Hydrocephalus is a medical condition characterized by an excessive buildup of cerebrospinal fluid (CSF) within the brain’s cavities, known as ventricles. This accumulation causes the ventricles to enlarge, placing pressure on brain tissues. Non-communicating hydrocephalus, also called obstructive hydrocephalus, is a specific type where CSF flow is blocked along one or more narrow passages connecting these ventricles.
Understanding Non-Communicating Hydrocephalus
Cerebrospinal fluid is a clear, colorless liquid that surrounds and protects the brain and spinal cord. It also delivers nutrients and removes waste products from the brain. Most CSF is continuously produced by specialized tissue called the choroid plexus, located within the brain’s ventricles. The body typically produces about 500 milliliters of CSF daily, with approximately 150 milliliters present at any given time, meaning the entire volume is replaced several times a day.
Normally, CSF circulates through a pathway within the brain’s ventricular system. It flows from the two lateral ventricles through the interventricular foramina into the third ventricle. From the third ventricle, the fluid passes through the cerebral aqueduct into the fourth ventricle. After exiting the fourth ventricle through specific openings, CSF enters the subarachnoid space, which surrounds the brain and spinal cord, where it is reabsorbed into the bloodstream.
Non-communicating hydrocephalus arises from a physical obstruction within this ventricular system, preventing CSF from flowing freely. This blockage causes CSF to accumulate upstream, leading to enlarged ventricles and increased pressure inside the skull. The term “non-communicating” highlights that fluid within the ventricles cannot freely flow with the subarachnoid space due to this internal barrier.
Causes and Recognizable Signs
Various factors can obstruct CSF flow, leading to non-communicating hydrocephalus. Congenital malformations, such as aqueductal stenosis—a narrowing of the aqueduct—are common causes present at birth. Other developmental issues like Dandy-Walker malformation can also impede CSF circulation. Tumors, whether benign or malignant, can press on or grow within the CSF pathways, blocking fluid movement.
Infections of the central nervous system, such as meningitis, may cause inflammation and scarring that obstruct passages. Bleeding within the brain, known as hemorrhage, can also lead to blockages or scarring that interferes with CSF flow. These acquired causes can develop at any point after birth.
The signs and symptoms of non-communicating hydrocephalus vary depending on the individual’s age, the location and severity of the blockage, and how quickly pressure increases. In infants, whose skull bones have not yet fused, a rapid increase in head circumference is a notable sign. Other indications include a bulging soft spot (fontanelle) on the top of the head, vomiting, irritability, and a downward gaze of the eyes.
For older children and adults, symptoms are typically related to increased pressure within the confined space. These can include persistent headaches, nausea, vomiting, and vision problems like blurred or double vision. Balance and coordination difficulties, changes in walking patterns, and cognitive alterations like memory issues or reduced concentration may also occur. Lethargy, or excessive sleepiness, is another common symptom.
Identifying and Treating the Condition
Diagnosing non-communicating hydrocephalus begins with a physical and neurological examination to assess symptoms and neurological function. Imaging studies are crucial for confirming the diagnosis and identifying the obstruction site. Computed tomography (CT) scans or magnetic resonance imaging (MRI) of the brain are commonly used to visualize enlarged ventricles and pinpoint where CSF flow is blocked. These images provide detailed views of the brain’s internal structures, aiding in treatment planning.
Treatment for non-communicating hydrocephalus primarily involves surgical interventions to relieve pressure and restore CSF flow. One common approach is the surgical insertion of a shunt system, such as a ventriculoperitoneal (VP) shunt. A shunt is a flexible tube with a valve placed in a brain ventricle to drain excess CSF. The tubing is tunneled under the skin, often to the abdominal cavity (peritoneum), where the fluid is absorbed by the body. This system helps maintain healthy CSF levels and reduces pressure on the brain.
Another surgical option for certain cases of non-communicating hydrocephalus is an Endoscopic Third Ventriculostomy (ETV). This procedure involves using a neuroendoscope to create an opening in the floor of the third ventricle. This pathway allows CSF to bypass the obstruction and flow directly into the subarachnoid space, where it is reabsorbed. ETV is often considered for cases with a clear internal blockage and can potentially eliminate the need for a permanent shunt.
Outlook and Long-Term Care
With timely diagnosis and treatment, many individuals with non-communicating hydrocephalus can experience improvement in symptoms and lead full lives. Prognosis varies based on the underlying cause, age of onset, and how quickly the condition is addressed. Surgical intervention, whether a shunt or ETV, aims to manage fluid buildup and prevent further brain damage.
Ongoing medical follow-up is necessary to monitor the condition, especially for individuals with shunts. Regular check-ups help ensure the shunt functions properly and detect potential complications like malfunction or infection. Symptoms like headaches, nausea, or excessive tiredness might indicate a shunt problem. Managing non-communicating hydrocephalus often involves a multidisciplinary approach, with care coordinated by neurologists, neurosurgeons, and other specialists to address any long-term effects or specific needs.