Changes in the thalamocortical component of high frequency oscillations following botulinum toxin treatment in cervical dystonia.

[OBJECTIVE] This study aims to investigate the central effects of Botulinum toxin type A (BoNT-A) on the somatosensory system in patients with cervical dystonia (CD), focusing on the thalamocortical pathway using high-frequency oscillations (HFOs) and short-latency afferent inhibition (SAI).

[METHODS] An observational longitudinal study was conducted on 10CD patients and 10 healthy controls (HC). HFOs and SAI were assessed for CD and HC at baseline (T0; the day before BoNT-A treatment). Then only for CD patients, SAI and HFOs were assessed again 30 days after (T1) BoNT-A treatment. Changes in SAI values and HFO early and late area between T0 and T1 in CD patients were evaluated with the Wilcoxon signed-rank test.

[RESULTS] At T0, CD patients exhibited significantly reduced early HFOs compared to HC, with no significant differences in late HFOs or SAI values. After BoNT-A treatment, a significant increase in early HFOs was observed in CD patients at T1, while late HFOs and SAI values remained unchanged.

[CONCLUSION] The findings suggest that BoNT-A treatment may have central effects on thalamocortical activity, as evidenced by changes of early HFOs in CD patients following injections.

[SIGNIFICANCE] This study provides neurophysiological evidence supporting the central effects of BoNT-A on the somatosensory system and corroborates the idea of a somatosensory involvement in CD pathogenesis. This funding could pave the way for future integrated treatment approaches.