What is it?
Chemical Perfusion (C.P.) is a new treatment for the application/delivery of specific medication(s) into the inner ear with the goal of curing or controlling diseases affecting the hearing and/or balance nerves and fluid pressures of the inner ear.
C.P. is a procedure which can be performed either in the office setting or at an outpatient surgical facility. The procedure is done alone or in conjunction with other “non-destructive” operations of the inner ear.
Presently chemical perfusion is used to control dizziness arising from diseases of the inner ear, e.g., Meniere’s disease, and for sudden deafness, severe tinnitus and cohlear hydrops. Depending on the inner ear disease being treated and its severity, medications currently used are: aminoglycosides (gentamicin), corticosteroids (dexamethasone) or anesthetics (lidocaine).
Points to remember. Anesthetics in the middle ear will lead to big time vertigo. Never do an ablative therapy in Meneire’s patients for 2-3 years as the propensity for bilaterality is real. Hearing must be followed carefully.
C.P. occurs with the application of a specific concentration of medication (the “chemical”) into the middle ear so that it can be transmitted (“perfused”) into the inner ear via the semi-permeable round window membrane separating the middle and inner ear compartments. A successful technique is the placement of a ventilation tube within the tympanic membrane and a microwick (which acts like a sponge) through the lumen of the tube. The wick extends through the middle ear to the round window membrane. Drops of the medication are placed into the ear canal at surgery, transferred by the wick, and absorbed through the round window membrane into the inner ear. Medication is then instilled on a daily basis by the patient for two to three weeks.
The patient is closely monitored pre- and post-operatively with serial hearing and balance tests as well as clinical examination until the desired result is attained. The desired result may be control of the dizziness, reversal or stabilization of the hearing loss or reduction of the tinnitus or fluid pressure.
The most highly effective application of C.P. is in the treatment of Meniere’s disease, which has failed to respond to dietary and medical management. Its success rate is approaching 85 percent in controlling the disabling vertigo. The risk to hearing is less than 15 percent. It is, therefore, a valuable addition to the treatment of Meniere’s disease.
Intratympanic Dexamethasone Paper