Background: Epileptic seizures, predominantly or exclusively during sleep had been the focus of attention for many electroencephalographers. Though few epileptic syndromes are associated with sleep seizures (SS) its frequencies in Indian patients is still unknown.
Aim: To find out the patterns of epilepsies in patients having SS and compare them with patients having wake seizures (WS).
Setting and design: Open label hospital based study.
Materials and methods: One hundred and forty-four (13%) patients having predominantly SS were compared with 976 (87%) patients of WS by various clinical, electrophysiological and radiological factors.
Statistical analysis: Chi square test and student T test, using software SPSS (version 10, 1999) was applied to compare various parameters. Relative risk was calculated by 2 x 2 contingency table.
Results: The seizure semiology was better defined in patients with WS and GTCS was more common in SS (P=0.001). Wake-electroencephalogram (EEG) was abnormal in significantly (P=0.001) higher number of patients with WS. Symptomatic etiologies were found in more than half patients. Left lobe involvement was more common in patients having SS (P=0.000). After symptomatic, idiopathic generalized and frontal lobe epilepsy were most frequent with SS. Undetermined epilepsy was found in 37 (25.7%) patients with SS.
Conclusion: Epilepsies associated with SS were less frequent and had symptomatic cause in most cases. Left hemispherical and frontal lobe lesion were more commonly associated with SS. Frontal lobe and idiopathic generalized epilepsy was most frequent in patients of SS. Sleep EEG should always be done in patients with sleep seizures.