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Biomedical subjects

Y Hosobuchi

Publications and source records attributed to Y Hosobuchi.

At least 19 recordsLinked to original sources
PubMed1992

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. In all patients, neuralgia ceased immediately postoperatively and has not recurred during 9 months to 15 years follow-up. Descending trigeminal tractotomy provides a satisfactory solution to this relatively rare but paroxysmal pain syndrome.

Adult↗
PubMed1991

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. Stimuli (72 pulses/s) above and below such minimum train durations (0-750 ms) were delivered to the ventrobasal thalamus via electrodes chronically implanted for the therapeutic control of intractable pain. Detection was measured by the subject's forced choice as to stimulus delivery in one of two intervals, regardless of any presence or absence of sensory awareness. Subjects also indicated their awareness level of any stimulus-induced sensation in each and every trial. The results show (1) that detection (correct greater than 50%) occurred even with stimulus durations too brief to elicit awareness, and (2) that to move from mere detection to even an uncertain and often questionable sensory awareness required a significantly larger additional duration of pulses. Thus simply increasing duration ('time-on') of the same repetitive inputs to cerebral cortex can convert an unconscious cognitive mental function (detection without awareness) to a conscious one (detection with awareness).

Awareness↗
PubMed1991

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. In all three cases, cSCS alleviated the symptoms of ischemia. Xenon-CBF studies or single-photon emission computer tomography (SPECT) showed increased CBF in response to cSCS. Although no mechanism clearly responsible for this remarkable therapeutic efficacy can be proposed yet, further clinical trials of cSCS for inoperable cerebral ischemia may be justified.

Adult↗
PubMed1979

Stimulation of human periaqueductal gray for pain relief increases immunoreactive beta-endorphin in ventricular fluid.

Immunoreactive beta-endorphin was measured in the ventricular fluid of six patients with chronic pain. Stimulation of the periaqueductal gray matter in three patients with pain of peripheral origin resulted in significant increases (50 to 300 percent) in the concentration of ventricular immunoreactive beta-endorphin. In three other patients suffering deafferentation dysesthesia, stimulation of the posterior limb of the internal capsule did not alter the concentration of this peptide. These results provide evidence of the release of human immunoreactive beta-endorphin in vivo and suggest that naloxone-reversible pain relief achieved by stimulation of the periaqueductal gray matter may be in part mediated by the activation of beta-endorphin-rich diencephalic areas.

Aged↗
PubMed1979

Direct surgical treatment of giant intracranial aneurysms.

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.

Adult↗
PubMed1978

Treatment of intracavernous extensions of pituitary adenomas.

Two cases of pituitary adenomas invading the cavernous sinus are presented. The technique of radical extirpation of intracavernous tumor is described. Clinical, radiologic and pathologic features diagnostic of invasive adenomas are discussed, as well as alternative treatments. Craniotomy for radical resection is recommended as primary treatment for tumors which can be identified preoperatively as invasive tumors.

Adenoma↗
PubMed1977

Pain relief by electrical stimulation of the central gray matter in humans and its reversal by naloxone.

Relief of intractable pain was produced in six human patients by stimulation of electrodes permanently implanted in the periventricular and periaqueductal gray matter. The level of stimulation sufficient to induce pain relief seems not to alter the acute pain threshold. Indiscriminate repetitive stimulation produced tolerance to both stimulation-produced pain relief and the analgesic action of narcotic medication; this process could be reversed by abstinence from stimulation. Stimulation-produced relief of pain was reversed by naloxone in five out of six patients. These results suggest that satisfactory alleviation of persistent pain in humans may be obtained by electronic stimulation.

Adult↗
PubMed1977

Opiate antagonist, naloxone, strongly reduces analgesia induced by stimulation of a raphe nucleus (centralis inferior).

The analgesic effects obtained in the cat by central inferior raphe nucleus stimulation are greatly reduced by the administration of a specific opiate antagonist, naloxone. In 12 of 16 cats analgesia, tested by pinches applied on the 4 limbs or the tail, was totally abolished. Analgesia tested by considering the increase of the threshold of the jaw opening reflex was reduced to 44% of the initial value. These results emphasize the relation existing between morphine analgesia and analgesia induced by central stimulation. To try to explain the effects of naloxone, one may suppose that central stimulation releases an endogenous morphine-like substance such as enkephalin.

Analgesia↗
PubMed1977

beta-Endorphin: behavioral and analgesic activity in cats.

beta-Endorphin has been shown to possess potent behavioral and antinociceptive activities when administered intraventricularly in cats. On a molar basis, beta-endorphin is 72-96 times more potent than morphine and its actions are blocked by the specific opiate antagonist, naloxone.

Analgesics↗
PubMed1977

beta-Endorphin: development of tolerance and its reversal by 5-hydroxytryptophan in cats.

Tolerance to beta-endorphin developed acutely in cats if the administration of the peptide was repeated within the first 24 hr. The tolerance was reversed immediately by systemic administration of the serotonin precursor, 5-hydroxytryptophan. It was further shown that 5-hydroxytryptophan potentiates the analgesic effect of the subliminal dose of beta-endorphin.

5-Hydroxytryptophan↗