We investigated the changes of mismatch negativity (MMN) in patients with temporal lobe epilepsy (TLE) and explored the possible role of MMN in lateralizing their seizure focus. Thirty patients with TLE and thirty healthy controls were included. MMN was elicited in each subject. Patients with TLE were divided into three subgroups: unilateral left TLE; unilateral right TLE, and bilateral TLE. MMN amplitudes and latencies were compared between the patients with TLE and the control group, and also among the three subgroups of TLE, using repeated measures analyses of variance (ANOVA). To assess the lateralizing value of MMN, MMN latencies and amplitudes at the mastoid sites between the ipsilateral and contralateral sides of epileptic focus in patients with unilateral TLE were compared using t-test. Compared with controls, each subgroup of patients with TLE had longer latencies of MMN at both fronto-central and mastoid sites, but the amplitudes of MMN were not significantly different. The amplitudes and latencies of MMN were not significantly different between the ipsilateral and contralateral sides of seizure focus at mastoid sites. The present findings of prolonged latencies of MMN are suggestive of cognitive impairment in TLE. Both the mastoid sites and the fronto-central sites are involved, which likely reflect widespread cortical abnormalities in TLE. However, the changes of MMN during the interictal phase are not useful for lateralizing the seizure focus in patients with TLE.

ObjectivesTo assess the cognitive impairment in patients with type 2 diabetes mellitus (T2DM) using mismatch negativity (MMN) and to explore the relationship between cognitive impairment and diabetic peripheral neuropathy (DPN).Methods Sixty-six T2DM patients and 40 healthy controls were included. For each participant, mini-mental state examination (MMSE) was applied to assess the general cognitive function and MMN was elicited. T2DM patients were divided into two subgroups: subgroup DPN−, patients without DPN; subgroup DPN+, patients with DPN. The MMSE scores, MMN amplitudes and latencies were compared between the T2DM group and the control group using univariate analysis of variance procedures, and also among the controls, subgroup DPN− and subgroup DPN+. Pearson's correlation coefficients (r) were used to analyze potential confounding clinical factors associated with MMN. Results T2DM patients had significantly lower MMSE scores compared with controls (23.25 ± 2.86 vs. 27.15 ± 1.83; P < 0.01), whereas those of the two subgroups were not significantly different. Both subgroup DPN+ and DPN− had longer latencies and lower amplitudes of MMN than the controls. The latencies of MMN were significantly longer in subgroup DPN+ compared with subgroup DPN−. The latency of MMN was positively correlated with the duration of the disease. Conclusion Cognitive decline exists in patients with T2DM irrespective of the presence of DPN. Patients with DPN may have more severe cognitive dysfunction than those without DPN. MMN may be a promising tool for evaluating cognitive function.