481 - Unmasking Parsonage-Turner Syndrome: Severe Bilateral Upper Extremity Weakness in a Patient with Recurrent Cancer Post-Surgery

A 60 year-old male with history of uncontrolled T1DM and rectal adenocarcinoma treated with chemoradiotherapy was admitted for colectomy and resection due to recurrence of adenocarcinoma. Due to body habitus and anatomic difficulty, the surgery required multiple surgeons, unconventional instrumentation, and a prolonged operation three times the planned duration. Postoperatively, the patient experienced bilateral upper extremity weakness and impaired sensation. An MRI a week later revealed an intact brachial plexus of the right with bilateral proximal muscle atrophy, right greater than left. At week 3, an NCS/EMG evaluation was suggestive, but not conclusive of a bilateral panplexus injury, worse on the right and primarily involving the right lateral cord, right lower trunk and left lateral trunk. The patient is currently managed in neuromuscular clinic.

Discussions:

Neuralgic amyotrophy, also known as Parsonage-Turner Syndrome, is a neurological disorder characterized by sudden onset of severe pain followed by muscle weakness and atrophy. Several case reports have identified cancer as a risk factor for development due to immune-mediated treatments, systemic stress, and the inflammatory state associated with malignancy. He had multiple risk factors predisposing him to nerve injury, including previous platinum based chemotherapy, recent cancer reemergence, prolonged surgical resection, and uncontrolled type 1 diabetes. Unfortunately, he developed significant bilateral upper extremity weakness following surgery without any other known inciting event or injury. His electrodiagnostic study was highly suggestive of a panplexus injury, but not conclusive due to severely affected sensory NCSs bilaterally.

Conclusions:

Traditionally, neuralgic amyotrophy is believed to be an immune response to recent infection or immune-mediated pharmaceuticals. Our case demonstrates it can also occur with comorbidities and significant stressors. Electrodiagnostic study is helpful, but may be limited in severe cases due to significantly affected nerve conduction studies. In such cases, clinical correlation is imperative to make a diagnosis.