P006: ULTRASOUND-GUIDED PUDENDAL NERVE BLOCK FOR PERIOPERATIVE ANALGESIA: A NEWLY ESTABLISHED TECHNIQUE FOR REFRACTORY PAIN AFTER ANAL SURGERY?
Hadia Maqsood, MD; Linda T Le-Wendling
University of Florida
Introduction: Anorectal surgery has been performed in the outpatient setting for cost-savings. However, extensive anal surgery results in moderate to severe pain refractory to systemic multimodal analgesics. Spinal or caudal anesthesia can be utilized for postoperative analgesia but are limited by side effects such as urinary retention and lower extremity weakness.
Pudendal nerve blocks (PudNB) have been included in the latest PROSPECT (procedure specific postoperative pain management). Though, PudNB techniques have been heterogenous, being performed by obstetricians, surgeons, interventional pain physicians and pediatric anesthesiologists. In recent years, ultrasound-guided (USG) PudNB technique targeting the pudendal nerve (PudN) at the level of the ischial spine or proximal Alcock’s canal has been described. We present the case in which a rescue PudNB resulted in excellent postoperative recovery.
Case report: A 39-year-old female with multiple comorbities presented to our ambulatory surgical center for anorectal exam under anesthesia with biopsy, excision and fulguration of diseased lesions. The procedure was performed under deep sedation. Intra-operatively, the surgeon performed a bilateral pudendal field block with 10mL of a mixture of 0.25% bupivacaine and 1% lidocaine with 1:200,000 epinephrine. Postoperatively, the patient complained of severe perianal pain refractory to medical management. USG bilateral PudNBs were performed in the post-anesthesia care unit by injecting 5 ml of 0.5% ropivacaine bilaterally. Patient reported immediate improvement in pain lasting 6-8 hours post-discharge.
Case Discussion: Blockade of the PudN results in analgesia of the perineum, distal genitourinary (GU) and gastrointestinal (GI) tracts. Blockade at the level of the ischial spine will result in anesthesia of its 3 branches (inferior rectal, perineal, nerve to penis/clitoris).
The duration of analgesia appears to last up to 24 hours but is longer than perianal infiltration of local anesthetic. Though severe pain appears to recede at about 48 hours after extensive anal surgery, readmission after block regression was minimal in initial studies.
Complication rates of PudNB are similar to other targeted nerve block procedures and include local anesthetic (LA) systemic toxicity and nerve injury. Interestingly, incidence of urinary retention is reduced in this patient population, possibly due to reduced reliance on spinal anesthesia or improved pain relief.
The question arises whether this block should be performed preoperatively and routinely in the ambulatory setting. Perhaps not yet. Not all anal surgeries result in the same degree of pain, and PudNB performed at the ischial spine or Alcock’s canal is difficult due to deep nature of the target structure, difficulty in visualizing the PudN at this level, reliance of injecting near the pudendal artery and potential intravascular injury, and potential of guiding the needle into the deeper perineum and damaging visceral structures. However, in skilled and experienced hands, this USG PudNB can be another technique in the acute pain specialist’s repertoire to address severe pain in the recovery area for those patients with refractory pain after anal surgery, penile/clitoral/urethral pain, and distal GU surgery.