Four cases of malingering were reported. Case 1: a 36 years old man. Bilateral hearing loss was noted after head injury. In spite of profound sensorineural hearing loss, speech discrimination score was comparatively better than that expected from his hearing loss. Threshold of stapedial reflex was within normal limits. Case 2: a 44 years old man with bilateral hearing loss occured after gas explosion. There were no abnormal neurological findings except hearing loss. True hearing acuity seemed much better than that was predicted from pure tone audiogram, which showed a profound deafness. Speech discrimination score was relatively good. Case 3: a 53 years old woman with sudden deafness in the right ear. The left ear has been deaf for the past 35 years. Her hearing recovered 30 to 40 dB in speech range 2 months after the onset, but her speech discrimination was better than expected from pure tone audiogram. ERA which was performed after she received manetary payment for her social security demonstrated 15 to 20 dB lower than the pure tone threshold on the last audiogram. Succesively performed audiogram was identical with ERA threshold. Case 4: a 11 years old boy was found profound hearing loss at regular physical examination at school. His hearing loss was 70 to 75 dB bilaterally in speech range. He seemed to understand what his mother is saying, and after a week during which he was completely free from school and enjoyed his vacation, his audiogram returned to normal.
Six cases of simulated deafness were found in the Kyushu University Hospital in recent three years. They have overlaid on their actual hearing loss caused by traffic accidents for purpose concerned with compensation by the car-insurance or trials. In four cases malingering was detected because of inconsistency of the results of the conventional hearing test, not specially for the malingering, and the patiets' behavior. In another two cases, Lomberd's test, delayed feedback test and EEG-audiometry successfully disclosed the presence of overlaid deafness.
The purpose of this study is to discuss the characteristics of the audiograms obtained in cases with simulated hearing loss. Twelve subjects with normal hearing were asked to simulate a moderate hearing loss on pure tone audiome try and Békésy audiometry. They were examined twice at one week interval. The following results were obtained: (1) The saucer type audiogram was found in 75 per cent. (2) Type V Békésy audiogram was present in 89.6 per cent of 48 Békésy audiograms. (3) TTD was positive in most of cases on Békésy audiograms. Furthermore TTD was also positive on interrupted tone tracing. (4) Significant test-retest variation was not found in most subjects. Analyzing the date mentioned above, the causes for this phenomenon were discussed.
The fixed-frequency threshold tracings at 1, 000 Hz and 4, 000 Hz for periodically interrupted and continuous tones were obtained on 452 cases with various types of auditory disorders. Eleven cases among them showed type V audiogram in that the threshold for periodically interrupted tone is tracked at lower levels than thethreshold for continuous tone on one or more frequency tracings. One case was suspected of non-organic hearing loss, and another case was diagnosed of reflex epilepsy with normal threshold. Other 9 cases was diagnsoed of sensori-neural hearing loss and they showed type V at only one frequency threshold tracing. Authors considered that type V obtained at only one frequency threshold tracing did not indicate nonorganic hearing loss.
By means of self-recording audiometer combined with taperecorder, the Kawamura's malingering test (1959) was performed. At first, bilateral self-recording audiometry was carried out and the tones from audiometer which subject responded in the worse ear was recorded in tape. And when the better ear was examined, the recorded tones in the tape were submitted to the worse ear simultaneously. In these examinations, continuous tones of 500-4, 000 Hz were used. When the difference between two audiograms of the better ear was within 10 dB, malingering can be excluded. This method was comparatively objective and simple as well as practical.
Applying ERA methods to 7 suspected cases of malingering, we obtained the results as follows. (1) In general, ERA methods can be crucial test for diagnosis of malingering when the threshold of ERA was lower than subjective threshold produced by pure tone audiometry. (2) It seems difficult to diagnose malingering of unilateral case, because the masking in ERA is controversial. (3) There were 2 cases in which the difference between subjective threshold and ERA threshold could not be clearly explained. (4) The probability of appearance of evoked response in malingering was discussed.
As a newly developed test of diagnosing pseudohypoacusis, electrocochleography has been applied to the cases of suspected non-organic hearing loss at our clinic for the last three years. In the course of investigation of 23 cases of suspected non-organic hearing loss, six categories can be distinguished, as follows 1) pure pseudohypoacusis, 2) feigned overlay, 3) pure psychogenic hearing loss, 4) psychogenic overlay, 5) peripheral organic hearing loss, and 5) central organic hearing loss. It is possible, by the use of electrocochleography, to differentiate these six categories of suspected nonorganic hearing loss. Needless to say, it is useful to supplement ERA and impedance audiometry with electrocochleography by which neurophysiological information of the cochlea can be obtained.
During past three years, fourteen hundred patients injured by traffic or labour accident, complaining hearing disturbance were treated and tested in our clinic. Forty percents of the patient had no any objective findings nor symptoms, might be called stigmata hearing disturbance in a wide sense. During last year, fourteen patients among four hundred complaining of hearing disturbance according to traffic or labour accidents were suspected to be simulated, and ten of them were diagnosed to have stigmata hearing disturbance after several close examination for hearing, and psychology. The cause of the accidents were following, seven patients were injured by labour accidents, and the others were by automobile accidents. The six of them had uncosciousness at accident. The six of them had a facial fracture, one of them had a skull depression fracture, and one had fracture of the basis of skull, and the other four had no fracture in x-ray study. In standard audiometry, all cases had flactuation in its threshold, so it was very difficult to determine their threshold. Saucer shape audiogram were obtained in three patients and Stenger's test was positive in six cases. Using average response computer, the threshold of evoked response audiometry was lower than that of standard audiometry in all cases.
A case of psychogenic deafness in a 13 years old boy is reported. The patient complained of bilateral severe deafness for 5 months and used a hearing aid in his daily life. The pure tone test revealed scale out but the voice test revealed better than the result of pure tone test. In spite of subjective hearing loss, by EEG audiometry his hearing was normal. His life history and psychological tests showed hysteric sign and character neurosis. On the examination of visual field, a moderate defect was revealed. By these tests, the diagnosis of psychogenic deafness was established. Then, by a treatment for hysteria, his hearing loss was remarkably recovered.
This is to report a malingerer who received a series of hearing tests for malingering, and confessed later that he was deceiving the examiner. True hearing threshold was obtained thereafter. The case showed that intolerable stress from pretending deafness gave influence upon the test-retest discrepancy. SRT was a useful tool for detecting true threshold in this case.