Impaired sensorimotor gating in patients with non-epileptic seizures

The aim of the study was to identify possible disturbances of sensorimotor gating and habituation of the eye blink startle response, in patients with non-epileptic seizures (NES). Prepulse inhibition (PPI) of the startle reflex, as an operational measure of sensorimotor gating and habituation was studied in 21 patients with NES and in 22 healthy control subjects. Six NES patients were taking antiepileptic drugs at the time of testing. PPI was significantly impaired in the NES group compared to the control group, with deficits being greater in unmedicated patients. There was a trend for medicated NES patients to show higher PPI than unmedicated patients, but this was not significant. Habituation was intact in both medicated and unmedicated NES patients. It is proposed that deficits of information processing related to sensorimotor gating in patients with NES may be associated with abnormalities within the limbic system-basal ganglia circuitry which has been shown to be the substrate of 'gating' assessed by PPI. It was also found that NES patients had greater psychopathology than the control group when rated by the Traumatic Symptom Checklist (TSC-40). Overall, the anxiety subscale was the only element that was negatively correlated with PPI. It is suggested that anxiety may contribute to impairment of PPI in patients with NES.