Objectives:

We evaluated the factors that are aşociated with the development of resistance to antiepileptic drugs.

Patients and Methods:

We reviewed 173 consecutive patients with epilepsy (89 females, 84 males; mean age 28 years; range 9 to 67 years) with regard to the clinical, electroencephalographic (EEG), and radiologic factors aşociated with the response to antiepileptic drugs. Drug-resistant epilepsy (DRE) was defined as the occurrence of at least a seizure in a month during the past six months despite the use of at least two antiepileptic drugs at an appropriate dose and duration. Well-controlled epilepsy (WCE) was defined as the lack of seizures during the past year. Clinical, EEG and radiologic findings were compared.

Results:

Ninety patients (52%) had DRE. Eighty-three patients (48%) developed no resistance to a n t i e p i l e p t i c drugs, of which 42.2% had WCE. The overall WCE rate was 20.2%. The patients with DRE manifested significantly higher rates of remote symptomatic epilepsy (p=0.020), mental retardation (p=0.000) and motor deficits (p=0.006) on neurologic examination, seizure frequency (p=0.000), and early age of seizure onset (p=0.024). Univariate analysis showed the presence of a positive family history for epilepsy, remote symptomatic epilepsy, disease duration longer than 10 years, and EEG abnormalities as significant risk factors for DE development. Logistic regreşion showed the presence of mental retardation and high seizure frequency as independent risk variables.

Conclusion:

Epileptic patients with mental retardation and high seizure frequency present higher risks for DRE.

Keywords: Anticonvulsants/therapeutic use/adverse eff e c t s, drug resistance, electroencephalography, epilepsy/drug therapy, prognosis, regreşion analysis, treatment failure