Giant subcortical high-frequency SEPs in idiopathic generalized epilepsy: A protective mechanism against seizures?

objective: recently, we found that high-frequency somatosensory evoked potentials (HF-SEPs), which are modulated by arousal-related structures, were abnormally enhanced during N-REM sleep in two seizure-free IGE patients [restuccia d, rubino m, valeriani m, della marca g. increase of brainstem high-frequency SEP subcomponents during light sleep in seizure-free epileptic patients. clin neurophysiol 2005; 116: 1774-1778]. Here, we aimed at verifying whether similar HF-SEP abnormalities were significantly correlated to the clinical outcome in a larger population of untreated IGE patients. methods: patients were classified as juvenile myoclonic epilepsy (JME; six patients) and childhood or juvenile absence epilepsy (CAE and JAE, six patients). they were untreated because newly diagnosed, or because seizure-free. HF-SEPs from patients were compared with those obtained from 21 healthy volunteers. results: HF-SEPs were abnormally enhanced in all seizure-free CAE-JAE patients, whereas they were normal in all JME patients and in CAE-JAE patients with frequent seizures. not only scalp distribution, but also dipolar source analysis suggested a subcortical origin for these enhanced subcomponents, possibly in the brainstem. conclusions: the enhancement of HF-SEPs might reflect the hyperactivity of arousal-related brainstem structures; such an enhancement was found in all seizure-free CAE-JAE patients, while it was never observed in JME patients. significance: we speculate that the hyperactivity of arousal-related brainstem structures might account for the different clinical outcome among IGE subsyndromes. (c) 2006 international federation of clinical neurophysiology.