Macrocrania caused by subarachnoid fluid collections (SFC) in 12 very low birth weight (VLBW) infants is reported from the Department of Pediatrics, University of Manitoba, and the Newborn Follow-up Program, Health Sciences Centre, Winnipeg, Manitoba, Canada. Ultrasound had shown grade II and III intraventricular hemorrhages in 7 infants in the neonatal period. The prevalence of SFC in VLBW infant survivors attending this clinic was 2.6%. SFC accounted for 30% of cases of macrocrania in VLBW infants. The incidence of SFC was 3.3 per 1000 VLBW survivors annually. The occipitofrontal circumference was at 5 to 50th percentile at birth and >95th percentile at age of diagnosis (mean, 7.7 months). A frontal subarachnoid space 6 mm or more, an interhemisperic fissure 8mm or more, and normal ventricles on ultrasound were required for diagnosis of SFC. Head growth stabilized along a curve above and parallel to the 95th percentile by age 15 to 18 months. Transient neurodevelopmental abnormalities (hypertonia and hyperreflexia) found in 5 infants at 6 to 8 months had disappeared by 18 months, and all had normal findings at 25 month follow-up. No infant had cerebral palsy or retardation <70, and none required neurosurgery. [1]

COMMENT. Various names used to describe benign SFC include “external hydrocephalus,” and “benign subdural collection of infancy.” If sonograms are normal except for SFC the infant may be followed with periodic head circumference measurements and clinical evaluation. An abnormal ultrasound may require follow-up with CT. The prognosis is usually favorable without intervention. Fukuyama Y et al have provided norms for age-specific CT measurements of subarachnoid spaces up to 1 year [2]. The abnormal measurements by ultrasound used for diagnosis of SFC in the above study exceeded the Fukuyama upper limits of CT norms: >5.7mm sa spaces and >7.6 mm ih fissures.

Cerebral ventricular enlargement in female adolescents with anorexia nervosa corelated with the degree of malnutrition and returned to normal after refeeding and weight gain in an MRI quantitative study at the Schneider Children’s Hospital, Albert Einstein College of Medicine, New Hyde Park, NY [3]. Body mass and ventricular volume were inversely correlated.