[Misdiagnosis and factors associated with drug resistance in idiopathic generalized epilepsy]

Objective: To investigate and analyze the profiles of misdiagnosis and risk factors for drug resistance in patients with idiopathic generalized epilepsy (IGE). Methods: The data of 188 patients with IGE treated at the Epilepsy Center of the Second Affiliated Hospital of Zhejiang University School of Medicine from January 2014 to December 2022, who met the latest diagnostic criteria of the International League Against Epilepsy (ILAE) were retrospectively collected. All the patients were followed up for over 12 months. The rates of misdiagnosis and inappropriate medication use were determined. The differences in demographic, clinical and electroencephalography (EEG) characteristics between the drug-resistant and drug-responsive groups were compared. Multivariate logistic regression analysis was employed to identify risk factors for drug resistance in patients with IGE. Results: Among the 188 patients with IGE, there were 105 males and 83 females, with a median onset age of 14 years (Interquartile range: 12.0-16.0). Thirty-five patients (18.6%) were misdiagnosed with focal epilepsy, and 33 (28.0%) patients with juvenile absence or myoclonic epilepsy had ever received inappropriate medication. With a median follow-up duration of 3.8 years (1.4, 6.8), 25 patients(15.4%) were diagnosed with drug-resistant epilepsy at the end of follow-up. Risk factors associated with drug resistance included catamenial cycle-related epilepsy (OR=26.93, 95%CI: 3.44-211.04), presence of≥2 seizure types (OR=5.20, 95%CI: 1.15-23.46), coexistence of generalized and focal discharges on interictal EEG (OR=39.25, 95%CI: 1.76-873.31), and spike and slow wave complex burden grade ≥3 (OR=6.26, 95%CI: 1.59-24.64). Conclusions: Misdiagnosis and inappropriate medication use in IGE are not uncommon. Approximately 15% of patients develop drug-resistant epilepsy, while catamenial cycle-related epilepsy, multiple seizure types, and interictal epileptiform discharge characteristics may be risk factors for drug resistance.