Abstracts

Rationale: Previously retrospective studies have described the frequency of abnormal EEG findings in autistic or pervasive developmental disorder-not otherwise specified (PDD-NOS) populations studied with routine or prolonged 24 hour EEG. Although it is known that epilepsy occurs in 10-30%, occult epileptiform EEG findings remain even more frequent in this population ranging between 30-80%. One prior study by this author of 889 autistic patients who had 24 hour EEG studies had abnormal frequencies of 61%.This study performed by that same author now asks how many perspective new cases at initial screening will have an abnormal EEG in patients under 4 years of age. Methods: Patients identified by DSM IVTR criteria of meeting either PDD-NOS or autism (12 autism; 6 PDD) were given the clinical recommendation to obtain a 24 hour ambulatory digital EEG or video-telemetry study to assess for the presence of occult EEG epileptiform activity as part of their neurological assessment. Those patients sequentially having been tested who are under the age of 4 were kept as an ongoing database for clinical purposes. Patients are excluded from this analysis if they have known structural lesions on MRI, focally abnormal neurological examinations, or had known metabolic or genetic disorders. Only patients without known clinical seizures are included in this data analysis. Results: Sequentially enrolled patients who met criteria showed 18 children studied between February 2007 and June 1, 2007 with 24 hour digital EEG(13 were male, 5 female). There were abnormal EEG results in 10/18 patients (55.5%). Abnormal temporal-central region rhythmic sharp slowing seen only in sleep was seen in all positive patients. This was localized to left hemisphere in 4 patients, bilaterally but independently in 8 patients. Also in 5 patients by the 3rd or 4th sleep cycle there were isolated bursts of generalized polyspike-wave activity seen. Although males outnumbered females, 3/5 girls had abnormal EEG findings, while 7/13 males had EEG abnormalities. Males accounted for 3/5 patients with polyspikes, females were 2/5. Clinical regression occurred in only 2/18 patients, but both had abnormal EEG findings. Patients with autism diagnosis had 5/12(41.6%) with abnormal sleep EEG results, while the PDD-NOS population had 5/6(83.3%)abnormal.Conclusions: This prospective data collection of sequential EEG findings in populations of PDD-NOs and Autism show in total a very high percentage of EEG abnormalities similar to larger prior retrospective populations in a broader age range. This study again shows a temporal-central sharp wave localization with some secondary generalized polyspikes. There is also higher percentages of EEG abnormalities so far in the PDD-NOS population than the autism group.