Abstracts

Changes in cardiovascular tone is noted in Temporal Lobe Epilepsy patients. The dysfunction of sympathetic and/or parasympathetic activity is a potential cause of sudden unexpected death in epileptic patients . The present study was aimed at finding out the effect of epilepsy surgery on autonomic functions in intractable epileptic patients. 27 patients of mean age 27.3 +/-10.8 who were intractable for over two years or more and selected for surgery. They underwent a battery of tests that assessed their autonomic reactivity. Baseline autonomic activity (tone) was also measured by Heart rate variability (HRV) analysis. The patients underwent the same tests again 3 months later. The indices of Deep Breathing test (DBT)- before and after surgery, i.e. E:I ratio (1.27 +/-0.13 vs. 1.4 +/- 0.1) and delta changes in heart rate (20.5 +/- 8.75 vs. 23.0 +/- 1.3) show an increase, though not significant, in parasympathetic reactivity after surgery. No changes were observed in the Valsalva Maneuver or in the 30:15 ratio in the Head Up Tilt test (HUT). The rise in Diastolic BP in Hand Grip Test (28.0 +/- 7.0 vs. 16.0 +/- 10.4) was significantly less after surgery. The reactivity tests show that there may be a trend towards increase in parasympathetic and decrease in sympathetic reactivity after surgery. Among the parameters in the HRV which denote the autonomic tone, most of the time domain measures between pre and post surgery patients, i.e. SENN (1.4 +/- 0.4 vs. 1.6 +/- 1.2), SDSD (20.3 +/- 8.8 vs. 25 +/- 21.6), RMSSD (20.3 +/- 8.8 vs. 25 +/- 21.6), NN50 (0.55 +/- 3.3 vs. 5 +/- 26.1), pNN50 (0.4 +/- 0.1 vs. 0.51 +/- 0.2) showed an increase in values post surgery, denoting an increase in parasympathetic tone. In the frequency domain measures, LF (nu) and % LF denote the sympathetic tone; LF (nu) ( (45.5 +/- 19.6 vs. 34 +/- 14.6) showed a significant decrease after surgery and %LF (20.8 +/- 13.1 vs. 22.2 +/- 8.8) was also reduced, thereby showing a decrease in sympathetic tone. HF (nu) and % HF denote parasympathetic tone and HF (nu) showed an increase (48.6 +/- 21.5 vs. 57.2 +/- 22.8), while %HF (36.5 +/- 21.8 vs. 43.2 +/- 16.9) showed a significant increase after surgery, denoting an increase in parasympathetic tone after surgery. The LF/HF ratios, which show the sympathovagal balance, also showed a significant decrease (1.1 +/- 1.1 vs. 0.63 +/- 0.4) after surgery.Two patients who had abnormal tone before surgery showed normalization after surgery. The present study shows that the autonomic functions are modulated after surgery; exhibiting a decrease in sympathetic reactivity and increase in parasympathetic reactivity. An increase in parasympathetic tone and a significant decrease in sympathetic tone is also noted after surgery.