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Biomedical subjects

B M Stein

Publications and source records attributed to B M Stein.

At least 55 records · Page 3Linked 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↗
PubMed1990

Sporadic cerebral amyloid angiopathy with giant cell reaction.

We report a case of intracerebral hemorrhages due to sporadic cerebral amyloid angiopathy in a 43-year-old male with a luxuriant giant cell reaction. The amyloid was resistant to potassium permanganate-sulfuric acid oxidation and reacted with an antiserum to synthetic beta-protein. The distribution and histologic characteristics of the multinucleated giant cell reaction suggest that it represents a foreign-body reaction rather than giant cell arteritis.

Adult↗
PubMed1990

A study of the reactivity of feeding vessels to arteriovenous malformations: correlation with clinical outcome.

Isolated segments from the feeding arteries to arteriovenous malformations (AVMs) from 24 patients were studied in vitro. In a perfusion chamber, isometric contraction of these arterial rings to various vasoactive substances was recorded and correlated with the following: spontaneous activity, spasm as seen in the operating room; radiographic evidence of ectasia preoperatively and postoperatively; and postoperative course. Of the 24 patients studied, four patients had nonreactive AVM nutrient vessels upon in vitro testing. In addition, these vessel segments displayed no spontaneous activity although all of the other vessels tested developed spontaneous activity while in the perfusion chamber. The patients with "unreactive vessels" had an increased incidence of postoperative edema and hemorrhage in the surrounding brain, consistent with the symptoms of normal perfusion pressure breakthrough. Thus, our study utilizes an in vitro technique to evaluate a specific segment of the AVM complex, the feeding vessel, which permitted us to assess abnormalities of reactivity in these vessel segments. This method may be useful for future evaluations of the pathophysiology of AVMs.

Animals↗
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

Intramedullary ependymoma of the spinal cord.

A consecutive series of 23 patients underwent operative removal of an intramedullary spinal cord ependymoma between January, 1976, and September, 1988. Thirteen women and 10 men between the age of 19 and 70 years experienced symptoms for a mean of 34 months preceding initial diagnosis. Eight patients had undergone treatment prior to tumor recurrence and referral. Mild neurological deficits were present in 22 patients on initial examination. The location of the tumors was predominantly cervical or cervicothoracic. Radiological evaluation revealed a wide spinal cord in all cases. Magnetic resonance (MR) imaging was the single most important radiological procedure. At operation, a complete removal was achieved in all patients. No patient received postoperative radiation therapy. Histological examination revealed a benign ependymoma in all cases. The follow-up period ranged from 6 to 159 months (mean 62 months) with seven patients followed for a minimum of 10 years after surgery. Fourteen patients underwent postoperative MR imaging at intervals ranging from 8 months to 10 years postoperatively. No patient has been lost to follow-up review and there were no deaths. No patient showed definite clinical or radiological evidence of tumor recurrence during the follow-up period. Recent neurological evaluation revealed functional improvement from initial preoperative clinical status in eight patients, no significant change in 12 patients, and deterioration in three patients. The data support the belief that long-term disease-free control of intramedullary spinal ependymomas with acceptable morbidity may be achieved utilizing microsurgical removal alone.

Adult↗
PubMed1990

Clinical evaluation of the spinal cord and nerve roots.

In this article the techniques of clinical neurological evaluation are discussed. It is suggested that correlation of the initial clinical evaluation with radiological investigation remains the most efficient method to determine the type, timing, and appropriateness of surgical intervention. An appreciation of the logical somatotopic organization of spinal cord tracts and cell groups forms the basis of precise localization and provides some insight into the etiology and prognosis of spinal cord dysfunction.

Humans↗
PubMed1990

Pineal tumors.

Pineal-region tumors constitute a diverse group of tumors. We recommend an aggressive surgical approach to these tumors for diagnostic as well as therapeutic purposes. Approximately one third of all pineal tumors are benign, resectable lesions and surgical therapy provides the best opportunity for a cure. Debulking procedures are beneficial in patients with malignant tumors both surgically and because they provide tissue specimens for diagnostic purposes to properly direct postoperative adjuvant therapy. Surgical results have been excellent, with an overall mortality and morbidity rate of 12 per cent and virtually no permanent deficits in patients with benign tumors.

Adolescent↗
PubMed1990

Functional anatomy of the spinal cord and related structures.

This article reviews the anatomy of the vertebral canal and its contents from a surgical perspective. The normal and pathological relationships of intradural structures are addressed. Spinal cord blood supply, metabolism, and ischemia are discussed in detail. A clinically oriented biomechanical analysis of forces acting within the spinal canal under both physiological and pathological conditions is also presented.

Arteries↗
PubMed1990

Intradural extramedullary tumors in adults.

Meningioma, nerve sheath tumors, and filum terminale ependymoma account for over 90% of primary intradural extramedullary tumors in adults. The demographics, radiological evaluation, and surgical techniques employed for their removal are reviewed in this article. The authors' approach to intraspinal tumors with extraspinal extension is discussed.

Adult↗
PubMed1990

Intramedullary tumors in adults.

The authors review their approach to the surgical management of intramedullary neoplasms. An emphasis is placed on surgical technique and judgment based primarily on the gross characteristics of the tumor. Aggressive removal, irrespective of tumor histology, is recommended for those neoplasms that are clearly demarcated from surrounding spinal cord tissue.

Adult↗
PubMed1990

Miscellaneous intradural pathology.

The topics discussed in this article include secondary neoplasia, hemorrhage, meningeal cysts, infectious and inflammatory conditions, and intradural disc herniation. Although they are relatively uncommon in occurrence it is important that these disorders be included in the differential diagnosis of patients harboring intradural pathology. The epidemiology, clinical features, and treatment considerations of these conditions are presented.

Follow-Up Studies↗
PubMed1989

Regional distribution of cerebral arteriovenous malformations. Interactions with sex and handedness.

On the basis of clinical observation and a developmental theory of cerebral laterality, Geschwind and Galaburda suggested that cerebral arteriovenous malformations (AVMs) are more common in the left hemispheres of male patients. We tested this hypothesis by examining interactions among sex, handedness, and location of lateralized, supratentorial AVMs. Data from 112 cases were analyzed by log-linear procedures. We found that (1) females had a greater proportion of left-hemisphere AVMs, whereas males showed an opposite trend; (2) there were no interactions between sex and handedness; and (3) nondextrals showed a higher proportion of AVMs located in frontal regions, regardless of the hemispheric side of the lesion. Although these findings appear to be inconsistent with the Geschwind-Galaburda hypothesis, the inconsistency may be attributable to the embryonic stage at which this developmental abnormality occurs. In addition, the unexpected findings may also reflect our use of multivariate statistical procedures, which control for interaction effects.

Adolescent↗
PubMed1989

Immunoreactive S-antigen in cerebrospinal fluid: a marker of pineal parenchymal tumors?

This investigation evaluated the possibility that the occurrence of S-antigen in cerebrospinal fluid (CSF) might be used as a preoperative marker of pineal parenchymal tumors (pineoblastoma and pineocytoma). Such a marker could provide a means of preoperatively differentiating these neoplasms from pineal region tumors of other origin. The S-antigen, also known as the 48-kD protein or arrestin, is a highly antigenic protein originally found in the retina and pineal gland. In the retinal photoreceptors and submammalian pineal photoreceptors the protein is thought to be involved in phototransduction; its function in the mammalian pinealocyte is unknown. S-Antigen immunoreactivity also occurs in certain neoplastic cells of retinoblastomas, pineocytomas, pineoblastomas, and cerebellar medulloblastomas. This study included a group of 13 patients with tumors of the pineal region. Samples of CSF were obtained preoperatively and analyzed for the S-antigen using western blot technology. Tumor biopsy material was classified according to conventional neurohistological criteria and was also examined by immunocytochemical techniques for the presence of the S-antigen. S-Antigen immunoreactivity was found in the preoperative CSF of the one patient found to have pineocytoma; tumor tissue removed from this patient was the only neoplastic tissue examined in this study which contained S-Antigen immunoreactive tumor cells. Furthermore, hydroxyindole-O-methyltransferase activity was detectable in the pineocytoma but not in three other pineal tumors, and melatonin levels in the CSF of the pineocytoma patient were the highest in the patient group examined. These preliminary results suggest that testing for S-antigen in CSF might be useful in characterizing and treating tumors of the pineal region and, when identified in conjunction with other markers, it might also help to better define pineal parenchymal tumors. This study needs confirmation with a larger number of patients. If this approach is eventually found to be a reliable predictor of pineal cell tumors, it may supplant the need for surgical biopsies before initiating appropriate adjunctive therapy.

Antigens↗
PubMed1988

Normal brain-stem auditory evoked potentials with abnormal latency-intensity studies in patients with acoustic neuromas.

Brain-stem auditory evoked potentials (BAEPs) are highly sensitive for detecting acoustic neuromas but false-negative results occur. We studied BAEPs preoperatively in 39 cases of acoustic neuroma. Absolute and interpeak latencies ipsilateral to the tumor, and interaural latency differences, were normal in four patients with small tumors. In three of these, however, results of latency-intensity studies were abnormal. In one patient, the latency-intensity result became normal postoperatively. If acoustic neuroma is suspected, and BAEPs are normal by usual criteria, latency-intensity functions should be examined to maximize chances of detecting a small tumor.

Acoustic Stimulation↗
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↗