1648 - Type 2 complex regional pain syndrome following needle electromyography

Case Diagnosis: Type 2 complex regional pain syndrome (CRPS) following needle electromyography.

Case Description: 43-year-old female patient experiencing right hand weakness, numbness, and paresthesias referred for electrodiagnostic examination. Differential diagnosis included radiculopathy vs. carpel tunnel.  Nerve conduction studies demonstrated median mononeuropathy at the wrist. Needle EMG was normal; however during needle EMG of bicep, patient reported intense pain. The needle was removed and re-inserted with alleviation of discomfort. One month later, patient was evaluated for ongoing pain and swelling of right upper extremity. Physical exam was notable for allodynia and hyperalgesia in the right medial antebrachial cutaneous nerve (MAC) distribution, mild erythema, mild edema, and giveaway weakness. Right MAC was non recordable on nerve conduction studies. At this time, patient met 4/4 on subjective Budapest criteria and at least the sensory and sudomotor objective criteria, and was diagnosed with CRPS type 2 (causalgia). Treatment to date has included OT, acupuncture, a stellate ganglion block, and gabapentin.

Discussions: Commonly observed complications of needle EMG include discomfort during procedure and swelling around needle insertion site. Significant complications are rare, but have included bleeding, pneumothorax, and compartment syndrome. To our knowledge, there have been no reports of CRPS or local nerve injury as a direct result of needle EMG.  We speculate that it is possible that iatrogenic nerve injuries secondary to needle EMG are underreported due to difficulty discriminating its clinical presentation from the underlying neuropathic complaints that often prompt the EMG, as well as generally not having any follow up with the electromyographer.

Conclusions: CRPS is complex and can present with a varied clinical picture from patient to patient. Standard of care for this diagnosis is based on universally agreed upon principles. Even with appropriate treatment, outcomes are variable. Further study is indicated to identify the frequency of nerve injury secondary to needle diagnostic procedures.