Obstructive Hydrocephalus
Fluid buildup in the brain from a blockage in fluid flow
Quick Facts
- Type: Neurological condition (form of hydrocephalus)
- Cause: A blockage in the brain's fluid pathways
- Key risk: Raised pressure inside the skull
- Main treatment: Surgery to drain or reroute the fluid
Overview
Obstructive hydrocephalus is a condition in which cerebrospinal fluid (CSF), the clear fluid that cushions the brain and spinal cord, cannot drain normally because something is blocking its path. The brain continuously makes this fluid, which flows through a series of connected spaces called ventricles. When a narrow channel in this system is blocked, fluid backs up, the ventricles enlarge, and pressure inside the skull rises.
This type is also called non-communicating hydrocephalus because the blockage prevents fluid from communicating freely between the spaces. Because rising pressure can damage the brain, obstructive hydrocephalus often needs prompt treatment.
The fluid pathways of the brain are narrow in places, so even a small blockage can cause fluid to back up quickly. The point at which the blockage occurs determines which fluid spaces enlarge and how fast pressure builds. This is why imaging is so important: it shows both the enlarged spaces and the level of the blockage, helping doctors choose the right treatment.
Symptoms
Symptoms come from rising pressure in the skull and can develop quickly. In adults and older children they include:
- Headache, often worse in the morning or when lying down
- Nausea and vomiting
- Blurred or double vision
- Drowsiness, confusion, or trouble concentrating
- Balance and walking problems
In infants, whose skull bones have not yet fused, signs include a rapidly enlarging head, a bulging soft spot, irritability, poor feeding, and eyes that appear to look downward. A sudden, severe headache with vomiting and decreasing alertness is an emergency.
Causes
Obstructive hydrocephalus is caused by anything that physically blocks the narrow channels through which CSF flows. Common causes include:
- A brain tumor or cyst pressing on a fluid channel
- A narrowing of a channel called the aqueduct, which can be present from birth
- Bleeding within the brain
- Inflammation or scarring from a past infection
In children, it is sometimes present at birth due to a developmental problem. In adults, tumors and other growths are common causes. Identifying the exact cause of the blockage is an important part of planning treatment, because addressing the cause directly, such as removing a tumor, can sometimes resolve the buildup at its source rather than only managing the symptoms.
Risk Factors
- A brain tumor, cyst, or other growth
- A history of brain bleeding, such as from a stroke or injury
- A previous brain or spinal infection such as meningitis
- A congenital narrowing of the fluid channels present from birth
Diagnosis
Diagnosis relies on imaging of the brain:
- CT or MRI scan: These show enlarged ventricles and can reveal the blockage, such as a tumor or narrowed channel. MRI gives detailed views of the fluid pathways.
- Neurological examination: A doctor checks alertness, vision, balance, and reflexes to judge the effect of raised pressure.
- Head measurements in infants: Tracking head circumference over time helps detect fluid buildup in babies before other symptoms appear.
Treatment
Treatment aims to relieve the pressure and, when possible, address the blockage.
- Shunt placement: A thin tube (shunt) is surgically placed to drain excess fluid from the brain to another part of the body, where it is absorbed.
- Endoscopic third ventriculostomy: A surgeon creates a small opening inside the brain to let fluid bypass the blockage, an option for certain types of obstruction that can avoid the need for a permanent shunt.
- Treating the cause: Removing a tumor or cyst that is blocking flow can relieve the buildup and, in some cases, resolve the hydrocephalus once the obstruction is gone.
After treatment, regular follow-up is important because shunts can sometimes become blocked or infected and may need adjustment. People with a shunt, and their families, are usually taught the warning signs of shunt failure, such as returning headaches, vomiting, drowsiness, or changes in behavior, so they can seek help quickly if problems develop.
When to See a Doctor
Obstructive hydrocephalus can be a medical emergency because pressure can rise quickly. Seek emergency care or call emergency services right away for:
- A sudden, severe headache with vomiting
- Decreasing alertness, confusion, or difficulty waking
- New vision changes, weakness, or trouble walking
- In an infant, a rapidly enlarging head, bulging soft spot, persistent vomiting, or extreme sleepiness
Prompt treatment can prevent lasting brain damage.
Frequently Asked Questions
What is the difference between obstructive and communicating hydrocephalus?
Obstructive hydrocephalus is caused by a physical blockage in the brain's fluid channels, so fluid cannot flow through. Communicating hydrocephalus has no such blockage; instead, the problem is with how the fluid is absorbed or flows around the brain.
Is obstructive hydrocephalus an emergency?
It can be. A blockage can cause pressure inside the skull to rise quickly. A sudden severe headache with vomiting, decreasing alertness, or new vision or walking problems needs emergency care.
How is obstructive hydrocephalus treated?
Treatment usually involves surgery to drain or reroute the trapped fluid, such as placing a shunt or creating a new pathway with an endoscopic procedure. Removing a tumor or cyst causing the blockage can also help.
What causes the blockage?
Common causes include a brain tumor or cyst, a narrowed fluid channel present from birth, bleeding in the brain, or scarring from a past infection. The cause varies with age.
Can a shunt have problems later?
Yes. Shunts can sometimes become blocked or infected and may need adjustment or replacement. Regular follow-up helps detect and fix problems early, so report new headaches, vomiting, or drowsiness.
References
- National Institute of Neurological Disorders and Stroke (NINDS). Hydrocephalus.
- MedlinePlus, U.S. National Library of Medicine. Hydrocephalus.
- Mayo Clinic. Hydrocephalus — Symptoms and causes.
- Hydrocephalus Association. About Hydrocephalus.