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Biomedical subjects

H Kumagami

Publications and source records attributed to H Kumagami.

At least 55 records · Page 3Linked to original sources
PubMed1983

Chronological changes of electrocochleogram in experimental endolymphatic hydrops. Special reference with AP output potential and hair cell cilia.

Chronological changes of the whole nerve action potential (AP), cochlear microphonics (CM) and summating potential (SP) in experimental endolymphatic hydrops in guinea pigs were studied during a period from 1 week to 13 months after the endolymphatic sac obliteration. Endolymphatic hydrops became extensive in month 3 and persisted thereafter. The threshold of AP increased with the lapse of time but good AP output potential was obtained, being maximum in month 3. The threshold of CM increased with the lapse of time. The CM output potential was the highest around week 3 when endolymphatic hydrops was slightly formed, and it decreased thereafter. SP responses at the frequencies of 8, 4, 1 and 0.5 kHz showed the reversed polarity of -SP in month 3 and changed towards potential 0 thereafter. In animals showing super-normal AP output potential, the cilia in the third row of outer hair cells were disarranged. This seems to be involved in recruitment.

Action Potentials↗
PubMed1982

Electrocochleographic study of Ménière's disease.

Auditory nerve action potential (AP), cochlear microphonics (CM), and summating potential (SP) were recorded from 32 patients with Ménière's disease. Patients were classified into three groups according to the degree of their hearing impairment. The group of patients that had a mild to moderate hearing loss and whose hearing was reversible showed notably satisfactory responses for AP, CM, and negative SP (-SP), and also showed a high incidence of positive SP (+SP). Low responses for AP and CM with an increase of detection thresholds and a high -SP/AP ratio were obtained from patients with moderate hearing impairment, whose hearing fluctuated slightly. These electrocochleographic findings were suggestive of the pathophysiologic differences at the various stages of Ménière's disease.

Audiometry, Evoked Response↗
PubMed1981

Cancer of the head and neck in atomic bomb survivors: Hiroshima and Nagasaki, 1957-1976.

A search was conducted in Hiroshima and Nagasaki for all cases of cancer of the lip, nose and nasal cavity, accessory sinuses, larynx, and the oral cavity and pharynx with their subdivisions occurring during the period 1957-1976 among a large, fixed cohort of atomic bomb survivors. A total of 232 cases were identified, of which 154 (66.4%) were histologically confirmed (definite cases). Among definite cases, cancer of the epiglottis and larynx predominated (31.2%), followed by accessory sinus (24.7%) and tongue (18.8%). Of the 154 definite cases, 141 (91.6%) were squamous-cell carcinomas. Only two sarcomas were identified, neither of which was attributable to radiation exposure. Analysis of both total and definite cases, by both total group and major anatomic site, failed to reveal definite evidence of a radiation relationship. Although a suggestive relationship to radiation dose was found for accessory sinus cancers (P = 0.06) among the definite cases, inconsistencies in the data do not permit the conclusion that the incidence of tumors in this group increased as a result of atomic bomb radiation exposure. The medical literature concerning post-irradiation head and neck tumors is briefly reviewed.

Carcinoma, Squamous Cell↗
PubMed1981

Electrocochleographic study of patients with cerebral vascular lesions.

Electrocochleographies were performed on three patients with deafness resulting from cerebral vascular lesions. Recording was made by the transtympanic needle electrode technique. In a patient who had anterior-inferior cerebellar artery aneurysm that showed fluctuating hearing loss, auditory nerve action potential (AP), cochlear microphonics (CM), and summating potential fluctuate in amplitude in concert with episodes of ischemic hearing loss. This indicates the pathophysiology of reversible impairment of the cochlear nerve and of sensory epithelium of the inner ear caused by disturbance of blood flow into the inner ear. It was also conjectured that the cochlea is hardly impaired in the case with normal AP and CM responses despite the increased threshold in pure-tone audiometry and that the cochlea undergoes irreversible organic changes in the patient who has no AP or CM response in tests after a long period.

Action Potentials↗
PubMed1981

Changes of the action potential, the summating potential and cochlear microphonics in experimental endolymphatic hydrops.

The changes of the action potential (AP), the summating potential (SP) and cochlear microphonics (CM) were investigated in reference to the grade of endolymphatic hydrops produced by endolymphatic sac obliteration in guinea pigs. In a few cases with minimum endolymphatic hydrops, super-normal AP was obtained. With an increase of endolymphatic hydrops, CM responses were reduced although AP responses at intensive stimulation were maintained relatively well. It is thought that the polarity of positive SP, as observed in control, was influenced to deflect towards negative SP by an interaction between the increased degree of endolymphatic hydrops and the changes of the biochemical components of the inner ear fluids.

Action Potentials↗
PubMed1981

Conditions of clinical recovery from partial facial palsy caused by injury to a branch of the facial nerve.

This study was conducted to elucidate the pattern of clinical recovery from partial facial palsy caused by injury to a branch of the facial nerve in rabbits. In the experiment, the state of recovery from palsy was investigated by observing the movement of the m. orbicularis oris of the rabbit at the time of food intake, as well as by observing the evoked wave and muscle contraction caused by nerve stimulation, and the muscle contraction caused by muscle stimulation. Recovery from peripheral facial nerve palsy is complete within 1 month after nerve impairment if over half of the nerve fibers of the impaired nerve are maintained intact without degeneration.

Animals↗
PubMed1980

Experimental labyrinthine disorders and direction of nystagmus.

The purpose of this paper is to demonstrate the variation of the direction of nystagmus which is elicited from the peripheral labyrinth. The direction of nystagmus depends, among other things, on the nature of the stimulus. Depending on the degree of pathophysiological conditions in the labyrinth, atypical nystagmus which does not comply with the rule is occasionally elicited even though the same stimulus is given. Hyperfunctional stimulation to the labyrinth, such as allergy, causes nystagmus which beats to the affected side and also shows hyperactivity of the whole nerve action potential and cochlear microphonics.

Animals↗
PubMed1980

Regional difference in susceptibility to damage of vestibulo-semicircular canals in experimental labyrinthine lesion.

In the study on regional difference in susceptibility to damage of vestibulo-semicircular canals upon causing labyrinthine lesion by four different procedures, namely, by intracranial approach, through the middle ear, through the facial nerve and by means of experimental endolymphatic hydrops, the following results were obtained. 1. The crista of posterior semicircular canal among the semicircular canals and the macula of the saccule within the vestibule were most susceptible to impairment. In other words, the most susceptible region was the so-called pars inferior. In regard to the impairment of the cupulas, the posterior semicircular canal was the most susceptible region. 2. Recovery from markedly reduced caloric nystagmus within a short period so as to see provocation of caloric nystagmus may result from the reconstruction of the cupulas and the normalization of vacuole-like findings of the sensory epithelium.

Animals↗
PubMed1980

Anisocoria in inner ear lesions.

In experiments using rabbits, the pupil on the side of irritative inner ear lesion showed dilatation, and that on the side of paretic lesion showed constriction. In the clinical observation of patients with unilateral inner ear diseases (134 cases), anisocoria was recognized in 54.5%. In 68.5% of these, anisocoria was induced after applying a drop of neosynephrine. The size of the pupil on the healthy side was smaller in 65.8% than the pupil on the healthy side. Anisocoria in inner ear lesions is believed to be due to vestibulo-sympathetic imbalance through the superior cervical sympathetic ganglion.

Adolescent↗
PubMed1977

Diagnostic significance of summating potential in sensorineural deafness.

The polarity of the summating potential wave induced by electrocochleographical examination has an important bearing upon the pathophysiology or the prognostic evaluation of sensorineural deafness. Electrocochleographical examination was performed on cases of sudden deafness, Ménière's disease, progressive sensorineural deafness, sensorineural deafness due to barotrauma, etc. When the polarity of the summating potential showed an increased negative wave, physiological blockage in sensorineural structures was revealed. In other words, under such conditions sensorineural structures have a potential for activity although hearing acuity was damaged. On the other hand, when the summating potential has an increased positive polarity wave, gradual decrease of the hearing acuity was revealed.

Action Potentials↗
PubMed1976

Prognostic criteria of sudden deafness as deduced by electrocochleography.

Electrocochleography was performed at first examination in 34 patients with sudden deafness. Recording was made with the use of the transtympanic needle electrode technique. A notable difference in the electrocochleographic findings was shown between the cases of complete recovery or remarkable improvement and the cases of slight improvement or no change. Electrocochleography may be prognostic of sudden deafness at initial onset.

Acoustic Stimulation↗