Abstract
Background: We aimed to evaluate heart rate variability (HRV) changes in insulo-opercular epilepsy (IOE) and after insulo-opercular surgery. Methods: We analyzed 5-min resting HRV of IOE patients before and after surgery. Patients’ SUDEP-7 risk inventory scores were also calculated. Results were compared with age- and sex-matched patients with temporal lobe epilepsy (TLE) and healthy individuals. Results: There were no differences in HRV measurements between IOE, TLE, and healthy control groups (and within each IOE group and TLE group) in preoperative and postoperative periods. In IOE patients, the SUDEP-7 score was positively correlated with pNN50 (percentage of successive RR intervals that differ by more than 50 ms) (p = 0.008) and RMSSD (root mean square of successive RR interval differences) (p = 0.019). We stratified IOE patients into those whose preoperative RMSSD values were below (Group 1a = 7) versus above (Group 1b = 9) a cut-off threshold of 31 ms (median value of a healthy population from a previous study). In group 1a, all HRV values significantly increased after surgery. In group 1b, time-domain parameters significantly decreased postoperatively. Conclusions: Our results suggest that in IOE, HRV may be either decreased in parasympathetic tone or increased globally in both sympathetic and parasympathetic tones. We found no evidence that insulo-opercular surgeries lead to major autonomic dysfunction when a good seizure outcome is reached. The increase in parasympathetic tone observed preoperatively may be of clinical concern, as it was positively correlated with the SUDEP-7 score.
Highlights
The role of the insula in drug-resistant epilepsy has been increasingly recognized with the report of several cases of insular, insulo-opercular or temporo-insular epilepsy successfully treated by resection, radio-frequency thermocoagulation, or laser ablation [1,2,3,4,5,6]
We evaluated the effect of each factor of the Sudden Unexpected Death in Epilepsy (SUDEP)-7 inventory on heart rate variability (HRV); we found that RMSSD and pNN50 values of patients who had at least one bilateral tonic-clonic seizure during the last year were significantly higher than those of patients without bilateral tonic-clonic seizure (p = 0.039 and 0.030 respectively)
In refractory insulo-opercular epilepsy (IOE), our preliminary findings suggest that HRV may be either lower in parasympathetic tone or higher in both parasympathetic and sympathetic tones
Summary
The role of the insula in drug-resistant epilepsy has been increasingly recognized with the report of several cases of insular, insulo-opercular or temporo-insular epilepsy successfully treated by resection, radio-frequency thermocoagulation, or laser ablation [1,2,3,4,5,6]. While most studies suggested the presence of resting HRV alterations in patients with refractory epilepsy [35], especially in patients with focal to bilateral tonic-clonic seizure [36], it is not clear whether HRV changes are associated with the risk of SUDEP [28,37,38,39,40,41]. An international, multicenter, retrospective and nested case-control study provided Class III evidence that, in patients with epilepsy, some measures of HRV are associated with SUDEP [42]. We aimed to evaluate heart rate variability (HRV) changes in insulo-opercular epilepsy (IOE) and after insulo-opercular surgery. In IOE patients, the SUDEP-7 score was positively correlated with pNN50 (percentage of successive RR intervals that differ by more than 50 ms) (p = 0.008) and RMSSD (root mean square of successive RR interval differences) (p = 0.019). The increase in parasympathetic tone observed preoperatively may be of clinical concern, as it was positively correlated with the SUDEP-7 score
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