Lamotrigine add-on therapy for childhood-onset refractory epilepsy: Comparison of efficacy between 3 months and 6 months after initiation

We investigated the effect of lamotrigine (LTG) add-on therapy in 50 patients with childhood-onset refractory epilepsy (25 males and 25 females): 15 with localization-related epilepsy, 33 with generalized epilepsy, and 2 with undetermined epilepsy. Twenty-four patients had experienced a period of West syndrome during their clinical course. Age at the start of LTG therapy ranged from 2 years 6 months to 41 years 2 months: < 16 years in 43 and ≥ 16 years in 7. Seizure frequency was ≥1 per day in 36 patients (72%) and ≥1 per week in 14 (28%). We increased the LTG dosage every two weeks in accordance with usage recommendations. We evaluated efficacy at two points : 3 and 6 months after the start of LTG. At the 6-month point, seizure freedom was achieved in 2 patients (4%), ≥50% seizure reduction in 14 (28%), 25 to 50% seizure reduction in 20 (40%), no effect in 6 (12%), and aggravation in 4 (8%). Only 4 patients (8%) stopped LTG therapy within 6 months due to LTG-related mild skin rash in 2 and suspicion of seizure aggravation in the other 2. In terms of seizure types, seizure freedom or ≥50% seizure reduction was achieved in 29% for epileptic spasms, 32% for tonic seizures, and 29% for partial seizures. A comparison between the 3- and 6-month points revealed that the efficacy level was increased or maintained in 77% of the patients and decreased in 23%. In most cases, the highest level of efficacy appeared within 3 months with doses that were smaller than maintenance doses. Observed CNS-related adverse effects included somnolence in 16 patients, irritability in 14, and sleep disturbance in 11. Positive psychotropic effects in daily activities were seen in 28 patients (56%). These effects appeared regardless of the change in seizure frequency with doses that were smaller than maintenance doses.