Somatosensory evoked response abnormalities in high-risk newborns

In a previous study from our laboratory, the prognostic significance of the auditory brainstem evoked response was assessed in high-risk neonates. An abnormal auditory brainstem evoked response predicted neurologic deficits at age 1 year; however, a normal result did not predict a normal outcome. In order to evaluate the prognostic utility of examining other sensory pathways, somatosensory evoked responses were elicited following median nerve stimulation. Testing was performed at 37–44 weeks conceptional age (defined as gestational age plus chronologic age) and at 2 and 6 months conceptional ages. Those patients studied included 34 high-risk neonates and 18 healthy, term infants as controls. Ten of the 34 patients had abnormal somatosensory evoked responses. Abnormalities included increased absolute (N19, P22) and interwave (N13–N19, N19–P22) latencies and flat potentials, alone or in combination. Three children with flat potentials demonstrated a persistence of this abnormality on subsequent examination and they later presented clinically with spastic quadriparesis. Four infants with increased latencies manifested normal responses on subsequent examination. Recently, these 4 patients exhibited tone abnormalities and mild developmental deficits; developmental outcome, however, will be assessed in a blind study at 1 year of age as part of this ongoing prospective study. Preliminary results suggest that somatosensory evoked responses may be valuable as an electrophysiologic predictor of outcome.