The role of event related potentials in evaluation of subclinical cognitive dysfunction in patients with primary generalized tonic clonic seizures

Background and aim - P300 is the most commonly recorded event related potential. P300 latency increases systematically with the increase in cognitive dysfunction and has been used as an objective electrophysiological index for the assessment of degree of cognitive dysfunction, to study the mechanism underlying cognition and to characterize information in normal and cognitively disabled population. In the present study, Auditory event related potential (AERP) has been used as an electrophysiological tool to assess the cognitive status in patients with primary Generalized Tonic Clonic Seizures (GTCS). Materials and methods - The study involved 30 patients with primary GTCS (20 males and 12 females) in the age group of 18-30 years. The control group consisted of age and sex matched 30 healthy volunteers. First, the subjects of the present study (both controls and GTCS patients) were evaluated using Mini Mental State Examination (MMSE). Their scores were between 26 and 30 (mean 29). Recording of P300 was done by standard Odd ball paradigm with random sequences. Results - No significant difference was observed in mini mental state examination score of both controls and GTCS patients. There was no significant difference in N100, P200 and N200 latencies between controls and primary GTCS patients. The mean P300 latency in GTCS patients (335.4715.52 ms) was significantly higher than the mean P300 in the control group (295.0019.34). The mean P300 amplitude in controls was 12.713.6 V and in GTCS patients was 8.351.71 V, a difference of 4.36V, which is significant. Conclusion - From the present study, it can be concluded that event related potential especially latencies of ERP have an important role in the evaluation of subclinical cognitive dysfunction in GTCS patients as evidenced by increased P300 latency, even though these patients did not have any clinical evidence of cognitive dysfunction.