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Biomedical subjects

B M Stein

Publications and source records attributed to B M Stein.

At least 73 records · Page 4Linked to original sources
PubMed1988

Surgical approaches to aneurysms of the vertebral and basilar arteries.

This report details the surgical treatment of 44 patients with aneurysms of the vertebral and basilar arteries. Three different surgical approaches were utilized depending on the location of the aneurysm. These were an anterior supratentorial approach, a lateral suboccipital approach, and a combined supratentorial and infratentorial approach along the petrous apex, with section of the lateral sinus and the tentorium. Using these operative exposures, aneurysms located anywhere on the vertebral-basilar arteries may be safely visualized and clipped. In this series, 1 patient died, 4 other patients had significant, long-lasting morbidity as a result of operation, and 32 patients returned to work and a normal life-style. These data support operative intervention under proper conditions and with selection of the correct exposures for the treatment of vertebral-basilar aneurysms.

Adult↗
PubMed1988

Cavernous malformations of the spinal cord.

Six patients with intramedullary cavernous malformations of the spinal cord are presented. Four men and two women presented with acute, subacute, or episodic signs and symptoms of spinal cord dysfunction, ranging in duration from 3 days to 25 years. All patients underwent operative resection of the malformation. Complete removal was achieved in five patients. Neurological function either stabilized or improved postoperatively in all patients; follow-up ranged from 4 to 84 months. The increasing awareness of the propensity for recurrent hemorrhage, clinical features, and resectability of these malformations are discussed.

Adolescent↗
PubMed1988

Unusual spinal cord enlargement related to intramedullary hemangioblastoma.

In a series of 60 intramedullary spinal cord tumors, there were eight cases of hemangioblastoma. Seven of these eight patients displayed evidence of diffuse spinal cord enlargement over multiple levels at a considerable range beyond the actual location of the tumor. One patient had a large intramedullary cyst that accounted for only part of the enlargement, and one had multiple tumor nodules. Six other patients had no obvious explanation for the diffuse cord enlargement. This phenomenon of extensive spinal cord enlargement appears to be unique to this type of tumor and not related to multiple tumors or extensive cyst formation. The cord enlargement seems to be related to edema and congestion of the spinal cord, perhaps secondary to the vascular shunt present in the hemangioblastomas. The possible pathophysiology and clinical importance of this observation is discussed.

Adult↗
PubMed1987

Intramedullary melanotic schwannoma of the cervicomedullary junction.

We report a case of a patient with an intramedullary tumor of the cervicomedullary junction. At operation, the tumor was noted to be highly pigmented, and pathological study demonstrated that the tumor was a melanotic schwannoma. Both intramedullary schwannomas and melanotic schwannomas in any location in the body are exceedingly rare. This is the first reported case of an intramedullary melanotic schwannoma of the central nervous system. The possible origin of this tumor is discussed.

Aged↗
PubMed1987

Interhemispheric approach for the surgical removal of thalamocaudate arteriovenous malformations.

A series of 250 surgically treated cerebral arteriovenous malformations (AVM's) is presented, in which 22 lesions were located primarily in the thalamus and caudate nucleus. A standardized interhemispheric approach through the posterior corpus callosum and into the atrium of the lateral ventricle was utilized for the surgical removal of these AVM's. Total removal was confirmed by angiography in 18 patients; removal was subtotal in four cases. There were no deaths in this group of patients. Disturbances of recent memory pre- and postoperatively were seen in half of the patients, but most of these deficits were temporary. Other complications included: postoperative homonymous hemianopsia (six cases), transient hemiparesis (three cases), hemisensory loss (two cases), Parinaud's syndrome (one case), and recurrent hemorrhage 2 years after surgery (one case). All 22 patients returned to their previous occupations and are leading independent lives. The results of this experience indicate that thalamocaudate AVM's can be effectively treated by resection.

Adolescent↗
PubMed1986

Surgical management of arteriovenous malformations that follow the tentorial ring.

In a series of 200 intracranial arteriovenous malformations (AVMs) treated surgically, 33 malformations were situated very close to the tentorial incisura. All but one of these AVMs were totally removed. Four operative approaches were utilized in this group of patients: an interhemispheric approach for lesions of the medial hemispheres, splenium of the corpus callosum, and posterior 3rd ventricle; a subtemporal approach to the inferior and medial temporal lobe; a supracerebellar-infratentorial approach to anterodorsal cerebellum and quadrigeminal regions; and a subtemporal transtentorial exposure to the dorsolateral mesencephalon. There were no surgical deaths. Three patients had unsatisfactory outcomes. Our experience with this series indicates that deep cerebral AVMs in the region of the tentorial incisura may be safely removed if there is proper selection of operative approach and attention to surgical technique.

Adolescent↗
PubMed1986

CT of pineal region tumors.

The computed tomographic (CT) features of pineal region tumors were analyzed in 60 histologically proven tumors. This is the largest reported series of histologically verified pineal region tumors studied with CT. The tumors were classified as germ-cell tumors, glial tumors, pineal parenchymal tumors, and meningiomas. Preenhancement germinomas revealed characteristically high-density areas with calcification; uniform enhancement was seen after injection of contrast material. When present, pineal calcification was engulfed by the tumor. Teratomas, present only in male patients, revealed areas of mixed densities (e.g., calcification and fatty areas) and did not show significant contrast enhancement. Spontaneous intraventricular rupture was noted in one case. Unlike other tumors, the original pineal calcification could be recognized in two-thirds of glioma cases and was displaced anteriorly and superiorly in most. Gliomas were hypodense to isodense on precontrast scans and enhanced in a nodular and a ring fashion. Benign pineal parenchymal tumors showed iso- to hyperdense areas with nodular enhancement after injection of contrast material. Pineoblastomas were well defined hyperdense masses without calcification on precontrast scans. After injection of contrast material, they showed well defined enhancement with occasional small, central lucencies. Meningiomas were hyperdense in most cases, uniformly enhanced in a homogeneous fashion, and showed a tentorial attachment.

Brain Neoplasms↗
PubMed1986

Management of arteriovenous malformations of the brain stem.

In a series of 250 intracranial arteriovenous malformations (AVM's), 12 malformations involved the brain stem. Nine of these lesions were treated surgically, with complete obliteration in eight. There were no operative deaths, and only two patients were made worse by surgery. In the nonsurgically treated group, one patient had embolization therapy and two patients underwent radiation therapy. Results in these three patients have not been satisfactory. These data indicate that brain-stem AVM's can be surgically removed with acceptable morbidity.

Adolescent↗
PubMed1986

Neuroendocrine aspects of pineal tumors.

The evaluation and treatment of pineal region tumors has changed dramatically in the past decade. New imaging techniques result in earlier diagnosis. Surgical techniques now permit removal of benign tumors (about one third of cases). Pathologic diagnosis is obtained for the remainder, and postoperative therapy can be planned rationally. Germ cell tumors pose a particularly difficult problem for the pathologist because they often contain mixed germ cell elements. Biologic markers, beta HCG and AFP, aid diagnosis and can be monitored in serum and CSF to assess response to treatment. Only boys develop precocious puberty with pineal tumors. What appears to be puberty is actually pseudoprecocious puberty, due to ectopic production of HCG by their neoplasms (choriocarcinomas or germinomas with syncytiotrophoblastic giant cells). HCG can stimulate tests to produce testosterone, but FSH is necessary (together with LH or HCG) to stimulate ovaries to produce estrogen. Diabetes insipidus with pineal tumors is usually due to spread to the hypothalamus by ventricular seeding, but we report a case of aqueductal stenosis with diabetes insipidus resulting from a massively dilated third ventricle. Rarely, hydrocephalus may trigger true precocious puberty, a syndrome easily differentiated from pseudoprecocious puberty by endocrinologic tests. There are no biologic markers to diagnose pineal parenchymal tumors. Elevation of melatonin in plasma or CSF and increased tumor biosynthetic activity has been reported in isolated cases, but the range of melatonin values in normals is very wide, and melatonin levels do not correlate with specific pathologic tumor types. Both parenchymal and nonparenchymal tumors may increase melatonin nonspecifically by interfering with regulatory mechanisms of the normal pineal gland.

Brain Neoplasms↗
PubMed1985

Operative approaches to midline tumors.

We have now operated and confirmed 80 tumors of the pineal region. Our experience is that 30 percent of these are benign, encapsulated and can be removed, and that only 30 percent represent germinomas. Another 30 percent are astrocytomas of varying grade. The preferred therapy in the majority of these tumors is radiotherapy and its extent depends upon the analysis of the lumbar spinal fluid. Chemotherapy has been reserved for tumors of the primitive embryonic type. The result of surgery for benign tumors has been excellent and the recurrence rate extremely low. In the germinoma series, the response to radiation therapy in our experience has been promising initially with resolution of the tumor by CT scan. However, we have noted recurrence of some of these tumors after radiotherapy approximately 6 to 8 years after the institution of therapy. The pineoblastomas are extremely difficult to treat by whatever means and the same holds true for the malignant pineocytomas. Our experience is too limited to say what the outcome will be in the chemotherapeutic management of the more primitive and embryonal tumors.

Astrocytoma↗
PubMed1985

Immunocytochemistry of pineal astrocytes: species differences and functional implications.

Immunohistochemical demonstration of glial fibrillary acidic protein (GFAP) was performed in human, sheep, rat and guinea pig pineal bodies to determine if there were species differences. Specialized "basket-like" arrangements of many GFAP-positive astrocytic processes were shown around sheep pinealocytes. Human pineals contained scattered astrocytic cell bodies and a moderate number of GFAP-positive astrocytic processes which, as in sheep, also surrounded pinealocytes, but without the dense basket-like arrangements. In both species GFAP-positive fibers were concentrated at the periphery of pseudolobules and around blood vessels. Rat and guinea pig pineals contained only rare astrocytic cell bodies and few GFAP-positive fibers throughout the glands, but had a concentration of parallel GFAP-positive fibers at the stalk. GFAP-positive fibers in human and sheep pineals may be derived from both intra- and extraglandular sites, whereas in rodents only rare processes appear to be derived from within the gland. Astrocytes may play a role in modulation of pineal indoleamines and norepinephrine, and the species differences observed suggest that this effect may be important in sheep and human pineals but not in rodents.

Adult↗
PubMed1985

Intraoperative BAER monitoring and hearing preservation in the treatment of acoustic neuromas.

We treated 20 cases of acoustic neuromas in the last 2 1/2 years using the suboccipital approach with intraoperative monitoring of eighth nerve function in an attempt to preserve hearing. Total tumor removal was accomplished in 18 cases. Three tumors were small (less than 2 cm in size); 3 tumors were moderate sized (2 to 3 cm) and 14 tumors were large (greater than 3 cm). In 15 cases, all BAER components were lost during surgery. These patients had no postoperative hearing. In five patients there was intraoperative preservation of some or all BAER components. These included the three patients with small tumors and two other patients with moderate sized tumors. One patient with a moderate size tumor had preservation of wave 1 only, and had no postoperative speech discrimination. One patient with a small tumor retained all 5 BAER components, but had no postoperative hearing. Three patients in our series retained functional hearing after surgery, including 3 of 5 patients with tumors 2 cm or smaller. Intraoperative BAER monitoring appears to be useful in predicting postoperative hearing. Tumor size seems to be the primary factor in preservation of hearing following acoustic neuroma surgery.

Adult↗
PubMed1985

Therapeutic modalities for pineal region tumors.

Since there is no radiographic test that can definitely predict the histology of a pineal tumor, we believe all patients should be treated first with a surgical approach to the tumor. This usually is accomplished by the supracerebellar-suboccipital route. Hydrocephalus is best treated at the time of surgery with ventricular drainage. Sometimes, surgery can decompress the CSF obstruction, and the need for a shunt can be averted following surgery; if not, the ventricular drain is converted to a shunt several days later. If a pineal tumor is found to be benign and encapsulated, it is removed by surgery, and the patient requires no additional therapy. Meningiomas, cysts, and low grade cystic astrocytomas all fall into this category. Some germ cell tumors are well differentiated and can also be grossly excised, but one must exercise caution in assuming that the entire tumor is benign. Many seemingly well-differentiated teratomas contain admixtures, sometimes microscopic, of more malignant elements. Careful pathological evaluation of the operative specimen and analysis of biological markers (AFP and beta-HCG) can alert the clinician to the presence of malignant tumor. With germinomas, radiation therapy is initially effective, and chemotherapy has a proven role in treating recurrences. Spinal radiotherapy is withheld unless there is a strong suspicion of spinal seeding. Tumors of pineal cell origin are radiosensitive and should be treated with radiation therapy. Because these tumors are rare, there is little data to date to justify one particular form of chemotherapy over another for recurrent pineal cell malignancies. Likewise, whether chemotherapy is preferable to radiation therapy in the initial treatment of nongerminomatous germ cell malignancies is as yet unclear.

Brain Neoplasms↗
PubMed1984

Hemangioblastoma of the third ventricle.

A case of intraventricular hemangioblastoma not associated with von Hippel-Lindau disease is presented. Only one other case of intraventricular hemangioblastoma has been reported. The literature on supratentorial hemangioblastomas is reviewed, and the problems of histological identification of such lesions are discussed.

Brain↗
PubMed1984

Arteriovenous malformations of the medial cerebral hemisphere and the limbic system.

In a series of 164 resected arteriovenous malformations (AVM's), 25 were located on the medial aspect of the cerebral hemispheres. These AVM's require special attention because of the following characteristics: 1) their obscure location, making resection more difficult than the usual AVM; 2) a high incidence of intraventricular hemorrhage; 3) their frequent involvement of the choroid plexus of the ventricles and the arteries and veins related to the choroid plexus; and 4) the configuration of their venous drainage, which is often to superficial veins as well as to the deep venous systems. The results achieved with excision of these difficult AVM's were good. There was no mortality and the morbidity rate was under 4%. The surgical exposures, which were tailored to the location of these malformations, are described in detail.

Cerebral Angiography↗
PubMed1983

Ablations of the mammillary nuclei in monkeys: effects on postoperative memory.

A new procedure was developed for ablating the mammillary nuclei in nonhuman primates via direct visual exposure. Using this technique, monkeys receiving lesions of the mammillary nuclei were compared to control animals after surgery to assess the retention of preoperatively acquired visuospatial discriminations and subsequent postoperative ability to attain a demanding spatial memory task. Although the lesions proved to be accurate and complete, no changes in gross behavior or deficits in preoperatively acquired visual and spatial behaviors were noted. The monkeys with mammillary body lesions were, however, impaired in their ability to acquire postoperatively the demanding spatial memory task. These findings are consistent with previous investigations suggesting that the mammillary bodies are involved in the acquisition of spatial discriminations and skills.

Animals↗