Benign congenital hypotonia. A clinical study in 43 children.

The clinical features and short-term follow-up of benign congenital hypotonia (BCH) were studied in a group of 43 children. All children were referred for the evaluation of delayed motor performance during the first year of life. The hypotonia was mild in 35 children and moderate in 8. A "sitting-on-air" posture was found in 26 children (60%), and bottom shuffling (scooting) in 8 (19%). Thirty-six children were followed to the end of their third year of life. At this age minor neurological abnormalities could be found in 16 (44%) including hypotonia in 7, clumsy gait in 11 and speech delay in 3. In 30% of the cases there was a family history of delayed motor achievements. However, no significant differences were found between familial and non-familial cases regarding either clinical presentation or residual neurological findings. In view of the similarity in the clinical presentation of different causes of infantile hypotonia, the syndrome of BCH should be recognized. In such cases, because of the expected benign course, invasive diagnostic procedures may be withheld while the child is kept under follow-up, and be considered only in cases without complete recovery.