Increased intracranial pressure and ventricular and subarachnoidal dilatation 
are common manifestations in achondroplasia. They rarely lead to major 
neurologic and/or psychomotor deficits and neurosurgical intervention is seldom 
needed. The present study was undertaken to detect signs of minor cerebral 
dysfunction and discuss possibilities of their prevention. Thirty children with 
achondroplasia were compared to 3 control groups: their next-born sibs, 30 
children with other forms of dwarfism, and 30 children with normal height. Early 
development was assessed by means of questionnaires. Cognitive skills were 
evaluated with the German version of the Cognitive Abilities Test and the 
Lorge-Thorndike Intelligence Test. Personality data were tested using 
standardized neuroticism, extraversion, and anxiety scales. Children with 
achondroplasia had more frequent histories of delayed motor development, 
retarded speech development, and lower school grades in language-related 
specialties. Psychometric testing disclosed total and subtest scores in the 
population-based normal range. In comparison with their sibs and matched 
controls children with achondroplasia had significantly lower total scores 
mainly caused by low scores in the subtest "verbal comprehension." We conclude 
that verbal comprehension is significantly impaired in children with 
achondroplasia. This partial deficiency is probably related to frequent middle 
ear infections and resulting conductive hearing loss. Hypotonia with delayed 
oropharyngeal muscle coordination and parental response to an altered, more 
infantile instinctive releasing pattern may be contributing factors.