INTERICTAL CARDIOVASCULAR AUTONOMIC RESPONSES IN PATIENTS WITH EPILEPSY

Purpose: To evaluate the interictal autonomic nervous system function in 84 patients with epilepsy: 37 with newly diagnosed, previously untr eated epilepsy, and 47 patients receiving long-term carbamazepine (CBZ ), phenytoin (PHT), or valproate (VPA) monotherapy, or CBZ plus PHT, o r CBZ plus VPA for their seizure disorder. Methods: We assessed autono mic control of the cardiovascular regulatory system by standardized ca rdiovascular reflex tests measuring changes in heart rate (HR) and blo od pressure (BP) at rest and after certain stimuli. Results: The HR an d BP responses were similar to those of control subjects in patients w ith newly diagnosed epilepsy. However, HR variation during normal brea thing and maximum systolic BP increase in isometric work were diminish ed in patients, who had been treated with antiepileptic drugs (AEDs) f or epilepsy for a long time. Diminished HR responses to the Valsalva m aneuver were noted in patients receiving CBZ as monotherapy and during deep breathing in patients receiving CBZ combined with PHT or VPA. Fu rthermore, patients receiving CBZ had diminished BP responses in isome tric work. When analyzed in relation to epilepsy type, suppressed HR r esponses in normal breathing were associated with primary generalized epilepsy (PGE), whereas diminished BP responses in isometric work were associated with partial epilepsy. Two patients with recently diagnose d partial epilepsy and 1 patient receiving long-term CBZ monotherapy f or partial epilepsy had two abnormal cardiovascular response test resu lts. Conclusions: Our results show that cardiovascular responses media ted by both the parasympathetic and sympathetic nervous system are dim inished in patients with epilepsy. However, the changes appear to be c linically significant in only a few of them and appear to be associate d with CBZ medication. Further studies are needed to detect the underl ying complex interactions and clinical significance of autonomic nervo us system dysfunction in patients with epilepsy.