Abstracts

Rationale: While genetic generalized epilepsy is well-documented in several baboon subspecies (Papio hamadryas papio, anubis, cynocephalus, hamadryas), little is known about seizure occurrence in other nonhuman primates (NHP). We performed a database review for seizures in nonbaboon NHPs housed at the Southwest National Primate Research Center (Texas Biomedical Research Institute, San Antonio, Texas).  Methods: After review of the clinical database (CAMP) and necropsy records, seizures were suspected or witnessed in 44 NHPs between 1993 and 2005.   These included two grivets (Chlorocebus aethiops, both female), 2 marmosets (Callithrix jacchus, one female), 13 rhesus monkeys (Macaca mulatta, 9 female), 27 cynomolgus  monkeys (Macaca fascicularis, 19 female), and two chimpanzees (Pan troglodytes, 1 female).  Convulsive seizures were identified or were suspected due to craniofacial trauma or being found down in the cage. Potential triggers, etiologies and/or co-morbidities were evaluated.  Results: One grivet experienced a ketamine-induced convulsion at age 9 year old, while the other had a single idiopathic seizure at 8 years old. Both marmosets had Langur Herpes Virus infections; their seizures were witnessed only when handled by veterinary staff.  In rhesus monkeys, seizures occurred at a mean age of 6.5 (range 0.5-11) years, excluding 2 animals with only ketamine-induced seizures. Four had at least two seizures; seven had suspected seizures.  Four had terminal seizures related to infection, while the remaining 7 monkeys had idiopathic seizures. The mean age of the first seizure in cynomolgus monkeys was 3 (range 0.5-11) years old, excluding animals without a specified birthdate (N=3), and only ketamine-induced seizures (N=4). All but three cynomolgus monkeys had single witnessed or suspected events, and these three had two events each. Four monkeys had seizures suspected based upon craniofacial trauma, and 2 had seizures associated with handling.  In 17 cases, the seizures were related to infection or anemia. One chimpanzee had three reported convulsions, the first at age 13 years old. She had a diagnosis of idiopathic thrombocytopenic purpura, with cerebral artery stenosis, intracardiac fibrosis and brain hemorrhages at autopsy.  The second had seizures in the setting of meningoencephalitis.  Conclusions: In contrast to baboons housed at the same primate center, captive NHPs overwhelmingly presented with seizures symptomatic for intercurrent illnesses or related to ketamine, although idiopathic seizures may have been most prevalent in rhesus monkeys. This study is limited by its retrospective nature and dependence upon rigorous and complete necropsies. More research is needed into the prevalence of seizures, their electroclinical classification and treatments in non-baboon NHPs, both in captivity and in the wild. Funding: This study was supported by NIH/NINDS (R01 NS047755, R21 NS065431 and R21 NS084198), NIH/NCRR  (P51 RR013986) and NIH/ORIP (P51 OD011133), and conducted in facilities constructed with support from Research Facilities Improvement Grants C06 RR013556, C06 RR014578, and C06 RR015456.