[Patient with limbic encephalitis associated with anti-voltage-gated potassium channel antibodies who presented with insomnia and hand tremor].

A 65-year-old man presented with bilateral postural hand tremor (3 Hz) followed by memory impairment, which improved spontaneously after admission to our hospital. Two weeks after admission, he had another bout of memory impairment and complained of insomnia. Brain magnetic resonance imaging (MRI) showed a signal intensity change in the medial part of the right temporal lobe, which suggested limbic encephalitis (LE). Serum hyponatremia and absence of cerebrospinal fluid pleocytosis suggested the possibility of anti-voltage-gated potassium channel (VGKC) antibody-associated LE. Serum hyponatremia and hand tremor showed immediate improvement after steroid pulse therapy, and memory impairment and insomnia showed gradual improvement. Brain MRI on day 110 of admission showed partial resolution of medial temporal signal abnormalities with mild bilateral hippocampal atrophy. Serological tests confirmed the clinical diagnosis of anti-VGKC antibody-associated LE. This report may expand the phenotypic profile of anti-VGKC antibody-associated LE, which is characterized by remission and relapse of disease course, insomnia, and hand tremor.