What are the symptoms if the needle hits the pudendal nerve during and after a pudendal nerve block procedure?

Symptoms of Needle Contact with Pudendal Nerve During and After Pudendal Nerve Block

Direct needle contact with the pudendal nerve during a pudendal nerve block can cause immediate sharp, electric shock-like pain radiating to the perineum and genital area, followed by potential persistent neuropathic symptoms if nerve injury occurs.

Immediate Symptoms During Procedure

• Sharp, electric shock-like pain that radiates along the distribution of the pudendal nerve (perineum, genitals, and rectum) when the needle directly contacts the nerve 1, 2
• Burning or stabbing sensation in the vagina, perineum, or rectum that may be unilateral or bilateral depending on which pudendal nerve is contacted 3
• Patient may experience a sudden jolt or movement in response to the nerve stimulation 4
• Paresthesias (tingling, pins and needles sensation) in the pudendal nerve distribution 2

Post-Procedure Symptoms of Nerve Injury

• Persistent burning, stabbing, or electric shock-like pain in the perineal region that may be worse with sitting 3, 2
• Neuritis (inflammation of the nerve) causing symptoms more difficult to control than the original pain 5
• Sensory changes in the pudendal nerve distribution, including:
  • Hypesthesia (decreased sensation) 2
  • Hyperalgesia (increased sensitivity to pain) 2
  • Allodynia (pain from normally non-painful stimuli) 3
• Potential bowel, bladder, or sexual dysfunction if significant nerve injury occurs 2

Risk Factors and Prevention

• Lack of proper imaging guidance increases risk of direct nerve contact 4, 6
• Ultrasound guidance significantly improves safety by allowing visualization of:
  • The pudendal nerve
  • The internal pudendal artery (using color Doppler)
  • The sacrospinous and sacrotuberous ligaments
  • Real-time needle advancement
  • Local anesthetic spread 4, 6
• Fluoroscopic guidance can also improve safety compared to blind technique 1

Assessment of Nerve Contact

• After pudendal nerve block, sensory changes should be assessed using pinprick examination of the pudendal territory 2
• Complete anesthesia of all six pudendal nerve branches occurs in only about 13.2% of patients 2
• The quality of the nerve block correlates with the number of nerve branches successfully anesthetized 2

Management of Nerve Contact Complications

• If symptoms of nerve injury persist after the expected duration of the local anesthetic:
  • Consider anti-inflammatory medications 7
  • Physical therapy including pelvic floor strengthening exercises may be beneficial 5
  • Pharmacologic options such as muscle relaxants, SNRIs, antiepileptic drugs, and tricyclic antidepressants may be needed for persistent symptoms 5
  • In severe cases, consider referral to pain specialist for consideration of dorsal column stimulation 5

Technique Considerations to Minimize Risk

• Use of ultrasound guidance is recommended to improve safety and efficacy 4, 6
• The transperineal approach with ultrasound guidance has shown good success rates with improved safety 6
• Proper needle positioning should be confirmed before injecting the local anesthetic 4
• Visualization of local anesthetic spread around the nerve confirms proper placement 4, 6

Remember that proper technique, appropriate imaging guidance, and careful attention to patient feedback during the procedure are essential to minimize the risk of nerve injury during pudendal nerve blocks.