Altered pelvic floor muscle activity associated with the use of intravaginal probes in severe vulvodynia

Abstract

[EN] Vulvodynia is usually associated with a hypertonic dysfunction of the pelvic floor muscles (PFM), so surface electromyography (sEMG) can be used to assist patient¿s assessment. Although recordings are typically performed with intravaginal probes, they provoke pain and may alter PFM activity, so the aim of this study was to assess differences in sEMG signals recorded with self adhesive electrodes in the presence vs. absence of an intravaginal probe according to pain intensity. Twenty-four patients with vulvodynia were treated with incobotulinumtoxinA and monitored after treatment. Their PFM activity and pain were assessed by monopolar and bipolar sEMG recordings with self adhesive electrodes and by Visual Analogue Scale (VAS), respectively. Recordings performed before treatment and in a follow-up visit were classified into two groups: severe pain and moderate/mild/no pain. Root mean square (RMS), median frequency (MDF) and sample entropy (SampEn) of signals were compared when the probe was into vs. out of the vagina in both groups. In severe pain group, PFM contractile activity had a significantly lower power when the probe was into the vagina than out of it, as shown by lower RMS values in monopolar recordings, especially in M3 (median[interquartile range] in vs. out: 3.8[2.7]mV vs. 4.4[2.5]mV; p-value<0.01). This implies that deep PFM activation decreases during contractions when a probe is inserted into the vagina in severe vulvodynia, probably because of the patients¿ reluctance to perform maximum contractions, given the pain elicited by the pressure of the probe. Patient¿s evaluation should thus avoid using intravaginal probes and increase that of self-adhesive electrodes.