To assess the effect of chronic cholestasis and vitamin E deficiency on nervous system function, we did multimodality evoked potential testing of 17 children (mean age = 47 months) who had chronic liver disease. Evoked potential testing was repeated periodically in 11 patients 1 to 33 months after the initial study.
Eight children had abnormal delays of the P100 peak of the visual evoked potential, and these children each had significantly higher total serum bile acid levels than did children who had normal visual evoked potentials (p = 0.002). Bilateral brainstem auditory evoked potential abnormalities consistent with conductive hearing losses were initially present in six patients. However, persistent conductive losses were found in four patients, all of whom had arteriohepatic dysplasia. Four children had mildly abnormal somatosensory evoked potentials that were due solely to a mild peripheral neuropathy. Biochemical measures of vitamin E status were not consistently associated with either normal or abnormal visual, brainstem auditory or somatosensory evoked potentials or a combination of evoked potential abnormalities, and an abnormality of one evoked potential type was not associated with an abnormality of any other. A similar lack of relationship between evoked potential results and plasma vitamin A measurement was noted. Following marked improvement in or resolution of cholestasis in four patients, the visual evoked potential became normal, but other evoked potentials did not change. Visual evoked potential improvement was greatest in two patients who underwent orthotopic liver transplantation.
This is the first report that demonstrates frequent, potentially reversible visual system abnormalities that are associated with cholestasis and cannot be attributed solely to vitamin E and/or A deficiency. Bilateral brainstem auditory evoked potential abnormalities consistent with conductive hearing losses were repeatedly present only in patients with arteriohepatic dysplasia and may represent another extrahepatic feature of this syndrome; we are not aware of any previous report of this association. Evoked potential studies provide a sensitive means with which to monitor neurological function and give objective, quantitative assessments necessary for comparing patients, and they may prove useful in understanding the pathophysiology of nervous system disorders associated with chronic cholestasis.