Postpartum Parsonage-Turner syndrome with hourglass constrictions and spontaneous recovery without surgical intervention

Introduction: Parsonage-Turner syndrome (PTS), also known as neuralgic amyotrophy, is an uncommon neurologic disorder characterised by acute onset upper extremity pain followed by muscle weakness, atrophy and paraesthesias. Severity of symptoms is variable and can involve any peripheral motor nerves of the brachial plexus. Its occurrence in the immediate postpartum period is exceedingly uncommon. Case description: A 31-year-old G1P1002 with a twin gestation underwent an emergency caesarean delivery for non-reassuring foetal status of twin B following a spontaneous vaginal delivery of twin A. Her pregnancy was complicated by A2 gestational diabetes. Shortly after surgery, the patient experienced right arm numbness, followed by two weeks of severe pain. Upon resolution of pain, she developed profound weakness in the posterior interosseous nerve (PIN) distribution of the right hand. Physical examination revealed loss of finger extension at the metacarpophalangeal joints, weak thumb extension and loss of wrist extension, with decreased sensation to light touch in the radial four digits. Wrist flexion was preserved. Electromyography demonstrated right posterior PIN neuropathy; specialised MR neurography identified multiple hourglass constrictions, pathognomonic for PTS. Discussion: The patient was managed conservatively with analgesics, a trial of corticosteroids, electrical stimulation and occupational therapy. Eleven months after symptom onset, finger extension returned spontaneously. Conclusion: This case highlights the presentation of PTS in the immediate postpartum period following caesarean delivery. Recognition of characteristic clinical features and imaging findings is crucial for accurate diagnosis. Conservative management can result in full functional recovery, though symptom resolution may be delayed.