-IC bypass in the treatment of vertebrobasilar insufficiency, acute cerebral ischemia, cerebral vasospasm, and multi-infarct dementia, remains to be determined. Several alternative revascularization procedures, including proximal MCA anastomosis and omental transposition, are in development.

Brain Diseases↗
PubMed1988

Prophylactic volume expansion therapy for the prevention of delayed cerebral ischemia after early aneurysm surgery. Results of a preliminary trial.

From June 1986 to June 1987, 47 consecutive patients with ruptured intracranial aneurysms were treated with immediate aneurysm surgery and prophylactic volume expansion therapy for ten to 14 days after subarachnoid hemorrhage (SAH). Twenty-four patients were admitted within three days of SAH. Twenty-three of these patients had an excellent result, and one patient died. There were no cases of delayed cerebral infarction. In 18 of 23 patients admitted more than three days after SAH, there was an excellent result. The other five patients had permanent morbidity related to the original SAH. These preliminary data suggest that immediate aneurysm surgery and aggressive postoperative prophylactic volume expansion in all patients can substantially reduce rebleeding and delayed cerebral ischemia, potential causes of morbidity, after aneurysmal subarachnoid hemorrhage. A more extensive prospective trial of this approach will be required to test this hypothesis.

Adult↗
PubMed1988

Rupture of a previously documented asymptomatic aneurysm enhances the argument for prophylactic surgical intervention.

A case is presented of an incidentally discovered 6-mm aneurysm that was left untreated and subsequently produced a subarachnoid hemorrhage. The patient had no previous history of intracranial hemorrhage from any other source. A case of this type has not been previously documented in the literature. This experience points out the potential for catastrophe in small unruptured aneurysms found in patients without previous subarachnoid hemorrhage. The extremely low operative morbidity for repair of these types of lesions in otherwise healthy individuals would argue strongly for prophylactic surgery in properly selected patients.

Female↗
PubMed1988

Evaluation of first night effect using ambulatory monitoring and automatic sleep stage analysis.

Home sleep recordings were conducted over three consecutive nights in 12 normal subjects using the Oxford Medilog 9000 system and automatic sleep stage analysis. The equipment was well tolerated and adequate sleep recordings were obtained on each test evening. The results showed that there was no significant differences over the three nights for any of the sleep parameters measured.

Adult↗
PubMed1988

Subarachnoid hemorrhage fails to produce vasculopathy or chronic blood flow changes in rats.

Cerebral blood flow was measured by a [14C]butanol indicator fractionation technique in rats subjected to subarachnoid hemorrhage, in control rats, and in rats given injections of buffered saline into the subarachnoid space (sham hemorrhage). Cerebral blood flow was significantly decreased in both the subarachnoid hemorrhage and sham hemorrhage rats 3 hours after injection. However, blood flow returned to control levels by 24 hours, and measurement for 14 days after subarachnoid hemorrhage failed to show any delayed decrease in cerebral blood flow. Electron microscopic studies of basilar arteries from rats subjected to subarachnoid hemorrhage 72 hours before killing failed to show any of the morphologic changes that have been associated with vasospasm in humans or in higher animal models. Our studies indicate that the rat model of subarachnoid hemorrhage has limited applicability to the study of subarachnoid hemorrhage following ruptured cerebral aneurysms in humans. However, although rats are not a perfect model of this clinical condition, some pathophysiologic changes similar to those observed in human subarachnoid hemorrhage have been demonstrated in this model and deserve further investigation.

Animals↗
PubMed1988

133Xe blood flow monitoring during arteriovenous malformation resection: a case of intraoperative hyperperfusion with subsequent brain swelling.

Measurement of regional cerebral blood flow (rCBF) using the i.v. 133Xe technique was carried out during resection of a right temporooccipital arteriovenous malformation (AVM) with ipsilateral middle and posterior cerebral arterial supply. Intraoperatively, a rCBF detector was in place over the right frontotemporal area, about 5 to 6 cm from the border of the AVM. Anesthesia was 0.75% isoflurane in oxygen and nitrous oxide. After dural exposure, the rCBF was 27 ml/100 g/min at a pCO2 of 29 mm Hg and a mean arterial pressure (MAP) of 90 mm Hg. The pCO2 was then elevated to 40 mm Hg, and the rCBF was increased to 55 ml/100 g/min at a MAP of 83 mm Hg. After AVM removal, the rCBF rose to 50 ml/100 g/min at a pCO2 of 27 mm Hg and a MAP of 75 mm Hg. The pCO2 was elevated to 33 mm Hg and the rCBF increased to 86 ml/100 g/min at a MAP of 97 mm Hg. During skin closure, the rCBF was 94 ml/100 g/min at a pCO2 of 26 mm Hg and a MAP of 97 mm Hg. The patient was neurologically normal postoperatively except for a mild, new visual field defect. After 2 to 3 days, the patient gradually developed lethargy, confusion, and nausea with relatively normal blood pressure. An angiogram revealed residual enlargement of the posterior cerebral artery feeding vessel. Computed tomography showed edema extending from the area of AVM resection as far as the frontal region, producing a significant midline shift anteriorly. Intraoperative rCBF monitoring revealed significant hyperperfusion after AVM resection, which was associated with signs and symptoms of the normal perfusion pressure breakthrough syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗