In this report, we describe the case of patient who showed abnormal corticomotor responses after peripheral afferent stimulation, namely sensory afferent inhibition (SAI) and sensory afferent facilitation (SAF), and its reversibility after treatment in a patient with anti-N-methyl D-aspartate receptor (NMDAR) encephalitis. A 26-year-old woman was admitted to a hospital after experiencing fever and headache for 11 days. Comprehensive serological studies, a brain magnetic resonance imaging scan, and cerebrospinal fluid (CSF) analysis were unremarkable. In the following days, she developed hallucinations and generalized tonic seizures. A repeat CSF analysis showed lymphocytic pleocytosis (261 white blood cells/ mm; 97% lymphocytes) and a normal protein concentration (63 mg/dl). She continued to have hyperkinetic movements and hyper-pyrexia despite receiving antibacterial and antiviral treatments. Electroencephalography showed diffuse slow waves with unremarkable somatosensory evoked potentials and brainstem auditory evoked potentials. After 30 days, she became unresponsive and had respiratory failure, and was then transferred to our hospital. On examination, she presented with dystonic posturing, oro-lingual-facial dyskinesia, and myoclonic movements. A computed tomography scan of the chest and abdomen and a trans-vaginal sonogram disclosed no abnormalities. Her serum and CSF studies were positive for anti-NMDAR antibodies. Transcranial magnetic stimulation (TMS) demonstrated intact corticospinal tracts with normal latencies and thresholds for motor-evoked potentials (MEPs). However, the conditioned peripheral afferent stimulation failed to show an SAI response at inter-stimulus intervals (ISIs) in the range of 15–25 ms, while exaggerated SAF responses were observed at ISIs between 30 and 70 ms. These data are contrasted to data from a healthy control subject in Fig. 1a, b and Table 1. The patient’s condition showed a little improvement in that she started to have some slow responses to verbal stimulation after steroid pulse therapy and plasmapheresis. Intravenous immunoglobulin was then started, and her condition improved dramatically. In a 3-week follow-up SAI/SAF study, the SAF had made notable progress toward normalization, but a normal SAI response was still absent (Fig. 1c; Table 1). NMDARs are expressed at high levels in the central nervous system, and play an important role in excitatory synaptic transmission and synaptic plasticity. Patients with anti-NMDAR antibodies usually present with various neurological symptoms presumably resulting from an AMPA receptor-mediated hyperglutamatergic state [1]. The MEP amplitude and latency of the patient described herein were similar to normal values. Impaired SAI and exaggerated SAF, such as observed in the presently described case, are suggestive of abnormal motor-sensory Y.-H. Dou K.-L. Lai K.-K. Liao S.-P. Chen (&) Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, 112 Taipei, Taiwan e-mail: chensp1977@gmail.com