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Donald O. Quest

✓In his presidential address to the American Association of Neurological Surgeons, the author recounts lessons he learned while training to be a Naval Aviator and later a neurosurgeon. He describes his life as an aviator and neurosurgeon, compares naval aviation and neurosurgery, and points out lessons that neurosurgery can learn from naval aviation.

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Donald O. Quest and Michael Salcman

✓ The authors report a case of fibromatosis presenting as a mass lesion following previous craniotomy and radiation therapy. The clinical and pathological characteristics of this rare condition are discussed.

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Donald O. Quest and Roger W. Countee

✓ The authors report a case of mechanical failure of a medium-straight Heifetz aneurysm clip that resulted in the blades being widely open 10 months postoperatively. The need for postoperative angiography after intracranial aneurysm surgery is reemphasized. Plain skull film examination is also recommended should signs and symptoms suggest an intracranial event in the postoperative course.

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Allan M. Burke, Donald O. Quest, Shu Chien and Cesare Cerri

✓ To determine the effect of mannitol on blood viscosity, serial measurements were carried out on venous blood in patients undergoing craniotomies for intracranial aneurysms. Blood samples were drawn immediately prior to, and 30 minutes, 2, and 4 hours after administration of mannitol. Complete blood counts, serum osmolarities, and erythrocyte microsieving studies were also performed on each sample. Wholeblood viscosity decreased at 30 minutes and 2 hours, but not at 4 hours after mannitol administration. This decrease appeared at high shear rates only, where erythrocyte deformability is critical in determining viscosity. This effect was independent of the hematocrit. Removal of mannitol from the suspension returned red cell deformability to preadministration values, indicating that the increased erythrocyte deformability required the presence of mannitol and the relative hyperosmolarity induced by this agent. The reduced erythrocyte rigidity and subsequent decreased whole-blood viscosity should enhance tissue perfusion in the microcirculation.

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Michael Salcman, Donald O. Quest and Lester A. Mount

✓The authors present a case in which there was direct invasion of the spinal canal and its contents by a granuloma of histiocytosis-x, and emphasize the importance of considering this condition as a cause of spinal cord and cauda equina syndromes.

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Robert A. Solomon, Christopher M. Loftus, Donald O. Quest and James W. Correll

✓ In a consecutive series of 1930 carotid endarterectomies there were eight cases of postoperative intracerebral hemorrhage. One of these patients was operated on 2 weeks following cerebral infarction and had severe uncontrollable hypertension after surgery. A second patient had an intraoperative embolus and bled while fully heparinized on the 3rd postoperative day. Only one patient in the series bled into an area of documented cerebral infarction. The remainder of the cases represented hemorrhage into essentially normal brain.

Seven of the eight patients with intracerebral hemorrhage had high-grade internal carotid artery stenosis preoperatively. Although several factors have contributed to the brain hemorrhages in this series of patients, postoperative cerebral hyperperfusion which often follows endarterectomy may have played an important role. Defective cerebrovascular autoregulation in chronically ischemic brain regions may predispose patients to intracerebral hemorrhage after removal of a high-grade stenosis of the internal carotid artery.

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Donald O. Quest, Ronald Brisman, Joao L. Antunes and Edgar M. Housepian

✓ Ninety-nine patients with medulloblastoma who received surgery and radiotherapy, and had a statistically sufficient follow-up period were analyzed for factors influencing survival and the relevance of the “period of risk for recurrence” hypothesis. This postulate states that the period of risk for recurrence of a congenital tumor is equal to the age at presentation of illness plus 9 months' gestational time. The assumption is made that a tumor of embryonic origin will become manifest after a period of time determined by its inherent rate of growth and that tumor cells surviving treatment will multiply and present with recurrence in an equal period of time. Ten of 43 patients survived the period of risk, a presumed cure rate of 23%. None of these patients has subsequently developed evidence of tumor recurrence. Older patients at initial surgery had a somewhat greater survival rate for the first 5 years after treatment (10 of 26 older patients (38%) versus 15 of 54 younger patients (28%)), but by 10 years there was no appreciable difference in survival rates between those over 16 years of age and those younger. The beneficial effect of total neuraxis megavoltage radiotherapy is indicated by the improved 5-year survival rate from 9 of 41 patients (22%) to 16 of 39 patients (41%) with the newer techniques.

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William J. Mack, Christopher P. Kellner, Daniel H. Sahlein, Andrew F. Ducruet, Grace H. Kim, J Mocco, Joseph Zurica, Ricardo J. Komotar, Raqeeb Haque, Robert Sciacca, Donald O. Quest, Robert A. Solomon, E. Sander Connolly Jr. and Eric J. Heyer

Object

Recent data from both experimental and clinical studies have supported the use of intravenous magnesium as a potential therapy in the setting of cerebral ischemia. This study assessed whether intraoperative magnesium therapy improves neuropsychometric testing (NPT) following carotid endarterectomy (CEA).

Methods

One hundred eight patients undergoing CEA were randomly assigned to receive placebo infusion or 1 of 3 magnesium-dosing protocols. Neuropsychometric testing was performed 1 day after surgery and compared with baseline performance. Assessment was also performed on a set of 35 patients concurrently undergoing lumbar laminectomy to serve as a control group for NPT. A forward stepwise logistic regression analysis was performed to evaluate the impact of magnesium therapy on NPT. A subgroup analysis was then performed, analyzing the impact of each intraoperative dose on NPT.

Results

Patients treated with intravenous magnesium infusion demonstrated less postoperative neurocognitive impairment than those treated with placebo (OR 0.27, 95% CI 0.10–0.74, p = 0.01). When stratified according to dosing bolus and intraoperative magnesium level, those who were treated with low-dose magnesium had less cognitive decline than those treated with placebo (OR 0.09, 95% CI 0.02–0.50, p < 0.01). Those in the high-dose magnesium group demonstrated no difference from the placebo-treated group.

Conclusions

Low-dose intraoperative magnesium therapy protects against neurocognitive decline following CEA.