Abstracts

RATIONALE: Like Papio hamadryas papio, an animal model for photosensitive epilepsy, baboons of the subspecies P.h. anubis and cynocephalus are known to have spontaneous seizures. The aim was to characterize their epilepsy.
METHODS: Eight baboons (6 F/2M, ages 7 months to 20 years old), witnessed to have spontaneous seizures at their colony, were submitted to electroencephalography (EEG) using surface electrodes. Six baboons required sedation with ketamine (5-10 mg/kg) for placement in and out of a primate chair. The studies were 60-90 minutes long, including two trials of photic stimulation (3-50 Hz) 30 minutes apart. Two studies were performed in all sedated baboons, with varying doses of ketamine.
RESULTS: Interictally, generalized discharges of 3-5 Hz frequency were recorded in all baboons. Spontaneous myoclonic seizures involving face, arms, and legs were witnessed in 6 baboons and were enhanced by the second dose of ketamine in four. Myoclonic seizures were provoked by photic stimulation in 6 baboons, in five at 25 Hz. Photoparoxysmal changes were noted in 3 baboons at 3-6 Hz stimulus frequency. Generalized tonic-clonic seizures were only noted in two baboons, occurring spontaneously in one and with photic stimulation at 3 Hz in another. The discharge rate and photosensitivity were decreased at higher ketamine doses.
CONCLUSIONS: Initial data recorded in spontaneously seizing baboons suggest that the epilepsy of Papio h. anubis, cynocephalus and their hybrid is primary generalized and photosensitive. Seizures were induced by both photic stimulation and ketamine, however, more needs to be learned about the optimal parameters for both stimuli to interpret similar studies in nonepileptic baboons.