**7. Intratympanic delivery methods**

There is no standard protocol for IT corticosteroid injections; the frequency of injections, concentration and type of corticosteroid. Method of injection is determined by the individual surgeon.

Multiple intratympanic delivery methods are descripted:

**Syringe delivery is a** simple method. However, direct injections do not allow for prolonged delivery. We can anesthetize the tympanic membrane with 10 percent Xylocaine. A drop of phenol on the ear drum is one method. Another is a topical anesthetic such as "Emla" cream. The drug is injected, left in the middle ear for 30 minutes.

The myringotomy is placed in the most superior and anterior location to allow maximal filling of the middle ear space with the corticosteroid solution while the patient is supine. Placement of the tube eliminates the need for a new myringotomy for each subsequent injection. For injection, we use a 25-gauge spinal needle attached to a 1-mL tuberculin-type syringe. To equalize pressure, two needle punctures were made in the anterior superior quadrant of the tympanic membrane, the first for injection and the second (superior) for air escap. The initial injection was followed by a second injection about 15 minutes later for a total volume of approximately 0.5 mL. The patient remained supine for 30 to 40 minutes, with the head turned to the side and the injected ear upright, and was instructed to swallow as little as possible to help maintain the fluid in the middle ear space for longer duration.

**Microwick** is the polyvinyl acetate wick (1 mm diameter by 9 mm length). It absorbs medication and transports it directly to the RWM. It's placed through a tube, at the round window niche. It allows instillation by the patient himself at home. The MicroWick should be removed or replaced after 4 weeks of treatment to prevent it from becoming adherent to the mucosa of the round window (26).

**Microcatheter** is composed of two tubes: one for injection and the other for the return of excess liquid. It ends with a bulge that is placed at the round window niche under general anesthesia. Some researchers propose to link the catheter to a pump. This would allow continuous irrigation and delivery of the product constantly at the round window.
