Outcome of epilepsy surgery correlates with sympathetic modulation and neuroimaging of the heart
Hilz MJ, Platsch G, Druschky K, Pauli E, Kuwert T, Stefan H, Neundörfer B, and Druschky A (2003) Outcome of epilepsy surgery correlates with sympathetic modulation and neuroimaging of the heart. J Neurol Sci 216:1 153–62.
Abstract: Temporal lobe epilepsy (TLE) is frequently associated with sympathetic over-activity. Single photon emission computed tomography (SPECT) with 123iodine-meta-iodobenzylguanidine (MIBG), a norepinephrine analogue, showed reduced tracer uptake in cardiac sympathetic nerve endings, indicating myocardial catecholamine disturbance. We investigated whether outcome of epilepsy surgery correlates with cardiac autonomic function in TLE patients. We studied 16 TLE patients before and after epilepsy surgery. We recorded heart rate (HR) and determined sympathetic and parasympathetic cardiac modulation as powers of low (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.5 Hz) heart rate oscillations. The LF/HF-ratio was calculated as index of sympathovagal balance. Cardiac MIBG uptake was assessed with MIBG-SPECT and compared to control data. After surgery, eight patients were seizure-free and eight had persistent seizures. Sympathetic LF-power and LF/HF-ratio were higher in patients who had persistent seizures than in patients who became seizure-free. After surgery, both parameters decreased in seizure-free patients but increased in patients with persistent seizures. MIBG uptake was lower in patients than controls and even lower in the patient subgroup who had persistent seizures. In this subgroup, MIBG uptake further decreased after surgery (P<0.05). Sympathetic cardiac modulation decreased in TLE patients after successful surgery, but further increased if seizures persisted. Reduction of cardiac MIBG uptake progressed after surgery in patients with persistent seizures. Interference of epileptogenic discharges with autonomic neuronal transmission might account for sympathetic cardiac over-stimulation and reduced MIBG uptake. Both findings are possible risk factors for sudden unexplained death and might be relevant for risk stratification in epilepsy patients.
Keywords: Epilepsy surgery; Heart rate variability; Cardiac autonomic modulation; Cardiac [123I]-MIBG-SPECT; Sudden unexplained death in epilepsy
- Using SPECT imaging of an emitting norepinephrine analog the authors monitored catecholamine signaling to the heart before and after epilepsy surgery. The standard low- and high-frequency division of frequency-domain signal power was used. 8 patients became seizure-free after surgery and these had lower sympathetic activation as indicated by low-frequency power. Patients with persistent seizures showed reduced uptake of the catecholamine tracer, consistent with ongoing excessive sympathetic stimulation.