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Biomedical subjects

E Arbit

Publications and source records attributed to E Arbit.

At least 73 records · Page 4Linked to original sources
PubMed1989

Modified open thoracic rhizotomy for treatment of intractable chest wall pain of malignant etiology.

We describe the surgical technique of modified open thoracic rhizotomy for treatment of intractable chest wall pain of malignant etiology. In a series of 14 patients, 9 (64%) had an excellent result, 4 (29%) had a good result, and 1 (7%) had a poor result. Successful palliation was made possible by identification with computed tomographic scan or magnetic resonance imaging of the nerve roots involved. Pain control lasted in most patients until death (median, 22 weeks; range, 6 to 45 weeks). The extrathecal procedure described has certain advantages over intradural transection of nerve roots. Indications for performing this procedure are discussed along with other therapeutic options.

Adult↗
PubMed1989

Patterns of failure following treatment for glioblastoma multiforme and anaplastic astrocytoma.

Recurrence patterns of glioblastoma multiforme (25) and anaplastic astrocytoma (9) were studied using CT scans of 34 patients who received all or a portion of their surgical treatment at Memorial Sloan-Kettering Cancer Center from January 1983 through February 1987. Thirty-two patients presented with unifocal tumors and two with multifocal tumors. All patients received radiation therapy following initial surgery. Eighteen patients who underwent re-operation following CT evidence of recurrence had histologic verification of recurrent tumor; sixteen patients had radiographic evidence of recurrence only. Seventy-eight percent (25/32) of unifocal tumors recurred within 2.0 cm of the pre-surgical, initial tumor margin, defined as the enhancing edge of the tumor on CT scan. Fifty-six percent (18/32) of tumors recurred within 1.0 cm of the initial tumor margin. Tumors for which a gross total resection was accomplished tended to recur closer to the initial tumor margin than did subtotally resected tumors (p greater than 0.1). Extensive pre-operative edema was associated with a decreased distance between initial and recurrent tumor margins. Large tumors were generally not more likely to recur further from the initial tumor margin than were smaller tumors. No unifocal tumor recurred as a multifocal tumor. Only one tumor (initially near the midline) recurred in the contralateral hemisphere. The findings support the use of partial brain irradiation for post-operative treatment of glioblastoma multiforme and anaplastic astrocytomas, and may help to determine the most appropriate treatment volume for interstitial irradiation.

Adult↗
PubMed1989

Inability of computed tomography appearance of recurrent malignant astrocytoma to predict survival following reoperation.

Computed tomographic (CT) scans of 39 patients who underwent reoperation for recurrent malignant astrocytoma at Memorial Sloan-Kettering Cancer Center from 1980 through 1987 were reviewed and correlated with the patients' clinical course. Histologic diagnosis (anaplastic astrocytoma v glioblastoma multiforme) had a statistically significant impact on survival following reoperation (P = .038). Patients with high preoperative performance status (P = .29), total resection by postoperative CT scan (P = .15), and frontal lobe tumors (P = .17) tended to survive longer following reoperation. The size of the tumor at the time of recurrence did not correlate with survival following reoperation. Patients with a small amount of peritumoral edema at the time of recurrence tended to survive longer, but the effect was small (P = .16). Prognosis following reoperation cannot be accurately predicted on the basis of tumor appearance on CT scan.

Adolescent↗
PubMed1989

Intraoperative measurement of cerebral and tumor blood flow with laser-Doppler flowmetry.

A new technique, laser-Doppler flowmetry, has been used intraoperatively to measure blood flow responses in normal brain tissue and brain tumor to blood pressure and arterial blood gas alterations. We have observed that blood flow is reduced in most cerebral tumors, and that most tumors retain the normal response to changes in arterial blood gas; however, these responses are varied. One group of tumors in our study demonstrated an autoregulatory capacity; a second behaved passively--that is, blood flow changes followed blood pressure--while a third showed no response.

Animals↗
PubMed1989

An animal model of epidural compression of the spinal cord.

A new model of subacute compression of the spinal cord is described. Using an expanding epidural mass, a gradual, progressive, and highly reproducible neurological deficit was induced in rats over a 7-day period, resulting in paraplegia. Studies of spinal cord edema, disruption of the blood-spinal cord barrier, and somatosensory evoked responses, as well as histopathological and microangiographical studies, revealed a marked similarity to changes produced in other spinal compression models and in humans. The model may serve to answer some fundamental questions regarding the pathophysiology and efficacy of various treatment modalities of spinal cord compression.

Animals↗
PubMed1989

A dose-response study of dexamethasone in a model of spinal cord compression caused by epidural tumor.

In order to assess the clinical and biological effects of glucocorticoids in the therapy of epidural spinal cord compression, the T8-10 epidural space of 50 rats was implanted with Walker 256 tumor. The rats were studied 10 to 20 days later when they became paraparetic. The regional blood-spinal cord transport constant (K, a function of the blood-spinal cord barrier) of 14Carbon-labeled aminoisobutyric acid was measured with quantitative autoradiography 6 hours after intravenous injection of low-dose (0.1 mg/kg), intermediate dose (1 mg/kg), and high-dose (10 mg/kg) dexamethasone. The effects of dexamethasone in these doses on the clinical signs and water content of the compressed cord were also evaluated 40 hours after treatment began. The K factor increased 730% in compressed compared with noncompressed spinal cords (p less than 0.001). Dexamethasone induced a dose-related reduction of both K (p = 0.007) and water content of the compressed cord (p less than 0.0001). Stabilization or, more rarely, improvement of weakness at 24 and 40 hours posttreatment correlated with the dose of dexamethasone (r = 0.88, p less than 0.001). This study demonstrates that dexamethasone has a dose-related beneficial clinical effect associated with an improvement of blood-spinal cord barrier breakdown and a reduction of the water content of the compressed cord. This study supports the use of highdose dexamethasone for the initial treatment of epidural spinal cord compression.

Animals↗
PubMed1989

Sufentanil, alfentanil, and fentanyl: impact on cerebrospinal fluid pressure in patients with brain tumors.

In order to evaluate the safety of the new synthetic opioids, alfentanil and sufentanil, in neurosurgical patients, we administered sufentanil 1 microg/kg i.v., alfentanil 50 microg/kg i.v. followed by an infusion of 1 microg/kg/min, or fentanyl 5 microg/kg i.v. to 30 patients with supratentorial tumors anesthetized with nitrous oxide (N2O), 60% in O2. Lumbar cerebrospinal fluid pressure (CSFP) and mean arterial pressure (MAP) responses were recorded for 10 min thereafter, while ventilation was held constant [mean PaCO2 = 36.1 +/- 1.0 mm Hg (SEM)]. There was no change in CSFP after fentanyl. In contrast, both sufentanil and alfentanil caused increases in CSFP, equal to 89 +/- 31 % SE (p < 0.05) and 22 +/- 5% (p < 0.05), respectively. MAP decreased after administration of each opioid. Peak decreases in cerebral perfusion pressure (MAP - CSFP) were 14 +/- 3% after fentanyl, 25 +/- 5% after sufentanil, and 37 +/- 3% after alfentanil. It is concluded that because sufentanil increased CSFP in patients who have brain tumors, it also may be contraindicated in other neurosurgical patients at risk for intracranial hypertension. Alfentanil may share this propensity, since CSFP increased despite a profound reduction in MAP. Among the three opioids evaluated, only fentanyl appears to be appropriate for supplementing N2O-2 anesthesia in patients who have compromised intracranial compliance.

Journal Article↗
PubMed1988

High dose versus low dose dexamethasone in experimental epidural spinal cord compression.

A compound of methylcellulose-silicone expanding progressively over a 1-week period by moisture absorption was implanted in the midthoracic epidural space of 17 Sprague Dawley adult rats. When the animals became paraplegic 6.3 +/- 1.6 days later, they were randomized into three groups: untreated control (n = 5), high dose dexamethasone (HD, 1.25 mg/kg intramuscularly, twice daily, n = 5), and low dose dexamethasone (LD, 0.125 mg/kg intramuscularly, twice daily, n = 7). Motor strength was evaluated daily by an observer unaware of the treatment given to the rats. Animals treated with dexamethasone (HD or LD) improved faster than untreated control animals. No significant difference in the rate of recovery or degree of motor improvement was noted between the HD and LD groups. Mortality was higher in the HD group because of infections and gastrointestinal perforation/bleeding.

Animals↗
PubMed1988

Percutaneous electrocoagulation of the trigeminal nerve using CT guidance. Technical note.

Computerized tomography guidance can be used during placement of an electrode for the ablation of the trigeminal nerve or gasserian ganglion. A combination of a scout view and axial images through the skull base provides adequate visualization of the needle and foramen ovale. This method is recommended in patients who cannot be properly positioned for fluoroscopy or when there is poor visualization of the foramen on conventional radiographs.

Electrocoagulation↗
PubMed1987

One-stage meningomyelocele closure and ventriculoperitoneal shunt placement.

Thirteen myelodysplastic neonates were observed to have birth head circumferences below the 90th percentile but ventriculomegaly on preoperative computed tomograms. These infants all required later shunting for hydrocephalus. We then began performing a one-stage procedure of meningomyelocele closure and shunt insertion in all neonates with ventriculomegaly on preoperative computed tomograms without regard to head circumference. Seventeen of 24 additional patients have had the one-stage procedure; 4 have required later shunting; 1 shunt infection (6%) was encountered. We conclude that neonatal head circumference does not predict hydrocephalus, and that ventriculomegaly on preoperative computed tomograms identifies neonates who will require shunting.

Cerebrospinal Fluid Shunts↗
PubMed1987

Can calcium antagonists affect the hemostatic mechanism and promote rebleeding? An experimental study.

Calcium antagonists are currently under investigation as potential beneficial drugs in the prevention of cerebral vasospasm. However, some calcium antagonists have the propensity to inhibit platelet aggregation. This study investigated the danger posed by the administration of calcium antagonists for recurrent hemorrhage in a simulated rat model of subarachnoid hemorrhage. We found that verapamil, a calcium antagonist with antiplatelet activity, lowers clot resistance and may promote rebleeding.

Animals↗
PubMed1987

Reoperation in the treatment of recurrent intracranial malignant gliomas.

Fifty-five consecutive patients with recurrent intracranial malignant gliomas were reoperated at Memorial Sloan-Kettering Cancer Center from 1972 to 1983. The patients were 10 to 70 years old (median, 48 years). Thirty-five patients (64%) had glioblastoma multiforme, and 20 (36%) had anaplastic astrocytoma. The median interval between the first operation and reoperation was 43 weeks. The Karnofsky rating before reoperation ranged from 40 to 90 (median, 70). Eleven patients (20%) had more than one reoperation. The mortality rate was 1.4% per procedure, and the morbidity rate was 16% per procedure. After reoperation, 41 patients (75%) had chemotherapy and/or radiation therapy. The median survival for all patients was 92 weeks. The median survival after reoperation was 36 weeks. Patients with Karnofsky ratings of greater than or equal to 70, with anaplastic astrocytomas, or in whom gross total removal of the tumor was undertaken lived longer than their respective counterparts (P less than 0.05). Prereoperation Karnofsky rating and extent of surgical resection were the most important independent factors related to survival after reoperation according to multivariate analysis (P less than 0.01 and P less than 0.05, respectively). Twenty-five patients (45%) had improved Karnofsky ratings after reoperation, and the 32 patients (58%) who were independent after reoperation were able to stay so for more than 6 months of their survival time (median value). Reoperation is feasible and can be accomplished with acceptable mortality and morbidity. When intracranial malignant gliomas recur, the combined use of reoperation and adjuvant therapy prolongs good quality life.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Myiatic scalp and skull infection with diptera Sarcophaga: case report.

The authors describe an unusual infestation of an ulcerative squamous cell carcinoma of the scalp and skull with Diptera Sarcophaga larvae. Human myiasis is rare in temperate zones and presents a rather unique neurosurgical challenge. The clinical presentation and treatment of human myiasis are briefly discussed.

Carcinoma, Squamous Cell↗
PubMed1985

Utilization of the HTSCA and CFU-C assay to identify two new 2-chloroethylnitrosourea congeners of amino acid amides with increased in vitro activity against human glioma compared with BCNU.

AspCNU and SarCNU are two amino acid amide congeners (L-asparaginamide and sarcosinamide congeners) of chloroethylnitrosoureas. The in vitro myelotoxicity of these agents compared with BCNU at 1-8 micrograms/ml was determined in bone marrow cells from normal volunteers in the CFU-C assay. AspCNU and SarCNU were significantly (P less than 0.05) less myelotoxic than BCNU at equivalent microgram concentrations. SarCNU or AspCNU at 3 micrograms/ml demonstrate equivalent in vitro myelotoxicity to BCNU 1 microgram/ml. We used the human tumor stem cell assay (HTSCA) to investigate in vitro antitumor activity. We obtained four specimens of malignant glioma and one specimen of meningioma from patients not previously treated with chemotherapy. AspCNU and SarCNU were significantly (P less than 0.05) more active than BCNU at 1-3 micrograms/ml concentrations in the HTSCA in all four malignant glioma specimens. In the one meningioma specimen, BCNU was significantly (P less than 0.05) more active than either AspCNU or SarCNU at all concentrations studied. These results suggest that AspCNU or SarCNU at doses that should produce less myelotoxicity than BCNU may be more active than BCNU against gliomas.

Antineoplastic Agents↗
PubMed1985

Central action of gamma-aminobutyric acid ligands to alter basal water and electrolyte absorption in the rat ileum.

The gamma-aminobutyric acid agonist muscimol and the gamma-aminobutyric acid antagonist bicuculline were studied to determine their effects on basal net water and electrolyte transport in the rat ileum. Whereas the intraperitoneal injection of muscimol caused a reversible, dose-dependent decrease in net water absorption, bicuculline produced a reversible, dose-dependent increase in net water and ion absorption. The threshold doses of muscimol and bicuculline were greater than 2.1 and 2.2 micrograms/kg, respectively. Lower doses of muscimol (0.1 microgram) or bicuculline (0.3 microgram) administered into the cerebrospinal fluid had the same effect as higher doses given systemically. Vagotomy prevented the effect of intracerebroventricular muscimol. Atropine (6 micrograms intracerebroventricularly) alone did not alter basal water absorption but abolished the muscimol effect, suggesting that muscimol promoted the release of acetylcholine from central cholinergic neurons. Atropine did not prevent the bicuculline effect. We conclude that (a) muscimol decreases ileal water absorption and bicuculline enhances ileal water absorption by an action at a gamma-aminobutyric acid receptor in the central nervous system, (b) the muscimol effect is due to an alteration in parasympathetic vagal outflow to the intestine, (c) the muscimol effect is mediated by a central cholinergic interneuron, and (d) the bicuculline effect is not mediated by the release of acetylcholine from central cholinergic neurons.

Animals↗