Endolymphatic subarachnoid shunt operation for idiopathic endolymphatic hydrops.

In 1974 we reported on 92 patients who had endolymphatic subarachnoid shunt surgery for idiopathic endolymphatic hydrops. That group had a follow-up of at least 5 years, and only 41% had satisfactory control of vertigo. The purpose of this paper is to describe the results after a larger postoperative follow-up (12 1/2 years, with a range of 68 to 182 months), and to discuss some additional observations regarding endolymphatic sac operations. Two patients have died of unrelated causes, one in the 115th postoperative month and the other in the 124th postoperative month. Eight patients have been lost to follow-up. Our data show that 35% of the patients have had satisfactory control of their vertigo: 23% have had no vertigo, and 12% have had the vertigo improved by at least 75%. The remaining patients had improvement in vertigo, but not to a satisfactory degree, had pronounced improvement in vertigo, but with subsequent recurrence of severe attacks of dizziness, or had no improvement at all. In addition, there has been a steady deterioration in the success rate with increased time of observation. Nineteen percent of the patients showed significant improvement in hearing after surgery, 47% demonstrated no change in hearing, and 34% had a moderate to profound decline in hearing postoperatively. Of 17 patients who had socially adequate hearing in the afflicted ear preoperatively, 12 showed deterioration in hearing to the point that air-conduction thresholds were below the socially adequate level. Six patients with bilateral endolymphatic hydrops who had almost identical auditory acuity in each ear underwent a unilateral shunt operation. In each of these patients, the unoperated-on ear had better results from the hearing standpoint. The data show, therefore, that control of vertigo with the endolymphatic subarachnoid shunt operation was not only disappointing initially, but as the patients were followed over a longer time, the percentage of patients with satisfactory vertigo control declined. Additionally, one-third of the patients experienced further moderate to profound sensorineural deafness, either as a result of surgery or because the operation failed to control the disease process. Last, it is obvious that the endolymphatic subarachnoid shunt operation did not preserve hearing, even when the operation was performed early in the course of the disease.