From the Shore paper:
Animal-model studies have demonstrated that after cochlear damage, the neural circuitry of the dorsal cochlear nucleus (DCN) is altered, especially in animals that develop tinnitus. The DCN is the first central station of the auditory pathway that integrates auditory signals with sensory information originating in somatosensory ganglia and brainstem nuclei. Somatosensory projections synapse on cochlear nucleus granule cells whose axons form plastic synapses on fusiform-cell dendrites, in contrast to nonplastic synapses from the ear. Thus, repeated signals from the somatosensory system induce long-term plasticity in DCN neurons, and combined auditory and somatosensory signals can lead to either long-term depression (LTD) or long-term potentiation (LTP) of the fusiform-cell circuit, depending on the order and interval between the somatosensory and auditory signals (eFigure 1 in Supplement 1). After noise-induced tinnitus, guinea pigs demonstrated increased fusiform-cell spontaneous firing rates, bursting, and synchrony, which are important physiological correlates of tinnitus. Thus, it was hypothesized that properly timed auditory and somatosensory (bisensory) stimulation could be used to treat tinnitus by inducing LTD with precisely ordered and timed bisensory stimulation to reduce fusiform-cell synchrony and bursting, thereby reducing tinnitus.
The yellow highlighted section refers to "inducing long-term plasticity," which we describe using the neurological term "habituation." Some people view habituation negatively, thinking it means you "just have to get used to it." However, we understand habituation in the formal, neuroscientific sense: long-term changes in neural networks, or "neuroplasticity".
Our concern isn't that habituation doesn't help. We know that it does, which is why we include sound therapy in our program. Sound therapy leverages the concept of habituation to encourage beneficial neural changes. Similarly, bimodal (bisensory) stimulation may be effective in initiating neuroplastic changes that help alleviate tinnitus, perhaps more effective than sound therapy alone. We agree that this approach shows promise in modifying the neural circuitry involved in tinnitus, potentially providing relief for sufferers.
However, we worry that this progress could be undone by the migraine component of severe tinnitus. The migraine reaction not only causes sensory hypersensitivity but also stimulates negative neuroplastic changes. This process is mediated partly by calcitonin gene-related peptide (CGRP), a molecule that is not only proinflammatory but also initiates central sensitization. In most cases, this central sensitization will counteract the benefits of bisensory therapy, reversing the positive neuroplastic changes achieved after putting in long, boring hours of work.... not our words, but Shore's "the novelty... diminished relatively quickly, and the daily procedure of cleaning, applying, and sitting quietly for 30 minutes of treatment, removing, and cleaning became monotonous for many participants".
To address your point that the SSD reduces the volume of tinnitus, sound therapy also reduces the volume of tinnitus. When we did our randomized clinical trial of our sound therapy protocol, we found we found a 5.1 dB reduction in the
volume of tinnitus using customized sound therapy (Mahboubi H, Haidar YM, Kiumehr S, Ziai K, Djalilian HR. Customized Versus Noncustomized Sound Therapy for Treatment of Tinnitus: A Randomized Crossover Clinical Trial. Ann Otol Rhinol Laryngol. 2017 Oct;126(10):681-687.). Sound therapy alone reduced the THI by 11.3 points. When we combined sound therapy with online cognitive behavioral therapy
in this study (this is xTinnitus and BeyondTinnitus btw), we found a ~17 point reduction in the tinnitus functional index (TFI). Note that Dr. Shore's trial only found a decrease of 13 points, very similar to the Lenire device results (see our critical review
HERE). Note that in the Dr. Shore trial, nearly half the patients dropped out of the trial which can skew the results significantly. Generally patients who don't get better are more likely to drop out so the ones who stay can create an artificially better result. They reported the intent to treat analysis to make up for that, but something worth noting.
We sincerely hope for the success of the SSD, but we have doubts about its ability to overcome the migraine-related mechanisms underlying tinnitus pathophysiology. The challenge lies in addressing the fundamental issue of migraine-induced changes, which complicate the treatment landscape for tinnitus. While we remain optimistic, we recognize the need for a comprehensive approach that considers these complex interactions. If the device is approved, we believe it's success will be bolstered by our protocol.
I hope this helps!
Member
) and lifestyle changes around exercise and drinking water. Combining supplements/medication, CBT/counseling, and lifestyle changes can decrease tinnitus loudness and reduce the number of "bad" days or bad events. It's definitely preferable to *just* doing CBT and/or TRT.
Let's see a Dr. Djalilian / Dr. Shore superteam emerge!
