Clinical Reasoning: A 50-Year-Old Male Patient With Acute Severe Sensory Deafferentation and Bilateral Ptosis With Rapid Recovery.

A 50-year-old man presented with acute-onset numbness and tingling in his extremities, which progressively worsened, leading to severe gait instability and near-inability to walk. Two weeks earlier, he had experienced an upper respiratory tract infection. Neurologic examination revealed bilateral ptosis, truncal and gait ataxia, and impaired sensory function, with preserved motor strength. The differential diagnosis encompassed infectious etiologies as well as immune-related causes, including paraneoplastic syndromes. Nerve conduction studies demonstrated absent sensory nerve action potentials while motor nerve conduction was unremarkable. Repetitive nerve stimulation testing showed no decremental response. CSF analysis was normal. The patient experienced rapid clinical improvement after intravenous immunoglobulin therapy. This case underscores the importance of recognizing atypical subtypes of classical neurologic disorders, which may present challenges even to experienced clinicians.