Somatosensoriel cortex excitatory and inhibitory function in temporal lobe epilepsy

We aimed to investigate the inhibitory and excitatory function of somatosensory cortex by studying surround inhibition (SI) and somatosensory evoked potential (SEP) recovery in patients who received medical treatment or underwent surgery due to mesial temporal lobe epilepsy (MTLE). A total of 19 patients (epilepsy group n=9, operation group n=10) and 12 healthy volunteers admitted to the epilepsy outpatient clinic for a regular control visit within the last year were included in the study. SEP recording was administered after bilateral median and ulnar nerve stimulation in all patients and healthy volunteers. Regarding the SEP recovery, two separate recordings were made using two matched stimuli at different stimulus intervals (40 and 100 ms). As for the SI, the median, ulnar and median+ulnar nerves were stimulated together and the arithmetic sum of the amplitude values was compared. In our study, N20p-P25p and B-N20p amplitudes obtained by ulnar and ulnar + median nerve stimulation were found to be higher on the right side in healthy subjects. On the symptomatic side of the patients, there was N33 latency delay with simultaneous stimulation of the median + ulnar nerves compared to healthy subjects (p=0.028). No significant difference was observed between the patients and healthy individuals in terms of the SI loss. SI loss was seen on the asymptomatic side in selected patient groups only. No significant difference was found between the patient groups in terms of recovery functions, however there was a relationship between the duration of disease, history of status epilepticus and use of antiepileptic drugs on the symptomatic and asymptomatic sides. Our study results are noteworthy since this is the first study in the literature exploring the inhibition and excitation of the somatosensory cortex evaluated by SEP examination in patients with/without MTLE.