SPONTANEOUS OSCILLATIONS IN CEREBRAL BLOOD-FLOW VELOCITIES IN MIDDLE CEREBRAL-ARTERIES IN CONTROL SUBJECTS AND PATIENTS WITH EPILEPSY

Background and Purpose Cardiac arrhythmias mediated by the sympathetic nervous system have been implicated in sudden, unexplained deaths in patients with epilepsy. Cerebral blood flow velocities (CBFV) as measu red by transcranial Doppler are characterized by slow spontaneous osci llations in part attributed to changes in sympathetic activity (M wave s, 3 to 9 cycles per minute) and to discharges of monoaminergic neuron s in the brain stem (B waves, 0.5 to 2 cycles per minute). This study was designed to compare spontaneous fluctuations of CBFV in patients w ith epilepsy with those in normal control subjects. Methods Simultaneo us registrations of scalp electroencephalograms, with electrodes place d according to the 10-20 System, and transcranial Doppler recordings o f both middle cerebral arteries were performed in 27 patients (9 with primary generalized epilepsy, 18 with focal epilepsy). Data analysis o f CBFV was based on the envelope curves of the Doppler spectrum. A fas t Fourier transformation over the 20-minute CBFV curve was performed, and the amplitudes of B and M waves were calculated and compared with those in 20 normal, age-matched control subjects. Results While the am plitudes of the B waves in both groups were similar, patients with epi lepsy showed significantly in creased M waves. Patients with focal epi lepsy did not present asymmetries between the normal hemisphere and th e side of the epileptic focus with respect to both M and B waves. Conc lusions Enhanced M waves in epileptic patients may reflect increased s ympathetic activity even in the absence of seizures. This study provid es further evidence for an autonomic dysfunction as a possible mechani sm for sudden unexplained death in patients with epilepsy.