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Idiopathic external hydrocephalus: natural history and relationship to benign familial macrocephaly
Insights
Idiopathic external hydrocephalus in infants is a benign condition that resolves by age two without treatment. It is often linked to benign familial macrocephaly, with most infants experiencing normal development.
Area of Science:
- Pediatrics
- Neurology
- Radiology
Background:
- External hydrocephalus is a condition characterized by fluid accumulation.
- Idiopathic external hydrocephalus (IEH) in infants requires further understanding regarding its natural course and relationship with other conditions.
Purpose of the Study:
- To investigate the clinical course and outcomes of infants diagnosed with idiopathic external hydrocephalus.
- To explore the relationship between IEH and benign familial macrocephaly.
Main Methods:
- Retrospective analysis of 36 infants with idiopathic external hydrocephalus.
- Evaluation of head circumference, neuroimaging (CT scans), and developmental assessments.
- Review of family history for macrocephaly.
Main Results:
- All infants showed head circumference exceeding the 95th percentile by age one.
- Characteristic CT findings included prominent fissures, subarachnoid fluid, and prominent basal cisternae.
- Abnormalities resolved by 18-24 months; no treatment was required. Most infants (32/36) had normal development, though some had prior gross motor or language delays. 88% had a family history of macrocephaly, with familial links to benign familial macrocephaly observed.
Conclusions:
- Idiopathic external hydrocephalus is a self-limited, benign condition in infants.
- It typically resolves without intervention and is closely associated with benign familial macrocephaly.
- Close monitoring for developmental milestones is recommended.
Abstract:
External hydrocephalus was identified in 63 infants. The 36 infants in whom external hydrocephalus was idiopathic constitute the study population. The group was homogeneous. Although not all were macrocephalic at birth, the head circumference exceeded the 95th percentile in all cases by 1 year of age, and subsequent head growth was parallel to the 95th percentile. The head computed tomographic scan showed a characteristic picture of a prominent interhemispheric fissure, a collection of subarachnoid fluid over the frontal convexities, and prominent basal cisternae. Mild ventriculomegaly was present in ten cases. These abnormalities resolved after 18 to 24 months of age. No infant required therapy for the condition. Development was normal in 32 infants, suspect in three, and clearly abnormal in only one of the 36 infants. However, of the 32 infants with normal development, 14 were found to be delayed in gross motor development and five in language development at a prior time. There was a family history of macrocephaly in 88% of cases. Several families had a mixture of members with external hydrocephalus and benign familial macrocephaly throughout several generations. These findings suggest that idiopathic external hydrocephalus is a relatively benign, self-limited condition that resolves without treatment and is closely related to benign familial macrocephaly.