Gamma-band Intermuscular Connectivity Is Associated with Increased Neural Drive to Pelvic Floor Muscles in Women with Interstitial Cystitis/Bladder Pain Syndrome

Purpose:Interstitial cystitis/bladder pain syndrome patients can experience overactive pelvic floor muscle activity at rest. While the frequency power spectrum of pelvic floor muscle has briefly been explored, intermuscular connectivity of the pelvic floor muscle has yet to be studied, which may provide useful insight into the neurological component, ie, neural drive to muscles, in interstitial cystitis/bladder pain syndrome.Materials and Methods:High-density surface electromyography was collected from 15 female interstitial cystitis/bladder pain syndrome patients with pelvic floor tenderness and 15 urologically healthy female controls. Intermuscular connectivity was calculated across the maximally active locations of the left and right sides of the pelvic floor muscle as identified from the root mean squared amplitude at rest and compared with Student t tests for common sensorimotor rhythms involved in motor control: alpha (8-12 Hz), beta (13-30 Hz), and gamma (31-70 Hz) frequency bands. The root mean squared amplitudes at rest were also compared across groups.Results:The resting root mean squared amplitude of the pelvic floor muscle was significantly greater in female interstitial cystitis/bladder pain syndrome patients compared to healthy female controls (P =.0046). The gamma-band intermuscular connectivity was significantly different between rest and pelvic floor muscle contraction (P =.0001) for healthy female controls, but not for female patients with interstitial cystitis/bladder pain syndrome (P =.1214). Both results indicate an elevated neural drive to pelvic floor muscle at rest in female interstitial cystitis/bladder pain syndrome patients.Conclusions:Gamma-band pelvic floor muscle connectivity in female interstitial cystitis/bladder pain syndrome patients is increased at rest. The results of this study may provide insight into the impaired neural drive to pelvic floor muscle implicated with interstitial cystitis/bladder pain syndrome.