No abstract

Chronic subjective tinnitus is a common feature of clinical otosclerosis. Analysis of the records of 1,014 consecutive cases of clinical otosclerosis, all confirmed by stapes surgery in South Australia between 1960 and 1972, gives a preoperative prevalence of this symptom of 65%. The association of tinnitus with various predictors is considered, and a statistical analysis is presented. Tinnitus has an association with gender (p < .0001), mean preoperative bone conduction (BC) level (p = .0012), mean air conduction (AC) level (p = .0192), and mean air-bone gap (p = .0075). The associations between tinnitus and the age of the patient, the duration of deafness, the presence of Schwartze's sign, and the severity of footplate pathological involvement were all nonsignificant. The association of tinnitus with the AC and BC thresholds is unexpectedly paradoxical. An economic predictive model for tinnitus in otosclerosis has been constructed from the 2 strongly significant variables, gender and mean BC hearing level, by logistic regression. In this large series of cases, the log odds in favor of finding tinnitus are about 0.810 for male subjects and 1.394 for female subjects when the BC level is zero. The log odds fall by 0.014 for each decibel of mean BC rise.

A retrospective study has been made of a sample of 479 women with deafness from otosclerosis, classified according to the number of pregnancies they have had and whether there had been a subjective impression of deterioration of hearing during or immediately after at least 1 pregnancy. The study confirms previous reports that pregnancy does involve a risk of aggravating deafness in clinical otosclerosis. The chance of female patients with bilateral otosclerosis reporting a subjective deterioration of hearing in pregnancy can be accurately described by a simple mathematical model and varies from about 33% after 1 pregnancy to about 63% after 6 pregnancies. In women with unilateral otosclerosis pregnancy-related deterioration of hearing is much less commonly perceived. There is no strong evidence that pregnancies cause any alteration to the actual footplate pathology of female patients.

The diameter (0.6 or 0.8 mm) of the pistons selected for reconstruction after stapes surgery appears to have little effect on the outcome, except perhaps at 6 and 8 kHz, where the slim piston appeared to have a significant advantage. The size of the footplate fenestra is of paramount importance to the outcome. A small footplate fenestra has statistically significant advantages for hearing gain over all other sizes of fenestra (ie, total, three-quarter, or half removal of the footplate), at least for the first 10 years after surgery, at frequencies of 2 kHz and above. Total stapedectomy has given the worst results for hearing gain at frequencies above 2 kHz, and the rate of deterioration of gain over time seems to be more rapid than after small-fenestra techniques. Small fenestras are recommended as the preferred technique in all cases of surgically treatable otosclerosis.

1. The massive otosclerotic focus, obliterating the oval window niche, has a relatively high case incidence of 11-2 per cent in South Australia. The three classes of obliterated footplate are defined. 2. Basic data of 109 consecutive surgical cases of obliterative otosclerosis are given. A brief description of operative techniques--vein graft and polyethylene tube in nine, and piston technique in 100--is given and the difficulties and complications arising at or after surgery are discussed. 3. Post-operative follow-up of patients with yearly audiometric assessment has been achieved in 105/109 (= 96-33%) at four years, and in 94/109 (= 86-26%) at five years. 4. The results of surgery are presented by many and varied methods including bar diagrams, post-operative hearing gains, post-operative bone-air gaps, speech discrimination studies and standard statistical analysis techniques. 5. The vein graft technique (nine cases) is very much inferior to the piston technique. Vein graft cases had a 33% incidence of profound sensori-neural loss due to bony reclosure of the window. 6. The piston technique (100 cases) gave hearing gains of 20 decibels or more in 91%, 30 decibels or more in 71%, and 40 decibels or more in 41% of cases at five years post-operatively. The bone-air gap at five years post-operatively was diminished to 20 decibels or less in 88%, to 15 decibels or less in 85%, to 10 decibels or less in 77%, and complete closure or over-closure occurred in 52% of the patients. 7. Data analysis has established there is no change with time of the post-operative mean bone-air gap 500--2,000 Hz. over a period of at least five years, and thus that the piston operation gives a persisting and stable hearing result. 8. In predicting the effect of the piston operation only a rough guide can be obtained from other variables. In particular bone hardness, mucosal characteristics, sex and piston diameter appear to be irrelevant. Patients with a large bone conduction reading or a large air-bone gap appear to do slightly worse than patients with smaller values for these variables. There are no grounds for excluding a patient from operation on account of age, or the finding of active otosclerosis (soft bone and thickened vascular muco-periosteum). 9. From the data of piston operations, the estimated mean bone-air gap for the five-year examination period was 4-14 db. with a standard deviation of 12-5 db. 10. The piston operation is highly recommended as a safe and suitable method of alleviating, in the long-term, the conductive hearing loss of patients with obliterative otosclerosis of the oval window.