A Real World Study on the Efficacy and Safety of Lacosamide as Add-on Therapy for Focal-onset Epilepsy

Inclusion Criteria: * Before the start of the trial, to obtain the informed consent approved by the ethics committee voluntarily signed by each subject. For underage subjects, the informed consent jointly signed by the subjects themselves (≥10 years ) and their parents or legal guardian (in which the underage needs the signature with their parents or legal guardian, and the underage is defined as the subject under 18 years of age) ; * Male and female, between the ages of 4 and 75 years; * Diagnostic criteria of focal onset seizures (with or without focal to bilateral tonic clonic seizures) was based on the 2017 Classification of Epileptic Seizures from the International League Against Epilepsy (ILAE); * In the 4 weeks before enrollment and during the baseline period, patients have been on only one stable dosage of antiepileptic drug and suitable for lacosamide add-on therapy according to their investigators criteria; * During the 8-week retrospective baseline period, patients must have had at least 4 focal onset seizures per 28 days on average. Exclusion Criteria: * Patients had received previous lacosamide treatment; * Female patients are pregnant, breast-feeding, and will not use contraception during the trial; * Patients had known allergies to lacosamide or any ingredients of the drug, or with allergic constitution; * Patients have a history of status epilepticus in the last 12 months; * History of chronic alcohol or drug abuse; 6.history of suicide attempt or suicidal ideation in the past 6 months; * Current use of Antidepressants, anxiolytics or antipsychotics; * Patients suffer from progressive diseases that affect the patient's brain and its function; * Sychogenic nonepileptic seizures; * Patients suffer from serious lung and blood system diseases, malignant tumor, lower immune function and psychosis; * Patients wil receive ketogenic diet therapy, or Four weeks before entering the screening period, patients used other drugs that may affect the absorption, distribution, metabolism and excretion of lacosamide, such as antipsychotics, monoamine oxidase inhibitors, barbiturates (except for combined use as anticonvulsant therapy), narcotic analgesics. * Patients Had epilepsy brain surgery, or will undergo epilepsy surgery in the next four months. * Investigators considered Patients as unsuitable for this trial.