P83-T ONAMIG: Effect of BOTOX® over cortical excitability (measured by transcranial magnetic stimulation) in chronic migraine

Abstract

Background Several transcranial magnetic stimulation (TMS) studies have demonstrated cortical excitability changes in patients with migraine. It has been suggested that central sensitization may be associated with poor response to treatment. The recognition of these phenomena and the effect of different treatments on them may have clinical relevance. The aim of the study is to evaluate changes in cortical excitability parameters in patients with chronic migraine (CM) after treatment with BOTOX®. Material and methods Patients with CM and candidates for treatment with BOTOX® were included. In addition, patients with episodic migraine (EM) were recruited as controls. Clinical data and disability scales were collected as well as cortical excitability parameters measured by TMS: motor threshold at rest (RMT), cortical silence period (CSP) and intracortical inhibition (SICI) ). A baseline clinical and neurophysiological study was performed and repeated after two cycles of botox treatment. Results We included 19 patients with CM and 16 with EM. After treatment with BOTOX® in CM the RMT was reduced (58.9 ± 13.3% vs 55.1 ± 11.9%, p = 0.004) approaching the values of controls (53.75 ± 9.88%, p = 0.019); increased CSP (85.6 ± 26.4 ms and 100.9 ± 33.0 ms, p = 0.004) approaching the values of controls (121.53 ± 39.92, p = 0003). In addition, parameters of greater inhibition in the SICI predicted an improvement in frequency and intensity >50%. Conclusions Treatment with BOTOX® is associated with changes in the cortical excitability of patients with CM who can translate mechanisms of central cortical modulation.