Probable Postsurgical Parsonage-Turner Syndrome Following Endoscopic Endonasal Pituitary Surgery: A Diagnostic Challenge Case Report: Illustrative Case.

Brachial neuritis is a rare inflammatory brachial plexopathy characterized by acute and severe shoulder or upper-extremity pain followed by progressive weakness and sensory disturbances. Commonly associated with viral illness, vaccination, or trauma, it can also occur as a postoperative complication. A 65-year-old gentleman presented with visual loss from a large recurrent pituitary adenoma and underwent an uncomplicated resection. Shortly after surgery, he developed swelling and pain in the right forearm and hand, which later evolved into patchy sensory loss and progressive weakness throughout the arm. Examination demonstrated proximal and distal weakness, muscle wasting, and multifocal sensory deficits without signs of cervical radiculopathy, myelopathy, or carpal tunnel syndrome. Pregabalin and gabapentin provided minimal symptom relief. Electromyography and nerve conduction studies performed 6 weeks later showed a moderate right median mononeuropathy and chronic, inactive C7 radiculopathy, findings that did not fully explain his clinical picture. The clinical presentation was most consistent with probable postsurgical Parsonage-Turner syndrome after exclusion of structural and compressive causes, and the patient improved with physical and occupational therapy, achieving near-complete recovery at 6 months. While early recognition is essential, as electrodiagnostic or radiographic studies may be nondiagnostic, timely therapy can facilitate meaningful functional recovery.