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Biomedical subjects

R A Solomon

Publications and source records attributed to R A Solomon.

At least 73 records · Page 4Linked to original sources
PubMed1993

Cardiac performance preserved despite thiopental loading.

BACKGROUND: Some cerebral artery aneurysms require cardiopulmonary bypass and deep hypothermic circulatory arrest to be clipped safely. During bypass these neurosurgical patients often are given large doses of thiopental in the hope that additional cerebral protection will be provided. However, thiopental loading during bypass has been associated with subsequent cardiac dysfunction in patients with heart disease. This study was undertaken to determine how patients without concomitant heart disease would respond to thiopental loading. METHODS: Twenty-four neurosurgical patients with giant cerebral aneurysms and little or no cardiac disease were anesthetized with fentanyl, nitrous oxide, and isoflurane. Thiopental was titrated to achieve electroencephalographic burst-suppression before bypass, and the infusion was continued until after separation. Prebypass hemodynamic and echocardiographic measurements were obtained during a stable baseline and 15 min after thiopental loading began. They were repeated after bypass. RESULTS: Prebypass thiopental loading increased heart rate from 61 +/- 11 to 72 +/- 13 beats/min and decreased stroke volume from 43 +/- 10 to 38 +/- 8 ml.beat-1.m-2, but arterial and filling pressures, vascular resistance, cardiac index, and ejection fraction remained the same. Before bypass, thiopental plasma concentration measured 28 +/- 8 micrograms/ml. Loading continued for 2-3 h until after bypass was terminated, and the overall infusion rate was 18 +/- 5 mg.kg-1.h-1. All patients were easily separated from bypass without inotropic support. Following bypass, vascular resistance was decreased; heart rate, filling pressures, and cardiac index were increased; stroke volume had returned to its baseline; and ejection fraction was unchanged. CONCLUSIONS: It was concluded that if preoperative ventricular function is good, thiopental loading to electroencephalographic burst-suppression causes negligible cardiac impairment and does not impede separation from cardiopulmonary bypass.

Adult↗
PubMed1993

Transcranial Doppler detection of anterior cerebral artery vasospasm.

The performance of transcranial Doppler in the detection of anterior cerebral artery vasospasm and vasospasm in patients after subarachnoid haemorrhage was analysed. Transcranial Doppler and cerebral angiography were performed within the same 24 hours on each of 41 patients with acute subarachnoid haemorrhage. Sensitivity and specificity of transcranial Doppler to classify middle cerebral arteries, anterior cerebral arteries, and patients with angiographic vasospasm were determined at mean velocities of 120 and 140 cm/s. Accuracy of transcranial Doppler was better at 140 than at 120 cm/s. For the middle cerebral artery, sensitivity was 86%, specificity 98%. For the anterior cerebral artery, sensitivity was 13%, specificity 100%. Among all patients, sensitivity was 45%, specificity 96%. Among patients with anterior communicating artery aneurysms, sensitivity was 14%, specificity 90%. Therefore, transcranial Doppler accurately differentiates between middle cerebral arteries with and without vasospasm on angiography, but has a very low sensitivity for detecting anterior cerebral artery vasospasm and vasospasm in patients with anterior communicating artery aneurysms. Since vasospasm may involve anterior cerebral arteries while sparing middle cerebral arteries, especially after rupture of an anterior communicating artery aneurysm, caution should be exercised in using negative transcranial Doppler results to make treatment decisions based on the assumed absence of vasospasm.

Adult↗
PubMed1993

Nitric oxide production during focal cerebral ischemia in rats.

BACKGROUND AND PURPOSE: Nitric oxide has been implicated as a mediator of glutamate excitotoxicity in primary neuronal cultures. METHODS: A number of indicators of brain nitric oxide production (nitric and cyclic guanosine monophosphate [cGMP] concentrations and nitric oxide synthase activity) were examined after bilateral carotid ligation and right middle cerebral artery occlusion in adult rats. RESULTS: Brain nitrite was significantly increased in the right versus left cortex 5, 10, and 20 minutes after middle cerebral artery occlusion (P < .05), with a return to baseline at 60 minutes. There were no significant changes in cerebellar concentrations. Cortical levels of cGMP were increased at 10, 20, and 60 minutes after occlusion, with significant right-to-left differences (P < .05). Cerebellar concentrations of cGMP were also increased but without significant side-to-side differences. Nitric oxide synthase activity increased approximately 10-fold from baseline 10 minutes after occlusion in the right cortex but decreased markedly by 60 minutes from its peak at 10 minutes. The right-to-left difference in nitric oxide synthase activity was significant at 20 minutes (P < .05). Pretreatment of rats with NG-nitro-L-arginine, a nitric oxide synthase inhibitor, abolished the rise in nitrite and cGMP. CONCLUSIONS: These results suggest that a sharp transient increase in the activity of nitric oxide synthase occurs during the first hour of cerebral ischemia, which leads to a burst in nitric oxide production and activation of guanylate cyclase.

Amino Acid Oxidoreductases↗
PubMed1992

Sleep and 5-HT2 receptor sensitivity in recovered depressed patients.

The increase in slow wave sleep which followed administration of the 5-HT2 receptor antagonist, ritanserin, was not significantly different between a group of 12 recovered, drug free depressed patients and a group of 12 health matched controls. The results suggests that there is no underlying abnormality in the 5-HT2 receptor regulation of slow wave sleep in recovered depressives, and that abnormalities in this measure reported previously in such patients may have been caused by use of concomitant tricyclic antidepressant medication. The baseline sleep parameters did not differ between recovered depressives and controls with the exception of stage 1 sleep, which was increased in the patient group.

Adult↗
PubMed1992

Caudate hemorrhage with moyamoya-like vasculopathy from atherosclerotic disease.

BACKGROUND AND PURPOSE: Caudate hemorrhage usually results from hypertension, rupture of arteriovenous malformation or aneurysm, or rarely, moyamoya disease. Moyamoya-like changes related to severe atherosclerotic occlusive disease, usually causing ischemic stroke, have been reported. CASE DESCRIPTION: A 51-year-old normotensive patient was admitted with headache due to a left caudate hematoma with ventricular extension. There was a history of smoking, leg claudication, elevated cholesterol, and coronary artery disease. Angiography demonstrated complete extracranial carotid occlusion on the left and atherosclerotic stenosis at the bifurcation on the right, with supraophthalmic occlusion distally. At the base of the brain, bilateral moyamoya-like vessels, presumed to be secondary to atherosclerotic occlusion, were evident, but neither aneurysm nor arteriovenous malformation was present. Cerebral blood flow and transcranial Doppler studies indicated severely impaired cerebral perfusion that improved after bilateral extracranial-to-intracranial bypass surgery. CONCLUSIONS: Atherosclerotic occlusive carotid disease with moyamoya-like changes may be a rare cause of caudate hemorrhage. A decrease in moyamoya vessels with bypass surgery may reduce the risk of recurrent hemorrhage.

Carotid Arteries↗
PubMed1992

A simple and reliable technique to monitor intracranial pressure in the rat: technical note.

A technique for intracranial pressure (ICP) monitoring in the rat that uses a permanent cisterna magna cannula is described. The cannula is placed into the subarachnoid space through the atlanto-occipital membrane with the operating microscope and is secured with cement. The distal end is connected to a pressure transducer and a polygraph recorder. To study the consistency of this technique, 12 anesthetized adult rats were subjected to baseline ICP measurements 2 days after placement of the cannula. Baseline pressures ranged between 1.0 and 10.0 cm H2O, with a mean of 5.6 cm H2O. Respiratory variations were detected in all tracings, and manual abdominal compressions (Valsalva maneuver) correlated with immediate transient rises in ICP in all rats. While CSF pressure was being continuously monitored, rats were subjected to subarachnoid hemorrhage induced by transclival basilar artery puncture. Of the 12 rats, 10 showed a moderate transient rise in cerebrospinal fluid pressure, which peaked approximately 2 minutes after subarachnoid hemorrhage (mean peak change, 10.5 cm H2O; range, 0-32.5 cm H2O). Reliable pressure tracings were obtained in three of five animals examined 3 days after subarachnoid hemorrhage (ICP range, 4.0-4.5 cm H2O; mean, 4.2 cm H2O). We conclude that this cannula is easy and inexpensive to construct and that it provides reliable ICP tracings during experimental procedures in the rat.

Animals↗
PubMed1992

The effect of mild hypothermia on permanent focal ischemia in the rat.

The effect of mild hypothermia on cerebral injury was evaluated in a rat model of permanent middle cerebral artery (MCA) and ipsilateral carotid artery occlusion. The MCA occlusion was performed in rats at temporalis muscle temperatures of 30 degrees C, 33 degrees C, 34.5 degrees C and 36.5 degrees C (n = 10, 8, 10, and 13, respectively). The animals were kept at the desired temperature for 1 hour and rewarmed to 36.5 degrees C. In a separate group of animals (n = 11), the temperature was decreased to 33 degrees C 1 hour after performing the arterial occlusion at normothermia. These animals were rewarmed to 36.5 degrees C after another hour with side by side controls (n = 9) kept at 36.5 degrees C throughout the experiment. Twenty-four hours after the MCA occlusion, rats were killed and the percentage of infarcted right hemisphere was determined in coronal brain sections with 2,3,5-triphenyltetrazolium chloride. The percentage of infarcted volume at 30 degrees C, 33 degrees C, and 34.5 degrees C (9.3 +/- 2.1%, 8.2 +/- 2.2%, and 8.4 +/- 2.2%) (SEM) was significantly smaller than at 36.5 degrees C (19.6 +/- 1.6%, P < 0.01). There were no significant differences between the hypothermic groups. When rats were cooled to 33 degrees C 1 hour after the arterial occlusion, the percentage of infarcted volume was also significantly smaller than the control group (8.0 +/- 1.8% vs. 17.4 +/- 2.1%) (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Reduction by delayed hypothermia of cerebral infarction following middle cerebral artery occlusion in the rat: a time-course study.

The effect of hypothermia on neuronal injury following permanent middle cerebral artery (MCA) occlusion in the rat was examined. Moderate hypothermia (body temperature 24 degrees C) was induced before MCA occlusion (0-minute delay group) in six rats, at 30 minutes in eight rats, and at 1 (seven rats), 2 (seven rats), and 3 (nine rats) hours after occlusion. The rats were kept at a 24 degrees C body temperature for 1 hour, then allowed to rewarm over 90 minutes. The animals were sacrificed 24 hours after MCA occlusion, and infarction was visualized by staining of coronal sections with 2,3,5-triphenyltetrazolium chloride. Infarct volumes were compared to matched normothermic control rats (body temperature 36 degrees C). Additional groups of 0-minute delay hypothermic (10 rats) and control animals (nine rats) were sacrificed 72 hours after MCA occlusion to examine the effects of prolonged survival. A significant reduction in the percentage of infarcted right hemisphere was seen in the animals sacrificed after 24 hours with 0-minute, 30-minute, and 1-hour delays in inducing hypothermia (mean +/- standard error of the mean: 2.2% +/- 0.7%, 4.4% +/- 0.9%, and 3.6% +/- 1.1%, respectively) as compared to normothermic control rats (10.8% +/- 1.5%, p less than 0.01 by Student's t-test). In the 2- and 3-hour delay groups, the percentage of infarcted right hemisphere was 17.1% +/- 2.4% and 12.0% +/- 2.7%, respectively, and no decrease in infarct volume was observed. The 0-minute delay hypothermia group sacrificed after 72 hours also displayed a significant reduction in right hemisphere infarct compared to their respective controls (4.8% vs. 11.7%, p less than 0.05). These findings indicate that, in the setting of permanent MCA occlusion, hypothermia markedly decreases brain injury even when its induction is delayed for up to 1 hour after the onset of ischemia. Ischemic damage does not appear to be merely retarded but permanently averted.

Animals↗
PubMed1992

The treatment of associated intracranial aneurysms and arteriovenous malformations.

Cerebral arterial aneurysm associated with arteriovenous malformation (AVM) has been described with a variable incidence, averaging 10% of AVM cases. The present series includes 39 patients with this association, derived from a total of 400 patients with AVM's evaluated and treated since 1970. The aneurysms are classified into four major groups, each carrying particular therapeutic implications. Optimum treatment of these lesions is based in part on a knowledge of the hemodynamic alterations associated with the AVM's. In most of these cases, the symptomatic lesion was treated first; occasionally, when feasible, both lesions were treated during the same operation. All patients had some form of treatment, either surgical or endovascular, directed to at least one of the two types of lesions. All symptomatic lesions were treated and all ruptured aneurysms were obliterated. There were no deaths in this series.

Adolescent↗
PubMed1992

Unruptured aneurysms and postoperative volume expansion.

After a ruptured aneurysm has been clipped in patients with multiple aneurysms, the question often arises whether to use volume expansion and/or hypertensive treatment to prevent delayed cerebral ischemia (vasospasm). There is understandable concern regarding the possible rupture of unprotected aneurysms under additional hemodynamic stress. In a series of 199 patients with aneurysmal subarachnoid hemorrhage who underwent early surgery, 31 were left with one or more unprotected aneurysms postoperatively. All patients were treated with prophylactic volume expansion based on a previously reported protocol. Mean central venous pressure during treatment was 10.3 cm H2O and mean arterial blood pressure 141/76 mm Hg; volume expansion was continued for 7 to 10 days. Eight patients developed symptoms of delayed cerebral ischemia and required additional volume expansion and induced hypertension. After institution of hypertension, four of these patients experienced a reversal of their symptoms, while four others developed cerebral infarcts. One patient died from massive cerebral infarction following vasospasm refractory to all measures. No patient suffered rupture of an unprotected aneurysm during hypervolemic treatment. It is concluded that the benefit of prophylactic hypervolemic hypertension in postoperative aneurysm patients warrants its use even in patients with unprotected aneurysms.

Albumins↗
PubMed1991

Three psychological treatments for bulimia nervosa. A comparative trial.

The specificity and magnitude of the effects of cognitive behavior therapy in the treatment of bulimia nervosa were evaluated. Seventy-five patients who met strict diagnostic criteria were treated with either cognitive behavior therapy, a simplified behavioral version of this treatment, or interpersonal psychotherapy. Assessment was by interview and self-report questionnaire, and many aspects of functioning were evaluated. All three treatments resulted in an improvement in the measures of the psychopathology. Cognitive behavior therapy was more effective than interpersonal psychotherapy in modifying the disturbed attitudes to shape and weight, extreme attempts to diet, and self-induced vomiting. Cognitive behavior therapy was more effective than behavior therapy in modifying the disturbed attitudes to shape and weight and extreme dieting, but it was equivalent in other respects. The findings suggest that cognitive behavior therapy, when applied to patients with bulimia nervosa, operates through mechanisms specific to this treatment and is more effective than both interpersonal psychotherapy and a simplified behavioral version of cognitive behavior therapy.

Adolescent↗
PubMed1991

Quantitative EEG monitoring for patients with subarachnoid hemorrhage.

We evaluated the sensitivity of continuous quantitative EEG in 11 patients with subarachnoid hemorrhage (SAH). We correlated compressed spectral array (CSA) and trend analysis (TA) of total power (1-30 Hz), frequency centroid (1-30 Hz), alpha ratio and percent delta power with clinical and radiological findings. For all ischemic events (n = 11), the most sensitive TA parameter was a change in total power (91%), followed by changes in alpha ratio (64%), frequency centroid (55%), and percent delta (45%). Comparable CSA features were changes in power (44%) and slowing (39%). Total power and frequency varied independently. In 4 cases, EEG findings on TA appeared before clinical changes. Continuous quantitative EEG may be useful for monitoring and predicting ischemia following SAH. TA of individual EEG parameters is more sensitive than CSA, and total power is the most sensitive.

Adult↗
PubMed1991

Hypothermic protection following middle cerebral artery occlusion in the rat.

The effects of deep hypothermia on ischemic neuronal injury were examined using a permanent middle cerebral artery occlusion model in the rat. Animals were maintained at temporalis temperatures of either 24 degrees C or 36 degrees C and killed 6 hours after arterial occlusion. Normothermic rats displayed an average infarct volume of 25.1% +/- 1.6% of the right hemisphere, whereas hypothermic rats had an average infarct volume of 4.1% +/- 1.3% (p less than 0.001). The right/left hemispheric ratio was 1.05 +/- 0.02 in the normothermic group and 1.00 +/- 0.02 in the hypothermic group (p less than 0.05). These results suggest that hypothermia to 24 degrees C may reduce cerebral infarction and edema formation following middle cerebral artery occlusion in the rat.

Animals↗
PubMed1991

New aneurysm clip appliers for "key-hole" neurosurgery.

A new set of aneurysm clip appliers has been developed to overcome many of the obstacles to safe clipping of complex intracranial aneurysms. The applier set consists of six units, each one delivering clips at a different specified angle to the applier shaft. These appliers have been independently tested on over 250 aneurysm operations and found to be of great utility.

Equipment Design↗
PubMed1991

Transient hypothermia reduces focal ischemic brain injury in the rat.

The effect of transient hypothermia on focal cerebral ischemia was evaluated using a rat model of permanent middle cerebral artery (MCA) occlusion. MCA occlusion was performed on 10 rats at a temporalis muscle temperature of 24 degrees C (hypothermic group) and on 10 rats at 36 degrees C (normothermic group). Rats in the hypothermic group were maintained at 24 degrees C for 1 hour after MCA occlusion and then allowed to rewarm to 36 degrees C over the next 2 hours. Animals in both groups were killed 24 hours after MCA occlusion. Cerebral infarcts were visualized by staining of coronal brain sections with 2,3,5-triphenyltetrazolium chloride. Normothermic rats displayed an average infarct volume of 233.1 +/- 13.2 mm3 (standard error of the mean), whereas hypothermic rats had an average infarct volume of 166.2 +/- 22.8 mm3 (P less than 0.01). Expressed as a percentage of the volume of the right hemisphere, the normothermic group had an infarct volume of 22.1 +/- 1.5% and the hypothermic group an infarct volume of 16.0 +/- 2.2% (P less than 0.05). These results demonstrate that transient hypothermia to a temporalis muscle temperature of 24 degrees C significantly reduces subsequent infarct size in an experimental model of permanent arterial occlusion.

Animals↗
PubMed1991

Deep hypothermic circulatory arrest for the management of complex anterior and posterior circulation aneurysms.

Giant aneurysm surgery continues to be a technically difficult task with high operative morbidity. Recent advances in cardiac surgery have fueled interest in the technique of deep hypothermic circulatory arrest for the treatment of giant and complex intracranial aneurysms. Fourteen patients with giant intracranial aneurysms operated on with the technique of deep hypothermic circulatory arrest are presented. All 14 aneurysms were successfully treated. There were 2 intraoperative strokes: 1 resulted in severe disability and 1 resulted in mild disability. No significant neurological complications were related to the technique of cardiopulmonary bypass with deep hypothermic circulatory arrest. This initial experience indicates that patients with giant and complex intracranial aneurysms might benefit from a surgical approach that included the use of deep hypothermic circulatory arrest.

Adolescent↗
PubMed1991

Effect of massive intraoperative thiopental loading on cardiovascular hemodynamics and myocardial performance.

Anesthetics that protect the brain may also depress the heart. We recently anesthetized a patient with a giant cerebral aneurysm of the basilar artery who had it clipped during circulatory arrest. Thiopental loading was carried out prior to and during cardiopulmonary bypass, and we monitored transesophageal echocardiographic function and the hemodynamic profile throughout. The patient demonstrated little change in cardiovascular parameters or myocardial performance, and we conclude that the massive dose of thiopental was well tolerated.

Journal Article↗