Neuromuscular responses to disturbance of balance in children with prenatal exposure to alcohol.

Alcohol-exposed children display delayed motor development and impaired fine- and gross-motor skills, including deficits in the maintenance of balance. In a recent study, we assessed the contribution of visual, somatosensory, and vestibular information to the ability to maintain balance. Our findings suggested that alcohol-exposed children were overly reliant on somatosensory information and were unable to compensate by using the visual and/or vestibular systems. To understand the nature of these observed balance deficits, corrective postural reactions were examined by exposing standing subjects to rapid toe-up movements of the support surface. Subjects for this study were alcohol-exposed (ALC) and normal control (NC) children matched for age and sex. Postural reactions were quantified by measuring electromyographic activity of the triceps surae and anterior tibialis muscles. Analyses revealed no differences between the ALC and NC groups on short- and medium-latency electromyographic responses, which are thought to be involuntary mono- and polysynaptic spinal reflexes, respectively. However, when compared with the NC group, the ALC group displayed increased long-latency responses, which are thought to involve a transcortical pathway. Although we are not able to rule out the possibility of additional peripheral (e.g., vestibular) disturbance as a contributing factor to postural instability, our findings suggest that the balance deficits seen in alcohol-exposed children are, at least in part, central in nature.