CASE REPORT: A previously healthy 39-year-old man presented with subacute bilateral ascending paresthesias, fatigue and gait instability. Subsequently, he developed bilateral facial and symmetric limb weakness with diffuse hyporeflexia. Cerebrospinal fluid (CSF) revealed elevated protein (573 mg/dL) and 5 white blood cells.  Angiotensin-converting enzyme was minimally elevated. Cytology and flow cytometry were repeatedly normal. He received intravenous immune globulin (IVIG) for 5 days for suspected Guillain-Barre syndrome. Nerve conduction studies showed acquired demyelinating polyneuropathy. Despite additional IVIG and high dose steroid treatments, weakness progressed to severe quadriparesis without dysphagia or respiratory failure. Persistent sinus tachycardia suggested dysautonomia. After 3 weeks, CSF protein was persistently elevated (565.4 mg/dL). Vascular endothelial growth factor was normal. He had mild proteinuria with negative phospholipase A2 receptor (PLA2R) IgG. Serum protein electrophoresis with immunofixation showed a polyclonal pattern. Sural nerve biopsy revealed mild loss of myelinated fibers, occasional actively degenerating myelinated fibers without endoneural inflammation, vasculitis or amyloid deposition. Serum antibodies against VGKC, anti-striational and CNTN1 were positive. Positron emission tomography-computed tomography was negative for malignancy. After six sessions of plasma exchange, no significant improvement was noted. Due to lack of response, rituximab was started.