Abstracts

Rationale: Absence epilepsies are classified regarding age at onset and regarding clinical course into childhood (≤ 10^th year of life and pyknoleptic course), juvenile (> 10^th year and non-pykoleptic course) and overlap forms. Comparison of clinical outcome data of childhood (CAE) and juvenile absence epilepsy (JAE) may help to further clarify if these represent different entities or constitute parts of a clinical continuum that is based on the same neurobiological syndrome. Methods: 147 patients with absence epilepsy and a follow-up of ≥ 20 years were included. Diagnostic allocations to CAE, JAE and overlap groups were made on the basis of clinical and EEG data as documented in patient charts. Long-term outcome data were either derived from direct patient contact via questionnaire and personal interview (n=86) or, if patients had died or were lost to follow-up, from the exact documentation in patient charts as done for decades by of the authors (DJ). Terminal remission was defined as seizure freedom in the last 5 years before the interview or the last documentation in the charts. Results: Absences were allocated to classical CAE in 48.9% of cases, JAE 28.9%, and overlap syndromes 22.2%. After a mean follow-up of 45 ± 15 years, 75 patients (51%) were in 5-year-terminal remission, 22 of those were tapered off antiepileptic drugs (AED), i.e. 15% of all patients. Remission rates were not different in CAE, JAE and overlap groups. Following multivariate analysis, history of generalised tonic-clonic seizures (GTCS) (OR 7,680; CI95% 1.546-38.159; p = 0.013) and age at investigation (OR 0.958; CI95% 0.935-0.982; p = 0.001) were independent predictors for lacking remission. Stratified for different age groups, 69% of patients aged 40-50 years were not in remission compared to 31% in 60- to 70-year old subjects (p = 0.04). Forty-five patients (31%) withdrew AED at least once, 22 of those (49%) had seizure recurrence within the next 25 years. In half of the patients, seizures recurred within the first year after withdrawal. Predictors for seizure recurrence were history of GTCS (OR 3.994; CI 95% 1.216-13.117; p = 0.022) and epilepsy onset < 10^th year of life (OR 0.275; CI 95% 0.083-0.911; p = 0.035). Conclusions: Almost half a century after onset, more than half of patients with absence epilepsies were seizure free for the last 5 years, one third of those did not take AEDs. Lack of remission was a function of patients' age and occurrence of GTCS. Neither age at epilepsy onset nor the clinical course with pyknoleptic vs. non-pyknoleptic absences was associated with long-term outcome. This important clinical feature biologically rather argues for a syndromatic continuum than for a dichotomisation of absence epilepsies into childhood and juvenile forms. After AED withdrawal, half of patients will have recurrence, half of those within the first 12 months.