Permanent lesion of the lateral femoral cutaneous nerve after low-volume ethanol 96%application on the lumbar sympathetic chain.

Lumbar sympathetic blocks and chemical sympathectomies are used for the pain treatment of peripheral arterial occlusive disease or sympathetically maintained pain syndrome after nerve injury or complex regional pain syndrome (CRPS). A 30-year-old patient was referred to the pain department with all the clinical signs and symptoms of a CRPS of the right foot one and a half years after being surgically treated for rupture of the achilles tendon. An inpatient admission was necessary due to insufficient pain reduction upon the current treatment, strong allodynia in the medial distal right lower leg and decreased load-bearing capacity of the right foot. A computed tomography (CT)-guided lumbar sympathetic block at the right L3 (Bupivacaine 0.5%, 4 mL) led to a skin temperature increase from 21° C before block to > 34° C for about 5 hours after the intervention. The patient experienced significant pain relief, indicating sympathetically maintained pain. Thus, we performed a CT-guided lumbar sympathetic neurolysis at the same level (ethanol 96%, 2 mL) 5 days later, achieving again a significant skin temperature increase of the right foot and a slight reduction of his pain intensity from numeric rating scale (NRS) 7 prior to the intervention to NRS 4 after 8 hours (NRS, 0 = no pain, 10 = strongest pain imaginable). Eight months later a repeated inpatient admission was necessary due to considerable pain relapse and decreased load-bearing capacity of his right foot. A CT-guided lumbar sympathetic neurolysis was repeated at the L4 level on the right side and was successful, inducing a significant skin temperature increase. Despite a temporary irritation of the genitofemoral nerve 8 hours after the intervention, a delayed irritation of the lateral femoral cutaneous nerve occurred. This was a long-lasting lesion of the lateral femoral cutaneous nerve following a CT-guided chemical sympathectomy with a low-volume ethanol 96% application - a complication which has not been described in literature until now. This is probably caused by broad dissemination of the neurolytic agent along the psoas muscle despite a correct needle position and spread of contrast agent. The development of this nerve injury even after injection of a small volume of ethanol (2 mL) may be delayed.