Spinal evoked potential in man: a maturational study.

Summated evoked potentials to peroneal nerve stimulation which arise in the cauda equina and spinal cord afferent pathways were recorded from surface electrodes placed over the spine of 95 infants, children and adults. The conduction velocity of these potentials from lumbar to cervical recording sites was calculated. Additionally, segmental conduction velocities over peroneal nerve, caudal and rostral spinal cord were determined. In all age groups the speed of conduction up the spine was non-linear. It was slower over caudal spinal cord segments than over peripheral nerve or rostral cord. All these velocities were about half adult values in the newborn and progressively increased with age. The conduction velocity over peripheral nerve was within the adult range by 3 years of age. The speed of conduction over the spinal cord did not reach adult values until the 5th year. This suggests that spinal cord afferent pathways mature at a slower rate than peripheral nerve fibers.