Multimodal evoked potential studies in leukodystrophies of children.

Evoked potentials were studied in 22 children with leukodystrophy [10 metachromatic leukodystrophy (MLD), 4 Pelizaeus-Merzbacher (PM), 3 Krabbes, 2 adrenoleukodystrophy (ALD), and one each of Alexander's, Canavan's and multiple sulphatase deficiency (MSD) diseases]. The ABRs were abnormal in all patients (except for the younger ALD), but varied with the type of leukodystrophy. The PM and Krabbes patients had abnormal ABRs with a loss of the rostral waves, accompanied in Krabbes with delayed I-III interpeak latencies; in MLD, ALD and MSD prolonged interpeak latencies were found. Three patients who had no clinical signs, but were positively diagnosed as MLD on the basis of absent arylsulphatase A, also had abnormal ABRs. The SEPs were abnormal in all patients. Cortical SEPs were absent in 16 and abnormal in 5 who were in the earlier stages of their disease. Cervical SEPs were within normal limits except for the Krabbes and MLD patients studied, who showed peripheral slowing. The VEPs were normal in only 6 and, unlike the ARBs and SEPs, did not seem to covary with clinical severity across the various leukodystrophies but did correlate with disease progression. Thus, multimodal EPs are useful in the diagnostic differentiation of the leukodystrophies.