A STUDY OF VISUAL EVOKED POTENTIAL CHANGES IN FOLLICULAR AND LUTEAL PHASES OF MENSTRUAL CYCLE

Abstract

Background Visual evoked potential (VEP) is a   convenient and non-invasive tool for assessing the functional integrity of visual system. Apart from age and gender visual evoked potential can also be influenced by the varying levels of ovarian hormones in the different phases of menstrual cycle. Aim of the study To observe the changes of visual evoked          potentials in the follicular phase and luteal phase of the           menstrual cycle in healthy young women. Materials Methods Study group of thirty females between the age group of 18 to 22 years having regular menstrual cycle of 28 days were included in the study. The females with irregular menstrual cycles,           Polycystic ovarian diseases (PCOD), refractive error and who were on hormonal pills were excluded from the study. Pattern reversal VEP was recorded by using Neuroperfect EMG 2000 system with installed software during follicular (8 14days) and luteal phases (23-28days) of the same menstrual cycle. Peak P100, N75 and N145 latencies were recorded. Results                  Statistical analysis was done by using paired student test. In the present study, mean P100 wave latency (p0.0001) and mean N145 wave latency (p0.05) were significantly reduced in                       follicular phase when compared to luteal phase of menstrual cycle. Mean N75 wave latency was decreased in follicular phase when compared to luteal phase but statistically insignificant (p0.05).Conclusion The neuronal conduction in the optic             pathway was modulated by the fluctuating levels of oestrogen and progesterone in the follicular and luteal phases of menstrual cycle. From this study it was found that, In females during          follicular phase of menstrual cycle, PRVEP latencies were  shortened and it may due to the facilitating effect of estrogen on neural transmission. Estrogen increases the conduction velocity of optic nerve pathway by influencing the remodelling of GABAergic neurons. Prolonged VEP latencies during luteal phase might be due to the antagonising action of progesterone on oestrogen and by increasing the brain threshold for              generation of nerve impulse.