Biomedical subjects
Publications and source records attributed to J B Booth.
Patients with cholesterol granuloma of the middle ear cleft will usually present with a secretory otitis media, and exhibit evidence of diffuse disease within the mastoid upon roentgenographic evaluation. The following patient with an isolated middle ear cholesterol granuloma presented with signs and symptoms more closely resembling a glomus tumor.
Transtympanic electrocochleography has been used to measure the action potential (AP), summating potential (SP), and cochlear microphonic (CM) in patients with Menière's disease. In this condition the widening of the AP/SP complex is thought to be due to an enhanced negative SP which shows no adaptation and this may be the result of an increased asymmetry produced by endolymphatic hydrops. Measurements have also been made using two groups of agents -- those designed to increase the cochlear blood flow (the metabolic activator naftidrofuryl and inhalations of carbon dioxide) and those designed to reduce the hydrops "osmotically" (glycerol) or by diuresis. It was hoped that the "glycerol dehydration test" when assessed electrocochleographically would lead to a better selection of patients for surgical decompression of the saccus endolymphaticus. It was also hoped that it would lead to a fuller understanding of the electrophysiological changes which occur in Menière's disease. While it appeared that a decrease in the negative SP after glycerol may be a more sensitive indicator of the changes within the cochlea than either pure-tone audiometry or speech discrimination, no clearcut correlations between this change and the surgical result could be demonstrated. In many patients the AP/SP waveform remained unchanged after successful surgery, indicating perhaps that the pathological changes may have been checked but not reversed, while the hearing remained "pegged" at its preoperative level. Electrocochleography during operation failed to show any consistent change in the waveform or CM.
The aetiology of Menière's disease is unknown but in recent years many theories have been advanced to explain the observed pathological changes. These include abnormal metabolic states, allergy and personality type. In an attempt to throw more light on this and to confirm or refute the earlier work we studied twenty-seven (fifteen male:twelve female) patients with Menière's disease who conformed to the criteria set out by the Committee of Hearing and Equilibration of the American Academy of Ophthalmology and Otolaryngology (Alford, 1972). In this series the incidence of abnormal metabolic states was no higher than that of a comparable group in the general population. There was no significant difference in response to pin prick skin tests compared with a control group. Klockhoff and Lindblom's (1966) glycerol dehydration test was applied to twenty-one patients. The response to this test was measured by changes in the osmolality of the serum, the pure tone threshold of hearing and the maximum speech discrimination score. Continuous transtympanic electrocochleographic recordings during glycerol dehydration were carried out and in 10 patients there was a definite decrease in the negative summating potential. An electrophysiological explanation for this has been put forward and the possible use of this measurement in the diagnosis and management of Menière's disease has been discussed. The intercorrelation between these measures and their predictive value will become apparent in the future.
Using an otoadmittance meter the function of the middle ear was compared in 38 patients with rheumatoid arthritis (RA) and 30 matched controls with non-articular rheumatism. Patients with pre-existing ear disease were excluded from the study. No subjects in either group showed hearing loss on pure tone audiometry, but otoadmittance abnormalities were recorded in 16 of the RA (42%) and in 2 of the control groups (7%). The pattern of abnormality was similar in each case and indicated an increased laxity of the conducting system. The reason for this unexpected finding is unknown. There were no significant differences between the RA patients with normal or abnormal recordings as regards clinical or laboratory features or treatment.
Analysis of middle ear function has for many years been accomplished by acoustic impedance measurements and this has proved of great clinical value. The vectors which contribute to impedance are functions of mass, stiffness and resistance of the system and information about these components may be obtained by use of the otoadmittance meter. The shape of the tympanogram may be altered both by pathologies which change the relative magnitude of the vectors and by variation in the probe tone frequency. Patients with rheumatoid arthritis (55 ears) were compared with a series of controls (50 ears); 38% of 'rheumatoid ears' demonstrated a marked notch on the 660 Hz susceptance curve whilst only 8% of the control group showed this abnormality. The pattern suggests a decrease in the stiffness of the transducer mechanism in rheumatoid arthritis.
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