Sensory Nerve Conduction Studies in Children. Age-Related Changes of Conduction Velocities

Abstract

Normal values of sensory conduction velocities (CV) in four routinely examinated peripheral nerves are presented median, ulnar, radial and sural were gathered from the intact side of children with unilateral brachial plexus or different peripheral nerve lesions aged from two weeks to 15.5 years. The data were computer treated using an exponential function as the one which best reflects the dynamics of CV age-related changes i. e. its neurophysiological maturation. Approximated exponential curves and standard error, 95 per cent of confidence limits were computer-fitted to CV values and computer-plotted for each nerve. The values of sensory CV were computed for each month of age. The minimum and maximum values of CV (CVo, CVmax), the age when CV reaches 95 % of its maximum maturity (age 95 %), and maturation rate constant - k were computed for each nerve and used for comparative assessment of their neurophysiological maturation. In addition the increase of CV per month during the period equal to age 95 % was calculated. The results have shown: 1. Values of CV along the segment wrist to elbow in newborns (CVo) and after maturation (CVmax) were found to be significantly

higher than those along the distal fingers to wrist segment of both median and ulnar nerves (p < 0.001). The main reason for this is probably temperature difference between these two segments. 2. Smaller variations of CV values found in different nerves along the same nerve segment can be caused by measurement or other technical error. Besides, in case of infants it is also very important that age-groups are identical. 3. "Maturation" of CV along the more proximal segment of median and ulnar nerve takes respectively 9 and 8 months longer than that along the distal segment. 4. Maturation rate of sensory CV varies in different nerves even within the same segment. Median and ulnar nerves are comparable. Maturation of sensory CV of the radial nerve takes about 1.5 years longer than that of the median and ulnar nerve within the same wrist-to-elbow segment. It has the slowest maturation taking four years among four analyzed sensory nerves.

Key words

Peripheral nerves - Conduction velocity -Childhood