Presentations

Abstract

Introduction:

Parsonage-Turner Syndrome (PTS), also known as idiopathic brachial neuritis, is a rare neurologic disorder characterized by sudden-onset, severe shoulder and upper extremity pain followed by muscle weakness and atrophy. This case report describes the clinical presentation of a patient with PTS to increase awareness of this uncommon condition and highlight its diagnostic challenges.

Case Information:

A 47-year-old male presented to the neurology clinic with complaints of recurrent episodes of sudden- onset, severe bilateral shoulder pain and weakness starting several years prior. During workup of his most recent episode, he was found with moderate to severe C6-7 foraminal stenoses and underwent C5-7 anterior cervical discectomy and fusion. Five days after surgery, he reported right shoulder pain followed by weakness and muscle atrophy. He underwent epidural steroid injections with reported mild pain relief. Scapular atrophy was noted on follow up and the patient was referred for physical therapy. His symptoms continued to persist with loss of strength in his shoulder, difficulty raising things overhead, and right shoulder pain. Upon physical examination, the patient exhibited atrophy of the right infraspinatus and teres minor as well as scapular winging. Sensory examination revealed no abnormalities, and distal pulses were intact. No signs of systemic illness or inflammation were noted. Additionally, patient reported his brother had presented with similar symptoms and had been diagnosed with PTS.

Diagnostic workups prior to surgery included MRI of the shoulder and brachial plexus which revealed no evidence of inflammation or mass lesion. Electromyography (EMG) and nerve conduction studies demonstrated carpal tunnel syndrome that improved over time. Subsequent post-operative EMG demonstrated changes of chronic C6/7 radiculopathy and right brachial plexopathy with active denervation of the suprascapular nerve and long thoracic nerve. Right brachial plexus MRI demonstrated no inflammation or lesion. Right shoulder MRI displayed atrophy and increased T2 signal in the supraspinatus and infraspinatus muscles suggesting denervation changes along the course of the suprascapular nerve compatible with the diagnosis of PTS. Given his brother's history, the patient underwent SEPT9 genetic testing, which was negative.

Discussion:

Though PTS is often idiopathic, it has been noted in the post-operative, post-vaccination, and post-infectious setting. Ten percent of patients with PTS have a positive family history of hereditary neuralgic amyotrophy (HNA), a related disorder. Given our patient's brother's diagnosis of PTS, HNA was suspected but ultimately not confirmed. There have been reported cases of post-operative PTS with varying presentations following cervical spine procedures, but existing medical literature has yet to establish a definitive correlation between the site of surgery and PTS. Our patient presented with recurrent episodes of shoulder pain and weakness with negative MRI and EMG findings of PTS prior to his surgery. Cervical decompression was performed to improve the patient's symptoms, but interestingly he developed worsening symptoms post- operatively with positive findings of PTS, suggesting his surgery may have contributed to his presentation.

The clinical presentation often mimics other conditions, leading to diagnostic challenges. The diagnosis is primarily made based on clinical findings and confirmed through electromyography, which reveal signs of denervation. MRI is the mainstay of imaging diagnosis because it has been shown to be sensitive for detecting signal abnormalities in the shoulder girdle muscles and helps exclude other causes of shoulder pain, such as rotator cuff tears. Imaging features include T2-weighted images showing early high signal intensity indicative of muscular edema, with subsequent atrophy and increased intramuscular T1-weighted signal related to fatty infiltration as PTS progresses. The management of PTS is predominantly conservative. Most patients experience spontaneous recovery, although the process can range from several months to years.

Conclusion:

PTS is often misdiagnosed, leading to treatment that fails to control patient pain and consequently delaying optimal treatment of patients. Increasing awareness and knowledge of PTS to help differentiate it from other causes of post- operative shoulder pain and upper extremity weakness allows for early detection and management.