Is Multimodal Physiotherapy And/or Photobiomodulation Therapy Effective for Pain Reduction Among Those Who Experience Provoked Vestibulodynia: a Randomized Controlled Trial

Despite its high prevalence, surprisingly little is known about vulvovaginal pain in general and PVD more specifically. It is characterized by severe sharp and/or burning pain at the entrance to the vagina (i.e. the vulvar vestibule) when pressure is applied to it and it has been primarily attributed to inflammatory processes, hyper-innervation, and pelvic floor muscle (PFM) overactivity.

While it remains under-reported due to embarrassment and shame, the prevalence of PVD in premenopausal women is estimated at 12%, who account for 87% of cases. PVD pain can be intense and can last for days following attempts at sexual and non-sexual (e.g., tampon insertion) activities. It negatively impacts the physical, social and sexual health of women who experience it, and it can have major implications for reproductive health including functional infertility when those affected are unable to have penetrative intercourse, and delayed detection of cervical or uterine pathologies when gynaecological exams are avoided due to pain.

Current management of PVD involves multidisciplinary teams (including physicians, psychologists, sex therapists, and physical therapists) aiming to change the vulvar pain experience through analgesia, cognitive reframing, PFM relaxation and/or stretching and the reduction of vulvar sensitivity. Multimodal physiotherapy (mPT), in the form of education, biofeedback, manual therapies, and the vaginal insertion of dilators is recommended in clinical guidelines as a first-line treatment for PVD. The investigators have published two studies on the effectiveness of mPT intervention for women with PVD; both with positive results; yet their impact was limited since they were preliminary - the first was a prospective cohort study and the second was a pilot randomized controlled trial (RCT). Elsewhere in the literature, the first large-scale RCT on mPT compared the effectiveness of mPT to topical lidocaine for pain reduction and improved sexual function among women with PVD. The results were very promising; 79% of females in a mPT group reported being much or very much improved compared with 39% in a topical lidocaine group, coincident with reporting reduced pain during intercourse and improved sexual function. However, due to the lack of a comparable control group, the evidence for mPT was rated as "low" in systematic reviews, highlighting the need for further research.

A different, and likely complementary, treatment avenue for PVD is to focus interventions on the vulvar tissues themselves. One therapeutic option is photobiomodulation (PBM, aka low-level laser therapy, cold laser). PBM involves irradiation of tissue with a combination of red and near infrared light. PBM is theorized to initiate a series of physiological reactions within the cells exposed to light at specific wavelengths, leading to the restoration of normal cell structure and function. Although the mechanisms of action of PBM are not fully understood, positive effects of PBM have been found in clinical populations with chronic neuropathic pain, including carpal tunnel syndrome and trigeminal neuralgia. Recent evidence shows elevated bradykinin signaling (one of the most potent inducers of inflammatory pain) on the surface of vestibular fibroblasts collected from sites of intense pain in patients with PVD. The fibroblasts, in turn, respond vigorously to bradykinin, producing IL-6, which has strong expression in numerous pain conditions. Given our current understanding of PVD pathophysiology, and the suspected mechanistic actions of PBM, this intervention may provide an effective, non-invasive, approach to the management of PVD through reducing inflammation, promoting cell repair, and producing anesthesia.

The available evidence suggests that both mPT and PBM may be effective interventions for PVD; it is plausible that combining these two therapies may result in an additive effect and may result in a more effective approach than either intervention alone. The investigators have just completed a sham-controlled pilot RCT (NCT04234542) using a comprehensive PBM intervention, and the results are extremely promising. Those who received the real PBM improved by 25% on the pain severity domain of the Vulvar Pain Assessment Questionnaire (VPAQ), which was significantly greater than the sham PBM group. They also reported significant improvements in emotional responses to pain and sexual interference relative to baseline. Thirty-eight percent of participants who received the real PBM intervention reported >30% improvement in their condition. And while the sham PBM group did not demonstrate significant reductions in pain sensitivity, the real PBM group demonstrated a 59% increase in pressure pain threshold (PPThresh) at the vulvar vestibule. A full RCT is clearly warranted.