Look for Abraham Shulman tinnitus protocol. He used Clonazepam + Gabapentin combo successfully on tinnitus patients.
This is also what led me to this, combination, but, again it also has a lot to do with my personal medical history and history with benzos. That said, I would hardly say there's strong evidence.
We had this preliminary report in 2002 that put this on people's radar:
GABAA-benzodiazepine-chloride receptor-targeted therapy for tinnitus control: preliminary report
Interesting, but
hardly equivocal. 30 patients, with a 30% dropout rate (inherently casting doubt on claimed efficiency by at least that amount). The duration of effectiveness varied wildly, with some people seeing the effect wear off within a couple months. No control group, no RCT.
Also Shulman, 2002:
Benzodiazepine receptor deficiency and tinnitus
It provides some evidence people with tinnitus may have less benzo receptors in critical places. Again, interesting, but if this is correct then the effect of treating such people long term with drugs that manipulate the BDZ receptor "needs much study", since chronic BDZ use triggers downregulation.
So, then in 2006 we got this:
Benzodiazepines and GABAergics in treating severe disabling tinnitus of predominantly cochlear origin
(PDF - Full Text)
Still only 30 patients, but somewhat better design, 10 control (group 1), 10 benzo (group 2), 10 benzo + gabaergic (group 3). This references the earlier Shulman work, it's literally an attempt to reproduce the results with a more sound methodology, and this is where it concluded:
intensity and annoyance were significantly decreased in groups 1 and 3 as compared to group 1, but no statistically significant difference was detected between groups 2 and 3 (Tables 4–12). Two patients in group 1 experienced an increase in tinnitus intensity (see Table 4). Four patients in group 2 experienced drowsiness and nausea, and two patients had sexual dysfunction (clonazepam). Five patients in group 3 reported drowsiness and nausea, and two noticed interference with cognition (clonazepam and gabapentin).
Do these numbers look compelling enough for you to want to try a generally dangerous combination of controlled substances?
From "discussion":
Shulman et al. selected patients with SDT and brain perfusion changes detected by SPECT. They did not mention any otological disease affecting their patients. Our patients had SDT associated with otological diseases that are known to produce tinnitus. Therefore, it is reasonable to say that their symptom was of a predominantly cochlear origin. Another major difference between our patients and those of Shulman et al. is the fact that almost all their patients had psychiatric problems (e.g., depression, anxiety, and fear severe enough to require specialized medical care). None of our patients needed psychiatric treatment. Shulman et al. selected patients with SDT "predominantly central in origin" and showed the positive effect of treatment with benzodiazepines (clonazepam) and GABAergic (gabapentin) drugs, as seen both in the reduction of SDT and on the SPECT results: The brain perfusion was enhanced after treatment. We selected SDT patients with tinnitus of a predominantly cochlear origin; we compared the effect of placebo, benzodiaepines alone, and benzodiazepines combined with a GABAergic drug; and we found that the addition of GABAergic drugs does not enhance the results obtained with benzodiazepine drugs alone. The discrepancy between Shulman's results and ours may be due to the different patient populations but, to be sure about that, it is necessary to study patients with SDT of a predominantly central origin, comparing the results of placebo, benzodiazepines alone, and benzodiazepines combined with GABAergic drugs
So, sounds like a big wet fart to me. Also I am
firmly in the camp of "preexisting anxiety disorders" which would make me look somewhat like Shulman's sample group, and not at all like someone with severe idiopathic tinnitus and no prior psychological discomfort.
All in all -- I'd say the evidence that this works in any general or broad way simply doesn't exist,
and the existing data strongly implies to me that most people with tinnitus will NOT benefit from this combination.
It's also somewhat hard to get put on benzos long term, and if you do and then decide you want to get off that's even
harder...