Changes in pelvic floor electrical activity and vulvar pain after botulinum toxin treatment of vestibulodynia: are clinical and electrophysiological outcomes related?

Vestibulodynia is a gynecological condition with different treatment options available, including botulinum neurotoxin type A (BoNT/A) injections into the vulvar vestibule. Unlike other treatments, no studies have assessed changes in the myoelectrical activity of the pelvic floor muscles (PFM) after BoNT/A treatment. The aim of this study was thus to evaluate these changes and to correlate them with changes in vulvar pain sensitivity. To do this, 35 patients with vestibulodynia were recruited, the myoelectrical activity of their left and right PFM was recorded with surface electromyography (sEMG), and their vulvar pain sensitivity was monitored according to Visual Analogue Scale (VAS) and an algometer, both before and after BoNT/A treatment. According to our results, patients' signals during PFM relaxation showed a significantly higher power than those of healthy women at baseline, as shown by their root mean square values (RMS), but became similar at follow-up. Patients' mean vulvar pain VAS scores significantly decreased after treatment. Furthermore, baseline-to-follow-up differences of RMS at PFM rest vs. mean VAS were significantly correlated (CC=0.48, p<0.01) so that higher reductions in the PFM activity power were associated with higher decreases in vulvar pain.Clinical Relevance- Altered PFM electrophysiological condition of patients with vestibulodynia becomes similar to healthy women's after BoNT/A treatment. This study also points to a relationship between the evolution of clinical and PFM electrophysiological conditions.