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Biomedical subjects

M N Shalit

Publications and source records attributed to M N Shalit.

At least 19 recordsLinked to original sources
PubMed1993

The effect of intracranial hypotension on cerebral blood flow in a feline model.

Intracranial hypotension is a known clinical entity but its pathophysiology has been meagerly studied. Any setting with cerebrospinal fluid leakage or drainage can cause intracranial hypotension. A feline model of kaolin induced chronic hydrocephalus with controlled cerebrospinal fluid drainage from a lateral ventricle yields reproducible intracranial hypotension of up to -15 torr for several hours to -80 torr of about 10 minutes. The magnitude of this hypotension is significantly greater than can be attained by cisterna magna drainage. This new model allows multiple cerebral parameters to be studied during intracranial hypotension. In 11 cats with stable blood pressure and intracranial hypotension of at least -15 torr, regional blood flow utilizing the hydrogen clearance method in the cerebral cortex and subcortical nuclei was unchanged relative to the baseline. These results imply that: 1) cerebral vascular autoregulation is maintained during significantly increased perfusion pressure due to negative intracranial pressure, 2) the symptomatology of clinical intracranial hypotension is not due to decreased cerebral perfusion.

Animals↗
PubMed1992

Surgical outcome in an elderly population with intracranial meningioma.

Thirty seven patients aged 70 and over (mean = 74 years) with an intracranial meningioma who had craniotomy between the years 1978-88 were reviewed. There were 20 women and 17 men. Resection was total in 28 (76%) and subtotal in 9 (24%) cases and each tumour was histologically verified. The location of the tumours were: base of skull 11, convexity 10, parasagittal 9, falx 6, and tentorial 1. The most frequent associated diseases were: hypertension (35%), chronic ischaemic heart disease (22%) chronic obstructive pulmonary disease (19%), and diabetes (14%). The Karnofsky Scale (KS) score before surgery ranged from 30 to 90 (mean = 59). It was less than 40 in ten patients. The length of anaesthesia during the surgical procedure varied from 4 to 12 hours and was not related to the outcome. There were two perioperative deaths (mortality = 5.4%). There were major complications in 8 patients and minor complications in 7 patients. In a mean follow up period of 29 months (shortest 6 and longest 96 months) the results were: excellent (KS 90-100) 39%, good (KS 70-80) 49%, fair (KS 60) 6%, and poor (KS 40-50) 6%. The difference between the mean preoperative KS value (KS = 59) and the mean postoperative KS value (KS = 80) was statistically significant (P less than 0.001). The results support a more aggressive therapeutic approach to the elderly patient with an intracranial meningioma.

Aged↗
PubMed1990

[Transsphenoidal approach to pituitary tumors].

Over the past 2 years 44 patients with pituitary tumors underwent transsphenoidal resection. A specialized team performed the procedure so as to optimize the results. 20 patients had nonsecreting macroadenomas and 24 suffered from hormone-secreting adenomas. All who presented with visual deterioration had improved vision after operation. Only 3 developed new endocrine deficits following surgery, while in 4 with invasive prolactinoma vision improved following surgery but hyperprolactinemia persisted. 8 of 11 patients with acromegaly were cured, while in the other 3, who had invasive tumors, growth hormone decreased significantly. 8 of 9 patients with Cushing's disease were cured. In only 1 case did a permanent complication, diabetes insipidus, occur; there was no mortality. These results demonstrate the efficacy of the procedure and the advantages of a dedicated team.

Adenoma↗
PubMed1989

Intracranial meningiomas after high-dose irradiation.

Three patients who presented with intracranial meningiomas 12, 15, and 20 years, respectively, after therapeutic high-dose irradiation of a primary brain tumor are described. Analysis of these cases and similar documented cases suggests that meningiomas after high-dose irradiation constitute a recognizable entity. Patients with such tumors received radiation therapy at a young age (mean age, 9.4 years). After a latent period of 2 to 47 years (mean, 19.8 years) they developed meningiomas at the site of irradiation, at a much younger age than patients with "spontaneous" meningiomas. Similar to the situation with meningiomas after low-dose irradiation, a relatively high proportion of meningiomas induced by high-dose irradiation tend to be malignant and biologically aggressive. A very young age at the time of irradiation seems to predispose to the induction of malignant meningiomas, rather than benign tumors. These unusual features provide indirect evidence that high-dose radiation may play a role in the pathogenesis of meningiomas.

Adolescent↗
PubMed1989

Perioperative external ventricular drainage in obstructive hydrocephalus secondary to infratentorial brain tumours.

Of 148 patients with infratentorial brain tumours which were operated upon during a 5 year period, 59 patients had associated obstructive hydrocephalus, as evidenced by preoperative CT scan. External ventricular drainage was performed in these cases at time of surgery. CSF drainage was continued in the postoperative period for a mean of 2.3 (+/- 1.6) days. Only 6 of these 59 patients (10%) required a subsequent indwelling shunt. The infection rate was 10% and the total mortality was 8%. Perioperative ventricular drainage during and following the removal of posterior fossa tumours causing hydrocephalus provides an effective alternative to the preoperative placement of an indwelling shunt. Problems of shunt dysfunction, tumour seeding and upward herniation are thereby avoided. Postoperative ICP monitoring and drainage of blood and debris laden CSF is performed, increasing the safety of the postoperative period and possibly reducing the incidence of aseptic meningitis and postoperative shunt requirement.

Astrocytoma↗
PubMed1988

Technical note: the removal of free peritoneal catheters in the revision of ventriculoperitoneal shunts.

The widespread usage of ventriculoperitoneal shunts has been followed by a plethora of complications. One of these complications, the separation and migration of the distal tubing to be free intraperitoneally, has been relatively disregarded in the literature both as a phenomenon and as to treatment. We present our experience with nine such cases, four involving two peritoneal catheters. Unless contraindicated, we think that such tubing should be removed during shunt revision by single digit blind palpation of the tubing. No complications arose from this procedure, and the postoperative course was uneventful. The indications for this procedure are discussed in relation to the relevant literature.

Cerebrospinal Fluid Shunts↗
PubMed1988

Intracranial pressure monitoring after elective intracranial surgery. A retrospective study of 514 consecutive patients.

A retrospective study of 514 consecutive patients whose intracranial pressure (ICP) was monitored after elective supratentorial or infratentorial surgery is reported. Of the 412 patients operated on in the supratentorial region, 76 (18.4%) had a postoperative sustained ICP elevation exceeding 20 torr. Abnormally high ICP occurred after 13 (12.7%) of the 102 infratentorial operations. Risk factors for postoperative ICP elevation were: resection of glioblastoma in 27.2% of cases, repeat surgery in 42.9% of cases, and protracted surgery (greater than 6 hours) in 41.7% of cases. Of the 89 patients with elevated ICP, 47 (52.8%) had an associated clinical deterioration. In 19 of these, the rise in ICP occurred before this deterioration was noticed, leading as a rule to quick diagnostic and management response. In eight patients clinical deterioration was noticed before the rise in ICP, and in 20 it happened simultaneously. The higher the level of ICP elevation, the greater were the chances of associated deterioration. The most common findings on computerized tomography scanning in 35 of 89 patients with elevated ICP were brain edema (19 cases) and bleeding in the tumor bed (15 cases). Mannitol, thiopental, additional hyperventilation, and reintubation (in patients who were previously extubated) were used to reduce ICP, in addition to surgical decompression whenever indicated. Thirteen patients with raised ICP and clinical deterioration underwent reoperation. The postoperative infection rate was 1.2% (six cases). In only one patient could infection be attributed to ICP monitoring. It was concluded that ICP monitoring is advantageous in the immediate postoperative management after elective intracranial surgery and is almost risk-free. It should therefore be used liberally, especially when risk factors for ICP elevation can be identified prior to the end of surgery.

Brain Neoplasms↗
PubMed1985

Conus ganglioglioma in a 2 1/2-year-old boy. Case report.

Gangliogliomas are rare tumors, primarily seen in patients under the age of 30 years. They occur least commonly in the spinal cord. This report presents a 2 1/2-year-old boy who harbored an intramedullary conus tumor with the light microscopic appearance of a ganglioglioma. The neurobiological behavior of this tumor is yet to be determined.

Child, Preschool↗
PubMed1984

Neurosurgical management of single brain metastasis.

A series of 74 consecutive cases undergoing craniotomy for single brain metastasis in the Beilinson Medical Center between October 1975 and October 1981 were reviewed. All patients underwent radiation therapy after craniotomy. The most common metastasis was that of unknown origin (35%), followed by lung (24%) and breast (16%). Overall median survival after craniotomy was 6.6 months. Overall 1- and 2-year survival rates were 30 and 15%, respectively. Operative mortality (30 days) was 15%. For the patients with metastases to the lung, median survival was 7.5 months and 1-year survival rate was 33%. It appears from this report that two dominant factors affect the prognosis of these patients. The first is the long latent interval (time between diagnosis of primary tumor and detection of metastasis). The second is the location of the metastasis; those with lesions in the cerebral hemispheres had a far better outcome than those with cerebellar lesions (p less than 0.0001).

Adult↗
PubMed1984

Radiation-induced cerebral meningioma: a recognizable entity.

The authors retrospectively analyzed the clinical and histopathological findings in 201 patients with intracranial meningiomas operated on in the period 1978 to 1982. Forty-three of the patients (21.4%) had at some previous time received radiation treatment to their scalp, the majority for tinea capitis. The findings in these 43 irradiated patients were compared with those in the 158 non-irradiated patients. Several distinctive clinical and histological features were identified in the irradiated group, which suggest that radiation-induced meningiomas can be defined as a separate nosological subgroup. The use of irradiation in large numbers of children with tinea capitis in the era prior to the availability of griseofulvin may be responsible for a significantly increased incidence of intracranial meningiomas.

Adult↗
PubMed1983

Regional cerebral blood flow in the acute stage of experimentally induced subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) was induced in 13 adult mongrel cats by a slow injection of fresh autogenous blood into the cisterna magna. Serial determinations of regional cerebral blood flow (rCBF) in the cortex and deep-seated areas (internal capsule, thalamus, and caudate nucleus) were made during the following 2 hours, while intracranial pressure (ICP) was maintained at normal values. A decrease in rCBF was observed in all the areas examined. This reduction followed a characteristic triphasic pattern with an initial steep decline immediately after the SAH. The clinical implications of these findings are discussed.

Animals↗