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Yoshio Hosobuchi

✓ Chronic electrical stimulation of the subcortical area of the brain by implanted electrodes provides satisfactory control of a number of intractable pain syndromes that are refractory to medication. This series of 122 patients who underwent electrode implantation for the control of severe chronic pain was evaluated over a follow-up period of 2 to 14 years. Of the 65 patients with pain of peripheral origin, who were treated with stimulation of the periaqueductal gray region (PAG), 50 obtained successful pain control. Of 76 patients with a deafferentation pain syndrome, 44 obtained control of the dysesthesia with stimulation of the subcortical somatosensory region. Nineteen patients with both leg and back pain received electrodes in the PAG and the somatosensory regions; whereas back pain was relieved by PAG stimulation, dysesthetic leg pain was controlled more effectively by somatosensory region stimulation. The electrical stimulation technique appears to provide long-term pain control safely, with few side effects or complications.

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Treatment of experimental stroke with opiate antagonists

Effects on neurological function, infarct size, and survival

David S. Baskin, Yoshio Hosobuchi and Joachim C. Grevel

✓ The effects are reported of acute and long-term continuous administration of three opiate antagonists — naloxone, naltrexone, and diprenorphine — on neurological function, survival, and infarct size in a feline model of acute focal cerebral ischemia. All three drugs produced statistically significant improvement in motor function following acute administration without concomitant changes in level of consciousness; saline had no effect. Naloxone and naltrexone significantly prolonged survival (p < 0.01); diprenorphine did not. Infarct size was not altered by any treatment administered. These findings confirm previous work suggesting that, with the appropriate methodology, treatment with opiate antagonists partially reverses neurological deficits. They also show that opiate antagonists prolong survival in certain conditions of acute and subacute focal cerebral ischemia without altering the area of infarcted tissue.

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Stephen K. Powers, John E. Adams, Michael S. B. Edwards, James E. Boggan and Yoshio Hosobuchi

✓ Argon and carbon dioxide microsurgical lasers were used to produce lesions in the dorsal root entry zone (DREZ) experimentally in six cats and surgically in 21 patients who had denervation pain syndromes. The technique of producing lesions, the histological and physiological changes seen in the cat spinal cord, and the results of treatment in the clinical series are discussed. Lesions were produced within the DREZ without new involvement of the dorsal column system or corticospinal tract in all but one patient. Based on their subjective evaluation, two-thirds of the patients were relieved of more than 50% of their preoperative pain. These experimental results and clinical experience suggest that the argon and carbon dioxide lasers effectively produce localized microsurgical lesions in the DREZ. The concept that an abnormality involving either neurons in the substantia gelatinosa or internuncial fibers in Lissauer's tract is responsible for pain in patients with primary sensory nerve deafferentation is discussed.

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Mitchel S. Berger and Yoshio Hosobuchi

✓ A persistent carotid-basilar anastomosis (primitive trigeminal artery), identified by four-vessel vertebral angiography, was shown to be the cause of a cavernous sinus fistula in a 51-year-old woman. The fistula, but not the primitive artery, was identified on a carotid arteriogram. Because of the flow contribution from the posterior circulation, balloon embolization via the carotid system failed, and the fistula was repaired through a direct surgical approach. The operative technique is described and the hemodynamic aspects of a cavernous sinus fistula that is related to this primitive anastomosis are reviewed.

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Stephen K. Powers, Michael S. B. Edwards, James E. Boggan, Lawrence H. Pitts, Philip H. Gutin, Yoshio Hosobuchi, John E. Adams and Charles B. Wilson

✓ The argon surgical laser has been used in 68 neurosurgical procedures that included the removal of intracranial and intraspinal tumors, spinal cord fenestration for syringomyelia, and the production of dorsal root entry zone lesions. Characteristics that make the argon surgical laser a useful microneurosurgical instrument include the availability of a fiberoptic delivery system, a laser spot size that can be varied continuously between 0.15 and 1.5 mm, a single laser-aiming and treatment beam, the transmission of argon laser light through aqueous media such as irrigating or cerebrospinal fluids, and improved hemostasis compared to conventional techniques. The argon laser is limited primarily by its relatively low power output (less than 16 W), which makes the excision of large tumors difficult. However, even with these limitations, which can be used to advantage in the proper setting, the authors' laboratory and clinical experience suggests that the argon surgical laser may be useful in certain microneurosurgical operations.

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Philip H. Gutin, Theodore L. Phillips, William M. Wara, Steven A. Leibel, Yoshio Hosobuchi, Victor A. Levin, Keith A. Weaver and Sharon Lamb

✓ Thirty-seven patients harboring recurrent malignant primary or metastatic brain tumors were treated by 40 implantations of high-activity iodine-125 (125I) sources. All patients had been treated with irradiation and most had been treated with chemotherapeutic agents, primarily nitrosoureas. Implantations were performed using computerized tomography (CT)-directed stereotaxy; 125I sources were held in one or more afterloaded catheters that were removed after the desired dose (minimum tumor dose of 3000 to 12,000 rads) had been delivered. Patients were followed with sequential neurological examinations and CT scans. Results of 34 implantation procedures were evaluable: 18 produced documented tumor regression (response) for 4 to 13+ months; five, performed in deteriorating patients, resulted in disease stability for 4 to 12 months. The overall response rate was 68%. In 11 patients, implantation did not halt clinical deterioration.

At exploratory craniotomy 5 to 12 months after implantation, focal radiation necrosis was documented in two patients whose tumor had responded initially and then progressed, and in three patients whose disease had progressed initially (four glioblastomas, one anaplastic astrocytoma); histologically identifiable tumor was documented in two of these patients. All improved after resection of the focal necrotic mass and are still alive 10, 15, 19, 24, and 25 months after the initial implantation procedure; only one patient has evidence of tumor regrowth. The median follow-up period after implantation for the malignant glioma (anaplastic astrocytoma and glioblastoma multiforme) group is 9 months, with 48% of patients still surviving. While direct comparison with the results of chemotherapy is difficult, results obtained in this patient group with interstitial brachytherapy are probably superior to results obtained with chemotherapy.

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Yoshio Hosobuchi, Theodore L. Phillips, Terry A. Stupar and Philip H. Gutin

✓ Ten patients harboring inaccessible, slow-growing or recurrent malignant primary brain tumors were treated by the stereotaxic implantation of a radionuclide seed — iridium-192 (192Ir) or gold-198 (198Au) — either permanent or removable. The strength for 192Ir seeds was selected to deliver 10,000 to 12,000 rads to the periphery of the tumor, and that for 198Au seeds to deliver 4000 to 7500 rads. Three of the six patients treated with 192Ir showed objective responses lasting 8, 11, and 12 months, respectively; and one patient's disease stabilized for 18 months. Three of the four treated with 198Au showed responses lasting 5 months, 6 months, and 2 years, respectively. Because of the higher dose-rate attainable with 198Au, removable implants of this material are more effective against the faster-growing malignant tumors.

Another radionuclide, iodine-125 (125I), is now being tested against brain tumors. The radioactivity of 125I is high; but because its gamma emission is less energetic by a factor of 10 than that of 198Au or 192Ir, its radiation field is concentrated within a radius of 2.5 cm or less. This low-energy gamma emission also makes it easier to protect medical personnel and the patients' families against the nuclide when 125I is used.

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Philip H. Gutin, William M. Klemme, Raymond L. Lagger, Alexander R. MacKay, Lawrence H. Pitts and Yoshio Hosobuchi

✓ Four patients with primary and recurrent craniopharyngiomas that were grossly cystic were managed by intermittent aspiration through an indwelling Ommaya reservoir apparatus. The technique is safe and provides a reasonable alternative for the amelioration of signs and symptoms when total extirpation of the tumor is impossible.

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Yoshio Hosobuchi

✓ The author has operated on 40 patients with giant intracranial aneurysms, using various surgical approaches. Giant aneurysms predominated in females (3:1) and were most common in the age group 30 to 60 years. Patients presented with subarachnoid hemorrhage (17), visual disturbance (18), chronic headache (14), transient or progressive hemispheric deficit (6), seizure (2), dementia (2), and cerebrospinal fluid rhinorrhea (1). Giant aneurysms were located at the carotid artery (25), the basovertebral artery (8), the anterior communicating artery (5), and the middle cerebral artery (2). Eight of 40 patients had one or more other aneurysms and/or associated arteriovenous malformations. Aneurysms were treated with intramural thrombosis (21), neck occlusion (7), trapping (10), proximal parent artery ligation (1), and aneurysmorrhaphy (1). After as much as 8 years of follow-up, 32 patients (80%) showed complete or marked improvement in signs and symptoms; two patients (5%) had a poor recovery. There were six surgical mortalities (15%).

Giant aneurysms can be treated with respectable results if the surgeon selects the technique best suited to the particular aneurysm. In general, neck occlusion, trapping, and aneurysmorrhaphy are best for giant aneurysms of the anterior circulation, and intramural thrombosis is best for those of the posterior circulation. Extra- and intracranial vascular anastomotic techniques are also of value. For success, a flexible approach is essential.