- Acoustic CR®-stimulation for the treatment of tinnitus:
- Clinical tinnitus study:
- Mathematical modeling within the field of tinnitus:
Acoustic CR®-stimulation for the treatment of tinnitus:
The acoustic CR® stimulation is a spatio-temporally patterned stimulation of the central auditory system with therapy tones. The chronological timing of the CR®-stimulation is adjusted to the pathologically increased delta band activity. The stimulation tones are grouped around the dominant tinnitus frequency of the patient according to the CR® algorithm. Due to the underlying tonotopy of the auditory system the delta-band oscillations are going to be reset in different subpopulation (e.g. in the primary auditory cortex) and therefore desynchronized.
Clinical tinnitus study:
In a prospective, randomized, single-blinded, placebo-controlled clinical multicenter study, 63 patients with chronic subjective tonal tinnitus were screened (www.clinicaltrials.gov). For the evaluation of the therapy success subjective parameters and objective parameters were assessed: On the one hand, the effects of the acoustic CR® therapy on tinnitus (loudness, annoyance, quality of life, etc.) were examined. On the other hand, the neuronal activity in the auditory cortex underlying tinnitus was measured by EEG. With a treatment of four to six hours with acoustic CR® stimulation per day the perceived tinnitus loudness reduced significantly after twelve weeks of therapy by 51 percent, the subjective annoyance decreased by 48 percent. The CR® treatment effects are statistically significant - both in comparison to placebo and compared to baseline (i.e., the initial state prior to treatment). These treatment effects remained statistically significant even after a therapy break of 4 weeks, but weakened during this break again. This is a sign that for a maximum therapeutic effect a treatment of more than 12 weeks is necessary. This was also confirmed by the following voluntary after-treatment. After the treatment the percentage of all study participants with tinnitus severity “light” was more than doubled – compared to the begin of the study - (from 32 to 69 percent of study participants) and without any lasting side-effects. Within the first three months 71 percent of the patients improved by at least one tinnitus severity. Within the six months of after-treatment those patients could be stabilized at this high level. The measured EEG activity of the study patients showed that the CR®-therapy has also significant electrophysiological effects. The abnormal, synchronized slow-wave activity of the nerve cells within the frequency range between 1 and 3 Hz decreases significantly, while the healthy and for information processing important rest rhythm - the alpha rhythm - within in the range of 10 Hz, increased significantly again. In addition, the tinnitus frequency decreases significantly under therapy, which is described by patients as pleasant and also clearly shows that CR® induces plastic processes in the brain.
Mathematical modeling within the field of tinnitus:
Tinnitus is the perception of a sound or noise in the absence of acoustic stimuli. A frequent form of tinnitus is associated with a reduction of hearing. Tinnitus leads to a change in the tonotopic map (the spatial arrangement of the sound frequencies in the brain), an increase in the firing rate and a synchronization of neuronal firing in auditory cortical areas. The goal of this project is to create a neural network model for a better understanding of the mechanisms for these changes. With this neural network, the effects of the acoustic desynchronizing stimulation – which are used for the treatment of tinnitus - are then examined as a next step.