Otolaryngologists are increasingly using office-based intratympanic perfusion11 to deliver high concentrations of medication directly to the inner ear cavity with minimal side effects. The aminoglycoside antibiotic, gentamicin, is most often used, even though it is an ototoxin. Usually four injections are given over a period of a month, but some otolaryngologists are successfully switching to a low-dose gentamicin protocol of only one or two shots per month.4 The procedure itself, done with either single or multiple injections, is low-risk and simple to perform, but is considered destructive, as it can leave patients with little or no balance function. Even though studies show an efficacy at about 80% to 90% for vertigo control, authors report substantial worsening of hearing in up to 25% of patients.12,13
Explore This IssueJanuary 2008
Endolymphatic sac decompression involves removal of petrous bone from around the endolymphatic sac, whereas shunting requires the placement of a synthetic shunt to drain endolymph into the mastoid. Both procedures appear to reduce pressure, control vertigo, and stabilize hearing acuity equally.13
Even though this is a time-tested surgical operation, there is still some controversy due to a 1981 Danish study that suggested that outcomes from this procedure were no different than a sham procedure and were just a placebo effect, said Dr. Megerian. Almost two-thirds of my patients find that it controls their vertigo and I am very pleased with the results. The best thing is you don’t burn any bridges; if it isn’t successful, you can still use intratympanic gentamicin.
Other generally well-accepted therapies include vestibular nerve section and labyrinthectomy. In vestibular neurectomy, the diseased vestibular nerve is clipped where it leaves the inner ear and goes to the brain. This procedure often requires a neurosurgical approach (middle fossa or retrosigmoid performed through a small craniotomy) and is considered riskier than intratympanic gentamicin injections. Even though vertigo attacks are eliminated in about 95% to 98% of cases and hearing is preserved in the surgically treated ear about 95% of the time, patients are often reluctant to undergo this invasive treatment.13
There has been a dramatic reduction in the number of vestibular nerve sections or ‘Dandy operation’ as it is sometimes called, since the introduction of intratympanic gentamicin, said Dr. Megerian.
A labyrinthectomy is an old operation that is only recommended for a select group of patients who have lost all usable hearing on the affected side, failed other interventions or determined that vestibular nerve section is too dangerous for their situation, he continued.