Cases of benign infantile extracerebral fluid collections and nontraumatic chronic subdural hygroma or hematoma were reviewed retrospectively at Nebraska Medical Center, Omaha. Thirty-nine patients with benign extracerebral fluid collections presented at 3-12 months of age with macrocephaly. The birth was premature in 15 cases. Head size was normal at birth, 3 required shunt placement, but in most the accelerated head growth leveled off, approaching the 98th percentile after 24 months of age. Long-term developmental outcome was normal in 30 and mildly delayed in 3.
Of 9 patients with subdural hygroma, 3 presented with a large head and 3 with seizures. Birth was premature in 4. Five required subdural punctures and/or subduroperitoneal shunt placement. All developed normally. 
COMMENT. In this patient series, infants with benign extracerebral fluid collections had a favorable long-term outcome, and 44% of patients with nontraumatic subdural hygroma resolved without surgical intervention. Previous follow-up studies of infants with idiopathic macrocephaly and orbito-frontal extradural fluid collections have shown variable results regarding neurological, radiological, and neuropsychological outcome. Some showed normalization of head circumference by 18-24 months, and others had persistent radiological changes. A study of 41 infants wih idiopathic macrocephaly and extradural fluid collections followed to young adulthood showed resolution of the fluid collection but neuropsychological impairments in visuomotor skills and attention.