In a young adult male with an enlarged lateral ventricle, could this be a congenital form of hydrocephalus, and what work‑up and treatment are recommended?

Enlarged Lateral Ventricle in a Young Man: Congenital Etiology and Management

Is This Congenital?

Yes, lateral ventricle enlargement in a young adult male is most likely congenital in origin, particularly if asymptomatic or discovered incidentally, with congenital aqueductal stenosis being the most common cause in adults presenting with hydrocephalus. 1

Key Etiological Considerations

• Congenital hydrocephalus accounts for approximately 55% of all hydrocephalus cases, making it the predominant etiology when no clear acquired cause is identified 2
• In adults with hydrocephalus, aqueductal stenosis is responsible for 10% of cases and represents the most common congenital structural abnormality presenting in adulthood 1
• Congenital hydrocephalus is present at or near birth and has been linked to gene mutations that disrupt brain morphogenesis, though it may remain asymptomatic until adulthood 3

Distinguishing Congenital from Acquired Causes

Congenital etiologies to consider:

• Aqueductal stenosis causing non-communicating hydrocephalus with enlargement of lateral and third ventricles 1
• Midline telencephalic malformations including absence of septum pellucidum, corpus callosum abnormalities, or fornix anomalies 4
• Genetic mutations affecting brain development that alter CSF-brain interface biomechanics 3

Acquired causes that must be excluded:

• Post-infectious hydrocephalus from prior CNS infection (meningitis, ventriculitis) 5
• Post-hemorrhagic changes from prior intraventricular or subarachnoid hemorrhage 5
• Tumor-related obstruction particularly at the fourth ventricle outlet 5
• Post-traumatic changes affecting CSF pathways 6

Diagnostic Work-Up

Imaging Protocol

Obtain MRI brain without contrast as the first-line imaging modality to characterize the ventriculomegaly and identify structural abnormalities 7

MRI is superior to CT for detecting:

• Cerebral aqueduct patency and flow void 7
• Periventricular white matter changes suggesting chronicity 7
• Temporal horn enlargement disproportionate to hippocampal atrophy 7
• Midline structural anomalies (septum pellucidum, corpus callosum, fornix) 4

Apply quantitative measurements:

• Evans Index >0.3 indicates ventriculomegaly in adults 7
• Ventricular dilation >12 mm represents moderate-to-severe ventriculomegaly 7
• Callosal angle <90° and enlarged temporal horns support hydrocephalus diagnosis 8

Clinical Assessment

Evaluate for symptoms of increased intracranial pressure:

• Headaches (particularly morning headaches) 2
• Visual changes, papilledema, or optic atrophy 2
• Gait disturbance or cognitive changes 8
• Nausea/vomiting 6

Assess for signs of chronic hydrocephalus:

• Cognitive impairment (performance IQ typically worse than verbal IQ) 2
• Spasticity of lower limbs 2
• Hypothalamic dysfunction (delayed puberty, menstrual irregularities, short stature) 2

Obtain detailed history:

• Prior CNS infections or meningitis 5
• History of prematurity or neonatal complications 5
• Prior head trauma or intracranial hemorrhage 5
• Family history of hydrocephalus or neural tube defects 3

Treatment Approach

Asymptomatic Ventriculomegaly

Conservative management with close monitoring is appropriate for asymptomatic ventriculomegaly, as ventricular enlargement alone does not mandate surgical intervention 9, 8

Monitor for:

• Progressive ventricular enlargement on serial imaging 9
• Development of neurological symptoms 9
• Signs of increased intracranial pressure 8

Critical pitfall: Do not assume ventriculomegaly alone requires shunting—50% of patients with enlarged ventricles do not meet criteria for shunt surgery after comprehensive evaluation 8

Symptomatic Hydrocephalus

For symptomatic patients with confirmed aqueductal stenosis, endoscopic third ventriculostomy (ETV) is the treatment of choice in most neurosurgical centers 1

ETV advantages:

• Re-establishes physiological CSF flow 1
• Fewer complications than shunt surgery 1
• Rare need for revisions 1
• Avoids shunt dependency 9

Ventriculoperitoneal shunt surgery is reserved for:

• Failed ETV with persistent symptoms despite patent ventriculostomy 1
• Communicating hydrocephalus where ETV is not appropriate 1
• Patients requiring CSF drainage for symptomatic relief 5

Shunt considerations:

• High complication rates requiring multiple revisions 1
• Risk of infection (ventriculitis) and mechanical failure 5
• Lifelong shunt dependency in most cases 9

Critical Pitfalls to Avoid

• Do not perform lumbar puncture without imaging first if any signs of increased ICP or focal neurological deficits, as this risks herniation 8
• Do not assume all ventriculomegaly requires intervention—insufficient data exists to conclude ventricular size alone impacts neurocognitive development 8
• Do not delay neurosurgical consultation if symptomatic, as progressive hydrocephalus can cause irreversible neurological damage 6
• Do not overlook midline structural anomalies on imaging, as these indicate congenital etiology and may affect surgical planning 4

Long-Term Considerations

Even with successful treatment, long-term outcomes vary widely and depend on both intrinsic genetic factors and extrinsic factors such as timing of diagnosis and treatment 3

Ongoing surveillance is essential for:

• Shunt malfunction or infection if shunted 1
• ETV failure requiring conversion to shunt 1
• Development of new neurological symptoms 6
• Cognitive and functional outcomes 2