Title : Neuralgic amyotrophy in a patient following a neck biopsy
Neuralgic amyotrophy, or Parsonage-Turner syndrome (PTS), is a rare autoimmune inflammatory disorder of the brachial plexus. Patients will present with episodes of extreme shoulder pain with eventual development of paresis and atrophy of the innervated muscle. These symptoms may mimic other conditions, such as brachial plexus injury. Therefore, PTS may be difficult to recognize. Among the differential for PTS are radiculopathy from cervical disc herniation, compression of the brachial plexus by mass lesion, postherpetic neuralgia, calcific tendonitis, acute subacromial bursitis, and adhesive capsulitis. EMG showing denervation in an atypical pattern is highly supportive of PTS diagnosis. There are many trigger for the development of PTS, however the most common and documented is viral infection. We present a rare case in which PTS was diagnosed following biopsy over the right levator scapulae muscle. Initial physical exam findings were significant for right shoulder pain and droop with weakness in external rotation and shoulder abduction. As PTS is a diagnosis of exclusion, other conditions were first ruled out. To support the diagnosis of PTS, EMG was conducted and showed findings consistent with PTS. The patient was treated with analgesics and underwent physical therapy. Over the next eight months, EMGs were significant for spontaneous regeneration of nerve activity with concordant improved physical exam findings. This case highlights the importance of considering PTS when other leading differentials have been ruled out. Identifying PTS can protect the patient from excessive testing and inappropriate treatment. Regular administration of EMGs can identify improved nerve function that precede improvement in physical exam findings. Among PTS cases following surgery, this case brings attention to less invasive surgeries as a possible trigger of PTS. Our case shows that minor procedures with minimal risk of brachial plexus involvement can precipitate PTS. Confirmation of suspected PTS with EMG findings should be done. However, it is important to note that PTS is not reflected on EMG until at least 3 weeks after symptom onset. Most cases, including ours, report a self-limiting pattern of disease. Treatment is typically with analgesics and physical therapy. The patient in our case reported significant improvement in function and pain from physical therapy alone.
Audience Take Away
- Early diagnosis of neuralgic amyotrophy can protect patients from excessive testing and inappropriate treatment
- Consideration for neuralgic amyotrophy as a diagnosis should not be limited to viral infections or highly invasive procedures
- Significant intervention is not recommend as most patients report improvement with analgesics and physical therapy
- EMG findings are critical to confirming the diagnosis and follow-up EMGs should be used to track recovery