Abstracts

Rationale: Seizures and EEG abnormalities in children with Fragile X (FX) syndrome have not been well characterized. The purpose of this study is to describe the prevalence and characteristics of seizures and EEG abnormalities in a population of children, both male and female, with known FX. Methods: Charts of patients with genetically diagnosed FX and receiving care in a specialized clinic in a tertiary care hospital were reviewed. Patients who had at least one EEG recorded for any reason were included in the study. Patient age, sex, indication for EEG, and EEG findings were recorded. Additionally, data were collected regarding epilepsy diagnosis, seizure characteristics, antiepileptic drug (AED) use and clinical imaging. Results: A total of 135 charts were reviewed. Eighteen patients (13.3%, 1 female) had at least one EEG recorded. The mean patient age at EEG recorded was 6.0 years (standard deviation 3.8 years). Fourteen patients underwent outpatient EEG, three patients underwent EEG in the context of a sleep study, and one patient underwent inpatient long-term video-EEG. Indications for EEG included a history suggestive of seizure (n=12), global developmental delay (n=1), atypical febrile seizure (n=1), and follow-up of known epilepsy (n=1). Among those who had a history suggestive of seizure, six patients had a history of undiagnosed staring episodes. The three children who underwent sleep study were evaluated by polysomnography for complaint of excessive snoring. On review of EEG data, 13 patients (72%) had abnormal findings. Eleven patients had generalized EEG findings and one patient had findings localized to the temporal lobe. The most common EEG finding was slowing of the posterior dominant rhythm for age, seen in seven patients (53%). Other findings included epileptiform discharges (n=6). Five patients (3.7% of all patients in the studied population) were diagnosed with epilepsy on the basis of their clinical and EEG findings. There were insufficient females in our series to compare differences in seizures according to gender. Five patients in the series had a history of AED usage for seizure control. AEDs used in the seizure population included oxcarbazepine (n=1), levetiracetam (n=2), lamotrigine (n=1), clonazepam (n=1), valproate (n=1), and lacosamide (n=1). Of these five, four patients were seizure-free at last follow-up. Ten patients had undergone MRI of the brain. MRI abnormalities included thinning of the corpus callosum and white matter reduction (n=1, nonepileptic), dysplastic change of the amygdala and hippocampus (n=1, with epilepsy), and mesial temporal sclerosis (n=1, with epilepsy). Conclusions: The prevalence of seizures in children with FX is 3.7% in our small series, and staring spells are the most common clinical symptoms prompting an EEG. Slowing of posterior dominant rhythm was seen in many of the evaluated patients. These data suggest that patients with FX may have characteristic patterns in clinical seizure presentation and electrographic abnormalities that warrant further investigation.