Studies on pediatric patients with absent auditory brainstem response (ABR) later components.

Eleven pediatric patients with only wave I or waves I and II of their ABR were clinically analyzed. The clinical diagnoses of these patients were as follows: 1) anoxic encephalopathy in two cases; 2) neonatal asphyxia in one; 3) infantile Gaucher's disease in one; 4) mitochondrial encephalomyopathy in one; 5) suspected Pelizaeus-Merzbacher disease in three; 6) degenerative disease of unknown etiology in two (presumptive diagnosis were progressive supranuclear palsy and dentate-rubro-pallido-Luysian atrophy); and 7) infantile spasms with congenital malformation of the brain and bones in one. The incidence of the patients with this type of ABR abnormality was 0.67% among 1,650 of our pediatric patients whose ABRs were examined because of audiological or neurological problems. All eleven patients showed severe mental retardation. Nine of the eleven had convulsions and likewise, eight of eleven showed deterioration in mental and/or motor activities. Furthermore seven of eleven had disturbed consciousness and four of these seven were in deep coma. Other brainstem and bulbar signs and symptoms were frequently found in these patients. In our series, patients without the later components of ABR manifested marked neurological abnormalities inside and outside the brainstem.