Hemispheric influence on autonomic modulation and baroreflex sensitivity
Hilz MJ, Dütsch M, Perrine K, Nelson PK, Rauhut U, and Devinsky O (2001) Hemispheric influence on autonomic modulation and baroreflex sensitivity. Ann Neurol 49:5 575–84.
Abstract: Several studies suggest hemispheric lateralization of autonomic cardiovascular control. There is controversy regarding which hemisphere dominates sympathetic or parasympathetic activity. Hemispheric influences on baroreflex sensitivity (BRS) have not yet been evaluated. To determine hemispheric autonomic control in epilepsy patients, we assessed cardiovascular and baroreflex modulation before and during hemispheric inactivation. For 15 patients with drug-refractory epilepsy, we analyzed autonomic heart rate (HR) and blood pressure (BP) modulation and BRS before and during left and right intracarotid amobarbital procedure (IAP). After Blackman-Tukey spectral analysis, we calculated the low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF: 0.15-0.5 Hz) power of HR and BP as well as BRS as the LF transfer function gain between BP and HR. Right hemispheric inactivation induced a significant decrease of BP and an increase of HF power of HR and BP (p < 0.05). Left inactivation increased HR, BP, and LF power of both signals and decreased BRS by nearly 30% (p < 0.05). The results confirm previous IAP studies showing sympathetic lateralization in the right hemisphere and, moreover, demonstrate parasympathetic predominance and up-regulation of BRS in the left hemisphere. In epilepsy patients, unilateral electrical activity might derange autonomic balance between both hemispheres and contribute to cardiovascular dysregulation and sudden fatalities.
- Assessed heart rate and blood pressure during hemispheric inactivation with Wada testing to investigate lateralization of sympathetic control. BP and HR were analyzed as low-frequency and high-frequency components. In 15 patients with refractory epilepsy, right hemispheric inactivation produced an increase in high-frequency power of both HR and BP, consistent with increased parasympathetic activity. Left inactivation reduced low-frequency power of both signals. These results are consistent with findings of sympathetic lateralization to the right hemisphere and parasympathetic to the left; see Critchley et al.; Zamrini et al.