Abstract Introduction Parsonage-Turner syndrome (PTS), also known as neuralgic amyotrophy, is an uncommon peripheral neuropathy characterized by abrupt onset of severe shoulder or neck pain followed by progressive weakness. Involvement of the phrenic nerve can lead to diaphragmatic paralysis and disabling dyspnea. Although PTS most frequently affects the brachial plexus, phrenic nerve palsy is a distinctly rare manifestation that is often underrecognized in clinical practice. This case describes a delayed diagnosis of Parsonage-Turner syndrome with phrenic nerve palsy and highlights the importance of considering neuropathic etiologies of unexplained dyspnea. Case Report A 71-year-old woman with a history of right upper lobe adenocarcinoma treated with radiation therapy eight months prior, tobacco use, and obstructive sleep apnea presented with sudden-onset severe right-sided neck and shoulder pain upon awakening, followed by progressive exertional dyspnea. She was initially prescribed albuterol but continued to have significant symptoms, ultimately leading to admission for hypoxia months later when she was noted to desaturate to 85% with exertion. Inpatient workup was unremarkable except for chronic changes in the right upper lobe on CT chest with elevated right hemidiaphragm. Her symptoms were attributed to coronary artery disease after a stress test demonstrated mild inducible ischemia. However, her dyspnea was disproportionate to both the ischemia and radiographic findings, and she was discharged without a unifying diagnosis. At pulmonary follow-up one month later, she continued to report severe exertional dyspnea (mMRC score 4). Pulmonary function testing showed a reduced DLCO of 67% predicted with a preserved KCO of 114%, suggesting reduced alveolar volume rather than intrinsic parenchymal or vascular disease. Chest imaging revealed right hemidiaphragm elevation, and diaphragm ultrasound confirmed absent right-sided thickening (diaphragm thickening fraction (DTF) 0%) with preserved left function (DTF 85.7%). Given the sequence of acute neuropathic pain followed by unilateral diaphragmatic dysfunction and exclusion of cardiac and pulmonary causes, PTS with phrenic nerve involvement was diagnosed. The patient was started on a corticosteroid taper and referred for physical therapy, with plans for MIP/MEP testing and potential surgical evaluation if symptoms persisted. Discussion Unilateral diaphragm paralysis is an underrecognized cause of dyspnea. Ultrasonography and assessment of postural changes in lung volumes are key diagnostic tools. Most patients improve with conservative therapy, though refractory cases may require diaphragmatic plication. This case underscores the need to consider Parsonage-Turner syndrome in the differential diagnosis of unilateral diaphragmatic paralysis, particularly in cancer survivors with preceding neuropathic pain. This abstract is funded by: None
Umer et al. (Fri,) studied this question.