Review Question - QID 213994

This patient's history and clinical picture are most consistent with neuralgic amyotrophy (also known as Parsonage-Turner syndrome, or PTS). He has pain, weakness, atrophy to the musculature about his shoulder, and scapular winging, all preceded by a viral illness.

Neuralgic amyotrophy is an uncommon disorder characterized by severe shoulder pain followed by patchy muscle paralysis and sensory loss involving the shoulder girdle and upper extremity. Any nerve in the brachial plexus can be involved; however, the most common involved nerves include the long thoracic nerve, suprascapular nerve, axillary nerve, musculocutaneous nerve, and radial nerve. Twenty-five to 50% of cases are preceded by a viral illness.

Tjoumakaris et al. wrote a JAAOS review in which they identified an antecedent viral illness in 25-55% of patients with PTS. They also described the typical course as starting with intense pain followed by flaccid paralysis, muscle atrophy, and sensory loss of the shoulder girdle. Ten to 30% of the time this may be bilateral. They conclude that neuralgic amyotrophy may exhibit a broad range of clinical manifestations and must be distinguished from other more serious diagnoses.

Sumner et al. reviewed the history of idiopathic brachial neuritis. The nerves most frequently involved include: suprascapular, long thoracic, axillary and musculocutaneous. The author proposed that the etiology of PTS may be multifactorial, with combined inflammatory and mechanical interactions. One hypothesis that exists suggests that the mobility of the upper trunk allows for weakening of the blood-nerve barrier that normally prevents soluble immune factors or cells from coming into contact with the peripheral nervous system.

Figure A shows a patient with right sided medial scapular winging.

Incorrect Answers:
Answer 1: Amyotrophic lateral sclerosis (ALS) presents as a combination of UMN and LMN in the same extremity in the absence of pain or sensory symptoms. If cranial nerve findings are present, ALS would be high on the differential diagnosis.
Answer 2: A frozen shoulder presents as pain and stiffness with both active and passive range of motion.
Answer 3: The patient in the question stem does have a long thoracic nerve (LTN) palsy as evidenced by his medial scapular winging; however, an isolated LTN palsy does not satisfy his full clinical picture.
Answer 4: A rotator cuff tear may present as lack of active range of motion with forward flexion and external rotation; however, this would not explain his scapular winging.