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Obstructive Hydrocephalus

Hydrocephalus can occur as a result of a wide variety of conditions. The areas around the brain and spinal cord, as well as the cavities, or ventricles, in the brain and the spinal canal, are filled with a clear fluid called cerebrospinal fluid (CSF). The CSF helps support and cushion the brain and has a role in clearing potentially harmful substances. Structures in the brain, called the choroid plexuses, create CSF from blood. The CSF circulates around the central nervous system and then is reabsorbed. When there is an imbalance between the rates at which CSF is produced and reabsorbed, it builds up and increases the pressure inside the skull. This is one of the most common reasons that a person might have to see a neurosurgeon.


Obstructive hydrocephalus results from problems in the circulation and reabsorption of CSF. It can occur:

  • In children with congenital malformations that do not allow CSF to flow properly, or
  • In adults or children, when ...
    • Tumors or blood clots obstruct CSF circulation, or
    • As a result of injury or infection

Obstructive hydrocephalus typically is caused by a blockage in the normal circulation of CSF within the brain. This can be due to scarring of a ventricle or a tumor. When the obstruction is due to a tumor, it is important to realize that the tumor has only a 10% chance for growth and the only treatment required is for the hydrocephalus. Additional treatments for the tumor are only delivered if growth is documented.


In patients with hydrocephalus, the volume of fluid in the skull, or within a specific ventricle in the brain, increases. The ventricles may become dilated and there is an increased risk of intraventricular bleeding. The increases in pressure place stress on brain tissue and lead to:

  • Headache
  • Nausea
  • Vomiting
  • Mental status deterioration
  • Visual disturbances
  • Seizures
  • Problems walking
  • Permanent neurological deficits
  • The stress can even lead to death

In very young children, the first signs of hydrocephalus may be

  • Irritability
  • Poor head control
  • Poor feeding
  • A bulging soft spot

Furthermore, hydrocephalus in children may result in larger-than-normal head size.


The blockages and structural problems that lead to hydrocephalus can be examined with computed tomography (CT) and magnetic resonance imaging (MRI) scans.

Hydrocephalus may be diagnosed before birth by ultrasound. Fetal and neonatal ultrasound also may be used for very young children to monitor the ventricles of the brain and watch for intraventricular bleeding. The growth of a baby's head also may be tracked if it is larger than normal.


If the blockage is caused by a tumor, surgical tumor resection is used both to remove the tumor and to restore the normal flow of CSF. Endoscopic surgery, in which instruments and cameras are manipulated through tubes inserted in a small incision, may be used for some of these procedures. This technique is useful because CSF is clear, making it easy for surgeons to visualize an obstruction through an inserted camera. In addition, endoscopic surgery is less invasive than traditional surgery and can reach tumors that are not readily accessible.

If the blockage is caused by a blood clot, the neurosurgeon often places a shunt — an implantable tube that allows the excess fluid to drain to other parts of the brain or elsewhere in the body for reabsorption. Alternatively, the neurosurgeon may make a hole or incision in a ventricle in the brain to allow the fluid to exit.

In children, once the cause of obstructive hydrocephalus has been identified, a physician can determine whether the head will eventually grow enough to accommodate the imbalance of CSF on its own or whether surgical intervention is needed.

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