Hydrocephalus is a condition through which excess cerebrospinal fluid (CSF) builds up within the fluid-containing cavities or ventricles of the brain. Hydrocephalus is a word derived from the Greek words "hydro" (water) and "cephalus" (head). Even though it translates as "water on the brain," the word actually refers to the buildup of cerebrospinal fluid (a clear organic liquid that surrounds the brain and spinal cord). This liquid is in constant circulation within the ventricles of the brain, serving multiple crucial functions:
- Acts as a "shock absorber" for the spinal cord and brain
- Acts as a vehicle for delivering nutrients to the brain, removing waste in the process
- Flows between the cranium and spine to regulate changes in pressure.
When CSF accumulates around the brain, it may cause harmful pressures on the tissues of the brain confined within the skull. The accumulation of CSF may be due to an increase in production of the fluid, a decrease in its rate of absorption, or a condition blocking its normal flow through the ventricular system.
Hydrocephalus may happen to any age of patient; however, it is most common in infants and adults aged 60+. According to the National Institute of Neurological Disorders and Stroke (NINDS), hydrocephalus is thought to affect about 1-2 for every 1,000 children born in the US. The majority of these cases are often diagnosed pre-birth, if not then, then diagnosis comes at the time of delivery or in early childhood.
CAUSES
Not much is known or understood about hydrocephalus causes. Some cases are present at birth, but others develop in childhood or adulthood. It may be inherited genetically, can be associated with developmental disorders (like spina bifida or encephalocele), or occur as a result of brain tumors, head injuries, hemorrhage or diseases like meningitis.
Based on onset, presence of structural defects or high vs. normal CSF pressures, hydrocephalus may be divided into distinct categories.
- Acquired Hydrocephalus: Develops at birth/in adulthood and typically caused by injury or disease.
- Congenital Hydrocephalus: Present at birth and may be caused by events occurring during fetal development or as a result of genetic abnormalities.
- Communicating Hydrocephalus: Occurs when there is no obstruction to the flow of CSF within the ventricular system. Here, the condition arises due to inadequate absorption of an abnormal increase in the quantity of CSF produced.
- Non-communication (Obstructive) Hydrocephalus: Occurs when the flow of CSF is blocked along one of more of the passages connecting the ventricles, causing enlargement of the pathways upstream of the block and leading to an increase in pressure within the skull.
- Normal Pressure Hydrocephalus: Form of communicating hydrocephalus occurring at any age, but most common in the elderly. Characterized by dilated ventricles with normal pressure within the spinal column.
- Hydrocephalus Ex-vacuo:Primarily affects adults and occurs when a degenerative disease (like Alzheimer’s disease, stroke, or trauma) causes damage to the brain that may cause the brain tissue to shrink.
SYMPTOMS
The symptoms of hydrocephalus vary per person and age group. Infants and young children are more susceptible to symptoms from increased intracranial pressure like vomiting and adults may experience loss of function like walking or thinking.
Infants
- Downward deviation of eyes or sunset sign
- Vomiting
- Unusually large head size
- Rapidly increasing head circumference
- Irritability
- Prominent scalp veins
- Seizures
- Bulging and tense fontanelle or soft spot
- Sleepiness
Children and Adolescents
- Poor appetite
- Urinary incontinence
- Nausea and vomiting
- Balance and gait abnormalities
- Slowing or loss of developmental progress
- Inability to concentrate
- Seizures
- Changes in personality
- Swelling of the optic disc or papilledema
- Blurred or double vision
Adults
- Memory loss
- Mild dementia headache
- Loss of balance or coordination
- Lethargy
- Bladder incontinence
- Impaired vision
- Impaired cognitive skills
- Nausea and vomiting
- Difficulty walking or gait disturbances
TESTING AND DIAGNOSIS
Once a physician suspects hydrocephalus, the doctor performs a thorough clinical evaluation. They review and record a detailed patient history and perform a physical exam to assess the condition. A complete neurological examination like more of the following tests, is usually recommended to confirm the diagnosis and assess for treatment options:
- Lumbar puncture (spinal tap)
- Intracranial pressure monitoring
- CT or CAT scan
- Magnetic resonance imaging
- Isotope cisternography
Certain tests may reveal useful information about the severity of the condition and its likely cause. Once hydrocephalus is suspected, it is crucial that a neurosurgeon and/or neurologist become part of the medical team for their expertise on interpreting test results and treating the condition.
TREATMENT
This condition may be treated in many ways. Using the underlying etiology, it may be treated by removing the cause of CSF obstruction or indirectly by diverting the excess fluid. It is treated most commonly through the indirect method of implanting a device (“shunt”) to divert the excess CSF away from the brain. The shunt is a flexible tube that is placed under the skin to drain excess CSF from a ventricle inside the brain, along with a catheter and a valve, to a different body cavity like the peritoneal cavity (area surrounding the abdominal organs).
After being inserted, the shunt system typically remains in place for the rest of a patient's life (more operations to revise the shunt system are needed ati times). The shunt system continuously performs its function of diverting the CSF away from the brain. Thereby, the shunt system keeps the intracranial pressure within normal limits. Sometimes, two procedures are performed. The first of which diverts the CSF and another at a later stage to remove the cause of obstruction (e.g. a brain tumor).
A limited number of patients may be treated with an alternative operation called endoscopic third ventriculostomy. Asurgeon utilizes a tiny camera (endoscope) with fiber optics to visualize the ventricles and create a new pathway through which CSF may flow.
FOLLOW-UP
Neurological function will be evaluated post-procedure. If neurological problems persist, rehabilitation may be required for further improvement. However, recovery might be limited by the extent of the damage already caused by the hydrocephalus and by the brain's ability to heal.
Hydrocephalus is an ongoing condition, so long-term follow-up by a doctor is essential. Follow-up diagnostic tests (CT scans, MRIs, x-rays) help determine if the shunt is working correctly. A physician should be contacted if any of the following postoperative symptoms are experienced:
- Redness, tenderness, pain or swelling of the skin along the length of the tube or incision
- Fever
- Abdominal pain
- Irritability or drowsiness
- Nausea, vomiting, headache or double vision
- Return of preoperative neurological symptoms
PROGNOSIS
The prognosis for hydrocephalus depends on the cause, the extent of a patient’s symptoms, and the timeliness of diagnosis and treatment. Certain patients display a dramatic improvement with treatment, while others do not. For certain cases of normal pressure hydrocephalus, dementia may be reversed by shunt placement. Other symptoms like headaches may disappear almost immediately if the symptoms are related to elevated pressure.
Generally, the earlier hydrocephalus is diagnosed, the better chance a patient has for successful treatment. The longer the symptoms have been active or present, it becomes increasingly unlikely that treatment will be successful. There is no way to fully predict how successful surgery can be for every patient. Certain people will improve dramatically, while others will plateau, even declining a few months post-op.
Shunt failure or malfunction might occur. The valve may grow clogged, or the pressure located in the shunt might not match a patient’s specific needs, causing more surgery to be required. If an infection occurs, antibiotic therapy might be needed, along with the likely temporary removal of the shunt and replacement by a drain until the infection clears. At that time, the shunt may be re-implanted. A shunt malfunction may be indicated by vision problems, headaches, irritability, fatigue, difficulty in waking up or staying awake, personality change, loss of coordination, a return of walking difficulties, mild dementia, or incontinence. For infants, the symptoms of shunt malfunction may include the above, in addition to vomiting, inappropriate head growth, and/or sunsetting eyes. During a shunt malfunction, surgery is usually required to replace the blocked or malfunctioning portion of the system. Fortunately though, most complications may be dealt with successfully.
