Heart rate variability remains reduced and sympathetic tone elevated after temporal lobe epilepsy surgery

There is evidence of autonomic dysregulation in temporal lobe epilepsy. The structures removed during temporal lobectomy are important centers of central cardiovascular control; therefore surgery may conceivably alter the cardiovascular autonomic function. The effects of temporal lobectomy on autonomic cardiac control are controversial. We investigated the effects of temporal lobectomy on heart rate variability (HRV) in the early and late postoperative periods.

We used 1-h ECG recordings to assess heart rate variability by spectral analysis in 24 consecutive patients who underwent temporal lobectomy due to intractable temporal lobe epilepsy. ECG recordings were performed before and twice (early and late) after surgery. The results were compared with age and sex matched controls.

When compared with controls, all the time and frequency domain indices (SDRR, RMSSD, TP, LF and HF) were significantly lower in the patient group before surgery. Findings were similar in the early and late post-operative periods except that the LF/HF ratio increased in the patient group after the late post-operative period. Within the patient group, compared to pre-operative results, normalized HF was increased in the early post-operative period; however in the late post-operative period, LF/HF ratio was increased.

These findings show that in patients with intractable temporal lobe epilepsy, HRV is decreased globally in both sympathetic and parasympathetic domains. While the total HRV remains reduced throughout the postoperative periods, the LF/HF ratio, i.e., sympathovagal balance is altered, in favor of parasympathetic side early after surgery, but towards the sympathetic side after the first postoperative month.