三次元オージオグラムによる聴力経過観察-突発性難聴の予後診断に関する研究

We used a three-dimensional audiogram which displays hearing levels on the Z axis, frequencies on the Y axis, and duration on the X axis, which was developed to aid observation of hearing level changes during the course of various otologic diseases, to analyze the course of hearing recovery and outcome in patients with sudden deafness.<BR>1) An overall view of the change over time in a patient's hear ing level was easily obtainable with this technique, since the temporal element is shown on the X axis. The basal view position of the audiogram displays most of the information necessary in forming diagnosis, assessing prognosis, determining treatment, and evaluating its efficacy. The technique was found to be useful in predicting outcome in patients with otologic diseases ranging from sudden deafness, with its often rapid recovery period, to Meniere's disease, with its long-term fluctuating hearing loss.<BR>2) In some patients, a better under standing of the clinical course could be obtained through use of a view angle other than the basal view position.<BR>3) The time of recovery of middle-frequency hearing at 15 dB or more had great prognostic value in patients with deafness type and with scale-out sudden deafness. Recovery within 13 days of onset in patients with the former condition and within 17 days in those with the latter was correlated with excellent rate of hearing recovery.<BR>4) An initial mean hearing level of lower than 80 dB in patie nts with sudden deafness was generally correlated with good outcome; conversely, that above 80 dB was correlated with poor outcome. Patients without tinnitus showed unfavorable outcome with respect to hearing. Patients in whom glycerol test and electrocochleogram results suggested the presence of endolymphatic hydrops had good outcome.