Significance of microcephaly among children with developmental disabilities.

To assess the clinical impact of microcephaly among children with developmental disabilities, we reviewed the charts of 1393 consecutive patients from birth to 5 years of age referred to our child development center. Comparisons were made between normal and low IQ microcephalic patients and between children with cerebral palsy with and without small head circumference. Microcephaly was detected in 15.4% of patients. Although mental retardation was more common among microcephalic children (P < .001), almost half had normal intelligence. Prematurity (P < .001), perinatal asphyxia (P < .001), small for gestational age (P < .001), respiratory distress syndrome (P < .001), and brain hemorrhage (P < .001) were associated with microcephaly. Hypotonia (P < .001) and spasticity (P < .001) were the most common neurologic findings. Cerebral palsy (P < .001), growth retardation (P < .001), epilepsy (P < .001), and strabismus (P < .001) were the main associated diagnoses found. Mental retardation was significantly more common among microcephalic patients with cerebral palsy than among normocephalic ones (P < .0004). Microcephaly is common among children evaluated for developmental disabilities. Many of these patients have normal or borderline IQ. Of several perinatal conditions associated with later microcephaly, respiratory distress syndrome and intraventricular hemorrhage show the strongest correlation. Mental retardation is not a risk factor for other neurologic complications in microcephalic children. However, in children with cerebral palsy, microcephaly is a risk factor for mental retardation.