Hydrocephalus

1 What Is Hydrocephalus?

Hydrocephalus is a health problem that causes the head to bulge much larger in proportion to the rest of the body. It is caused by excessive quantities of cerebrospinal fluid inside the head. Most cases of hydrocephalus occur in babies, often soon after birth. It is a very troubling condition, because it causes the baby’s head to become very large. Aside from causing severe deformity, the condition may also cause mental defects. Hydrocephalus can happen in adults as well.

Hydrocephalus is dangerous because of the high pressure exerted by excess cerebrospinal fluid; the elevated pressure literally presses on the brain. The brain is a very delicate organ, and therefore sensitive to pressures inside the head. Untreated hydrocephalus makes the brain slowly lose its blood supply, resulting in the malfunction of its neurons. Therefore, it must be treated right away to prevent the onset of mental disability.

The head of a baby with hydrocephalus is unusually large and often continues to grow to the point of deformation. Aside from the enormous head, the baby may also exhibit signs of slowed mental development. Hydrocephalus can be caused by genetics as well as external factors, such as injury or certain medical conditions. 

Hydrocephalus is a recognized problem because, according to statistics, the condition is somewhat common. At least 6,000 babies per year in the United States develop the condition during their first two years of life. Hydrocephalus is often accompanied by other disorders, such as spina bifida (incomplete closure of the backbone, which exposes the spinal cord). About half the cases are a result of injuries, which means babies of any age are at risk. Leaving the condition untreated often leads to death.

Hydrocephalus

How Does Hydrocephalus Occur?

Hydrocephalus happens when there is too much cerebrospinal fluid inside the head, making it swell and enlarge. Cerebrospinal fluid is the fluid surrounding the brain and spinal cord, and it has several vital functions in the central nervous system.

The brain and spinal cord are very delicate structures. These are also made of cells working constantly, so they emit plenty of metabolic wastes. The small recesses inside the brain house the fluid, where it supports the entire brain structure and prevents it from collapsing under its own weight. It also protects the brain against external blows and promotes blood microcirculation to the neurons. Cerebrospinal fluid also distributes hormones and neuroendocrine factors around the brain, and at the same time allows for removal of waste products from neurons.

The functions of cerebrospinal fluid are so important that it is constantly produced and reabsorbed in the central nervous system. So much cerebrospinal fluid is produced that its turnover rate is three to four times a day. Any problem that blocks the drainage immediately increases the quantity of cerebrospinal fluid in the brain, resulting in hydrocephalus.

2 Symptoms

A newborn baby with congenital hydrocephalus looks normal at birth just like any other baby. Over time, the growth of the head’s girth becomes noticeable.

It is normal for a baby’s head to grow a lot during the first twelve months of life. In hydrocephalus, the head grows much faster in proportion to the child’s weight and height. Aside from the large head that increasingly becomes larger, here are the symptoms of hydrocephalus in babies:

  • The soft spot on the baby’s head (fontanel) is bulged or tense.
  • Frequent vomiting
  • High irritability
  • Poor feeding

At the start, the baby seems fine. As the head becomes larger, however, more symptoms appear and become worse. The baby’s eyes become fixed downward (called “sunset eye”) due to stretching of the forehead. The baby may experience seizures, gradual loss of muscle tone in the arms and legs, and slowed body growth.

Older babies and toddlers with hydrocephalus may have the following:

  • Headache
  • Blurred or double vision
  • Sleepiness and difficulty staying awake 
  • Nausea and vomiting
  • Poor or unstable balance
  • Seizures
  • Poor appetite
  • Profound irritability
  • Change in personality
  • Problems maintaining attention
  • Decline in school performance
  • Delays in important milestones, such as walking or talking

School-age children and adults with hydrocephalus may not experience growth in head size. Instead, they may exhibit the following:

  • Urinary incontinence or loss of bladder control
  • Inability to memorize
  • Gradual loss of thinking and reasoning
  • Difficulty walking and assuming a shuffling gait
  • Slowed physical movement

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3 Causes

Hydrocephalus can be caused by congenital defects or can be acquired after birth. Most people, however, know it as a congenital condition.

The most common is aqueductal stenosis. Inside the brain are hollow channels called “aqueducts” that connect spaces called “ventricles.” Cerebrospinal fluid flows in these spaces, especially through an aqueduct known as the “aqueduct of Sylvius.” Aqueductal stenosis occurs when the aqueduct of Sylvius becomes significantly narrowed or blocked, preventing the flow of cerebrospinal fluid, which results in retention and compression of the brain. Abnormalities in brain development in the fetus, as in the cases of Dandy-Walker syndrome and Arnold-Chiari malformation, are associated with hydrocephalus. A significant number of babies born with a congenital condition called spina bifida are also born with hydrocephalus.

People of all ages may suffer from hydrocephalus as a consequence of head injuries. Head trauma before, during, or after birth may cause the baby to have hydrocephalus. Babies that experienced infections in the head, such as meningitis, may also have it. Development of tumors in the brain can also cause the condition if those growths block the flow of cerebrospinal fluid.

In children and adults, hydrocephalus does not make the head grow in size, as the skull has already become rigid. Instead, the increasing volume of fluid compresses the brain and makes it smaller, causing neurologic symptoms.

In both adults and babies, regardless of the cause, hydrocephalus worsens over time. The build-up of cerebrospinal fluid increases pressure inside the head, called “intracranial pressure”. It reduces blood flow in the neurons of the brain, causing deficits in brain function that worsen over time. 

4 Making a Diagnosis

Brain scans are used to diagnose hydrocephalus.

The various diagnostic modalities used are:

  • USG scan may be needed in a newborn to detect a congenital lesion that may be causing the obstruction.
  • For detailed evaluation of brain like for structural abnormalities, a CT or MRI may be ordered. For adults, a combination of CT and MRI reveals the causes of your symptoms like a brain tumor.

The diagnosis of Normal Pressure Hydrocephalus is based on Hakim’s triad of:

Small abnormalities that may not be detected using CT scan, such as cysts and abscesses, are often seen with MRI. These studies can also help the neurosurgeon differentiate between communicating and noncommunicating hydrocephalus.

In cases of suspected normal pressure hydrocephalus, a spinal tap may help determine CSF pressure. A cisternagram evaluates the dynamics of CSF flow in the brain and spinal cord. In this procedure, a diagnostic dye is injected into the subarachnoid space around the brain. A series of pictures is taken once the dye has circulated through the entire CSF path. Cisternography can reveal CSF concentration, obstruction, leakage, and pressure.

In older people, pressure in the head can cause papilledema, swelling of the optic nerve. Papilledema can often be seen while examining the eyes. Unfortunately, it typically indicates hydrocephalus that is well developed. In rare cases, long standing hydrocephalus causes blindness.

5 Treatment

Treatment of hydrocephalus depends on age, cause of hydrocephalus and overall status of the patient.

  • Ventriculostomy and coagulation: Endoscopic third ventriculostomy (ETV) with choroid plexus coagulation (CPC) is a relatively new procedure that is becoming common for kids who need surgery. In this technique, an evacuation route is created that helps to bypass the obstruction and thus the buildup of pressure and allowing later for the normal dynamics of fluid absorption.

Also, parts of choroid plexus are cauterized to reduce the amount of CSF produced. This technique is believed to have higher success rate than conventional shunt procedures.

  • Shunt procedures: This involves developing a communication between ventricles of brain and either the abdominal cavity, heart or spaces of lung. This allows easy vent for the fluid into these spaces from where they are absorbed into the blood stream and prevent developing of too much pressure inside the brain and thereby saving the vital structures of the brain.

A valve (flap that opens and closes) in the shunt system regulates the flow to prevent over-draining and under-draining. However, the long term outlook for patients implanted with shunts is not good. Many need revision surgeries for correcting the proper position of catheters or for a matter of fact the shunts may stop functioning altogether. Another complication of shunts is a high rate of infections.

Another complication can occur when CSF drains more rapidly than it is produced by the choroid plexus, causing symptoms like listlessness, severe headaches, irritability, light sensitivity, auditory hyperesthesia (sound sensitivity), nausea, vomiting, dizziness, vertigo, migraines, seizures, a change in personality, weakness in the arms or legs, strabismus, and double vision - to appear when the patient is vertical. If the patient lies down, the symptoms usually vanish quickly.

A CT scan may or may not show any change in ventricle size, particularly if the patient has a history of slit-like ventricles. Difficulty in diagnosing overdrainage can make treatment of this complication particularly frustrating for patients and their families.

Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure.

6 Prevention

Pregnant women can greatly reduce the chances of having a baby with hydrocephalus by sticking to scheduled prenatal checkups. If the pregnancy is healthy, nutritional deficits and preterm birth are less likely to happen. Note that mothers receiving inadequate nutrition during term are more likely to have babies with problems in the development of the central nervous system. Meanwhile, preterm birth is riskier for the baby, as it puts it at risk of developing hydrocephalus.

Growing children and adults may avoid having hydrocephalus by sticking to basic safety rules and protecting the head from injury. In case of head trauma, immediate treatment and monitoring can help detect early signs of hydrocephalus. 

7 Risks and Complications

Hydrocephalus is somewhat common, because it is caused by many conditions. The risks factors are:

  • Head trauma
  • Meningitis
  • Presence of lesions or tumors in the brain
  • Having mumps (the reason why we should vaccinate children)
  • Having brain surgery
  • Bleeding in the brain during childbirth, which may happen in premature or preterm births
  • Anything that causes trauma to the brain

Untreated hydrocephalus causes complications. It can also happen if shunt surgery fails. The longer hydrocephalus is left untreated, the poorer its prognosis, potentially leading to death. The complications include:

  • In babies, significant deficit and delayed mental and physical development
  • Gradual loss of awareness to surroundings
  • Continued enlargement of the head
  • Poor feeding
  • Having more severe initial symptoms
  • Frequent seizures
  • In adults, loss of memory
  • Onset of physical disabilities in adults
  • Coma
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