Descending trigeminal tractotomy for trigeminal neuralgia after surgical failure.

Percutaneous rhizotomy, microvascular decompression or rhizotomy by suboccipital craniotomy often cures medically untreatable trigeminal neuralgia with an acceptable complication rate. However, pain involving the same trigeminal distribution persists in a few patients despite both rhizotomies. For 7 patients with such surgically 'failed' trigeminal neuralgia, we performed descending trigeminal tractotomy.

Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus. The cerebral 'time-on' factor.

A 'time-on' theory to explain the cerebral distinction between conscious and unconscious mental functions proposes that a substantial minimum duration ('time-on') of appropriate neuronal activations up to about 0.5 s is required to elicit conscious sensory experience, but that durations distinctly below that minimum can mediate sensory detection without awareness. A direct experimental test of this proposal is reported here.

Treatment of cerebral ischemia with electrical stimulation of the cervical spinal cord.

We observed an increase in cerebral blood flow (CBF) for control of pain but were otherwise normal. Based on that observation, we implanted stimulators for cervical spinal cord stimulation (cSCS) in three patients who had symptomatic cerebral ischemia. Two had severe basivertebral occlusive disease and one had bilateral carotid occlusive disease.

Cerebrospinal fluid concentrations of laudanosine after administration of atracurium.

The concentration of laudanosine in cerebrospinal fluid (CSF) was measured in four patients undergoing brain electrode placement after the administration of atracurium. CSF: plasma laudanosine concentration ratios ranged from less than 1 to 14%, with a range of CSF laudanosine concentrations of less than 2-14 ng ml-1. One patient had no detectable laudanosine in CSF, but sampling in this patient was possible for only 30 min.

The effects of cervical spinal cord stimulation (cSCS) on experimental stroke.

Cervical spinal cord stimulation (cSCS) has been employed as a treatment for intractable pain for the past 20 years. Recently, we reported that cSCS increased regional cerebral blood flow (rCBF) in cats and humans. The present study was designed to examine the effects of cSCS on experimental cerebral strokes, using a cat middle cerebral artery occlusion model (MCAO).

Beneficial effects of cervical spinal cord stimulation (cSCS) on patients with impaired consciousness: a preliminary report.

Electrical stimulation of the spinal cord can be used for treatment of intractable pain and spasticity. Based on our experimental findings cervical spinal cord stimulation (cSCS) was performed on eight patients with severe brain dysfunction due to traffic accidents, pronounced vasospasm caused by subarachnoid hemorrhage or surgery of huge cerebral tumors (chordoma). After a 1 to 2 month period of stimulation, two patients became conscious and began to speak.

Brachytherapy of recurrent tumors of the skull base and spine with iodine-125 sources.

Thirteen patients with recurrent, previously irradiated tumors of the skull base or spine were reirradiated with 125I sources implanted interstitially using microsurgical or stereotactic techniques. Patients harbored difficult, end-stage recurrences of chordoma, meningioma, malignant meningioma, fibrosarcoma, invasive pituitary adenoma, and malignant schwannoma. In two other patients with malignant meningioma, the dose of external radiation was augmented by implanting 125I sources during the initial operation for excision of the lesion or at a separate surgical procedure after conventional teletherapy.

Consequence of dynorphin-A administration on anterior pituitary hormone concentrations in the adult male rhesus monkey.

This study examines the role of dynorphin-A(1-13) and dynorphin-A(1-10)-amide in the neuroendocrine regulation of anterior pituitary hormones in nonrestrained, adult male rhesus monkeys. The effects of these opioids on plasma concentrations of prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyrotropin (TSH) and growth hormone (GH) were assessed. Intravenous administration of dynorphin-A(1-13), 1-120 micrograms/kg, significantly increased plasma PRL levels.

Stereotactic heavy-particle irradiation of intracranial arteriovenous malformations.

Stereotactic irradiation appears to be effective in causing partial or complete thrombosis of AVM that are not surgically resectable. Use of heavy particles generated in a cyclotron allows better spatial definition and dose distribution than do other methods, allowing larger AVM to be treated. From these preliminary results, it is evident that heavy-particle irradiation therapy, like proton beam therapy, does not offer protection from recurrent hemorrhage for at least 12 months, nor is it devoid of major complications; it does offer a noninvasive mode of therapy for AVM that are difficult to treat surgically, however.

Dorsal periaqueductal gray-matter stimulation in humans.

Seven patients suffering intractable pain from head and neck cancer (age 48-73, mean 57.5 years) underwent acute stimulation of dorsal periaqueductal gray matter (PAG) with immediate cessation of pain. Two patients received chronic PAG stimulation with relief of pain during stimulation.

Dynorphin effects on plasma concentrations of anterior pituitary hormones in the nonhuman primate.

The role of dynorphin-(1-13) and dynorphin-(1-10)-amide in the neuroendocrine control of primate anterior pituitary hormones was studied in nonrestrained, ovariectomized rhesus monkeys. The effects of these opioids on plasma concentrations of prolactin (PRL), luteinizing hormone (LH), follicle stimulating hormone (FSH) and thyrotropin (TSH), and interactions with naloxone are reported here. Intravenous administration of dynorphin-(1-13), 30 to 120 micrograms/kg, significantly increased plasma PRL levels 3- to 4-fold.

Effects of dynorphin1-13 on opiate binding and dopamine and GABA uptake in stroked cat brain.

We previously reported that the opioid peptide dynorphin1-13 improves survival chances in stroked cats. Some evidence also suggests that changes in dopamine and gamma-aminobutyric acid (GABA) uptake may be associated with stroke. In the present study, therefore, we determined binding of the opiate [3H]ethylketocyclazocine (EKC), as well as dopamine and GABA uptake in various brain regions of control, stroked and dynorphin1-13-treated stroked cats.

Autopsy analysis of the safety, efficacy and cartography of electrical stimulation of the central gray in humans.

Electrical brain stimulation is effective in controlling certain intractable chronic pain syndromes in humans, but the specific target site(s) for stimulation producing a maximal analgesic effect is (are) not well defined. This prospective study correlates the clinical results of chronic stimulation of the periaqueductal gray (PAG) and periventricular gray (PVG) matter in humans with the anatomic site of electrode placement as determined at autopsy, and documents the histologic reactions to electrode implantation and electrical stimulation of the area. Seven patients underwent electrode implantation to control their chronic pain; two had electrodes implanted bilaterally.

Subcortical electrical stimulation for control of intractable pain in humans. Report of 122 cases (1970-1984).

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.

Treatment of experimental stroke with opiate antagonists. Effects on neurological function, infarct size, and survival.

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 less than 0.

Use of antidromic evoked potentials in placement of dorsal cord disc electrodes.

Intraoperative recordings of somatosensory evoked potentials were made in 16 patients undergoing implantation of a dorsal cord stimulation system. Antidromic recordings, obtained by stimulating through the dorsal cord electrode placed in the epidural space and recording over peripheral nerves in the painful region of the body, and much higher signal-to-noise ratios and could be obtained with greater reliability than standard orthodromic recordings. When the placement of the electrode was adjusted to obtain evoked responses in the painful region, paresthesias referred to that region were obtained in virtually every case.

Focal cerebral ischemia in the cat: effect of naloxone on cortical blood flow and neurological deficit following middle cerebral artery occlusion.

The effect of the opiate antagonist naloxone on both the neurological deficit and regional cortical blood flow after middle cerebral artery occlusion in the cat was investigated. In animals with mild symptoms, naloxone did not consistently produce a significant behavioral effect. In all cats with neurological deficits, including hemiplegia or severe hemiparesis, 2 mg/kg naloxone administered intravenously 4 h after the ischemic lesion produced a reversal of neurological symptoms.

Treatment of experimental stroke with the opiate antagonist win 44,441-3 effects on neurologic function, infarct size, and survival.

Cats were treated using a blinded protocol with either the dextrorotary or levorotary form of WIN 44,441-3 injected subcutaneously six hours after middle cerebral artery occlusion, followed by continuous subcutaneous infusion. The levorotary form acutely improved neurologic function in 90% of animals, whereas the dextrorotary form had no effect. Survival rate and infarct size were the same in both groups.

Reduced anesthetic requirement after electrical stimulation of periaqueductal gray matter.

To determine whether electrical stimulation of the periaqueductal gray region decreases anesthetic requirement, the authors studied the effect of such stimulation on the MAC of halothane and 60% nitrous oxide in 33 patients. These patients, who were undergoing implantation of a radio-frequency-coupled receiver and connection of that receiver to electrodes previously implanted in the periaqueductal gray area, were assigned randomly to receive (n = 16) or not receive (n = 17) electrical stimulation 1 h before surgery. The mean value (+/- SEM) for the minimum alveolar concentration of halothane combined with 60% nitrous oxide was significantly less (P less than 0.