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A Patient With Headache and Progressive Tremor

A 50-year-old man with no prior medical history sought care for new-onset daily headaches persisting for 3 months that did not improve after taking over-the-counter analgesics. He described asymmetric upper extremity action tremor and clumsiness affecting predominantly the right side. The patient’s wife also noted personality changes, anxiety, and depression. The review of systems was pertinent for a flulike syndrome in the weeks before his symptoms started.
 Neurologic examination showed reduced digit span, pyramidal signs with asymmetric hyperreflexia (right greater than left), and bilateral subtle lower extremity spasticity. He also had cerebellar ataxia and postural and action tremor of the upper extremities (right predominant). Ophthalmologic examination indicated mild bilateral optic disc edema with normal visual acuity.
 Brain magnetic resonance imaging showed linear radial perivascular enhancement in both cerebral hemispheres without associated T2 hyperintensities. Magnetic resonance imaging of the spine showed some hazy T2 hyperintensity in the thoracic cord with subtle gadolinium enhancement.
 Cerebrospinal fluid examination showed an opening pressure of 21 cm H2O, 63 white blood cells/µL with lymphocytic predominance, increased protein concentration of 130 mg/dL, and no oligoclonal bands.
 The patient’s cerebrospinal fluid was positive for immunoglobulin G antibodies specific for glial fibrillary acidic protein; no other neural autoantibodies were found in the serum or cerebrospinal fluid.
 The patient was diagnosed with autoimmune glial fibrillary acidic protein astrocytopathy.
 The patient was treated with high-dose intravenous corticosteroids followed by oral prednisone. The patient improved, the headaches disappeared, and he had only mild persistent tremor. After the corticosteroids were discontinued, he had an early relapse with increased headaches, confusion, and ataxia. Cerebrospinal fluid reevaluation showed reoccurrence of lymphocytic pleocytosis, and the patient was treated with oral prednisone. The corticosteroids were tapered over 6 months. Repeated imaging showed resolution of the abnormalities. At 3-year follow-up, the patient was relapse free.
 Autoimmune glial fibrillary acidic protein astrocytopathy is defined by the presence of glial fibrillary acidic protein-immunoglobulin G in the cerebrospinal fluid.