Hydrocephalus is a condition in which an abnormal amount of cerebrospinal fluid accumulates in the brain. It is sometimes referred to as “water on the brain,” and indeed the name “hydrocephalus” comes from the Greek words for water (hydro) and head (kephale). Cerebrospinal fluid, or CSF, is a clear, watery fluid that surrounds the brain and spinal cord. CSF serves many important functions. It cushions and protects the brain from injury; it delivers nutrients to nourish the brain; it removes waste from tissues; and it regulates pressure within the brain.
Normally, CSF is produced and continuously circulates in cavities called ventricles before being absorbed into the bloodstream. Obstructive hydrocephalus occurs when the passage of CSF is blocked. When this occurs, the fluid builds up inside the ventricle and causes pressure on adjacent brain tissue. Another kind of hydrocephalus, called non-obstructive or communicating hydrocephalus, occurs when the brain has trouble re-absorbing CSF or produces too much CSF. This article will review the common symptoms and treatment of obstructive hydrocephalus.
Causes
Hydrocephalus can occur at any age, but it is most common in infants and young children or in adults over the age of 60. According to the National Institute of Neurological Disorders and Stroke, hydrocephalus affects approximately one in every 500 children. Obstructive hydrocephalus can be a congenital condition, meaning it is present at birth. In these cases, it typically results from a genetic disorder such as spina bifida (a malformation of the spine), or as a complication of premature birth with brain hemorrhage. In other cases, the hydrocephalus is an acquired condition that develops later in life due to a brain tumor or cyst, head injury, or an infection such as meningitis.
Symptoms
The symptoms of hydrocephalus vary according to age and individual. Hydrocephalus can be more obvious in infants and toddlers because the bones of the skull are not yet closed, and the build-up of fluid can cause an enlarged head, a tense or bulging soft spot, a thin scalp, prominent veins in the scalp, or separated bones in the head. In addition, infants may suffer from symptoms such as vomiting, drowsiness, irritability, constant downward gaze, poor appetite, or seizures. The same symptoms may be present for toddlers and young children, along with headache, nausea, fever, delayed progress in walking or talking, poor coordination, inability to concentrate, or loss of sensory or motor functions.
In older children and adults, the bones of the skill are closed together and the head cannot enlarge. Therefore, the symptoms of hydrocephalus reflect increased pressure on the brain. These symptoms may include headache, loss of coordination or balance, nausea, vomiting, bladder control problems, impaired vision, and changes in concentration or memory.
Diagnosis
The diagnosis of hydrocephalus usually includes a physical and neurological exam as well as imaging tests. The neurological exam checks eye movement and vision, hearing, sensation, reflexes, balance and coordination, motor skills, thinking and memory. Imaging tests such as MRI, CT scan, and ultrasound (for infants) can help to determine the severity and cause of the hydrocephalus.
Treatment
The treatment of obstructive hydrocephalus depends on the cause of the obstruction and the severity of the condition. If the hydrocephalus is not creating symptoms, or if it is due to a temporary obstruction, intervention may not be required. In most cases, though, it is necessary to have surgery. If the hydrocephalus is due to a tumor or cyst that can be surgically removed, this is usually the best option. However, sometimes the obstruction cannot be removed, so instead surgery is required to divert the flow of CSF and avoid accumulation and pressure on the brain. This approach does not “cure” the hydrocephalus, but it does address the symptoms of the disease and allows for satisfactory long-term management.
There are two methods for diverting CSF. The first option is the surgical insertion of a shunt. This is a small, flexible plastic tube that sends the excess CSF into another area of the body where it can be safely absorbed, usually in cavities near the abdomen or the heart. The shunt has a valve that controls the flow of CSF and maintains normal pressure levels within the ventricle. All of the components of the shunt system are enclosed in the body. The surgery to insert a shunt is a relatively short and uncomplicated procedure. However, shunts have several drawbacks. They can malfunction or become infected or clogged. Children tend to outgrow the shunts and need later surgery to replace them.
The second method for diverting CSF is a relatively new, minimally invasive procedure called ventriculoscopy (sometimes called endoscopic third ventriculostomy, or ETV). In this treatment, the neurosurgeon uses an endoscope, which is a tiny telescopic camera that can be inserted into the ventricle to view the fluid and the obstruction. The surgeon can then create a hole in the membrane at the bottom of the ventricle to allow the CSF to detour around the obstruction and flow freely into the rest of the brain for re-absorption. Ventriculoscopy has many advantages. When successful, it avoids the need for a shunt and it has a lower long-term complication rate than shunts. However, ventriculoscopy is not usually recommended for children under two years of age, due to a higher rate of failure. In addition, sometimes the first hole in the membrane closes up over time and the procedure must be repeated. The procedure is also more complicated than a traditional shunt surgery, so it is important that you have a neurosurgeon who is trained in endoscopic techniques.