Study of sympathovagal imbalance by spectral analysis of heart rate variability in young prehypertensives.

Though prehypertension has recently been considered as a risk factor for cardiovascular accidents, the pathophysiological mechanism that causes the development of prehypertension in normotensive subjects has not been fully elucidated. Therefore, the present study was conducted to assess the sympathovagal imbalance in prehypertensives and normotensives by spectral analysis of heart rate variability (HRV) to understand the nature of change in autonomic balance in this dysfunction. Body mass index (BMI), waist-hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), rate-pressure product (RPP) and spectral indices of HRV such as total power (TP), normalized low frequency power (LFnu), normalized high frequency power (HFnu), ratio of low frequency power to high frequency power (LF-HF ratio), mean heart rate (mean RR), square root of the mean squared differences of successive normal to normal intervals; (RMSSD), the number of interval differences of successive NN intervals greater than 50 ms (NN50) and the proportion derived by dividing NN50 by the total number of NN intervals (pNN50) were assessed in two groups of young subjects: normotensives (n=68) and prehypertensives (n=66). Sympathovagal balance (SVB) was analyzed and correlated with BMI, WHR, BHR, BP and RPP in both the groups. It was observed that autonomic imbalance in prehypertensives was due to increase in both sympathetic activity and vagal inhibition. LF-HF ratio, the sensitive indicator of SVB was significantly correlated with BMI, WHR, BHR, BP and RPP in prehypertensive subjects. It was concluded that vagal inhibition might be important in the critical alteration of sympathovagal balance in the development of prehypertension in young normotensive subjects.

Obstetric brachial plexus palsy: a clinical and electrophysiologic evaluation.

BACKGROUND: Obstetrical brachial plexus palsy (OBPP) occurs as sequelae of birth-related trauma, antenatal and parturition related complications. It is associated with varying degrees of functional disability. Electrodiagnostic studies (EDS) are an adjunctive tool and help to localise and prognosticate the outcome of OBPP. METHODS: Fourteen children, presenting with OBPP to the Clinical Neurophysiology Lab, were analyzed. Details of birth history were obtained, and EDS were performed to characterize the lesion. RESULTS: The age ranged from one month to one year. Ten had unilateral and four bilateral brachial palsy. On EDS, five had pan-plexus, six predominantly upper plexus and three lower plexus involvement. A poor re-innervation pattern on EMG correlated with inadequate recovery. CONCLUSION: OBPP, a condition associated with considerable disability, needs to be prevented. Electrodiagnostic studies are a useful adjunctive tool for characterizing the site of injury and prognostication.

Correlation of clinical profile of myotonic dystrophy with CTG repeats in the myotonin protein kinase gene.

The molecular genetic analyses (PCR and Southern hybridization) of Indian patients with myotonic dystrophy (DM) were carried out to determine the degree of repeat expansion and an attempt was made to correlate the repeat number with disease severity. A scoring system based on the salient clinical features was devised to objectively assess the disease severity. The repeat expansion was seen in 11 of 12 patients examined and showed an inverse correlation with the age of onset confirming the phenomenon of anticipation. This was further established in the two pedigrees studied, clearly demonstrating both clinical and genetic anticipation. The clinical severity score, however, did not correlate well with the repeat number. Nonetheless, such molecular genetic analyses may have immense value as a screening procedure to identify premutations as well as in prenatal diagnoses.