Lidocaine and seizures.

Lidocaine has a concentration-dependent effect on seizures. At lower concentrations it has anticonvulsant properties, whereas concentrations above 15 microg/mL frequently result in seizures in laboratory animals and man. Seizures induced by lidocaine in experimental conditions invariably start in the amygdala. Despite the clear focal onset in these experimental models, the seizures emerging in patients given intravenous (i.v.) lidocaine are almost invariably generalized and without any clear signs of focality. Given the prevalence of partial seizures and the frequent use of lidocaine, a higher incidence of partial seizures would be expected with its use. Yet this is clearly not the case. These facts suggest that a history of partial seizures is not a major risk factor for the precipitation of partial seizures in patients treated with intravenous lidocaine.