Abstracts

Rationale: In Down syndrome(DS), a clear relationship between age and type of seizures or epilepsy is known. A bimodal distribution of epilepsy, with early onset (<1y) and late onset (>30y) was also noted by Pueschel et al. in 1991. Now that life expectancy of patients with DS becomes longer, it is clinically relevant to reappraise the characteristics of epilepsy with Down syndrome in relation to age. Methods: We retrospectively investigated 22 patients (male 16, female 6) with DS and epilepsy based upon their medical records. Evaluated were the distribution of age at seizure onset, patients demographics, characteristics of seizures, types of epilepsy, electroencephalographic findings, treatment, and course of the disease. Results: As age at onset of epilepsy showed triphasic distribution, we divided our subjects into three groups; infant onset, juvenile onset, and presenile onset group. Infant onset group consists of 8 patients, whose age at onset ranged from 2 month to 18 month. Seizures of this group were exclusively epileptic spasms with head nodding. In 6 patients, spasms in clusters were described, and 5 patients were diagnosed as West syndrome and treated by ACTH therapy and/or antiepileptic medication. Response to these treatments varied from complete cessation to persistence into later life. Juvenile onset group consists of 11 patients, whose age at onset ranged from 10 years to 24 years. Although most of patients in this group had multiple seizure types, the commonest was astatic seizure which was complicated with various motor components described as tonic, clonic, jerky, versive, or rotatory. Intractability to medication was marked. Furthermore, 3 of 11 patients entailed elements of reflex epilepsy. Their triggering factors were touching hot water by foot, stumbling, or unexpected loud sound. Presenile onset group consists of 3 patients whose age at onset ranged from 41 years to 56 years. Seizure type of 3 patients in this group was generalized tonic-clonic seizure. In the course of disorder, 2 of 3 patients progressively show marked myoclonus on awakening. Around the onset of epilepsy, progressive deterioration of cognition and behavior along with gait disturbance were noticed. Significant diffuse cerebral atrophy with marked enlargement of ventricles was already evident on MRI/CT scan even at the onset of epilepsy. Seizures were refractory to medication. Conclusions: Types of seizures and epilepsy were uniform in each group of infant onset and presenile onset, while elusive and various forms of seizures including reflex pathology were recognized in juvenile onset group. Progressive deterioration of cognition and motor function was seen in epilepsy of presenile onset. It may be clinically significant to provide the patients with DS and their families with appropriate treatment and perspectives based on these characteristics of epilepsy.