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What is hydrocephalus?

Hydrocephalus is a condition that is caused by an increase of cerebrospinal fluid (CSF) in and around the brain. Normally, the circulating CSF is constantly replenished and absorbed, so that the amount of fluid inside the brain and skull remains basically constant over the course of a lifetime.

With “obstructive hydrocephalus,” the normal flow of cerebrospinal fluid throughout the brain and spinal cord is blocked in some way and backs up behind the obstruction leading to increased pressure. In “communicating hydrocephalus,” there is no obvious obstruction to the flow of CSF, but the reabsorption of CSF back into the bloodstream is impaired.

Our approach

Northwell Health has many resources dedicated to diagnosing and treating hydrocephalus in children and adults—including Cohen Children’s Medical Center, the Normal Pressure Hydrocephalus Center at the Northwell Health Institute for Neurology and Neurosurgery, the Movement Disorders Center and the Chiari Institute.


Adults with hydrocephalus and brain cysts often have a combination of symptoms that can help establish the diagnosis, including headaches, mental confusion, difficulty walking, urinary incontinence, vomiting and loss of interest in normal activities. In addition, their head circumference may be above normal. (Note that symptoms of hydrocephalus are often mistaken for those of other brain disorders, including dementia, Alzheimer’s disease or Parkinson’s disease.)

Infants with hydrocephalus may have enlargement of the head and bulging of the “soft spot” or fontanelle. This is commonly the first sign of early hydrocephalus and often requires ultrasound or MRI for evaluation.


In childhood, hydrocephalus may be due to prematurity, genetics, bleeding in the brain and tumors.

In adulthood, hydrocephalus can be caused by a brain tumor, hemorrhage, infection or a trauma such as falling down or hitting your head. This is called secondary hydrocephalus. With idiopathic hydrocephalus, there is no known cause. It typically happens in individuals in their 60s, 70s and 80s, and symptoms are often very mild or not even detectable.

Related conditions

A brain cyst, or arachnoid cyst, is when part of the brain’s membrane forms a pouch and fills with CFS. Brain cysts are less common than hydrocephalus but can be treated using similar techniques.

How is it diagnosed

Hydrocephalus can sometimes be difficult to diagnose since not all of the symptoms may appear at the same time, and symptoms can be similar to those of other disorders. Rest assured, our team of specialists provides thorough neurological evaluations using the latest diagnostic technology to diagnose hydrocephalus, including:

  • Patient history and examination
  • CT scan of the head—A CT scan is often done as the first test, but may not be needed if an MRI has been obtained. The scan shows enlargement of the ventricles, or cavities, and is helpful in ruling out other specific causes of hydrocephalus.
  • MRI—An MRI is more sensitive to abnormalities of the brain tissue and is a key component of the diagnostic workup.
  • Neuropsychological testing—A thorough neurological evaluation will be done by a trained neuropsychologist and can be helpful in getting a clearer picture of the type and severity of mental impairment. It can also help in following the course of a patient’s disease.
  • Gait testing—This computerized measure helps in quantifying a patient’s gait (walking) impairment and is also helpful in documenting improvement with treatment.
  • Spinal tap or lumbar puncture (LP)—A very fine-gauge needle is placed into the spinal canal, and the pressure of the cerebrospinal fluid is measured. At this time, the CSF is also examined for any other abnormal findings.
  • Lumbar CSF drainage—A catheter is often inserted into the spine in the lower back for continuous drainage of cerebrospinal fluid over a three-day period. This procedure is more sensitive to improvement than a lumbar puncture alone.
  • Intracranial pressure monitoring—This is sometimes used in cases where the diagnosis is unclear and actual monitoring of the pressure inside the head is thought to be necessary.

With pediatric patients, we prefer to use MRI for diagnosis rather than CT scan, to limit the patient’s exposure to radiation. Cohen Children’s Medical Center recently opened a new MRI suite on the top floor of the hospital featuring state-of-the-art equipment, and we have a sedation program specifically for conducting MRI, led by our pediatric anesthesiologists.

Types of treatment

Since hydrocephalus affects a wide variety of people, we offer numerous treatments, allowing us to take a unique approach to each case. The traditional treatment for hydrocephalus is insertion of a shunt, or a tube that goes from the brain to elsewhere in the body, to drain the excess fluid using a one way pressure valve.

Newer treatments involve minimally invasive endoscopic techniques, which can be used depending on the cause and nature of the hydrocephalus. For instance, an endoscopic third ventriculostomy is when we insert a camera and create a new hole in the bottom of the brain, creating a new passageway without having to implant a shunt. In addition to or in place of this treatment, we may perform choroid plexus coagulation, where we use electric current to manipulate the brain to produce drastically less cerebrospinal fluid, so that the absorption and production ratio falls back in alignment. Our surgeons are experts at all types of treatment and the nuances of even the most complex cases.

What to expect after treatment

In children, hydrocephalus requires lifelong observation, even after successful treatment. Cohen Children’s pediatric neurosurgeons will continue to follow up with your child after they turn 21. If further treatment is required, it will be done at a Northwell Health facility for adults, ensuring a smooth transition and continuous care.

Normal pressure hydrocephalus can be difficult to diagnose. At our center, we have a unique collaboration of neurologists, neurosurgeons and neuropsychologists to expertly diagnose and treat patients with this condition.

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