Patients were first observed for a 4-week baseline period, which required no medication adjustments and a seizure frequency of greater than or equal to 2 times per 4-week . After the baseline observation period, if the patients met the criteria for enrolment and there were no contraindications, zonisamide was added as an additional therapeutic drug.Clinical data were collected before the initiation of treatment, at 1 month, 3 months and 6 months after taking zonisamide respectively, with regular review of blood tests and urinary ultrasound, and imaging and electrophysiological examinations according to the clinical needs of the patient's actual condition.

1. Before starting zonisamide treatment, a 4-week baseline observation period is required, which needs to meet the following criteria: no medication adjustment and at least 2 times of seizure per 4 weeks.
2. If patients meet the criteria for the baseline period, after the baseline observation period, they are required to complete the blood routine, urine routine, renal function, liver function, ultrasound of the urinary tract, and scale completion (including the QOLIE-31 quality of life scale, GAD-7, C-NDDI-E, Pittsburgh sleep quality, and the Epworth Sleepiness Scale (ESS)) prior to initiating treatment. If the patient still meets the inclusion criteria, zonisamide may be added to the treatment, and the patient's seizures and medications prior to zonisamide treatment will be recorded.
3. Outpatient follow-up and scale filling were carried out in the 1st, 3rd and 6th month of zonisamide treatment, and blood tests were reviewed in the first/third (according to the clinical situation) and sixth month, and urological ultrasound was reviewed in the sixth month, and imaging and electrophysiological examinations were carried out according to the clinical need in the light of the actual situation of the patients, and the changes of seizures and side effects during the medication period were recorded in detail.

Inclusion Criteria:

1. Meet the International League Against Epilepsy 2017 diagnostic criteria for epilepsy; and the patient's seizures can be clearly classified as partial seizures according to the seizure classification proposed by the International League Against Epilepsy, including simple partial seizures, complex partial seizures, and secondary generalised seizures;
2. Be greater than or equal to 2 years of age;
3. Have been on antiepileptic medication, and during the 4-week period of the retrospective baseline period, the patient did not medication adjustments and had at least 2 seizures greater than or equal to 2 seizures per 4-week period;
4. The patient demonstrated good compliance and was able to complete the scale assessment and record the epilepsy diary on his/her own or with the assistance of a parent;
5. The informed consent form was signed and dated by the patient or a parent or legal guardian.

Exclusion Criteria:

1. Patients who are allergic to zonisamide ;
2. CT or MRI suggestive of progressive intracranial tumours;
3. Severe mental retardation or severe psychiatric disorders;
4. Patients suffering from serious underlying diseases that can affect brain function, such as heart disease, liver disease, renal disease, haematological disorders, malignant tumours, and patients who are immunocompromised;
5. Ultrasound suggestive of renal stones 6) Pregnant or breastfeeding

As this is a real-world study,we prospectively enrolled patients with focal epilepsy who are suitable for taking zonisamide as an add-on medication