What Is Ventricular Enlargement of the Brain?
Understand what enlarged brain ventricles mean. This finding on a scan has various causes, from brain tissue loss to fluid buildup, impacting diagnosis and care.
Ventricular enlargement is a finding on brain imaging that indicates the fluid-filled spaces in the brain are larger than normal. This observation is not a disease but a sign that can point to various underlying medical conditions. Its significance depends on the cause and related symptoms, ranging from a harmless finding to an indicator of a neurological issue requiring intervention.
Defining Ventricular Enlargement in the Brain
The human brain contains four cavities known as ventricles: two lateral ventricles, a third ventricle, and a fourth ventricle. These interconnected spaces are filled with cerebrospinal fluid (CSF), a clear liquid that the brain continuously produces. CSF circulates through the ventricles and around the brain and spinal cord, providing cushioning against injury, delivering nutrients, and removing waste products.
Ventricular enlargement, or ventriculomegaly, describes a state where the ventricles are dilated from an increased volume of CSF. This expansion can be generalized, affecting all ventricles, or focal, affecting only certain ones. The condition is defined by specific measurements on imaging scans, such as a lateral ventricle width greater than 10 millimeters. This change signals a disruption in CSF production, circulation, or absorption, or it may reflect changes in the surrounding brain tissue.
Underlying Causes of Enlarged Ventricles
One primary cause of ventricular enlargement is hydrocephalus, the accumulation of excess CSF that increases pressure inside the skull. Obstructive hydrocephalus occurs when CSF flow is blocked by a tumor, cyst, or congenital narrowing of a channel. Communicating hydrocephalus happens when CSF flows between ventricles but is not properly absorbed into the bloodstream, often due to inflammation from infection or brain bleeding.
Another cause is brain atrophy, the loss of brain tissue. The ventricles expand to fill the space left by the diminished brain matter, a compensatory change known as hydrocephalus ex vacuo. Brain atrophy is associated with neurodegenerative conditions like Alzheimer’s and Huntington’s disease, traumatic brain injuries, or age-related changes.
Enlarged ventricles can also result from conditions present at birth that affect brain formation or from acquired issues like strokes, head injuries, and infections. These can obstruct CSF flow or cause brain tissue damage. A specific condition in older adults is Normal Pressure Hydrocephalus (NPH), where ventricles enlarge despite intermittently elevated CSF pressure. The cause of NPH is often unknown but involves impaired CSF absorption.
Identifying Symptoms and Indicators
Symptoms of ventricular enlargement are variable and depend on the cause, the patient’s age, and how rapidly the condition develops. In infants, whose skull bones have not yet fused, signs include a rapid increase in head circumference and a bulging soft spot (fontanelle). Other indicators are prominent scalp veins, vomiting, irritability, and a downward eye gaze known as the “sunsetting sign.”
In older children and adults, symptoms reflect increased pressure within the skull. These can include persistent headaches, nausea, and vomiting. Vision problems like blurred or double vision may occur, along with balance and coordination issues (ataxia). A shuffling walk is a common feature, particularly in individuals with Normal Pressure Hydrocephalus (NPH).
Cognitive changes are also common, including memory loss, confusion, difficulty concentrating, or personality shifts. In NPH, urinary incontinence appears alongside gait disturbances and cognitive decline. It is also possible for the enlargement to be discovered incidentally on a brain scan without any symptoms, especially if it is mild or developed slowly from brain atrophy.
How Doctors Diagnose Ventricular Enlargement
The primary method for identifying enlarged ventricles is neuroimaging. Magnetic Resonance Imaging (MRI) is preferred for its detailed images of the brain’s soft tissues, clearly showing the ventricles. Computed Tomography (CT) scans are another method, used in emergencies for quick assessment of acute hydrocephalus or bleeding.
In infants, a cranial ultrasound can visualize the ventricles non-invasively by placing a probe over the fontanelle (soft spot). These imaging techniques confirm the enlargement and help identify potential causes, such as tumors or evidence of a stroke.
Beyond imaging, a neurological examination is performed to assess motor skills, balance, cognitive abilities, and reflexes. This helps correlate any deficits with the imaging findings. Additional tests, like a lumbar puncture (spinal tap), may be needed to measure CSF pressure and analyze the fluid for infection or blood.
Managing Enlarged Brain Ventricles
Management focuses on treating the underlying cause, not the enlargement itself. For hydrocephalus, the goal is to divert excess CSF and reduce brain pressure. The most common treatment is surgically placing a shunt, which drains CSF from a ventricle to another body part for absorption. Another option for obstructive hydrocephalus is an Endoscopic Third Ventriculostomy (ETV), creating a new CSF flow pathway.
If enlargement results from brain atrophy (e.g., Alzheimer’s disease), care is directed at managing the underlying disease’s symptoms. The ventricular expansion is a secondary consequence and is not treated directly. For other causes like a brain tumor or infection, treatment addresses the primary issue with surgery, radiation, or antibiotics.
When ventricular enlargement is mild, asymptomatic, and not progressing, a doctor may recommend active monitoring with periodic follow-ups and imaging. Supportive therapies can help manage symptoms like balance or cognitive difficulties. These include physical, occupational, and cognitive therapy to improve daily function.