Evoked potentials in infant brainstem syndrome associated with Arnold-Chiari malformation.

This study evaluated the contribution of brainstem auditory evoked potentials (BAEPs) and median nerve somatosensory evoked potentials (SEPs) to the assessment of brainstem dysfunction in infants with myelomeningocele and Arnold-Chiari malformation. 16 infants under one year of age were studied. Six had infant brainstem syndrome (IBS). 11 had abnormally prolonged I-V interwave latency (brainstem transmission time, BSTT); BSTT did not differentiate those patients with and without IBS. The cortical 'N20' component of the median-nerve SEPs was absent or had low amplitude and prolonged latency in all six patients with clinical signs of brainstem dysfunction and in four without. Median-nerve SEPs were normal in the patients without IBS. There was a significant difference between patients with and without IBS. Median-nerve SEPs may be a helpful measure of brainstem function in infants with Arnold-Chiari malformation.