The patient developed progressive left lower extremity numbness in 2014, followed by severe neuropathic pain, sensory ataxia, and rapid left-sided weakness. MRI revealed only mild lumbar disc bulging. CSF protein was elevated (43 mg/dL). Initial NCS (2016) demonstrated prolonged latencies and slowed conduction velocities; repeat studies in 2019 were normal. By 2018, examination showed 4/5 strength in the left extremities, hemisensory loss to multiple modalities, asymmetric reflexes (1+ LUE; 2+ RUE and BLE), and impaired gait without upper motor neuron signs. Due to largely nondiagnostic testing, she enrolled in a functional neurologic rehabilitation program to regain ability to walk, though no formal diagnosis was established.

After transient response to oral steroids, beginning IVIG during November 2019 (140 g over 3 days) produced near-complete symptom resolution within 2–3 days, with recurrence after three weeks. Presently, ongoing immunotherapy every three weeks has resulted in sustained functional improvement.