Abstracts

Spontaneous seizures have been reported in several baboon subspecies housed at the Southwest Foundation for Biomedical Research (SFBR), including [italic]P.h. anubis[/italic] as well as[italic] cynocephalus/anubis [/italic]and other hybrids. This study classified clinical and electroencephalographic (EEG) phenotypes in these subspecies based upon interictal and ictal findings, as well as photosensitivity, by scalp EEG. One hundred baboons underwent one-hour EEG studies with photic stimulation (PS), 49 with previously witnessed seizures and 51 without. The animals were classified according to these electroclinical phenotypes: presence or absence of interictal epileptic discharges (IEDs), seizures and photoparoxysmal or photoconvulsive responses. Effects of age, gender, and species on EEG phenotypes were also examined. Six discrete electroclinical phenotypes were identified. Generalized IEDs of 2-3 Hz, 4-6 Hz, and or 6-7 Hz were identified in 67 baboons. Epileptic seizures were recorded in 40 animals, including myoclonic and generalized tonic-clonic seizures. Thirty-three animals were photosensitive. Although the prevalence of IEDs and seizures were similar in seizure and asymptomatic animals, photosensitivity was more prevalent in the seizure animals (p=0.001). [italic]P.h. anubis/cynocephalus[/italic] hybrids were more likely to be photosensitive than [italic]P.h. anubis[/italic] (p=0.004)[italic].[/italic] The P. hamadryas subspecies have a generalized, photosensitive epilepsy. The association of photosensitivity with clinically evident seizures suggests a lower seizure threshold or greater propensity for ictal propagation in seizure animals. The reliable characterization of distinct epileptic phenotypes in this pedigreed colony is critical to the success of future genetic analyses to identify genetic factors underlying their epilepsy. (Supported by the South Texas Veterans Health Care System (VISN 17) and the National Institutes of Health (1 R01 NS047755-01). This investigation was supported in part by facilities constructed with support from Research Facilities Improvement Program Grants C06 RR15456 and C06 RR014578 from the National Center for Research Resources, National Institutes of Health.)