Anti-NMDAR encephalitis preceded by dura mater lesions

Abstract

Limbic encephalitis is characterized by psychosis, memory loss, and seizures. It is sometimes caused by autoimmune mechanisms, including anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Anti-NMDAR encephalitis is typically a multistage disorder. After a prodromal event, psychiatric symptoms develop, followed by seizures, suggesting cortical involvement. Subsequent subcortical involvement is observed in most patients leading to movement disorder, and reduction in consciousness. The signal changes in brain magnetic resonance imaging (MRI) have been reported in the cerebral parenchyma such as the hippocampi, cerebellar or cerebral cortex, frontobasal and insular regions, basal ganglia, and brainstem [1]. Herein, we present a case with anti-NMDAR encephalitis preceded by dura mater lesions in brain MRI. A 50-year-old man with no medical history and head contusion suddenly developed tonic–clonic seizure. Brain MRI showed signal changes in the dura mater of the occipital areas (Fig. 1a, b). A day later, he developed status epilepticus (SE) and was sedated with propofol. Cerebrospinal fluid (CSF) examination showed normal cell counts and elevated concentration of total protein (48.0 mg/dl) and IL-6 (51.0 pg/ml). The laboratory investigations for herpes simplex viruses and human herpesvirus-6 were negative. Antinuclear antibody, thyroid antibodies, onconeuroal antibodies (Hu, CV2, Ma2, Ma1, Yo, Ri, amphiphysin), and glutamic acid decarboxylase antibodies (GAD-ab) were negative. Although high-dose intravenous methylprednisolone (1,000 mg/day for 3 days) led to recovery from SE, he exhibited cognitive impairment (15/30 on the Mini-Mental State Examination), psychomotor agitation, nystagmus, rigidity, postural tremor, and ataxia. Brain MRI on the 14th hospital day showed signal changes in cerebellum and cingulate gyrus with improvement of lesions in the dura mater (Fig. 1c). No additional treatment led to complete recovery from the neurological deficit within 2 months after disease onset. Antibodies to NR1/NR2B heteromers of the NMDA receptor (antiNMDAR antibody), examined by a cell-based assay as described previously [2], were positive in serum and CSF obtained upon admission. Despite an extensive oncologic workup such as whole-body CT and fluorodeoxyglucosepositron emission tomography (FDG-PET), there was no evidence of tumor. He has not had relapsing episodes of encephalitis for 26 months. Repeat FDG-PET every 6 months showed no tumor. Anti-NMDAR encephalitis was originally considered as having paraneoplastic syndrome in young women with ovarian teratoma [1]. However, recently it has become clear that patients with anti-NMDAR encephalitis are not always women and paraneoplastic [3–5]. Brain MRI abnormalities have been reported in the cerebral parenchyma such as the hippocampi, cerebellar or cerebral cortex, frontobasal and insular regions, basal ganglia, and brainstem [1]. Abnormalities in medial temporal lobes are H. Suzuki (&) M. Kitada S. Ueno S. Kusunoki Department of Neurology, Kinki University School of Medicine, Osaka, Japan e-mail: hide_green74@yahoo.co.jp