Hyperekplexia-epilepsy syndrome

Hyperekplexia-epilepsy syndrome (Orphanet code 163985) is an extremely rare neurological disorder characterized by the combination of hyperekplexia (exaggerated startle responses to unexpected stimuli, particularly tactile or auditory) and epileptic seizures. This condition affects the central nervous system, specifically involving dysfunction of inhibitory neurotransmission, particularly glycinergic signaling. Hyperekplexia typically manifests in the neonatal or infantile period with excessive startle reactions, neonatal hypertonia (increased muscle stiffness), and episodes of stiffness that can be dangerous due to the risk of apnea (breathing pauses). The epilepsy component may include various seizure types that develop in addition to the startle episodes. The syndrome has been associated with mutations in genes involved in glycine receptor function or related inhibitory neurotransmission pathways. Affected individuals may experience developmental delay and intellectual disability of variable severity. The exaggerated startle response can sometimes be mistaken for seizure activity, making accurate diagnosis important for appropriate management. Treatment is primarily symptomatic. Clonazepam, a benzodiazepine, is often considered a first-line treatment for the hyperekplexia component, as it enhances inhibitory GABAergic neurotransmission and can reduce the severity and frequency of startle episodes. Antiepileptic drugs are used to manage the seizure component, with the specific choice depending on seizure type and individual response. Early diagnosis and treatment are important to reduce the risk of complications such as apneic episodes in neonates. Genetic counseling is recommended for affected families.

Common questions about Hyperekplexia-epilepsy syndrome