What is the Nature of Pelvic Floor Muscle Involvement in Dyspareunia?

Transcranial magenetic stimulation will be used to probe the excitability of cortical projections to the pelvic floor muscles. The outcomes of interest will include motor evoked potential amplitude and silent period.

Electromyography will be used to determine whether the pelvic floor muscles (PFMs) respond to pressure applied to the vulvar vestibule as anticipatory (i.e. PFMs are active before the pressure is applied) and as behavioural (i.e. PFMs are active after the pressure is applied) responses. The amplitude of the EMG responses will also be recorded.

A custom vulvalgesiometer will be used to determine the mean pressure at which participants first report pain at the posterior vaginal fourchette.

A custom vulvalgesiometer will be used to apply the same pressure (rated as 4/10 duiring PPS testing as described above) to the vulvar vestibule across 10 repetitions. The difference in pain rated on the tenth application and that rated on the first application will be the outcome.

Electromyography will be used to measure the mean smoothed, rectified activation amplitude across 1 second of complete rest, across three maximal effort PFM contractions, and across three attempts at a bearing down maneuver.