Intra-Tympanic Gentamicin (ITG) is considered an “ablative” procedure. While most of the treatments discussed in the earlier blogs in this series are intended to “repair” or regulate the fluid dynamics of the diseased labyrinth, ITG does not have the same goal. When the diagnosis is certain, the diseased ear has been identified, and the patient has not responded to more conservative treatment options, ITG may be considered.
ITG is selectively toxic to the sensory hair cells in the labyrinth. In proper doses, the hair cells can be weakened or killed so that fluctuations in endolymphatic volume and/or pressure do not trigger the acute episodes of vertigo the patient has learned to fear. Essentially, the fluid levels are still fluctuating; however the post-ITG ear is not registering these fluctuations any longer (or at least not as acutely). For patients with severe, frequent Meniere’s episodes, ITG has a high likelihood of quickly and dramatically reducing the severity of these episodes.
In the past, this condition could be accomplished through surgery to section the vestibular nerve, or in the case of a patient with severe hearing loss in the affected ear, a labyrinthectomy to destroy the entire inner ear could be performed. ITG can easily be performed in the Otolaryngologist’s office. The two commonly used techniques are
- Injecting the gentamicin through the eardrum after a topical anesthetic has been applied.
- Placing a ventilating tube through the eardrum, then instilling small amounts of gentamicin using an eye dropper.
Well, this sounds great. Is there a catch? Unfortunately, there are a few. We will discuss them next week.