PubMed · 5269051
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S C Dalsgaard. 1969. Evoked-response audiometry.. https://pubmed.ncbi.nlm.nih.gov/5269051/
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A morphological analysis was performed on a human cochlea removed during skull base surgery. The patient experienced a noise-induced hearing loss following 30 years of mechanical exposure. The tissue was processed according to the block surface technique and the organ of Corti, osseous spiral lamina and spiral ganglion were analyzed at different levels. There was a circumscribed lesion approx. 10 mm from the round window extending to about 13 mm. At this site, the dominant pathological feature was the loss of outer hair cells that was comprehensive in the centermost area and partial in the peripheral region of the damage. The degradation of inner hair cells was less severe with signs of cell atrophy yet with limited loss. Outer pillar cells were often collapsed leading to deformation of the acoustic ridge. The Deiters cells were often present and physically interactive with remaining nerve fibers. In the reticular lamina, surgical manipulation and dissection resulted in tears which may be attributed to a reduction of intercellular strength between cells. In the damaged area, there was a 45% loss of myelinated nerve fibers measured at the osseous spiral lamina. Pathological changes could not be observed in the spiral ganglion with certainty although the type II cells innervating the outer hair cells were often difficult to discern.
A 62-year-old woman who complained of repetitive vertigo with a left fluctuating hearing loss was admitted to our hospital three times. A glycerol test was done on the third admission. Two hours after the administration of glycerol, the patient complained of rotatory vertigo with a downbeat vertical nystagmus. This nystagmus then changed its direction upward. Her left hearing loss was improved during the glycerol test. On the day after the glycerol test, a caloric test was done. The caloric response of the right ear was remarkably improved. Although she had not felt a hearing loss in the right ear, an overwritten audiogram showed a fluctuation of hearing in the right ear. The bilateral caloric responses fluctuated. From these findings, it appears that the function of the inner ear on both sides fluctuating. We speculate that the administration of glycerol elicited an asymmetry in the function of the inner ear on both sides and ocuured vertigo with vertical nystagmus because of the irritation of both ears.
OBJECTIVE: The purpose was to find out whether there is a relationship between the central nervous system involvement and retinopathy in diabetes mellitus. STUDY DESIGN: In a multidisciplinary clinical study, diabetic patients with and without retinopathy were examined utilising auditory brainstem response (ABR) testing, and the results were interpreted from clinical and pathophysiological point of view. PATIENTS AND METHODS: Thirty-three diabetic patients with retinopathy (study group) and 20 diabetic patients without retinopathy (control group) were included. Audiometry and ABR testing were made. The results of both groups were compared for ABR parameters. RESULTS: Audimetric results of the study and control groups were similar. In the study group, ABR testing revealed prolonged absolute and interpeak latency of the waves. The difference was significant for I-III interval (P<0.01). The amplitudes of the waves were similar in both groups and wave V amplitude was significantly diminished in the study group. Abnormal waveforms were recorded by 40 and 12.5% in the study and control groups, respectively. CONCLUSION: Retinopathy is accompanied with lower brainstem disintegration. Microangiopathy is the possible mechanism that is involved in the occurrence of retinopathy and brainstem neuropathy. ABR can help diagnose retinopathy. Better understanding the role of ABR in diagnosis and early detection of retinopathy in diabetic patients needs further study.