Lidocaine/Josef Rauschecker

Josef Rauschecker mentioned intravenous Lidocaine again and potentially similar drugs but with a prolonged effect, in the new Tinnitus Talk interview at Patreon. In my opinion he made it sound rather appealing, but what about the ototoxicity?

 

Lidocaine is used to treat ear infections, I'm using it right now in the form of ear drops. Not sure how different it is to IV.

 

I suppose that the difference is that, as an IV, Lidocaine gets into your blood stream, and therefore can reach your cochlea.

As ear drops, it is called topical application and, unless you have a perforated ear drum, the drops will be prevented from making their way from the canal to the middle ear, so they are unlikely to get anywhere near your cochlea.

 

They are doing a clinical trial for Lidocaine at Mass Eye and Ear. After the injection you undergo an MRI to analyze the brain.

 

There is a warning on the bottle not to use it if you have a perforated eardrum alright.

 

There seems to be two Lidocaine derivatives that could be taken orally. Mexiletine and Tocainide. Both have been trailed heavily in the 80s and 90s with rather good results but due to the effect being only temporary it was not worth the risk as these drugs can not be taken long term. I guess this is why those drugs never got approved as a tinnitus treatment.

 

Interesting. I will look for the studies. I thought only Lidocaine worked.

 

Did you find any studies?

This paper mentions intravenously administered Mexiletine.

Mexiletine Hydrochloride (powder) is available in Belgium on request at the pharmacies.

 

Only intravenous Lidocaine and the ear shots in another thread.

 

In this paper, they mapped Lidocaine related changes in neural activity, measured by regional cerebral blood flow (rCBF) PET.

Does anyone have the full paper?

 

Here it is.

 

I think there is a current trial in America using Lidocaine whilst measuring brain activity. It's on Tinnitus Talk somewhere.

This study finished 8 months ago:

→ Action of Intra-auricular Topical Lidocaine on Tinnitus

 

Yes, Massachusetts Eye & Ear is recruiting for the following "exploratory pilot open-label study". I will be very interested to see the results.

→ An fMRI Investigation of the Effects of IV Lidocaine on Tinnitus

 

Thank you @annV!

This is interesting. It is an easy-to-perform procedure. They still seem to be reviewing the results.

If Lidocaine works for me (temporarily), they have to cut my 8th nerve on the left. And I mean it.

Interesting, but what if (some specific) tinnitus is neuropathy?

 

Thanks for sharing. I emailed them to see if they're taking more participants for the "normal hearing (NH) with tinnitus (T+)" cohort. I'd fly up to Boston for this in a heartbeat. It seems like a small study, though. 40 participants total, only some of whom actually have tinnitus.

EDIT:

So I almost immediately heard back from the US lab on their Lidocaine study. I'd have to fly up to Boston (not a huge deal) but then it's a pretty noisy affair which might be tricky with my right ear hyperacusis and reactive tinnitus. Here's a synopsis of everything I'd be signing up for. The MRI is my main concern due to sheer noise and claustrophobia. I'm gonna mull it over today/tomorrow.

 

Dr. Pulec also tried Lidocaine on the subject of the case report in his paper.

 

Another Lidocaine study.

Too bad the paper is behind a paywall.

→ Lidocaine: neurobiological targets and effects on the auditory system

 

Attached is the full paper.

 

Thank you, @annV!

Here is another paper that is referenced in the previous one. For some, Lidocaine seems to have an effect (and in the cochlea). It would be interesting to know the cause of the patients' tinnitus. But again, this paper is behind a paywall, and this information will probably not be available.

But the previous paper also stated that Lidocaine does not cross the blood-labyrinth barrier (BLB). How can we then get these results?

And again, we see a relationship between OHCs and tinnitus. Forget IHCs.

 

Attached is the full paper of that one, too.

 

I'm not an expert, but maybe Lidocaine blocks HCN2 channels in auditory nerve fibers.

 

I had an online consultation with Dr. Boedts yesterday. I sent him an email earlier with my questions so I didn't have to talk too much, but unfortunately, he didn't read it. Half an hour and my head felt bad afterward due to the talking. He seems to be experimenting with Botox and Xylocaine and seems to prefer the latter. He also injects in the mouth (soft palate) and even up the nose. He does not recommend intratympanic injections; this is very unpleasant for the patient. He suggests a series of weekly injections. Some have no improvement, others only for an hour, some for a few days or weeks/months. What he also noticed is that if a patient has a noise incident during this series of injections they often relapse.

I'd like to try it, but because of my current condition, I don't think I can handle the trip. A local ENT could do it, too, he said, but then again, they probably don't have any experience.

EDIT:

I asked Dr. Boedts if he had data on the relationship between the cause of tinnitus/hyperacusis and the success of Lidocaine treatment. Unfortunately, he didn't.