<b><i>Introduction:</i></b> Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a recently described steroid-responsive meningoencephalomyelitis positive for cerebrospinal fluid (CSF) anti-GFAP antibody. Area postrema syndrome (APS) involves intractable hiccups, nausea, and vomiting, which is caused by medulla oblongata (MO) impairment. APS is a characteristic symptom of aquaporin-4 (AQP4) autoimmunity, and it helps to differentiate between AQP4 and GFAP autoimmunity. Conversely, although 6 cases of autoimmune GFAP astrocytopathy with APS and MO lesions have been reported, the association between GFAP autoimmunity and APS is unclear. We report the case of a patient with autoimmune GFAP astrocytopathy presenting with APS-like symptoms without MO lesions and discuss the mechanisms underlying the symptoms. <b><i>Methods:</i></b> CSF anti-GFAP antibody was detected using cell-based assays and immunohistochemical assays. <b><i>Results:</i></b> A 54-year-old Japanese man developed persistent hiccups, intermittent vomiting, fever, anorexia, and inattention. Brain magnetic resonance imaging (MRI) showed periventricular lesions with radial linear periventricular enhancement, suggesting autoimmune GFAP astrocytopathy. However, no obvious MO lesions were identified on thin-slice images. Spinal cord MRI revealed hazy lesions with patchy enhancement along the cervical and thoracic cord. CSF analysis demonstrated inflammation, with positive results for anti-GFAP antibodies. Anti-AQP4 antibodies in the serum and CSF were negative. Esophagogastroduodenoscopy revealed gastroparesis and gastroesophageal reflux disease, and vonoprazan, mosapride, and rikkunshito were effective only against persistent hiccups. Steroid therapy was initiated, allowing clinical and radiological improvements. Repeated MRIs demonstrated no obvious MO lesions. <b><i>Conclusion:</i></b> This report suggests that autoimmune GFAP astrocytopathy presents with APS-like symptoms without obvious MO lesions. The possible causes of hiccups were gastroparesis and cervical cord lesions. Gastroesophageal reflux disease was not considered a major cause of the hiccups. Intermittent vomiting appeared to be associated with gastroparesis, cervical cord lesions, and viral-like symptoms. Testing for anti-GFAP antibodies should be considered in patients with APS-like symptoms in the context of typical clinical-MRI features of autoimmune GFAP astrocytopathy.

Autoimmune encephalitis (AE) is a group of inflammatory brain diseases that are characterized by prominent neuropsychiatric symptoms. Early therapeutic intervention is important for AE. Therefore, without waiting for autoantibody test results, clinicians must consider the possibility of AE based solely on clinical symptoms and conventional test results. The case described herein is of antibody-negative encephalitis with abnormalities shown only by EEG, which contributed to the diagnosis and treatment. The patient, a 20-year-old woman, showed autonomic seizures in addition to movement disorders, psychiatric symptoms, and cognitive dysfunction, which worsened subacutely. Her seizures and movement disorders were not responsive to antiepileptic medications. Results obtained from MRI and cerebrospinal fluid (CSF) were normal; EEG findings showed repeated spikes in the right temporal area, with changes over time. Based on the clinical course and EEG, along with administered immunotherapy, which resolved seizures, movement disorders, and psychiatric symptoms, we suspected AE. For diagnosis of AE and for evaluating treatment responsiveness, EEG was useful. Results indicate that EEG can assist clinicians even with AE cases for which MRI and CSF findings are normal.