Medically Reviewed By William C. Lloyd III, MD, FACS

What is hydrocephalus?

Hydrocephalus is a condition in which excess fluid collects in the brain. The fluid, called cerebrospinal fluid, is produced in cavities located deep within the brain known as ventricles. The fluid fills the ventricles and flows into the spinal cord and out into the subarachnoid space where it absorbed. The subarachnoid space is a space between the layers of the membrane that cover the brain and spinal cord.

Normally, cerebrospinal fluid is absorbed as quickly as it is produced, so that the amount stays relatively constant. Hydrocephalus occurs when something blocks the flow or absorption of the fluid, or if an excess amount of fluid is produced. As the pressure of the fluid increases, the ventricles enlarge and the brain is pressed against the skull, damaging the brain tissue.

Hydrocephalus may be present at birth, and can occur with other abnormalities, genetic conditions, or infections. It can also occur after birth as a result of certain infections, bleeding in the brain, injury, or tumors of the brain or spinal cord. Unlike adult skulls, which are solid bone, infant skulls have fibrous tissue connecting the bony plates, allowing their heads to expand if hydrocephalus is present. With age, the fibrous connections ossify, or become bony, which means that the skull cannot expand if hydrocephalus occurs later in life.

Symptoms of hydrocephalus depend upon age, and may range from irritability, sleepiness, and poor feeding to vomiting, personality and memory changes, difficulty walking, and urinary incontinence. Treatment is aimed at fixing the cause of the hydrocephalus and relieving the pressure on the brain. It is not known how many adults are affected by hydrocephalus, but it is estimated that it occurs in about one in every 500 children (Source: NINDS).

Hydrocephalus can have serious complications, so it is important that it be evaluated and treated without delay. Seek immediate medical care (call 911) for serious symptoms, such as difficulty breathing, absent pulse or heartbeat, high fever (higher than 101 degrees Fahrenheit), seizures, severe headache, stiff neck, or severe sleepiness or drowsiness. Poor feeding, unusual irritability, high-pitched, shrill cries, and persistent vomiting in infants and children also need emergency evaluation.

Seek prompt medical care if you or someone you are with has symptoms suggestive of hydrocephalus, such as progressive memory loss, personality changes, difficulty thinking, increasing sleepiness, headache, coordination and walking problems, urinary incontinence, or vomiting. Additional symptoms in children may include slow growth, changes in facial appearance, increase in head size, and downward gaze.

What are the symptoms of hydrocephalus?

Hydrocephalus symptoms can be quite subtle or very obvious depending upon age, rapidity of onset, cause, and how much damage has occurred.

Common symptoms of hydrocephalus in infants and small children

Infants and small children may not be able to express their symptoms directly, but some changes may be apparent including:

  • Bulging of the soft spot on top of the head, near the front (anterior fontanelle)

  • Developmental delays and failure to thrive

  • Downward gaze

  • High-pitched, shrill cry

  • Increasing head size or change in head shape and facial features

  • Irritability, fussiness, poor feeding, and poor sleeping

  • Persistent vomiting

  • Sleepiness

Additional symptoms of hydrocephalus in older children and adults

Older children who are able to express their symptoms and adults may have symptoms, such as:

  • Changes in mood, personality or behavior

  • Difficulty initiating movements or slowed movement

  • Difficulty walking (gait apraxia: walking as if shoes were magnetically attracted to the floor)

  • Difficulty with memory, thinking, talking, comprehension, writing or reading

  • Diplopia (double vision)

  • Droopy eyelid

  • Excessive fatigue

  • Headaches, which may be worse in the morning or when lying down

  • Impaired balance and coordination

  • Loss of vision or changes in vision

  • Nausea with or without vomiting

  • Urinary incontinence (inability to control urination)

Serious symptoms that might indicate a life-threatening condition

Hydrocephalus can have serious complications, so symptoms should be evaluated without delay. In some cases, hydrocephalus can be life threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Change in level of consciousness or alertness such as passing out or unresponsiveness

  • Change in mental status or sudden behavior change such as confusion, delirium, lethargy, hallucinations or delusions

  • Decreased vision (including decreased color perception)

  • High fever (higher than 101 degrees Fahrenheit)

  • High-pitched, shrill cries in an infant or small child

  • Irritability, fussiness, poor feeding, and poor sleeping in infants and young children

  • Respiratory or breathing problems such as shortness of breath, difficulty breathing, labored breathing, wheezing, not breathing, or choking

  • Seizure

  • Stiff or rigid neck

  • Unusual sleepiness in a child or infant or difficulty waking a child or infant

  • Worst headache of your life

What causes hydrocephalus?

Hydrocephalus results from an imbalance between the formation of cerebrospinal fluid and its absorption. The cause of this is not always known.

In some cases, hydrocephalus can occur with other birth defects such as spina bifida (incomplete closure of the spinal cord) or it may be related to genetic abnormalities, infection, or trauma. Premature babies who have cerebral hemorrhage (bleeding in the brain) may develop hydrocephalus. Sometimes it can occur as a result of a tumor that blocks the flow of cerebrospinal fluid.

What are the risk factors for hydrocephalus?

A number of factors increase the risk of developing hydrocephalus. Not all people with risk factors will get hydrocephalus. Risk factors for hydrocephalus include:

  • Abnormalities of brain development and formation

  • Brain or spinal cord injury

  • Brain or spinal cord tumors

  • Family history

  • Inadequate maternal folic acid consumption (neural tube defects occur in fetus)

  • Meningitis (infection or inflammation of the sac around the brain and spinal cord) or other brain infection

  • Prenatal infection

  • Preterm birth

  • Spina bifida (incomplete closure of the spinal cord)

How is hydrocephalus treated?

The goals of treating hydrocephalus are treating the underlying condition, alleviating any blockage if possible, relieving pressure, and preventing ongoing brain damage.

Common treatments of hydrocephalus

Common treatments of hydrocephalus include:

  • Antibiotics to treat infection if one is present

  • Lumbar puncture to temporarily drain excess fluid

  • Medication to help resorption of excess fluid (Diamox)

  • Placement of a shunt to continuously drain excess fluid into a location where it can be absorbed back into the circulation

  • Surgery to remove any obstruction

What are the potential complications of hydrocephalus?

Complications of untreated hydrocephalus can be serious, even life threatening in some cases. You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of hydrocephalus include:

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  1. Hydrocephalus. PubMed Health, a service of the NLM from the NIH. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002538/.
  2. Hydrocephalus fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/hydrocephalus/detail_hydrocephalus.htm.
  3. Hellbusch LC. Benign extracerebral fluid collections in infancy: clinical presentation and long-term follow-up. J Neurosurg 2007; 107:119.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 19
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