Uncovering Ankylosing Spondylitis from a Diagnosis of Parsonage-Turner Syndrome: A Case Report of Bilateral Shoulder Pain and Weakness

INTRODUCTION: Parsonage-Turner syndrome is a rare condition that is often misdiagnosed by physicians due to the overlapping symptoms with other conditions such as rotator cuff injury and cervical radiculopathy. The etiology of the Parsonage-Turner syndrome is unknown, but has been associated with an immune-mediated response to rheumatic disease, infection, surgery, and immunizations. CASE PRESENTATION: A 18-year-old female former tennis player with a history of complex regional pain syndrome (CRPS), Ehler-Danlos syndrome (EDS), and two prior right shoulder surgeries presented to the orthopaedic clinic with bilateral shoulder pain. After a third surgery on the right shoulder, the patient later developed constant burning and sharp pain around the right shoulder that radiated toward the chest. She also experienced numbness, tingling, and weakness in the right shoulder along with pain and weakness in the left shoulder. The patient was tender over the right musculocutaneous nerve and both shoulders were inflamed on ultrasound. Electromyography (EMG) and nerve conduction studies were performed, which were consistent with a bilateral subacute on chronic brachial plexopathy, suggestive of Parsonage-Turner syndrome. Rheumatology was consulted due to an extensive family history of autoimmune diseases, leading to an additional diagnosis of ankylosing spondylitis. The patient’s bilateral shoulder pain slowly improved over the following year with physical therapy and prolotherapy treatments. CONCLUSION: The case described, herein, represents a unique patient who presents with the rare conditions of ankylosing spondylitis, CRPS, EDS, and Parsonage-Turner syndrome. EMG was critical to differentiate Parsonage-Turner syndrome from the overlapping CRPS symptoms and without this, the diagnosis of ankylosing spondylitis may have been delayed. It is imperative physicians take a thorough history, include uncommon or rare conditions as a potential diagnosis, and undergo thorough testing while evaluating a patient to avoid unnecessary treatment therapies and patient dissatisfaction.