Traumatic low attenuation subdural fluid collections in children younger than 3 years.

Objective: To determine the time course for the development of posttraumatic nonhemic subdural fluid collections in infants and young children.

Design: Retrospective consecutive case series during 16 years. Patients Fifty-five head trauma patients younger than 3 years with low attenuation subdural fluid on computed tomography.

Main Outcome Measure: Time after head trauma when low attenuation fluid first becomes visible.

Setting: Regional pediatric medical center.

Results: The initial visualization of low attenuation subdural fluid was within 4 days of the trauma for 44 of the patients. The mean +/- SD size of the subdural fluid collections when first identified was 4.6 +/- 2.0 mm (range, 2-12 mm), and the maximum observed size was 7.7 +/- 3.5 mm (range, 3-21 mm). The mean +/- SD time after injury until the maximum observed size was 16 +/- 18 days (range, 0-87 days). Low attenuation subdural fluid and high attenuation intracranial hemorrhage coexisted on at least 1 computed tomographic study during the first week after the trauma in 42 (81%) of the 52 patients with hemorrhage.

Conclusion: Low attenuation subdural fluid collections (distinct from clotted blood) in infants and young children with head injuries most often develop during the first week after the traumatic event.