Phrenic nerve palsy: Cervical spine stenosis or Parsonage and Turner syndrome? A case series and review of the literature.

Introduction: Phrenic nerve palsy is a rare cause of dyspnea. The differential diagnosis between cervical spine stenosis and Parsonage and Turner syndrome (PTS), the 2 main causesof phrenic nerve palsy, can be challenging. Research question: How to differentiate cervical spine osteoarthritis from PTS in front of a patient with phrenic nerve palsy? Material and methods: We retrospectively reviewed 8 patients suffering from phrenic nerve palsy. Clinical presentation, imaging, and electrophysiological data are analyzed. A literature review is conducted to support the diagnostic management. Results: The 8 patients, 5 men and 3 women, were 36 to 78 year-old. Six patients presented with acute or subacute onset of symptoms, and clinical as well as electrophysiological features were consistent with PTS. In 3 of them, Magnetic Resonance neurography demonstrated hourglass constrictions along the phrenic nerve. No surgery was performed, and they all had a favourable outcome following conservative treatment. In one patient, cervical foraminal stenosis was clearly implicated, with rapid improvement after decompressive surgery. In another case, cervical surgery was performed on severe C3C4 and C4C5 osteophytic changes with no significant clinical improvement; the rapid elevation of the hemidiaphragm over six weeks and the prior recurrent febrile/inflammatory episodes raise doubts in retrospect about the cervical compressive etiology. Discussion and conclusion: Phrenic nerve palsy results mostly from PTS or cervical spine stenosis, requiring distinct diagnostic and therapeutic strategies. A careful clinical, biological, electrophysiological and radiological assessment is essential to distinguish between these entities and provide timely and appropriate management.