Delayed endolymphatic hydrops: Study and review of clinical implications and surgical treatment - Brief Article

Ear, Nose & Throat Journal, Feb, 2001 by Tsun-Sheng Huang, Ching-Chen Lin

The slow injection of 0.1 ml of artificial perilymph, containing 25 [micro]g/ml of streptomycin, into the perilymphatic space of the lateral semicircular canal is called Shea's technique. [26] This procedure is performed with a 30-gauge needle in an attempt to destroy the vestibular receptors. [27] In theory, the perilymphatic trabecular meshwork and the membrana limitans should prevent, or at least minimize, the spread of streptomycin into the cochlea, thus preventing adverse effects to cochlear function. Since 1986, Shea has performed 166 streptomycin perfusions, and vertigo was controlled in all cases. [26]

In our series, the three patients who received streptomycin perfusion (two primary and one revision) experienced a complete resolution of their vertigo In each case, the operated ear showed no response to the maximal caloric test postoperatively, confirming that vestibular function had been destroyed. This suggests that in order to relieve symptoms in patients with ipsilateral DEH, more conservative measures such as ELS surgery, cochleosacculotomy, [27] and streptomycin perfusion can be chosen arbitrarily as either primary or subsequent procedures as an alternative to labyrinthectomy. Studies show that these more conservative procedures are equally efficacious in terms of alleviating vertigo (even among elderly patients) and in preserving the inner ear structure. [28]

Preserving the inner ear structure might become increasingly important, even in a deafened ear, now that cochlear implantation has become a standard procedure for patients with total or profound bilateral hearing loss. However, we do not recommend streptomycin perfusion for patients with contralateral or bilateral DEH, in whom hearing preservation is extremely important. In our experience, attempts to titrate streptomycin compound doses can be problematical because some of the compound is often regurgitated on administration. It is also very likely that titration is made difficult by differences in individual patients' inner ear pathology, which might reduce the effect of the trabecular meshwork and membrana limitans. Therefore, predicting the amount of streptomycin, the injection pressure, and the injection speed necessary to avoid damage to the cochlea is difficult.

In patients with contralateral DEN or Meniere's disease who still have significant hearing, preservation of hearing during surgery on the only-hearing or better-hearing ear is of the utmost importance. Therefore, only the safest techniques should be attempted. In 1978, Schuknecht wrote that there was no satisfactory therapy available for contralateral DEH. [3] In 1983, Morrison reported on ELS surgery on the only-hearing or better-hearing ear in patients with contralateral DEH and concluded that because the risk of surgical anacusis was only 1% with ELS surgery, it should be the only option for these patients. [28] In 1988, Hicks and Wright argued that only ELS surgery should be performed to alleviate disabling vertigo in contralateral DEH. [5] We agree. In our study, ELS cured vertigo in 13 of the 16 patients on whom it was performed (table 4). The other three patients continued to experience dizziness, which was controlled medically. Hearing was preserved in all but one patient. One patient experienced an improvement of 10 dB.