Matthew R. Allen, BS
Medical Student
School of Medicine, University of California San Diego
La Jolla, California, United States
Ghassan Akkad, BS
Medical Student
School of Medicine, University of California San Diego
La Jolla, California, United States
Wei-Xian Li, MD
Physician
VA San Diego Healthcare System, Department of Physical Medicine and Rehabilitation
La Jolla, California, United States
David Bakal, MD
Assistant Clinical Professor
UC San Diego
La Jolla, California, United States
A 50-year-old female presented with sudden, atraumatic severe right shoulder pain following viral symptoms. Examination revealed diffuse shoulder pain, mild weakness (4/5 strength in shoulder flexion, abduction, and internal rotation), and full passive range of motion (PROM). Differential diagnoses included cervical radiculopathy, brachial plexopathy, rotator cuff injury, and calcific tendinopathy. Cervical spine and right shoulder radiographs were normal. Right shoulder MRI showed denervation edema of the subscapularis. Routine electromyography and nerve conduction studies were normal, although subscapularis was not assessed due to anatomical limitations. Given these findings, Parsonage-Turner Syndrome (PTS) was diagnosed, and the patient was referred to physical therapy.
At 2-month follow-up, shoulder strength had improved but severe PROM limitations had gradually developed. Subsequent MRI revealed new glenohumeral pericapsular edema, suggesting adhesive capsulitis (AC). An ultrasound-guided glenohumeral joint corticosteroid injection (CSI) resulted in symptom resolution.
Discussions:
PTS is characterized by sudden, severe shoulder pain and weakness with preserved PROM, often occurring following viral illness. It most commonly affects the upper trunk of the brachial plexus but can present in a non-specific distribution due to its autoimmune etiology. Typically, PTS is self-limiting and managed conservatively with physical therapy.
While AC also causes shoulder pain, it is distinguished from PTS by the presence of PROM restrictions and an absence of weakness. AC can occur following prolonged shoulder immobility and is typically self-limiting. Unlike in PTS, a glenohumeral CSI can be helpful in managing AC.
Initially, this patient presented with shoulder weakness consistent with PTS, but subsequently developed PROM limitations and pericapsular edema indicative of AC. Treatment with a glenohumeral CSI relieved her symptoms.
Conclusions: This is the first documented case of AC following PTS. This highlights the need for careful follow-up of PTS to accurately diagnose evolving symptoms. Misattributing new symptoms to PTS can delay effective treatment.
