EEG after sleep deprivation is a sensitive tool in the first diagnosis of idiopathic generalized but not focal epilepsy

Abstract

OBJECTIVES: Electroencephalography (EEG) is an essential tool in the diagnosis of epilepsy. EEG after sleep deprivation might increase the likelihood of finding specific epileptiform abnormalities. However conflicting data exist concerning the sensitivity and specificity of this method. We aimed to evaluate the role of EEG after sleep deprivation in the first diagnosis of epilepsy.
METHODS: We analyzed retrospectively the medical histories of patients who underwent at least one unspecific standard EEG and a subsequent EEG after sleep deprivation during the time period from 2001 to 2014 at the University Hospital Zurich because of suspected epilepsy.
RESULTS: Out of 237 patients who fulfilled all inclusion criteria, 69 were finally diagnosed with epilepsy. Seventeen of them showed interictal epileptiform patterns in EEGs after sleep deprivation, giving this method an overall sensitivity of 25%. Sensitivity of EEG after sleep deprivation was superior in patients with primary generalized epilepsies compared to patients with focal epilepsies (64% vs. 17%, p=0.0011). Overall EEG after sleep deprivation was not more sensitive than a subsequent repeated standard EEG in a subgroup of 55 patients (22% vs. 9%; p=0.065).
CONCLUSION: After an unspecific standard EEG, EEG after sleep deprivation is a useful tool to increase diagnostic sensitivity in patients with idiopathic generalized epilepsy but not in those with focal epilepsy.
SIGNIFICANCE: This study provides further evidence about the usefulness of EEG after sleep deprivation as an additional diagnostic tool in epilepsy.