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Michael H. Lavyne and Mark H. Bilsky

✓ Intraoperative epidural corticosteroids have been used by some surgeons to decrease pain following surgery for a herniated lumbar disc. In this study, 84 consecutively treated, comparable patients with unilateral lumbar disc herniation were prospectively assigned randomly to receive either epidural corticosteroids (40 mg methylprednisolone acetate) or saline at the conclusion of the operative procedure. The postoperative morbidity of these two groups was evaluated by tabulating the following parameters: pain relief as measured by consumption of postoperative pain medications; the length of hospital stay; postoperative functional status; and the time interval from surgery until return to work. The mean postoperative analgesic medications consumed was 12.2 ± 1.9 mg of morphine equivalents in the corticosteroid group versus 12.2 ± 1.8 mg of morphine equivalents in the control group. The mean hospital stay was less than 2 days in each group, and the mean interval until return to work was 21.2 ± 2.7 days in the corticosteroid group versus 25.4 ± 3.1 days in the control group. Moreover, no statistically significant difference was measured between the steroid-treated and control groups when the data were stratified for sex, age, and site of disc herniation. The mean outcome scores, which are derived from a postoperative assessment of pain relief resulting from surgery, functional status, and interval until return to work, were identical in the corticosteroid and control groups. This study concludes that epidural corticosteroid administration after microsurgical lumbar discectomy for unilateral disc herniation does not lessen postoperative morbidity or improve functional recovery.

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Daniel H. O'Leary and Michael H. Lavyne

✓ A simple method is presented for localizing the anatomical site of vertex lesions seen on a computerized tomography (CT) brain scan, using the patient's plain lateral skull film.

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Michael H. Lavyne, Rand M. Voorhies and Raymond H. Coll

✓ This case presents a rare occurrence of femoral neuropathy due to iliopsoas bursitis as a consequence of hip osteoarthritis. A computerized tomography scan of the hip revealed a smooth-walled nonenhancing cystic mass adjacent to the hip joint and elevating the components of the homolateral femoral triangle. The differential diagnosis and operative management of this entity are reviewed.

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Gary A. Zimmerman, Karen Weingarten and Michael H. Lavyne

✓ Lumbar epidural varices have been infrequently described in the literature and rarely accepted as a primary pathophysiological entity. The authors' total experience with symptomatic lumbar epidural varices over the last 15 years includes four cases (incidence 0.067% of all lumbar spine operations), two of which are described in detail in this paper. The mechanism for their formation is proposed: central disc herniations obstruct the anterior epidural venous flow leading to anterolateral caudal venous distention. Subsequent venous endothelial injury predisposes to varying degrees of phlebothrombosis. Decompression of partially thrombosed varices may occur during operative discectomy or spontaneously during regression of the nonoperated disc prolapse. Regression of the central disc herniation may also explain the “disappearing disc” phenomenon, in which patients with clinical and radiographic evidence of apparently large caudal disc herniations exhibit clinical and radiographic resolution. Magnetic resonance (MR) imaging characteristics of the epidural varix depend upon the degree of thrombosis within this anomaly. A thrombosed varix is hyperintense on T1-weighted, proton-density, and T2-weighted images, whereas flowing blood is hypointense. The variable hypo- and hyperintensity on the T2-weighted MR imaging sequences correlate with a partially patent lumen within the varix.

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Martin Zonenshayn, Mark A. Edgar and Michael H. Lavyne

✓ The authors describe a patient with Carney's complex who presented with sciatica due to a lumbar nerve root sheath tumor. A far-lateral approach was used to resect a nonpsammomatous melanotic schwannoma. Neurosurgeons surgically treating peripheral nerve sheath tumors should be aware of the features of Carney complex because the extent of the preoperative evaluation and postoperative management of an otherwise routine surgical condition can be significantly affected.

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Robert H. Brown Jr., Brian D. Beyerl, Richard Iseke and Michael H. Lavyne

✓ Neurogenic pulmonary edema (NPE) occurs in association with central nervous system disease without underlying cardiopulmonary problems. It is characterized by profound pulmonary vascular congestion and a fulminant clinical course. Although several reports document a role for experimental brain-stem lesions in the production of NPE, there have been only two studies in man correlating specific brain-stem lesions with NPE. The authors report a case of NPE occurring in a patient with von Hippel-Lindau disease and a dorsal medullary syrinx with postoperative dorsal medullary edema. The anatomical location of this patient's lesion is reviewed in the context of alternative theories of the pathogenesis of NPE.

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Robert J. Hariri, Elizabeth L. Supra, John Paul Roberts and Michael H. Lavyne

✓ Transient global cerebral ischemia (TGI) was induced in awake rats using the “four-vessel” occlusion model of Pulsinelli and Brierley. Blood pressure, arterial blood gases, cerebral blood flow, and cardiac output were measured during the acute (up to 2 hours) and chronic (2 to 72 hours) postischemic time periods. Coincident with the onset of TGI, cardiac output and caudate blood flow were depressed. The former returned to baseline within 30 minutes after the conclusion of TGI, and the latter progressed to hyperemia at 12 hours (81.8 ± 4.9 vs 68.6 ± 3.9 ml/min/100 gm tissue (mean ± standard error of the mean)) and oligemia at 72 hours (45.5 ± 4.8 ml/min/100 gm tissue) post-TGI in the untreated control rats. Arterial blood gases and blood pressure were unchanged. Naloxone (1 mg/kg) given at the time of TGI or as late as 60 minutes post-TGI and every 2 hours thereafter for 24 hours or bilateral cervical vagotomy prevented the depression in cardiac output and blocked the hyperemic-oligemic cerebral blood flow pattern that was predictive of stroke in this rat model.

Changes in cardiac output after TGI in this model appear to be mediated by parasympathetic pathways to the heart from the brain stem. Opiate receptor blockade probably blocks endogenous opioid peptide stimulation of these brain-stem circulatory centers, which results in inhibition of parasympathetic activity and improvement in cardiac output. The usefulness of naloxone in the treatment of experimental stroke may be a function of its ability to improve cerebral perfusion in pressure-passive cerebrovascular territories. Variations in cardiac output during experimental stroke may explain the dissimilar responses to naloxone treatment reported by other investigators of experimental stroke.

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Rand M. Voorhies, Michael H. Lavyne, Timothy A. Strait and William R. Shapiro

✓ The viability of debris containing C6 rat tumor cells generated by the CO2 laser was investigated using standard tissue culture techniques. No evidence of cell viability was found in the plume of laser smoke.