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Pablo M. Lawner and Frederick A. Simeone

✓ A patient with a meningioma of the medial sphenoid wing underwent inadvertent intraoperative occlusion of the middle cerebral artery. Neurological deficit and infarction were presumably prevented by immediate administration of pentobarbital followed by extracranial-intracranial bypass.

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Ronald F. Young and Pablo M. Lawner

✓ The authors report the results of a randomized, prospective study to assess the effectiveness of perioperative antibiotic prophylaxis in preventing postoperative infections following clean neurosurgical operations. The study group comprised 846 patients treated between October, 1979, and June, 1984. Antibiotics, including cefazolin and gentamicin, were administered only in the immediate preoperative and intraoperative periods. Sixteen patients, none of whom developed infections, were excluded from final statistical analysis because they had inadvertently been entered into the study while failing to meet entry criteria. Fifteen wound infections (3.64%) developed in the group of 412 patients who did not receive antibiotics, whereas only four infections (0.96%) were identified among the 418 patients who received antibiotics. The difference is statistically significant (p = 0.008) and represents a 74% reduction in infection rate with antibiotics. An analysis of subgroups of surgical procedures revealed a dramatic decrease in craniotomy infections from 6.77% to 0% (p = 0.003). Of the four infections that occurred among the antibiotic-treated patients, three were in cases where foreign bodies had been implanted.

No complications of antibiotic usage were identified. The rates of infection in areas of the body other than the surgical wound were no different in the antibiotic-treated and nontreated groups. All wound infections in both antibiotic-treated and nontreated patients involved similar types of Gram-positive organisms, suggesting that antibiotic prophylaxis did not produce infections with resistant or unusual organisms. This study, combined with other recently published analyses, suggests that routine perioperative antibiotic prophylaxis can significantly reduce the incidence of postoperative neurosurgical infections.

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Paul A. LaHaye and Pablo M. Lawner

✓ The case is reported of a patient who presented with a skull fracture and delayed neurological deterioration due to a cortical arteriovenous fistula at the fracture site. The clinical course and surgical therapy are described. Theories as to the pathogenesis of this lesion as well as a discussion of other intracranial vascular injuries are presented.

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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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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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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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Isabel C. Guerrero, Gail Barsky Slap, Rob Roy MacGregor, Pablo Lawner, Sebastian Ruggeri and Thomas Gennarelli

✓ An acute spinal epidural abscess is reported from which a pure growth of the anaerobe Fusobacterium necrophorum was isolated. The mode of infection and pathogen makes it unique. The literature concerning the bacteriology of epidural abscess and the implications of anaerobic epidural infection are discussed.