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Nerve conduction velocity (NCV), according to age, was studied in normal children. Motor distal ulnar NCV (in 63 children, from 1 day to 4 years of age), motor distal tibial NCV (in 93 children, from birth to 15 years of age), proprioceptive tibial NCV (in 59 children, from birth to 5 years of age) and proximal CV (in 133 children from birth to 15 years of age), as well as VIIth superior branch CV (in 67 children) and XIIth CV (in 56 children) from birth to 3 years of age, were measured. These measurements showed that NCV changes were similar; NCV was 45-50% of the adult value during the first month of life. Then NCV increased very quickly, the progression being 90% of the first month's value during the first 18 months of life. The adult value was reached between 2 and 5 years of age. Proprioceptive NCV was 8-13 m/sec higher than motor NCV; proximal NCV was also 10-13 m/sec higher than distal motor tibial NCV. Ulnar NCV remained higher than tibial NCV, although changes in velocity as a function of age remained parallel. These NCV measurements proved significant in some diseases. The were useful for diagnosis of Krabbe's disease or of metachromatic leucodystrophy and to calculate the degree of disturbance in toxic polyneuritis, polyradiculoneuritis and some cranial nerve injuries; they were also useful in following up children undergoing chronic haemodialysis. In each case, NCV was only one aspect of a more complete neurophysiological study.

Neurological and cerebral computed tomography examinations were conducted in 25 infants and young children with uni- or bilateral maxillomandibular neurocristopathies (Goldenhar's, Franceschetti's first arch syndromes or transient forms). Taking all lesions into account, 18 children (82%) presented morphological and motor anomalies of the brain stem (mesencephalus, metencephalus) and its corresponding cranial nerves: four had morphological anomalies of the cerebellum and pons; four presented disorders of bulbopontine control (heart, lungs, deglutition); fifteen demonstrated sensory, sensorial, and motor deficiencies of the paired cranial nerves III, V, VI, VII, and VIII. The high frequency of ocular malformations in this series is emphasized: there were three cases of cryptophthalmia and one case of bilateral iris coloboma. These findings are in agreement with recent acquisitions in the field of cephalic developmental biology: the cephalic neural crest cells, after migration from the mesencephalorhombencephalic neural fold, contribute to the latero-facial and ocular organogenesis. The unity of origin of the face and brain provides an explanation for the predictive role of the former in case of malformations of the brain and its cranial nerves.