Neurophysiological study of newborns with hypocalcemia.

The EEG, sleep cycle, visual and auditory evoked potentials (VEP and AEP) were studied in 38 newborns who presented with seizures and had serum calcium levels below 7 mg/dl. Nineteen infants displayed increased theta and alpha, and decreased delta waves with variable but mild degrees of background EEG depression during sleep, which may reflect neuronal hyperexcitability induced by hypocalcemia. Hypocalcemic infants spent less time in quite sleep than control infants, but the time spent in active sleep did not change significantly. Seventy-seven percent of seizures occurred in active sleep. 17% in indeterminate sleep and 1% during wakefulness. Most infants demonstrated normal VEP and AEP, although a few displayed prolonged latency. No correlation was found between peak latency and serum calcium levels. Two infants with complicated hypocalcemia who showed moderately depressed background EEG and other two with loss of sleep cycles developed abnormally, while the other infants showed normal development.