Normality and Normalization as Seen in a Long-Term Neurological Follow-Up of 286 Truly Premature Infants

This second part of our study represents the positive aspect of the long-term neurological follow-up of 286 prematures analyzed longitudinally, from birth, through the same examinator, using an identical method. They represent the postnatal survivors of our Unit (422). But, as so often noticed in study devoted to prematurity, 32% of the initial group failed to follow-up.

To carry out such an analysis only an extensive follow-up period can enable us to make a definitive assessment (until age 7 for 55% of our cases, age 9 for 35%, age 12 for 18%, and until age 23 for 13%), and the method used is specially designed to evaluate high-risk infants who are still evolving.

Two categories of former premature infants compose this second part:

1. The normal or normalized prematures: 161 children, i.e. 56% of the total. They are defined here and described with their traits, characteristic of former premature infants.

This global percentage varies between 44 and 69% as a function of the degree of prematurity and of the associated IUGR.

In our population, the point of definitive normalization seldom occurred precociously (only 12%), and seldom belatedly (3 years for 16%). The highest frequency of normalization was observed between 1 to 2 years of age.

Belated normalization may be hoped for in either one of the two previous situations encountered here: a long period of simple suspicion, or a short pathological period, from 6 to 12 months after birth.

In this normal category, we note a great frequency of isolated minor defects: sensory (visual impairment predominates: 11%), or psycho-affective (9%); epilepsy is quite rare.

2. The long-term subnormal prematures: 65 children, i. e. 23% of the total, and were here defined as such. Two main evolutive patterns lead to this situation: a long period of uncertainty, the child having been suspect or already subnormal from birth (37%), or a frankly pathological condition (45%).

The characteristics of this definitive subnormality are described:

1. vestiges of motor disorders, 2. slight personality, behavioral or affective problems, and 3. frequency of minor intellectual deficiencies reflected only by conventional difficulties in school time.

Moreover, these disorders are associated with minor defects: sensory or speech difficulties, which were more frequent than in the normal prematures. 1 child out of 2 (instead of 1 out of 3) suffers from one or several disorders. Epilepsy remains rare. In the subnormal group, the dominant abnormality was of psychic type as it was previously observed for the dominant severe sequelae in the pathological group.

The infants discussed in the first two parts of this series were studied for two reasons: first, to examine the very long-term outcome (up to 20 years) of prematures born before 1962; and second, to compare these results with those of a group of 100 recently born prematures who had the benefit of modern intensive care (part II).

Premature infants - long-term neurological - follow-up