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Lance H. Perling, John P. Laurent and William R. Cheek

✓ Centripetal fat deposition is a well-recognized consequence of excessive use of corticosteroids, either endogenous or exogenous. Recently, several patients receiving large doses of corticosteroids have suffered compressive myelopathies due to excessive epidural fat collections, labeled “epidural lipomatosis.” Two of these have been children, and a third child is reported here. This child was receiving chronic steroids for juvenile rheumatoid arthritis when he presented with such a myelopathy, which was confirmed by metrizamide computerized tomography myelography as well as by surgical exploration. Histological examination revealed that the epidural tissue was a brown-fat tumor or “hibernoma.” An epidural hibernoma has not been described previously. The histological and endocrine features of fat in Cushing's syndrome are discussed, and the literature concerning hibernoma and epidural lipomatosis is reviewed.

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William R. Cheek, John P. Laurent and David A. Cech

✓ A technique is described for closure of lumbosacral myelomeningoceles. The pathological anatomy of these lesions is examined, and the junction of the skin and dura is identified as the “junctional zone.” This zone permits maximal preservation of the available dura for watertight closure after operative dissection. The junctional zone also serves as an anchor for traction sutures, permitting skin closure without tension. Seventy consecutive repairs have been completed by the authors without significant complications. There have been no instances of cerebrospinal fluid leaks, meningitis, or wound dehiscence. In all cases the repair was carried out rapidly and in a single stage.

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John P. Laurent, Pablo Lawner, Frederick A. Simeone and Eugene Fink

✓ Barbiturates were administered to normal dogs, establishing an isoelectric electrocorticogram. Cortical cerebral blood flows (CBF) and deeper CBF's were respectively measured by krypton-85 (85Kr) and xenon-133 (133Xe). Following barbiturate administration, the two methods of measuring CBF showed a poor coefficient of variation (r = 0.12, p < 0.05). The cortical flows decreased less than the fast compartment flows. A shifting of percentage contribution of flow to the slow compartment (60% increase, p < 0.001) was observed after barbiturate infusion. A selective shunting of blood flow to the slower areas may explain the lowering of intracranial pressure and protection of the deep white matter observed by many authors who use barbiturates in clinical and experimental situations.

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John P. Laurent, Pablo M. Lawner and Michael O'Connor

✓ A major factor determining the severity of neurological deficits caused by cerebral ischemia is the ability of the vasculature to provide collateral circulation to the ischemic areas. By establishing a major conduit by means of extracranial-intracranial anastomosis, the increased perfusion pressure through the collateral arterioles may reduce morbidity in these patients. Twenty-seven patients were selected for superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis based on clinical and angiographic evidence of lesions of the internal carotid arterial system. Cerebral blood flows (CBF's) were determined by the xenon-133 inhalation method using 16 symmetrically placed scintillator probes; two-compartment analysis was used to compute a mean flow for the compartment. An average mean flow was computed for each hemisphere, and for four regions with the lowest mean CBF in each hemisphere. The CBF was measured preoperatively and within 8 weeks postoperatively.

The average mean flow was 29 ml/100 gm/min in the symptomatic hemisphere, and 30 ml/100 gm/min in the asymptomatic hemisphere. In 11 patients, the mean flow for the symptomatic hemisphere increased by 24% postoperatively, and for the asymptomatic hemisphere by 23%. Regions with lowest CBF showed an increase of 32% in the symptomatic hemisphere, and of 35% in the asymptomatic hemisphere. The low-flow regions differed from the total hemisphere (symptomatic: p < 0.02; asymptomatic: p < 0.05). Areas of lowest blood flow preoperatively had the greatest increase in flow postoperatively. Postoperative elevation of CBF in the contralateral hemisphere is consistent with an “intracerebral steal” before surgery. The postoperative elevation of flow in the asymptomatic hemisphere is related to improved perfusion pressure in the symptomatic hemisphere.

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Frederick A. Simeone, John P. Laurent, Peter J. Trepper, Daniel J. Brown and John Cotter

✓ Intermittent occlusion of the descending aorta just below the origin of the brachiocephalic vessels by a preformed balloon passed via the femoral artery is capable of significantly increasing the pressure and flow in the common carotid artery. Regional cerebral blood flow determination by the krypton-85 washout technique measured maximum increases of over 40% of the controls, which could easily be achieved and maintained. This technique apparently takes advantage of the finite delay in autoregulatory response to the increased arterial pressure before the onset of maximal autoregulation. Dogs were “pumped” in this way for up to 18 hours and survived in good health. Principal problems with this technique were the development of cerebral edema in the presence of diffuse established cerebral anoxia, and a shock-like cardiovascular response if the intermittent aortic occlusion was discontinued too abruptly. The clinical application of this technique to cerebral ischemia secondary to postoperative vasospasm may not require the extremes of hyperperfusion used in these experiments.

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Huda Y. Zoghbi, Sada Okumura, John P. Laurent and Marvin A. Fishman

✓ The effect of glycerol administration on cerebrospinal fluid (CSF) formation in dogs was studied by means of a ventriculocisternal perfusion technique. Net CSF production rate decreased after oral administration of glycerol (3 gm/kg) from a baseline level of 42.33 ± 6.68 µl/min (mean ± standard error) to a trough of 10.33 ± 4.88 µl/min at 90 minutes after administration (p < 0.025). Serum osmolality concomitantly increased from a baseline value of 296 ± 2.83 to 309 ± 4.7 mOsm/kg H2O at 90 minutes. The mean percentage change in CSF production inversely correlated to the mean percentage change in serum osmolality, r = −0.85. Thus, glycerol administration decreases net CSF formation, and this effect may be related in part to the rise in serum osmolality.

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John P. Laurent, Rita Lee, Saleh Shenaq, Julie T. Parke, Itzel S. Solis and Lisa Kowalik

✓ The authors review the cases of 116 infants treated consecutively for birth-related brachial plexus injuries. Twenty-eight infants with upper brachial plexus lesions who showed no neurological improvement by 4 months of age were selected for early surgical reconstruction (at a mean age of 5 months). Neurological improvement of the affected arm was observed in more than 90% (p < 0.05) of the children examined longer than 9 months after brachial plexus reconstruction. A conservatively managed control subgroup of 44 children, first examined at less than 3 months of age, demonstrated neurological improvement by 4 months of age and continued to show improvement at 1 year of age. Early surgical reconstruction is recommended for infants with birth-related upper brachial plexus injury who show no neurological improvement by the age of 4 months.

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Pablo M. Lawner, John P. Laurent, Frederick A. Simeone and Eugene A. Fink

✓ Ninety-three mongrel dogs underwent intracranial carotid and middle cerebral artery occlusions. They were then randomized into four groups: 1) the untreated control group (no surgical or medical therapy) showed significant neurological deficit, 16% mortality, and 17% mean hemisphere infarction; 2) in the bypass group (superficial temporal to middle cerebral artery (STA-MCA) anastomosis completed within 3 hours of occlusion), neurological deficit was diminished, mortality was 7%, and mean infarction 5.66%; 3) in the pentobarbital group (single dose of pentobarbital, 35 mg/kg administered intravenously 30 minutes after occlusion), neurological deficit was essentially the same as in the previous group, there was no mortality, and mean infarction was 5.52%; and 4) in the pentobarbital/bypass group (pentobarbital dose plus STA-MCA bypass), neurological deficit was slightly lower than in previous treatment groups, there was no mortality, and mean hemisphere infarction was 1.78%. Extracranial-intracranial bypass produced an immediate 31.6% increase in regional cortical blood flow. The combination of pentobarbital postocclusive therapy and early extracranial-intracranial bypass showed beneficial synergism.

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Jeffrey P. Krischer, Abdelsalem H. Ragab, Larry Kun, Tae H. Kim, John P. Laurent, James M. Boyett, Cornelius J. Cornell, Michael Link, Annette Ridolfi Luthy and Bruce Camitta

✓ In a randomized postoperative trial, adjuvant post-irradiation chemotherapy, consisting of nitrogen mustard, vincristine, procarbazine, and prednisone (MOPP), was tested versus radiation therapy alone for newly diagnosed medulloblastoma in patients between 1 and 21 years of age. Patients treated with irradiation plus MOPP had a statistically significant increase in overall survival rate at 5 years posttreatment compared to patients treated with radiation therapy alone (74% vs. 56%; p = 0.06, adjusted for race and gender). Although the overall study failed to show a statistically significant advantage for irradiation plus MOPP in event-free survival (p = 0.18), statistical significance was attained in children 5 years of age or older (p = 0.05). More severe hematological toxicities occurred in the group with irradiation plus MOPP; however, this hematotoxicity appeared to be tolerable and acceptable. These results suggest that patients may benefit from combined irradiation and chemotherapy following surgery for medulloblastoma.