What is the clinical evidence from this study?

Study design: Observational. Population: Temporal Lobe Epilepsy (n=52). Intervention: Left temporal lobe epilepsy (L-TLE) vs. Right temporal lobe epilepsy (R-TLE). Primary outcome: Low frequency/high-frequency (LF/HF) ratio (p=<0.0001).

August 14, 2020Open Access

Interictal Heart Rate Variability Analysis Reveals Lateralization of Cardiac Autonomic Control in Temporal Lobe Epilepsy

Q: What are the key findings of this study?

Left temporal lobe epilepsy is associated with increased cardiac vagal tone compared to right temporal lobe epilepsy, evidenced by a significantly decreased LF/HF ratio (p < 0.0001) and increased high-frequency values.

FDFedele DonoUniversity of Chieti-Pescara GEGiacomo EvangelistaUniversity of Chieti-Pescara VFValério FrazziniCentre National de la Recherche Scientifique

Key Result

Left temporal lobe epilepsy is associated with increased cardiac vagal tone compared to right temporal lobe epilepsy, evidenced by a significantly decreased LF/HF ratio (p < 0.0001) and increased high-frequency values.

Study Design

Type

Observational (n=52)

Multicenter

Yes

Structured PICO

Does the lateralization of temporal lobe epilepsy (left vs. right) affect cardiac autonomic control as measured by heart rate variability?

Population

52 adult patients (mean age 42.9 years, 53.8% female) with temporal lobe epilepsy and clear lateralization of interictal discharges underwent short-term EKG recordings to assess heart rate variability.

Exposure

Left Temporal Lobe Epilepsy (L-TLE) focus

Comparator

Right Temporal Lobe Epilepsy (R-TLE) focus

Outcome

Heart rate variability (HRV) parameters (time domain, frequency domain, and non-linear analysis) derived from a 20-minute resting state EKGsurrogate

Left temporal lobe epilepsy is associated with increased cardiac vagal tone compared to right temporal lobe epilepsy, suggesting lateralized cardiac autonomic control and potentially lower susceptibility to cardiac dysfunctions.

Main Result

p-value: p=<0.0001

Limitations

Small number of patients in the subgroup analysis
Not able to investigate the impact of every specific anti-seizure drug (ASD) in the modification of HRV features
Lack of long-term EKG monitoring to investigate whether R-TLE patients show a higher risk of developing arrhythmias

Abstract

Purpose: The temporal lobe, a critical hub for cognition, also plays a central role in the regulation of autonomic cardiovascular functions. Lesions in this area are usually associated with abnormalities in the regulation of heart rate (HR) and blood pressure (BP). The spectral analysis of the heart rate variability (HRV) is useful to evaluate the impairment of the autonomic control of cardiovascular functions. This study aims at comparing HRV changes occurring in two groups of patients suffering from Temporal Lobe Epilepsy (TLE). To that aim, we evaluated patients differentiated by the right or left location of the epileptic foci. Materials and Methods: Fifty-two adult patients with a diagnosis of TLE were enrolled. Each patient underwent a 20-minute EEG + EKG recording in resting state. According to the localization of epileptic focus, patients were divided into two subgroups: right TLE (R-TLE) and left TLE (L-TLE). HRV parameters were calculated with a short-lasting analysis of EKG recordings. Time domain-related, frequency domain-related, as well as non-linear analysis parameters, were compared between the two groups. Results: Compared to the R-TLE group, L-TLE subjects showed a statistically significant decrease in low frequency (LF) (p<0.01) and low frequency/high-frequency ratio (LF/HF) (p<0.001) as well as increased HF values (p<0.01), parameters indicative of the presence of an increased vagal tone. In a subgroup analysis that took into account the seizure types, responses to antiepileptic drugs, seizure frequencies, and etiology, the LF/HF ratio was significantly lower in all the L-TLE subjects. Conclusions: The main finding of the study is that, compared to R-TLE, L-TLE is associated with increased vagal tone. These results indicate that patients with TLE exhibit a lateralized cardiac autonomic control. L-TLE patients may have a lower risk of developing cardiac dysfunctions and less susceptible to develop SUDEP.

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