Teaching Video NeuroImage: Hereditary Hyperekplexia Mimicking Tonic Seizures in an Infant.

Hereditary hyperekplexia is a rare neurologic disorder characterized by an exaggerated startle response with profound muscle stiffness.1,2 Given the nature of the spells, this condition is often misdiagnosed as epilepsy. Mutations in glycine receptors and transporters are the primary cause of this syndrome.1 We present an example of stimulus-induced hyperekplexia captured on video EEG in a 7-week-old girl with compound heterozygous variants in the presynaptic glycine transporter gene SLC6A5 .