The lay term “water head” refers to the medical condition hydrocephalus, derived from the Greek words hydro (water) and cephalus (head). This condition involves an abnormal accumulation of cerebrospinal fluid (CSF) within the brain’s ventricles, which are fluid-filled cavities. The excess fluid causes the ventricles to enlarge, exerting harmful pressure on surrounding brain tissues. This increased intracranial pressure disrupts normal brain function and causes various symptoms.
How Cerebrospinal Fluid Flows
Cerebrospinal fluid (CSF) is a clear, colorless liquid that cushions the brain and spinal cord, delivers nutrients, and removes waste products. Most CSF is continuously produced by the choroid plexus, a network of specialized cells and blood vessels located primarily within the brain’s four ventricles. The body produces about 500 milliliters of CSF daily, though only 125 to 150 milliliters are present within the system at any time.
The fluid begins circulation in the lateral ventricles, flowing through the foramina of Monro into the third ventricle. From there, the CSF passes through the narrow cerebral aqueduct to reach the fourth ventricle. This pathway distributes the fluid throughout the central nervous system.
After exiting the fourth ventricle, the fluid enters the subarachnoid space surrounding the brain and spinal cord. The final stage involves reabsorption into the bloodstream, primarily through arachnoid granulations that project into the venous sinuses. Hydrocephalus results from an imbalance between this continuous production and reabsorption.
Categorizing the Causes
The disruption of the CSF cycle is classified into two main categories based on the location of the problem. Non-communicating, or obstructive, hydrocephalus occurs when a physical blockage within the ventricular system prevents the fluid from flowing freely. A common example is aqueductal stenosis, a narrowing of the cerebral aqueduct connecting the third and fourth ventricles.
Communicating hydrocephalus occurs when fluid flows freely between the ventricles, but absorption is impaired after exiting the ventricular system. This deficit usually happens at the arachnoid granulations, which may become impaired or scarred. Causes often include brain hemorrhage, such as a subarachnoid hemorrhage, or complications from infections like meningitis.
The condition is also categorized as either congenital (present at birth) or acquired (developing afterward). Congenital causes often relate to developmental disorders or genetic abnormalities, such as spina bifida. Acquired hydrocephalus can be triggered by tumors pressing on flow pathways, traumatic brain injury, or bleeding in the brain.
Recognizing the Signs in Infants and Adults
The signs of hydrocephalus differ significantly between infants and older children or adults due to the developmental state of the skull. In infants, whose cranial sutures have not yet fused, the skull can expand to accommodate the increased fluid volume. This results in a rapid increase in head circumference, often accompanied by a bulging or tense soft spot (fontanelle) on the top of the head.
The increased pressure also manifests as physical symptoms, including downward-fixed eyes (the “sun-setting” sign) and high-pitched irritability. Poor feeding, persistent vomiting, and excessive sleepiness are common behavioral indicators of rising intracranial pressure in babies.
In older children and adults, the skull bones are fully fused, preventing expansion and leading to a direct increase in pressure. The most frequent symptom is a severe headache, often worse upon waking in the morning. This morning worsening is thought to be due to fluid accumulation overnight while lying down.
Other symptoms include nausea, vomiting, and vision changes such as double or blurred vision. Individuals may also experience problems with balance and coordination, leading to difficulty walking or a decline in cognitive function and memory. Normal pressure hydrocephalus (NPH), common in the elderly, is characterized by a triad of symptoms: gait disturbance, urinary incontinence, and cognitive impairment.
Modern Treatment Approaches
The primary goal of managing hydrocephalus is to reduce pressure and restore proper CSF flow. The most common surgical intervention is the placement of a shunt system, a flexible tube and valve mechanism designed to drain excess fluid. The most frequently used device is the ventriculoperitoneal (VP) shunt, which diverts CSF from a ventricle into the abdominal peritoneal cavity for safe absorption.
The shunt contains a valve that regulates the rate and direction of fluid flow, helping to maintain normal pressure inside the brain. Shunt placement provides a mechanical solution for both communicating and non-communicating hydrocephalus. An alternative approach is Endoscopic Third Ventriculostomy (ETV), typically reserved for cases of obstructive hydrocephalus.
ETV is a minimally invasive surgery where an endoscope is used to create a small hole in the floor of the third ventricle. This opening creates a bypass, allowing CSF to flow around the blockage and into the subarachnoid space for reabsorption. This shunt-free procedure is an effective, long-term option for selected patients with obstructive hydrocephalus, avoiding permanent implanted hardware.