Communicating Hydrocephalus
Brain fluid buildup from poor absorption rather than blockage
Quick Facts
- Type: Neurological condition (form of hydrocephalus)
- Cause: Cerebrospinal fluid is not absorbed properly
- Flow: Fluid moves freely but builds up
- Main treatment: Surgery to drain excess fluid (shunt)
Overview
Communicating hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up in the brain even though it can still flow freely through the connected spaces called ventricles. Unlike obstructive hydrocephalus, there is no physical blockage in the fluid channels. Instead, the problem lies in how the fluid is absorbed back into the bloodstream or in how it circulates over the surface of the brain.
When fluid is produced faster than it is absorbed, it accumulates, the ventricles enlarge, and pressure inside the skull can rise. The term communicating means the fluid spaces still connect with one another, distinguishing it from blocked, non-communicating forms.
Cerebrospinal fluid is normally absorbed through tiny structures on the surface of the brain that act like one-way valves into the bloodstream. When these absorbing surfaces are damaged or scarred, the fluid cannot be cleared at its usual rate. Because the production of fluid continues, it gradually builds up. Understanding where the problem lies, in absorption rather than flow, helps explain why treatment focuses on draining the excess fluid.
Symptoms
Symptoms depend on how quickly fluid builds up and the person's age. In adults and older children, common signs include:
- Headache
- Nausea and vomiting
- Blurred or double vision
- Drowsiness, confusion, or difficulty concentrating
- Balance and walking difficulties
In infants, signs include a rapidly growing head, a bulging soft spot, irritability, and poor feeding. Some slower-developing forms, such as normal pressure hydrocephalus, cause a triad of walking trouble, memory problems, and loss of bladder control.
Causes
Communicating hydrocephalus happens when CSF is not absorbed properly. Common causes include:
- Bleeding around the brain, such as from a ruptured aneurysm or head injury, which can scar the absorbing surfaces
- Infection of the brain's lining (meningitis), which can cause scarring
- Inflammation following surgery or injury
In some people, especially older adults, the cause is not clear; this includes normal pressure hydrocephalus, a slowly developing form. Rarely, overproduction of fluid is involved. Whatever the cause, the common thread is that fluid is not cleared from around the brain as quickly as it is made, so it gradually accumulates and the fluid spaces enlarge over time.
Risk Factors
- A history of bleeding around the brain from injury, stroke, or a ruptured aneurysm
- A previous brain or spinal infection such as meningitis
- Older age, particularly for normal pressure hydrocephalus
- Prior brain surgery or significant head injury
Diagnosis
Diagnosis combines brain imaging with clinical evaluation:
- CT or MRI scan: These show enlarged ventricles and help confirm there is no physical blockage, pointing to a communicating type.
- Neurological examination: A doctor assesses walking, memory, alertness, and bladder control.
- Spinal fluid testing: Removing a small amount of fluid by lumbar puncture can measure pressure and check for signs of past infection or bleeding, and in normal pressure hydrocephalus it can help predict whether surgery will help.
Treatment
Treatment aims to remove excess fluid and relieve pressure.
- Shunt placement: A thin tube is surgically placed to drain excess CSF from the brain to another part of the body, where it is absorbed. This is the main treatment.
- Treating the underlying cause: Managing an infection or bleeding around the brain can help limit further damage to the absorbing surfaces and reduce ongoing fluid buildup.
- Follow-up care: Shunts require monitoring because they can become blocked or infected and may need adjustment or replacement over time.
For normal pressure hydrocephalus, a shunt can improve walking, thinking, and bladder control in carefully selected people. Because not everyone benefits, doctors often test how a person responds to removing some spinal fluid before recommending a shunt, which helps predict whether surgery is likely to help.
When to See a Doctor
See a doctor for a persistent headache, new walking or balance trouble, memory changes, or loss of bladder control. Seek emergency care or call emergency services for:
- A sudden, severe headache with vomiting
- Decreasing alertness or difficulty waking
- New vision loss, weakness, or rapidly worsening confusion
- In an infant, a quickly enlarging head, bulging soft spot, or extreme sleepiness
Rapid rises in pressure can be dangerous and need urgent treatment.
Frequently Asked Questions
What does communicating hydrocephalus mean?
It means fluid in the brain builds up even though it can still flow freely between the fluid spaces, with no physical blockage. The problem is usually with how the fluid is absorbed back into the bloodstream.
How is it different from obstructive hydrocephalus?
In obstructive hydrocephalus, a physical blockage stops fluid from flowing. In communicating hydrocephalus, the fluid flows freely but is not absorbed properly, so it accumulates.
What causes communicating hydrocephalus?
Common causes include bleeding around the brain, infections such as meningitis, and scarring from injury or surgery, all of which can impair fluid absorption. In some older adults, the cause is unclear, as in normal pressure hydrocephalus.
How is communicating hydrocephalus treated?
The main treatment is surgery to place a shunt that drains excess fluid from the brain to another part of the body. Treating any underlying infection or bleeding also helps limit further buildup.
Can it be an emergency?
Yes. If fluid builds up quickly, pressure inside the skull can rise rapidly. A sudden severe headache with vomiting or decreasing alertness needs emergency care.
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.