A significant recent advance in the treatment of inner ear conditions is the MicroWick®, which provides a means to deliver certain medications to the balance and hearing structures of the inner ear. In the past, attempts to reach the inner ear with medications delivered by the systemic route (oral, intravenous, intramuscular, etc.) have met with limited success, because the inner ear tends to be somewhat impervious to most medications reaching it through the blood stream. So, this means that large and extensive systemic doses must be given to be effective, if at all, leading to the risk of serious side effects throughout the body.

In recent years, it has been found that by placing medications though the eardrum into the round window area, the medication would be absorbed through the round window into the inner ear. Called the transtympanic, or intratympanic, route of administration, this has proven to be a highly successful method of treating certain inner ear conditions that are adversely affecting balance or hearing. Because this method is so much more efficient, only a small dose of medication is required, thus virtually eliminating systemic side effects.

However, this new route of administration required that multiple injections be carried out in the office over a period of time. This was inconvenient, and tended to provide poor control over the dosage reaching the inner ear. The first solution to the problem was provided by the Arenberg microCath®, whereby a minute catheter (tube) was placed in the round window area. This led out of the ear canal to a small pump that was carried in a pocket and supplied a slow flow of medication over a period of days. However, placement of the catheter required a hospital operation, and it was awkward to walk around with a tube hanging out the ear for weeks or more.

The Silverstein MicroWick®, developed by Herbert Silverstein, MD, of Sarasota, Florida, is designed to solve all these problems. Under local anesthesia in the office, a minute tube and a highly absorbent wick are placed so as to extend through the eardrum to the round window. In some cases, some minor surgery must be done in the round window area to insure access by the medication. Nothing is visible from the outside. Then, patients simply place the appropriate medication into the ear with a dropper or other dispenser, according to directions from their physician. The medication first stops at the eardrum, then is readily absorbed by the wick and drawn inward to the round window, whence it is absorbed into the inner ear.

It will require extensive studies to determine whether the Arenberg microCath® or the
Silverstein MicroWick® is the more effective. I have used both devices for my patients and they appear to be about equally effective. However, for ease of insertion and daily use, the MicroWick is more convenient and better tolerated.

So far, reported medications delivered by the Silverstein MicroWick® have been largely corticosteroids and aminoglycosides (gentamicin, streptomycin). These have been used in the treatment of Meniere's disease, as well as certain other forms of uncontrolled vertigo and hearing loss. I expect the list of medications and treatable conditions that can advantageously utilize this modality to grow significantly in the near future. This mode of treatment has great potential for controlling or resolving many inner ear conditions.

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