1535 - Rare case of neuralgic amyotrophy involving vocal cord dysfunction and suprascapular neuropathy.

A 50-year-old male presented one month after waking up with severe discomfort between the left shoulder and elbow. Pain improved and was followed by persistent shoulder and arm weakness. He subsequently developed hoarseness diagnosed as paralysis of the left vocal cord by otolaryngology.  

At one month, nerve conduction and electromyography (EMG) revealed left suprascapular neuropathy with acute denervation in infraspinatus and supraspinatus muscles. Acute right C6 radiculopathy was also noted. MRI C-Spine noted multilevel spondylosis which was most advanced at C6-C7 with mild central canal stenosis and mild bilateral neural foraminal narrowing.  

Vitamin B12, methylmalonic acid, ESR, Lyme antibody titer, and CPK were normal. HgbA1c was 6%. Hematology evaluation is pending for polyclonal increase in IgM on immunofixation and elevated free kappa light chain (33.6 mg/L). Repeat EMG at 2 months showed increased motor unit action potential duration and slightly increased polyphasic potentials in only the left supraspinatus muscle. 


Discussions: Neuralgic amyotrophy (i.e. acute brachial neuritis or Parsonage-Turner Syndrome), presents as severe pain followed by weakness in a distribution of one or more nerves. While it is most common in the upper extremity, presentation in the cranial nerves concurrently or in isolation may be seen. Incidence is estimated to be 1 per 1000. The cause is unknown but may be triggered by stressors such as surgery, trauma, infections, vaccinations, or strenuous exercise. Diagnosis is made by exclusion criteria and EMG allows topographic delineation of the lesion.  Prognosis is generally favorable with previous studies estimating 80-90% of cases recover within 2-3 years.  

Conclusions:

Neuralgic amyotrophy has a variable presentation. It should be considered as a diagnosis in patients with unconventional nerve involvement and may include cranial nerve abnormalities.