Effect of hypobaric hypoxia on visual evoked potential at high altitude.

The effect of hypobaric hypoxia on visual evoked potential (VEP) was studied in 27 male volunteers at sea level (SL), during the 1st and 3rd weeks of their stay at high altitude (HA) of 3,500 m and in the 1st week of their return to the sea level (RSL). Exposure to high altitude (HA) led to significant changes in VEP. The N1 wave latency of both right and left eye was significantly increased (P<0.05) during 3rd week of stay at the altitude which persisted even after the return to the sea level. The latency of P1 wave of both right and left eye was higher in 3rd week at high altitude but not significant statistically. But the delay in P1 latency persisted in 1st week of their return to sea level which was significant (p<0.05) statistically as compared to sea level. The latency of N2 wave was significantly decreased (P<0.05) during the 1st week of stay at HA and returned back to basal value in the 3rd week of stay at HA in both right and left eye. However, the changes observed in NPN complex in terms of wave latencies were within the physiological limits. The amplitude of wave N1-P1 of both the right and left eye did not show any change. The changes observed reflect the process of acclimatisation to 3500m high altitude.

Effect of high altitude (HA) on event related brain potentials.

Event Related brain potentials (ERPs) were recorded in 15 subjects using standard auditory odd ball paradigm, in which subjects were presented a sequence of two distinguishable sound stimuli of that occurred frequently (frequently (frequent stimulus-non target) and the other infrequently (rare stimulus-target). These recordings were made at sea level (SL) and then the subjects were air lifted to 3500 m altitude (HA), where they stayed for 3 weeks. Their ERPs were recorded during the first and third week of stay at HA and on return to sea level (RSL). Data indicated impairment in cognitive function as a result of exposure to HA as depicted by increase in the latency of P3 which was significant during the 1st week of stay at HA compared to sea level. The P3 wave latency during the 3rd week of stay at HA showed an increase compared to SL but was not statistically significant. From the results it may be concluded that high altitude hypoxia induced slow processing of stimulus evaluation, may be responsible for increase in P3 latency. The difference in the latent period of P3 waves during the first and third week of stay at HA may be due to continuous stay at HA which might lead to the time dependent adaptive processes occurring with increasing duration of exposure to HA which may induce learning effects.

Effect of Sahaja yoga practice on seizure control & EEG changes in patients of epilepsy.

The effect of Sahaja yoga meditation on seizure control and electroencephalographic alterations was assessed in 32 patients of idiopathic epilepsy. The subjects were randomly divided into 3 groups. Group I (n = 10) practised Sahaja yoga for 6 months, Group II (n = 10) practised exercises mimicking Sahaja yoga for 6 months and Group III (n = 12) served as the epileptic control group. Group I subjects reported a 62 per cent decrease in seizure frequency at 3 months and a further decrease of 86 per cent at 6 months of intervention. Power spectral analysis of EEG showed a shift in frequency from 0-8 Hz towards 8-20 Hz. The ratios of EEG powers in delta (D), theta (T), alpha (A) and beta (B) bands i.e., A/D, A/D + T, A/T and A + B/D + T were increased. Per cent D power decreased and per cent A increased. No significant changes in any of the parameters were found in Groups II and III, indicating that Sahaja yoga practice brings about seizure reduction and EEG changes. Sahaja yoga could prove to be beneficial in the management of patients of epilepsy.

Brainstem auditory evoked potentials in epileptics on different anti-epileptic drugs.

The effects of anti-epileptic drugs (AEDs) on brainstem auditory evoked potentials (BAEPs) were studied on 32 female patients of epilepsy and 10 age-matched normal healthy females (NS). The patients were divided into 6 groups, those not receiving medication (drug free, DF) and those receiving AEDs: Phenytoin (PHT), Carbamazepine (CBZ), Phenobarbital (PB), a combination of PHT and PB and a combination of CBZ and PB. DF epileptics had shortened were V absolute latency (AL) and I-V interpeak latency (IPL) as compared to NS. Phenytoin and CBZ monotherapy produced a prolongation of wave III AL (by PHT only), wave V AL, wave I-III IPL and I-V IPL, as compared to DF epileptics. Phenytoin monotherapy also prolonged wave III AL and I-III IPL, as compared to NS. When PB in the dosage of 30-60 mg/d was used in combination with PHT the above mentioned changes were not observed. These findings indicate altered neuronal conduction and/or synaptic transmission in epileptics. Anti-epileptic drugs in the dosages studied, with exception of PHT appear to lead towards "normalization" of BAEPs.

Effect of Sahaja yoga practice on stress management in patients of epilepsy.

An attempt was made to evaluate the effect of Sahaja yoga meditation in stress management in patients of epilepsy. The study was carried out on 32 patients of epilepsy who were rendomly divided into 3 groups: group I subjects practised Sahaja yoga meditation for 6 months, group II subjects practised postural exercises mimicking Sahaja yoga and group III served as the epileptic control group. Galvanic skin resistance (GSR), blood lactate and urinary vinyl mandelic acid (U-VMA) were recorded at 0, 3 and 6 months. There were significant changes at 3 & 6 months as compared to 0 month values in GSR, blood lactate and U-VMA levels in group I subjects, but not in group II and group III subjects. The results indicate that reduction in stress following Sahaja yoga practice may be responsible for clinical improvement which had been earlier reported in patients who practised Sahaja yoga.