What is hydrocephalus, or water on the brain?
What is hydrocephalus?
CT and MRI scans of the brain may be used to identify and diagnose hydrocephalus.
In hydrocephalus, the build-up of CSF can raise pressure inside the skull, which squashes surrounding brain tissue.
In some cases, this can cause the head to steadily grow in size, convulsions, and brain damage. Hydrocephalus can be fatal if left untreated.
Other symptoms include headaches, vomiting, blurred vision, cognitive problems, and walking difficulties.
The outlook for a patient with hydrocephalus depends mainly on how quickly the condition is diagnosed and treated, and whether there are any underlying disorders.
The term "water in the brain" is incorrect, because the brain is surrounded by CSF (cerebrospinal fluid), not water. CSF has three vital functions, it:
- protects the nervous system
- removes waste
- nourishes the brain
The brain produces about 1 pint of CSF each day, and old CSF is absorbed into blood vessels. If the process of producing and removing CSF is disturbed, CSF can accumulate, causing hydrocephalus.
There are a number of types of hydrocephalus:
Approximately 1 in every 500 American babies are born with hydrocephalus. It may be caused by an infection in the mother during pregnancy, such as rubella or mumps, or a birth defect, such as spina bifida. It is one of the most common developmental disabilities, more common than Down syndrome or deafness.
This type of hydrocephalus occurs when the CSF becomes blocked after leaving the ventricles. It is called "communicating" because CSF can still flow between the brain's ventricles.
Also called obstructive hydrocephalus, non-communicating hydrocephalus occurs when the thin connections between the ventricles become blocked.
Normal pressure hydrocephalus
This only affects people aged 50 or older. It may develop after stroke, injury, infection, surgery, or hemorrhage. However, in many cases, doctors do not know why it occurred. An estimated 375,000 older adults in America have normal pressure hydrocephalus.
This type occurs after stroke, traumatic brain injury, or degenerative diseases. As brain tissue shrinks, the ventricles of the brain become larger.
Symptoms of congenital hydrocephalus (present at birth):
- breathing difficulties
- arm and leg muscles may be stiff and prone to contractions
- some developmental stages may be delayed, such as sitting up or crawling
- the fontanel, the soft spot on the top of the head, is tense and bulges outward
- irritability, drowsiness, or both
- unwillingness to bend or move the neck or head
- poor feeding
- the head seems larger than it should be
- the scalp is thin and shiny and there may be visible veins on the scalp
- pupils of the eyes may be close to the bottom of the eyelid, sometimes known as "the setting sun"
- there may be a high-pitched cry
- possible seizures
- possible vomiting
Symptoms of acquired hydrocephalus, which develops after birth, are:
- rarely, bowel incontinence
- confusion, disorientation, or both
- drowsiness and lethargy
- irritability, which may get worse
- lack of appetite
- personality changes
- problems with eyesight, such as blurred or double vision
- seizures or fits
- urinary incontinence
- walking difficulties, especially in adults
Symptoms of normal pressure hydrocephalus. Signs and symptoms may take many months or years to develop.
- Changes in gait: The person may feel as if they are frozen on the spot when taking their first step to start walking. They may appear to shuffle rather than walk.
- Normal thinking process slows down: The person may respond to questions more slowly than normal, there may be delayed reactions to situations. The individual's ability to process information slows down.
- Urinary incontinence: This usually comes after changes in gait.
The following factors increase the risk of hydrocephalus:
- Premature birth: Infants born preterm have a higher risk of intraventricular hemorrhage, or bleeding within the ventricles of the brain, which may result in hydrocephalus.
- Problems during pregnancy: An infection in the uterus during pregnancy increases the risk of hydrocephalus in the developing fetus
- Problems with fetal development: Examples include incomplete closure of the spinal column.
Other conditions that increase the risk include:
- lesion and tumors of the spinal cord or brain
- infections of the nervous system
- bleeding in the brain
- severe head injury
Hydrocephalus occurs when too much fluid builds up in the brain; specifically, excess CSF (cerebrospinal fluid) accumulates in the cavities (ventricles) of the brain.
There are more than 100 possible causes of hydrocephalus, but the underlying reasons are:
- Too much CSF is produced.
- One of the ventricles in the brain is blocked or narrowed, stopping or restricting the flow of CSF, so that it cannot leave the brain.
- CSF cannot filter into the bloodstream.
Causes of congenital hydrocephalus (present at birth)
The baby is born with a blockage in the cerebral aqueduct, a long passage in the midbrain that connects two large ventricles. This is the most common cause.
The choroid plexus produces too much CSF.
Health conditions in the developing baby can cause problems in how the brain develops. For instance, hydrocephalus is common in children with severe spina bifida (a birth defect of the spinal cord).
Infections during pregnancy - these can affect the development of the baby's brain. Examples include:
Causes of acquired hydrocephalus
This condition develops after birth and is usually caused by an injury or illness that results in blockage between the ventricles. The following may be causes:
- Brain hemorrhage - bleeding inside the brain.
- Brain lesions - areas of injury or disease within the brain. There are many possible causes, including injury, infection, exposure to certain chemicals, or problems with the immune system.
- Brain tumors - benign (noncancerous) or malignant (cancerous) growths in the brain.
- Meningitis - inflammation of the membranes of the brain or spinal cord.
- Stroke - a condition where a blood clot or ruptured artery or blood vessel interrupts blood flow to an area of the brain.
Causes of normal pressure hydrocephalus
This condition affects people aged at least 50 - in most cases, doctors don't know what caused it. Sometimes, it may develop after a stroke, infection, or injury to the brain.
There are two theories:
- CSF is not reabsorbed into the bloodstream properly. Because of this, the brain starts to produce less new CSF, resulting in a gradual rise in pressure over a long period. The gradual rise in pressure may cause progressive brain damage.
- An underlying condition, such as heart disease, high blood cholesterol level, or diabetes affects normal blood flow, which may lead to a softening of brain tissue. The softened brain tissue results in increasing pressure.
Regularly measuring a baby's head may help to diagnose hydrocephalus.
Babies and young children (congenital hydrocephalus):
A routine prenatal ultrasound scan may detect hydrocephalus during pregnancy in the developing fetus.
After birth, the head of the baby is measured regularly. Any abnormalities in head size will probably lead to further diagnostic tests.
If an ultrasound scan shows any abnormality, further tests will be ordered, such as an MRI (magnetic resonance imaging) scan or a CT (computerized tomography) scan, which give more detailed images of the brain.
Acquired hydrocephalus (occurs after birth) - if the child or adult develops the signs and symptoms of hydrocephalus the doctor will:
- Examine the patient's medical history.
- Carry out a physical and neurological examination.
- Order an imaging scan, such as a CT or MRI scan.
Normal pressure hydrocephalus - diagnosing this type of hydrocephalus is more tricky because symptoms are more subtle and do not appear suddenly.
In this section, we will discuss treatments for congenital and acquired hydrocephalus and treatments for normal pressure hydrocephalus individually.
Treatments for congenital and acquired hydrocephalus
Both types of hydrocephalus require urgent treatment to reduce the pressure on the brain; otherwise, there is a serious risk of damage to the brainstem, which regulates functions such as our breathing and heartbeat.
A shunt is the surgical insertion of a drainage system. A catheter (a thin tube with a valve) is placed in the brain to drain away excess fluid from the brain into another part of the body, such as the abdomen, the chest cavity, or a chamber of the heart. Usually, this is all that is needed, and no further treatment is required.
Patients with hydrocephalus will usually need to have a shunt system in place for the rest of their lives. If the shunt is placed in a child, additional surgeries may be needed to insert longer tubing as they grow.
Ventriculostomy - the surgeon makes a hole in the bottom of a ventricle so that the excess fluid flows towards the base of the brain. Normal absorption occurs at the base of the brain. This procedure is sometimes performed when the flow of fluids between ventricles is obstructed.
Treatment for normal pressure hydrocephalus
Shunts may also be used for normal pressure hydrocephalus. However, shunts may not be suitable for some patients. Other procedures may be carried out to check suitability:
Lumbar puncture - some of the cerebrospinal fluid is removed from the base of the spine. If this improves the patient's gait or mental abilities, fitting a shunt will probably help.
Lumbar infusion test - a needle is inserted through the skin of the lower back into the spine. Measurements are taken of CSF pressure as fluid is injected into the spine. Patients usually benefit from having a shunt fitted if their CSF pressure is over a certain limit.
Hydrocephalus severity depends on several factors, including when it develops and how it progresses. If the condition is advanced when the baby is born, it is more likely there will be brain damage and physical disabilities. If cases are not so severe and treatment is proper and prompt, the outlook is much better.
Babies with congenital hydrocephalus may experience some permanent brain damage, which can result in long-term complications. Examples include:
- a limited attention span
- learning difficulties
- physical coordination problems
- problems with memory
- speech problems
- vision problems
Ensuring that all vaccinations have been performed, in particular, the meningitis vaccination, may help reduce the risk of hydrocephalus.
Pregnancy - regular prenatal care can significantly reduce the risk of having a premature baby, which reduces the risk of the baby developing hydrocephalus.
Infectious diseases - make sure you have had all your vaccinations and attended all the screenings that are recommended for you.
Meningitis vaccine - meningitis used to be a common cause of hydrocephalus. Vaccination is recommended for some individuals, check with a doctor.
Preventing head injuries
- Wear a seatbelt every time you drive your car or ride as a passenger.
- Make sure children are buckled up.
Never drive when you are under the influence of alcohol.
Helmets or specific protective headgear should always be worn when:
- Batting in baseball/softball or cricket.
- Engaged in contact sports.
- Riding on a horse, motorbike, bicycle, snowmobile, scooter, or all-terrain vehicle (both riders and passengers).
- Snowboarding, skiing, skating, or skateboarding.
Living areas for older adults:
- Grab bars should be installed next to the bathtub, shower, and/or toilet.
- Seniors should keep physically active to make sure lower body strength and balance is adequate (lowering the risk of falls).
- Make sure lighting in the house is bright enough.
- Use nonslip mats on bathtub and shower floors.
- Remove throw rugs and other objects that could cause tripping.
- Stairways should ideally have handrails on both sides.
Living areas for children:
- Install window guards.
- Place safety gates at the bottom and top of stairs if the children are young.
Children's play areas:
The ground surface of a child's playground should be made of hardwood mulch, sand, or some other shock-absorbing material.
Firearms should be stored unloaded in a locked safe or cabinet. Bullets should not be stored in the same location.