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Biomedical subjects

M H Weiss

Publications and source records attributed to M H Weiss.

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

Sixth nerve schwannomas. Report of two cases.

Two cases of sixth cranial nerve schwannoma are presented with a review of four other cases from the literature. The clinical spectrum, neuroradiological findings, and surgical outcome of the six cases are discussed. There are two distinct clinical presentations for sixth cranial nerve schwannomas. Type I sixth nerve schwannomas present with sixth nerve palsy and diplopia and arise from the cavernous sinus. In contrast, type II sixth nerve schwannomas have a more severe presentation with obstructive hydrocephalus, raised intracranial pressure, sixth nerve palsy, and diplopia. This type arises along the course of the sixth cranial nerve in the prepontine area. Cavernous sinus involvement in either type may preclude total surgical excision and indicate an increase possibility for recurrence.

Abducens Nerve↗
PubMed1991

Compulsive polydipsia following meningioma resection: an epileptic phenomenon? Case report.

The authors report the case of an individual who developed compulsive polydipsia following resection of a left sphenoidal ridge meningioma. The episodic, stereotyped nature of his symptoms, response to treatment, and electroencephalographic and magnetic resonance imaging findings are all highly consistent with temporal lobe-onset epilepsy. The pathophysiology of this underrecognized phenomenon is discussed.

Adult↗
PubMed1991

Monostotic fibrous dysplasia of the clivus. Case report.

A case report of monostotic fibrous dysplasia of the clivus in a postadolescent woman is described. Although fibrous dysplasia of craniofacial structures is well documented, involvement of the clivus has not been reported. Diagnosis by clinical, radiographic, and histopathological features is detailed. Implications for the role of surgery and management are discussed.

Adult↗
PubMed1991

Recidivism in congenital cholesteatoma surgery.

Forty-four cases of congenital cholesteatoma in the pediatric age group have been treated surgically. There have been three residual cholesteatomas, which were localized to the anterior aspect of the malleus and were easily excised. Two cases of postero-superior retraction pockets developed post-operatively, and these were treated by conventional tympanomastoid surgery with excision of the retraction pocket and grafting. All five of the patients with recidivism have experienced no further difficulty.

Child, Preschool↗
PubMed1990

Lack of efficacy of megestrol acetate in the treatment of unresectable meningioma.

The detection of hormone receptors on meningiomas raises the possibility of hormonal manipulation as a form of therapy. Since progesterone receptors are found on meningiomas more frequently and in greater amounts than estrogen receptors, manipulation of progesterone levels would be most promising. A trial of the oral progesterone agonist megestrol acetate for the treatment of unresectable meningioma was therefore performed. Megestrol acetate was administered at a dose of 40 mg four times daily which could be escalated to 80 mg four times daily. Nine patients (six meningothelial, two fibrous, and one anaplastic meningiomas) were treated for 1 to 12 months. No tumor responses were seen. However three patients required discontinuation of therapy due to deteriorating vision within 2 1/2 months. The major systemic toxicity of megestrol acetate was weight gain with a median weight gain of 14 kg for patients treated for at least 6 months. Due to the lack of efficacy and the significant toxicity noted, megestrol acetate is not recommended for the treatment of meningioma. However clinical trials of progesterone antagonists would still be of interest.

Adult↗
PubMed1990

Cochlear implant flap complications.

In a series of 52 patients who received cochlear implants, 4 patients suffered flap complications (7.7%). The problems encountered involved the postauricular flap and were usually minor in nature. None required explantation as a direct result of these complications. Flap ischemia in a patient with Cogan's syndrome and vasculitis, two cases of suture extrusion with one having exposure of the implant, and a case of receiver unit magnet extrusion repaired with a vascularized pericranial flap based upon temporalis muscle are presented. Flap design in patients who have had postauricular incisions demands special consideration. Principles useful for avoiding complications as well as their management are discussed.

Adult↗
PubMed1990

Predictive value of brainstem evoked response in the diagnosis of acoustic neuroma.

Predictive value positive is the probability that a positive test result represents a true positive finding. Twenty-six patients with brainstem evoked response findings characteristic of retrocochlear hearing loss were studied. Four acoustic neuromas were diagnosed in this group after radiologic workup. The predictive value in this population was 15%. Statistical considerations are presented.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1989

Computed tomography after skull base resection.

We have obtained serial CT scans in the evaluation and follow-up of 80 patients with lesions of the skull base. CT scanning has been useful for assessment of recurrence in this group of patients, many of whom underwent complex ablative and reconstructive procedures.

Follow-Up Studies↗
PubMed1989

Ultrastructure of the orbital pathway for cerebrospinal fluid drainage in rabbits.

An increasing number of physiological and morphological studies indicate that cerebrospinal fluid (CSF) drains via nonarachnoidal pathways in several mammalian species. Ultrastructural tracer studies were undertaken to examine the orbital route for CSF absorption in the rabbit. At the termination of the optic nerve subarachnoid space, an area of connective tissue containing numerous small tortuous channels is present. Ferritin (molecular weight 400,000) infused into the ventricles at normal and increased intraventricular pressure was present in these channels by 15 minutes postinfusion, and subsequently reached the intraorbital connective tissue. Elevating the intraventricular pressure did not noticeably alter the morphological appearance of this region or change the gross distribution pattern of the ferritin. Ferritin did not penetrate the scleral barrier to reach the choriocapillaris, nor did it breach the arachnoid barrier layer proximal to the transitional zone at the optic subarachnoid space to reach the dura mater. These results are very similar to those described for the hamster orbital region and the rabbit cribriform region. These experiments support the concept that macromolecules exit the subarachnoid space at the termination of the optic nerve via open channels, and that no significant barrier to drainage of macromolecules in CSF is present at this location.

Animals↗
PubMed1989

Pituitary gland metastasis from adenocarcinoma of the prostate. Case report.

A case of prostatic carcinoma metastasis to the pituitary gland is reported. The presentation and rarity of such a lesion is addressed. The literature review yielded only isolated case reports of symptomatic brain metastases unassociated with bone disease from adenocarcinoma of the prostate. The management options of such a lesion are discussed.

Adenocarcinoma↗
PubMed1988

Flow cytometric analysis of pituitary tumors. Correlation of nuclear antigen p105 and DNA content with clinical behavior.

Flow cytometric quantitation of the proliferation-associated nuclear antigen p105 and DNA content was performed on nuclear suspensions from 12 paraffin-embedded pituitary macroadenomas and one pituitary carcinoma and correlated with clinical outcome. Median follow-up was 41 months (range, 33 to 48 months). Three of the 13 tumors (23%) had an identifiable aneuploid peak. Of the four tumors that recurred or metastasized, only one was aneuploid. Nuclear antigen analysis of all diploid tumors showed enhanced p105 expression in G2M phase cells compared to G0G1 cells. The G2M/G0G1 fluorescence ratio for p105 was consistently higher (P less than 0.05) for the three diploid tumors that recurred (median, 1.32 arbitrary fluorescence units; range, 1.27 to 1.80) than for the seven nonrecurrent diploid tumors (median, 1.20 arbitrary fluorescent units; range 1.14 to 1.22). These findings indicate a low incidence of DNA aneuploidy among pituitary tumors and suggest that for diploid adenomas, measurement of p105 may provide information useful in predicting prognosis and directing postoperative adjuvant therapy.

Adolescent↗
PubMed1988

Metastatic carcinoma to pituitary adenomas: a report of two cases.

Two cases of carcinoma metastatic to pituitary adenomas are reported. One patient had a prostatic adenocarcinoma, giving rise to metastases in an adenoma found incidentally at autopsy; clinically and immunohistochemically, the adenoma showed lack of endocrine activity. The second patient had symptoms of cortisol excess. A corticotroph adenoma associated with a malignant neoplasm was diagnosed ante mortem; at autopsy a pancreatic endocrine neoplasm was found. Immunohistochemistry and electron microscopy were important in elucidating the primary tumor. The formation of extraportal vascular channels and altered blood flow may have importance in the pathogenesis of cancer metastases to pituitary adenomas.

Adenocarcinoma↗
PubMed1988

Dysphagia in infants and children.

The evaluation of dysphagia in pediatric patients involves many special considerations. A diagnostic approach to this problem is presented.

Abnormalities, Multiple↗
PubMed1987

Blood-cerebrospinal fluid barrier alteration following intraventricularly administered cholera toxin.

Cholera toxin (CT) has been reported to double cerebrospinal fluid (CSF) formation following its introduction into the ventricular system of cats and dogs. In our laboratory we noted that CT used in a similar fashion in rabbits and cats resulted in only a slight increase in CSF formation and was associated with a steadily rising protein content in the cisterna magna effluent. To further investigate this finding, rabbits and cats underwent ventriculo-cisternal perfusions, one group with CT introduced into the ventricles and the other without. In the rabbit only, radioiodinated serum albumin (125I-RISA) was given i.v. Other groups of rabbits had 125I-RISA or 125I-CT injected into the ventricles. The group of rabbits receiving intraventricular CT experienced a 4-10-fold elevation in the amount of both protein and 125I-RISA in the cisterna magna effluent compared with the control group. Electrophoretic pattern of the protein present in the effluent was similar to that of rabbit plasma. Autoradiography of the brains of those animals given intraventricular 125I-CT were found to have a very high uptake of 125I-CT in the choroid plexus and along all exposed ventricular surfaces, a finding not evident when 125I-RISA alone was given intraventricularly. It is concluded that CT altered the blood-CSF barriers allowing the reference marker to penetrate these barriers and plasma to leak into the CSF. These findings appear to account for most if not all of what was thought to be an increase in CSF formation in response to intraventricular CT.

Animals↗