Hearing results from endolymphatic sac surgery

This report examines the effect of the endolymphatic shunt on hearing. The study group was drawn from 101 shunt operations for intractable vertigo between 1983 and 1987. Thirty ears met criteria for diagnosis, level of preoperative hearing impairment, and length of follow-up. The control group consisted of 30 ears with symptoms severe enough to prompt recommendations for shunt surgery, but the patients either opted against surgery or improved. The results were analyzed using the 1985 AAO-HNS reporting criteria. When looking at worst postoperative (or worst scores after 2 years of follow-up in controls) compared to worst preoperative (or worst scores in the first 6 months of presentation in controls), we found no significant difference between the study group (average loss of 9 dB pure-tone average [PTA] and 16% speech discrimination [SD]) as compared to the control group (average loss of 3 dB PTA and 10% SD). However, when using the first and last audiograms for the control group, there was a statistically significant difference as compared to the worst preoperative and postoperative scores in the shunt group. Using the first and last scores, the control group had a better outcome (PTA improved 2 dB, SD score dropped 5%). There was no significant difference between groups for percentage of patients whose hearing improved, remained the same, or worsened. In conclusion, the endolymphatic shunt operation did not significantly effect the long-term hearing results.