Lack of heart rate variability during apnea in patients with juvenile myoclonic epilepsy (JME).

PURPOSE

Apneas occurring during sleep may precipitate autonomic instability in epilepsy patients making them susceptible to sudden death (SUDEP). Literature on heart rate variability (HRV) during apnea among patients with juvenile myoclonic epilepsy (JME) is sparse. The aim was to characterize the HRV during the peri-apneic/hypopneic period in patients with JME.

METHODS

Overnight polysomnography of 25 patients with JME (M/F = 14:11; mean age, 21.28 ± 4.34 years) and 25 gender-matched healthy controls (M/F = 11:14; mean age, 23.32 ± 3.68 years) were analyzed. In both patients and controls, the time domain, frequency domain, and nonlinear HRV indices were analyzed for two minutes before and after apnea/hypopnea termination and compared using paired t test (p ≤ 0.05). Additionally, the changes in HRV parameters in the peri-apnea/hypopnea period were compared between the two groups using independent samples t test (p ≤ 0.05).

RESULTS

In controls, there was a significant decrease of mean RR interval (p = 0.029) and a significant increase of standard deviation of RR interval (SDNN; p = 0.046) in the post-apneic/hypopneic period as compared with the pre-apneic/hypopneic period. Analysis using nonlinear measures showed a significant increase in the long-term HRV (p = 0.042) in the post-apnea period, but a comparable short-term HRV (p = 0.266). Conversely, in JME, all the HRV parameters, including nonlinear measures were comparable in the pre- and post-apneic/hypopneic period. Finally, comparison of the changes in HRV parameters in the peri-apnea/hypopnea period in patients with JME and healthy controls showed significant differences in SDNN (p = 0.026) and long-term HRV (p = 0.018).

CONCLUSIONS

This study showed that there was a lack of apnea-mediated HRV changes, including long-term HRV changes in patients with JME. This might suggest an alteration in reflex baroreceptor activation in patients with JME, which might explain the vulnerability for SUDEP in patients with epilepsy.