Regional anesthesia does not consistently block ischemic pain: two further cases and a review of the literature.

OBJECTIVE: Ischemic pain is complex and poorly understood. There is controversy regarding whether or not regional anesthetic techniques block ischemic pain. We present two further cases where regional anesthesia did not block ischemic pain despite adequate motor and sensory block. CASE REPORT 1: A 29-year-old healthy male underwent elective right lateral ankle ligament reconstruction for ankle instability with single-injection femoral and sciatic nerve blocks as the sole anesthetic. He reported no pain during or after surgery; approximately 90 min after the cast dressing was applied, he complained of severe pain in his medial ankle despite persistent complete sensory and motor blockade. The cast was removed, and he had immediate and complete resolution of his pain, which was thought to be due to ischemia. CASE REPORT 2: A 45-year-old female with a history of diabetes mellitus, hypertension, and 30 pack-year smoking history presented with increasingly cold, cyanotic, and painful fingers in her right hand. She suffered necrotic lesions of her 4th and 5th fingers accompanied by severe ischemic type pain. A continuous C7 cervical paravertebral block was placed. Despite dense sensory and motor blockade, she still reported excruciating pain that ultimately required amputation after developing demarcated gangrene.
CONCLUSION: The two cases support the growing body of evidence that ischemic pain is largely unaffected by regional anesthesia, even with adequate sensory and motor block. The prevailing understanding regarding peripheral nerve blocks in patients in danger of developing compartment syndrome should be reconsidered. Wiley Periodicals, Inc.