Differences between a single session and repeated sessions of 1 Hz TMS by double-cone coil prefrontal stimulation for the improvement of tinnitus.

Tinnitus related distress is associated with increased activity in the anterior cingulate cortex (ACC). In a recent study, it was demonstrated that a single session of low frequency prefrontal TMS using a double-cone coil (DCC) modulating the ACC (AC/DC TMS, anterior cingulate cortex targeted modulation by Double-Cone coil) yields a transient improvement in subjects with chronic tinnitus. An increasing number of studies demonstrated that repeated sessions of low frequency TMS to the temporoparietal area can significantly improve tinnitus complaints. Our aim is to determine the extent to which repeated sessions of AC/DC TMS can modulate tinnitus in comparison to a single session. Seventy-three tinnitus patients received a single (N = 46) or repetitive (N = 27) session(s) of TMS using a DCC placed over the prefrontal cortex. Our results indicate that both single sessions as well as multiple sessions (i.e. 8 sessions) of AC/DC TMS suppress both tinnitus distress (respectively 7.60% vs. 26.19%) and tinnitus intensity (respectively 7.12% vs. 19.60%) transiently. It was further shown that multiple sessions of AC/DC TMS generate a higher suppression effect in comparison to a single session of AC/DC TMS and that more patients responded to repeated sessions of 1 Hz stimulation in comparison to a single session. Our findings give further support to the fact that non-auditory areas are involved in tinnitus intensity and tinnitus distress and that more patients respond to repeated sessions with a higher suppression effect in comparison to patients who received a single session, suggesting that the approach of daily TMS sessions is relevant.