Is Hydrocephalus Congenital?
Hydrocephalus can be either congenital (present at or near birth) or acquired (developing at any time after birth), and distinguishing between these two categories is critical for determining etiology, prognosis, and treatment approach. 1
Congenital Hydrocephalus
Congenital hydrocephalus is present at or near birth and accounts for a substantial proportion of pediatric hydrocephalus cases. 1
Common Causes of Congenital Hydrocephalus
Spina bifida (myelomeningocele) is one of the most common causes, with approximately 80% of children with spina bifida developing hydrocephalus. 2, 3
Aqueductal stenosis represents another major congenital cause, often linked to gene mutations that disrupt brain morphogenesis and alter the biomechanics of the cerebrospinal fluid-brain interface. 1, 3, 4
Dandy-Walker malformation and other posterior fossa malformations are well-recognized congenital causes. 3, 4
Genetic mutations affecting brain growth and development have been increasingly identified as causes of congenital hydrocephalus. 1, 5
Clinical Presentation
Infants with congenital hydrocephalus typically present with progressive increases in head circumference (macrocephaly), bulging fontanels, and splaying of cranial sutures. 1, 4
Prenatal diagnosis is increasingly common with modern imaging technologies, allowing detection before birth. 4, 6
Acquired Hydrocephalus
Acquired hydrocephalus develops after birth and has distinct etiologies from congenital forms. 1
Common Causes of Acquired Hydrocephalus
Posthemorrhagic hydrocephalus from prematurity is a major acquired form, occurring in approximately 15-20% of infants weighing less than 1500g at birth who develop intraventricular hemorrhage. 2, 4
Postinfectious hydrocephalus is particularly prevalent in certain regions, especially Africa and Asia, where central nervous system infections are more common. 2
Brain tumors causing obstruction of cerebrospinal fluid pathways represent another acquired etiology. 2, 4
Trauma can lead to acquired hydrocephalus, particularly in older children. 2
Critical Diagnostic Distinction
The distinction between congenital and acquired hydrocephalus is not always straightforward and requires careful clinical evaluation. 2
Diagnostic Challenges
Approximately 20% of hydrocephalus cases have unclear etiology, making classification difficult. 2, 7
Aqueductal stenosis can be either congenital or acquired (from infection causing inflammation), complicating classification. 2
The hydrocephalus literature suffers from poor consensus regarding etiological classification, with non-uniform reporting across studies. 2, 7
Key Diagnostic Criteria
Absence of hydrocephalus at birth with subsequent development after a febrile illness or infection suggests acquired (postinfectious) etiology. 2
Prenatal or immediate postnatal detection with associated structural malformations strongly suggests congenital etiology. 4, 6
Advanced imaging (MRI when available) helps distinguish congenital structural abnormalities from acquired pathology, though access remains limited in many regions. 2, 7
Clinical Implications
The distinction between congenital and acquired hydrocephalus has significant implications:
Prognosis varies substantially based on whether hydrocephalus is congenital or acquired, with outcomes depending on both intrinsic (genetic) and extrinsic factors. 1, 3
Treatment approaches may differ, with some congenital cases potentially amenable to endoscopic third ventriculostomy, while acquired cases may require different surgical strategies. 7, 4
Genetic counseling is relevant for congenital cases with identified genetic causes but not for acquired forms. 6
Prevention strategies differ markedly: folic acid supplementation can prevent some congenital cases (spina bifida-related), while infection control and improved perinatal care can reduce acquired cases. 2