ABNORMAL SOMATOSENSORY-EVOKED POTENTIALS IN PATIENTS WITH CLASSIC GALACTOSEMIA - CORRELATION WITH NEUROLOGIC OUTCOME

In classic galactosemia, long-term neurologic sequelae can include low cognitive functioning and a curious neurologic syndrome with tremors, dysmetria, and ataxia. An abnormal white-matter signal on cerebral ma gnetic resonance imaging (MRI) is present in almost all patients; some have mild cerebral or cerebellar atrophy and focal white-matter lesio ns. The present study was undertaken to assess the integrity of myelin ated pathways by recording somatosensory evoked potentials. Results we re correlated with age at diagnosis, severity of illness, age at evoke d potentials, neurologic examination, MRI studies and cognitive outcom e as measured by the Woodcock-Johnson Revised Standard Cognitive Batte ry. Evoked potentials were abnormal in 17 (28%) of 60 patients who had median nerve, and 26 (77%) of 34 patients who had posterior tibial ne rve studies. Abnormalities of the central rather than the peripheral n ervous system were most common. Evoked potentials correlated with seve rity of presenting symptoms (P = .011), age at evoked potential testin g (P = .029), and presence of focal white-matter lesions on MRI (P = . 049). Results of neurophysiologic testing showed no correlation with t he Woodcock-Johnson Battery. Patients with classic galactosemia may ha ve abnormal conduction along myelinated pathways that is associated wi th other central deficits. Myelin, which contains galactose, may be ad versely affected in this inborn error of metabolism.