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Antonio S. Henriquez, David M. Robertson and W. John S. Marshall

✓ A case of spontaneous extracranial metastases from a cerebral neuroblastoma in the absence of prior surgery is reported. The tumor was discovered incidently through biopsy of an enlarged retro-auricular lymph node in an apparently well 7-year-old boy who had not previously received surgery or radiotherapy. The patient died 15 months later. Autopsy excluded neuroblastoma of the adrenal glands or the sympathetic chains.

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John P. Kapp, James T. Robertson and Isaac Gielchinsky

✓ A technique is described for closure of intracranial arteriotomies in areas of difficult exposure, using wire sutures that can be twisted rather than tied.

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John P. Kapp, James T. Robertson and Richard P. White

✓ Available data indicate that the concentration of prostaglandin F required to produce arterial spasm in an experimental model is approximately a thousand-fold higher than the concentration that occurs under physiological conditions. The spasmogenic platelet factor which has been previously described is shown to be a substance other than prostaglandin F because of differences in susceptibility of the two substances to enzymatic digestion.

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Jason A. Brodkey, Jon H. Robertson, John J. Shea III and Gale Gardner

✓ Cholesterol granulomas of the head are relatively rare. Isolated lesions of the cerebellopontine angle are even more uncommon. In this report, 17 cases of petrous apex cholesterol granulomas are presented and management is discussed.

Symptoms at presentation included dizziness (14 patients), pressure (nine patients), tinnitus (eight patients), hearing loss (eight patients), otalgia (six patients), headache (six patients), nausea (three patients), drainage from ear (two patients), facial pain (two patients), seizure (two patients), lightheadedness (one patient), hemifacial spasm (one patient), and facial numbness (one patient). Six cases were managed without surgery and 11 patients underwent operative procedures. The approaches used included the infralabyrinthine (eight patients), transcanal—infracochlear (two patients), and translabyrinthine (one patient). The mean follow-up period for all cases was 29.5 months. Of those patients managed without surgery, symptoms improved in all except one, whose tinnitus was slightly worse. Of surgically treated patients, symptoms improved or remained the same except in one with worsened dizziness. There were nine patients with hearing present presurgery and seven whose hearing was preserved postsurgery. The authors present a case that was managed at another center where an attempt at surgical resection through a subtemporal middle fossa approach was unsuccessful. This lesion was successfully treated using an infralabyrinthine approach with drainage into the mastoid cavity.

Cholesterol granulomas of the petrous apex can be managed without surgery when symptoms are stable or improve. Otherwise, a transmastoid extradural approach with simple drainage into the mastoid sinus or middle ear produces symptomatic improvement with low morbidity. Resection of petrous apex cholesterol granulomas is not necessary.

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John Dickerson, Alex B. Valadka, Tina LeVert, Kimberly Davis, Mary Kurian and Claudia S. Robertson

Object. The number of patients waiting for organ transplantation continues to grow, while organs are donated by very few of the thousands of potential donors who die every year. The authors' neurosurgical intensive care unit (NICU) has worked closely with coordinators from the local organ procurement organization (OPO) for many years. In this study, the authors analyze donation rates in the NICU and discuss factors that may be important in maximizing these rates.

Methods. All referrals from the NICU to the OPO from 1996 to 1999 were analyzed. Of the 180 referrals, 98 patients were found to be medically suitable as potential donors. Another 15 patients died of hemodynamic collapse shortly after admission to the NICU. If one assumes that all 15 patients would have been suitable donors, the unsuccessful resuscitation rate becomes 15 (13.3%) of 113. Of the 98 eligible donors, consent was obtained and organs or tissue were recovered in 72, yielding a successful organ procurement rate of 73.5%.

Conclusions. Close working relationships among physicians, nurses, and OPO coordinators can result in higher donation rates than have been reported previously. Aggressive resuscitation and stabilization of all patients, early identification of potential organ donors, prompt declaration of brain death, and attempts by the OPO coordinator to build rapport with families are all important factors that may increase donation rates. Because most organ donors have sustained catastrophic intracranial events, neurosurgeons are uniquely positioned to influence organ donation policies at their hospitals and thus to salvage some benefit from tragic cases of overwhelming brain injury.

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Thomas L. Ellis, Paulo A. Garcia, John H. Rossmeisl Jr., Natalia Henao-Guerrero, John Robertson and Rafael V. Davalos

Object

Nonthermal irreversible electroporation (NTIRE) is a novel, minimally invasive technique to treat cancer, which is unique because of its nonthermal mechanism of tumor ablation. This paper evaluates the safety of an NTIRE procedure to lesion normal canine brain tissue.

Methods

The NTIRE procedure involved placing electrodes into a targeted area of brain in 3 dogs and delivering a series of short and intense electric pulses. The voltages of the pulses applied were varied between dogs. Another dog was used as a sham control. One additional dog was treated at an extreme voltage to determine the upper safety limits of the procedure. Ultrasonography was used at the time of the procedure to determine if the lesions could be visualized intraoperatively. The volumes of ablated tissue were then estimated on postprocedure MR imaging. Histological brain sections were then analyzed to evaluate the lesions produced.

Results

The animals tolerated the procedure with no apparent complications except for the animal that was treated at the upper voltage limit. The lesion volume appeared to decrease with decreasing voltage of applied pulses. Histological examination revealed cell death within the treated volume with a submillimeter transition zone between necrotic and normal brain.

Conclusions

The authors' results reveal that NTIRE at selected voltages can be safely administered in normal canine brain and that the volume of ablated tissue correlates with the voltage of the applied pulses. This preliminary study is the first step toward using NTIRE as a brain cancer treatment.

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Daniel Yoshor, J. Brett Gentry, Scott A. LeMaire, John Dickerson, John Saul, Alex B. Valadka and Claudia S. Robertson

✓ The authors describe the case of a 24-year-old man who underwent an L-1 corpectomy for spinal decompression and stabilization following an injury that caused an L-1 burst fracture. Postoperatively, an accumulation of spinal fluid developed in the pleural space, which was refractory to 1 week of thoracostomy tube drainage and lumbar cerebrospinal fluid (CSF) diversion. The authors then initiated a regimen of positive-pressure ventilation in which a bilevel positive airway pressure (PAP) mask was used. After 5 days, the CSF collection in the pleural space resolved. Use of a bilevel PAP mask represents a safe, noninvasive method of reducing the negative intrathoracic pressure that promotes CSF leakage into the pleural cavity and may be a useful adjunct in the treatment of subarachnoid—pleural fistula.

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Menno Pennink, Richard P. White, John R. Crockarell and James T. Robertson

✓ An angiographic study of experimental cerebral vasospasm was performed in 40 dogs. Vasospasm was caused by injection of 4 ml of blood or 4 ml of blood mixed with prostaglandin F2a into the chiasmatic cistern. A statistically significant difference (chi-square test, p < 0.01) was found between the incidence of cerebral vasospasm obtained with injection of blood alone (6 out of 18 cases, 33%) and the cerebral vasospasm induced with blood and prostaglandin F2a (12 of 13 cases, 92%). In addition, cerebral vasospasm was obtained with injection of prostaglandin F2a alone, whereas prostaglandin E1 had no such effect. These findings, together with reports in the literature that the brains is rich in prostaglandin F2a which it releases into the CSF, suggest a role of prostaglandin F2a in the genesis of cerebral vasospasm seen clinically.

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James T. Robertson, Albert L. Meric, F. Curtis Dohan Jr., John B. Schweitzer, Jerome R. Wujek and Shafik Ahmad

✓ Spinal peridural fibrosis following total laminectomy in New Zealand White rabbits was significantly decreased by the intraoperative application of GT1587, a semi-synthetic carbohydrate polymer. The application of a similar polymer, GT1043, or phosphate-buffered saline (PBS) was not as effective. Laminectomies were performed at L-2 and L-4 in 25 rabbits. Absorbable gelatin sponge soaked with GT1043, GT1587, or PBS was applied in a blinded fashion to the operative sites, with untreated (sham) laminectomy sites serving as controls. Animals were sacrificed after 2 or 4 weeks. The extent of peridural fibrosis was evaluated by gross microdissection and histological analysis. Dense scar formation and dural adhesions were evident at both time intervals in the sham- and PBS-treated laminectomy sites. The sites treated with GT1587 showed significantly decreased peridural scar formation and dural adhesions, whereas GT1043 treatment caused modest reduction of scar formation at only the 2-week examination. The healing of skin and lumbosacral fascia was not affected by treatment of the laminectomy site with GT1587. These results suggest that GT1587 may prove beneficial in preventing postlaminectomy dural adhesions and peridural fibrosis in humans.