Rationale:
Sudden unexpected death in epilepsy (SUDEP) has been observed in a baboon colony housed at the Southwest National Primate Research Center in San Antonio, Texas. We compared clinical/semiological differences of generalized tonic-clonic seizures (GTCS) between two SUDEP baboons and four baboons that were euthanized due to persistent seizure activity.
Method:
Video-recordings of 42 spontaneous, unprovoked GTCS occurring in an observation period of 10 days to 10 weeks in 6 baboons undergoing baseline evaluations for VNS and RNS Therapy trials, were reviewed by two investigators. Four of the baboons were euthanized and 2 died of SUDEP. Semiological features, including seizure duration, postictal immobility (PI), time to recovery of recumbency and the presence or absence of postictal myoclonus (asynchronous myoclonus affecting the head, trunk and extremities) were evaluated. Adequate postictal video sampling through recumbency was available for 20 GTCS in the non-SUDEP cases, and for 13 GTCS in the SUDEP baboons.
Results:
The results are summarized by the attached table. The non-SUDEP cases were euthanized at the same age or older than the SUDEP animals. SUDEP animals had a higher GTCS frequency (3 vs 1.4), more prolonged PI (106 vs 37 sec), yet a similar duration of tonic-clonic motor activity and time to recumbency, than the non-SUDEP cases. Postictal myoclonus was observed in all of the euthanized baboons (17 of 20 GTCS, 85%), but only in one of two SUDEP animals (2 of 11, 18%) (two-tailed Fisher Exact Test, P< 0.001).
Conclusion:
This preliminary comparison of semiological features of spontaneous GTCS in epileptic baboons, demonstrates some risk factors identified in human SUDEP, such as GTCS frequency and PI duration, to be potential biomarkers in baboons as well. Postictal myoclonus, on the other hand, appears to be a more specific features of postictal recovery in the baboon, and may reduce SUDEP risk.
Funding:
:UT Brain, LivaNova
FIGURES
Figure 1