Microwick Procedure

thanks Muff,
this is Dr Hains take on the Microwick, he seems to favor low dose of gentamicin

http://dizziness-and-balance.com/treatment/ttg.html

Delivery methods:


Numerous methods have been used to deliver gentamicin including direct injection, delivery via a tympanostomy tube, and surgical catheters (Round window m-cath, Durect Corp; Silverstein MicroWick). Either the needle method (low dose) or tympanostomy tube method (high dose where hearing is already gone) seems to work, but there are big differences in cost. Procedures that require surgical placement of a catheter, at this writing, seem unreasonable as they add risk and cost (the surgery) without better results.

Procedures that involve placement of a "wick" in the tympanostomy tube (i.e. the "Silverstein MicroWick(tm)"), do not seem very different than simple use of the tympanostomy tube by itself. We do not doubt that it works, but we are not convinced that the additional effort and cost needed to place the special tympanostomy tube and wick as well as it's subsequent removal, is warranted. It is very difficult to compete with the low-dose procedure in terms of results, because they are so good. It is also difficult to understand the rationale of putting in a constant infusion of a drug, when it is well known from animals that gentamicin accumulates in the ear over many months. In this group of patients, better dizziness results are correlated with worse hearing results (Light et al, 2003).

Results of the low-dose gentamicin variant


In our practice in Chicago, we have had excellent results with the low-dose variant, with excellent control of dizziness (100% so far) with no hearing damage at all. Here are what others have reported:

A single dose treatment was reported by at the Mayo clinic, with 84% response rate of vertigo, and no change in hearing. (Driscoll et al, 1997; Harner et al, 2001) These results are attributed to claims that gentamicin destroys the endolymph secreting dark cells before destroying the sensory vestibular epithelium (Beck, 1978). Against this idea is the lack of a pathological change in dark cells after treatment with intravenous aminoglycosides (Cureoglu et al, 2003). The main alternative to the mechanism being destruction of dark cells is the hypothesis that there is a partial damage to the vestibular hair cells. Recent studies in animals suggest that the type-I hair cells are the most sensitive, and the type-II hair cells are more resilient.

A somewhat old meta-analysis (Chia, Gamst et al. 2004) reported that low-dose methods have significantly poorer vertigo control (66.7% overall). This has not been our experience.

Usually, our patients have durable results for dizziness control. For example, we got this email (in 2013):


"Hello, Dr. Hain, Today marks my 5 year anniversary since receiving a gent injection in my left ear. I have been essentially free of all vertigo. So I think we can say that this has been a complete success. Thought I'd let you know the good news."

Although it does seem reasonable that the low dose protocol might have more recurrence (at 1 year+), it is very easy to get another "touch up" injection at 1-2 years, but it is impossible to get one's hearing back after it has been damaged by the more intense protocol.

The long-term results of hearing is unclear at this writing. If low-dose does indeed reduce pressure in the inner ear, it may be that hearing will deteriorate to a lesser extent. At this writing though (2007), this conjecture remains to be proven.

Very low dose -- for older persons

Variant procedures where gentamicin is administered even less frequently than once/month, or in a more dilute solution than is conventional also seem well worth considering. We routinely recommend use of half-dose gentamicin in persons having this done who are over the age of 70.

Against this idea is the conjecture that transtympanic gentamicin rapidly "saturates" binding sites in the inner ear, and thus there is no real difference between giving very low dose or low dose -- but rather it is the number of applications of gentamicin that matter, more than the concentration. We don't think that this conjecture is correct, but it would be an interesting project for a researcher to investigate.

The low dose of gentamicin over a prolonged time is likely to have a more uniform effect on the ear than brief, concentrated administrations (Pender, 2003), and also would seem likely to pose much lower risk to hearing.

 

good luck! and keep us posted

 

Would the wick/steroid treatment be better
Than the intratypanic steroid injection?

 

Ok keep us posted