Botulinum toxin injection of the piriformis muscle for refractory pudendal neuralgia after decompression surgery: case report

Pudendal neuropathy is a cause of pelvic pain, specifically pudendal neuralgia. The pudendal nerve is related to sensory, motor, and autonomic functions. We present the case of a 41-year-old man who suffered from chronic pelvic pain. In detail, the patient described stinging burning pain in the glans penis, proctalgia, lower urinary tract symptoms, sensation of "muscle tension" and squeezing pain. He was diagnosed with prostatitis and, following, pudendal neuralgia. Our patient was treated with antibiotics and analgesics, without improvement of symptoms. He was then submitted to decompression surgery of the pudendal nerve, with partial improvement. The patient started a rehabilitation program and was treated with OnabotulinumtoxinA (BoNT-A) injections into the piriformis muscle with benefit. BoNT-A positive effects on pain relief may corroborate piriformis muscle compression of the pudendal nerve. BoNT-A may also reduce the release of neurotransmitters from the pain pathways. Early identification of pudendal neuralgia could have prevented the progression to chronic pain. There is still not an established role for BoNT-A in post-operative pudendal nerve decompression patients. Our case corroborates that more studies should be performed to explore BoNT-A administration in these patients.