VGKC antibodies in pediatric encephalitis presenting with status epilepticus.

BACKGROUND: Voltage-gated potassium channel antibodies (VGKC Ab) are associated with limbic encephalitis and neuromyotonia in adults. There have been no systematic investigations in children to date. METHODS: We looked for antibodies that are associated with CNS syndromes in adults including antibodies to VGKCs, NMDARs, glutamic acid decarboxylase (GAD), and glycine receptor (GlyR) in the stored acute serum from 10 children with unexplained encephalitis presenting with encephalopathy and status epilepticus. We also looked for antibodies to leucine-rich glioma-inactivated 1 (Lgi1) and contactin-associated protein-like 2 (Caspr2), which are now known to be tightly complexed with VGKCs in vivo. Sixty-nine pediatric controls were used for comparison. RESULTS: An elevated VGKC Ab (>100 pM) was detected in 4/10 patients with encephalitis compared to only 1/69 controls (p < 0.001). The outcome in the 4 VGKC Ab-positive patients with encephalitis was variable including good recovery (n = 1), cognitive impairment (n = 3), temporal lobe epilepsy (n = 2), and mesial temporal sclerosis (n = 1). No other antibodies were detected, including those to Lgi1 and Caspr2. CONCLUSION: Encephalitis associated with VGKC Ab occurs in children and presents with status epilepticus and focal epilepsy. These antibodies are not directed against Lgi1 or Caspr2.