Overview
Hydrocephalus is a neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles (cavities) deep within the brain. This excess fluid causes the ventricles to widen, putting harmful pressure on the brain’s tissues.
-
-
- a condition in which fluid accumulates in the brain, typically in young children, enlarging the head and sometimes causing brain damage.
-
-
-
- A build-up of fluid in the cavities deep within the brain. The extra fluid puts pressure on the brain and can cause brain damage. It’s most common in infants and older adults.
-
-
-
- Hydrocephalus is characterized by head enlargement in infants. Adults and older children experience headaches, impaired vision, cognitive difficulties, loss of coordination, and incontinence.
- Treatment is often a tube (shunt) inserted surgically into a ventricle to drain excess fluid.
-
-
- Difficulty walkingthat’s sometimes compared to the way a person walks “on a boat,” with the body bent forward, legs held wide apart and feet moving as if they’re “glued to the deck.”
- Mild dementia involves loss of interest in daily activities, forgetfulness, difficulty completing routine tasks, and short-term memory loss.
- A decline in thinking skills that include overall slowing of thought processes, apathy, impaired planning and decision-making, reduced concentration, and changes in personality and behavior.
- Loss of bladder control, which tends to appear somewhat later in the disease than difficulty walking and cognitive decline.
- The symptoms of hydrocephalus tend to vary greatly from person to personand across different age groups. Infants and young children are more susceptible to symptoms from increased intracranial pressure like vomiting and adults can experience loss of function like walking or thinking.
Infants
- Unusually large head size
- Rapidly increasing head circumference
- Bulging and tense fontanelle or soft spot
- Prominent scalp veins
- Downward deviation of eyes or sunset sign
- Vomiting
- Sleepiness
- Irritability
- Seizures
Symptoms of Congenital Hydrocephalus
Medical problems associated with congenital hydrocephalus may include:
-
-
- Chiari malformations, an abnormality at the base of the brain where the spinal column joins the skull
- Craniosynostosis is when the bones in the skull fuse together before the brain has stopped growing
- Dandy-Walker syndrome, when the fourth ventricle is enlarged because of partial or complete closure of its outlets
- Hydranencephaly is a rare condition in which the brain’s cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid
- Vein of Galen aneurysmal malformations, a tangled mass of dilated vessels supplied by an enlarged artery
-
Signs of Congenital Hydrocephalus
-
-
- Abnormal head enlargement
- Downward deviation of eyes
- Headache, irritability, nausea, sleepiness, vomiting
- Prominent scalp veins
- Skull bones may feel separated
- Tense, bulging fontanel (soft spot)
-
Children and Adolescents
- Nausea and vomiting
- Swelling of the optic disc or papilledema
- Blurred or double vision
- Balance and gait abnormalities
- Slowing or loss of developmental progress
- Changes in personality
- Inability to concentrate
- Seizures
- Poor appetite
- Urinary incontinence
Adults
- Headache
- Nausea and vomiting
- Difficulty walking or gait disturbances
- Loss of balance or coordination
- Lethargy
- Bladder incontinence
- Impaired vision
- Impaired cognitive skills
- Memory loss
- Mild dementia
Symptoms of Acquired Hydrocephalus
-
-
-
- Chronic headaches
- Cognitive challenges or complaints
- Difficulty walking/gait disturbances
- Urinary urgency or incontinence
-
-
CAUSES
For most types of hydrocephalus, surgery is the only treatment option. On this page, we discuss the different types of hydrocephalus, which are classified according to the cause and symptoms of hydrocephalus.
Speculation is that hydrocephalus may result from inherited genetic abnormalities, such as the genetic defect that causes aqueductal stenosis. One of the most common causes of hydrocephalus is “aqueductal stenosis.” In this case, hydrocephalus results from a narrowing of the aqueduct of Sylvius, a small passage between the third and fourth ventricles in the middle of the brain.
It can also be caused by developmental disorders, such as those associated with neural tube defects including spina bifida and encephalocele (in newborns, a protrusion of some or all of the brain through a defect in the skull).
Other possible causes include complications of premature birth such as intraventricular hemorrhage, and diseases such as meningitis, tumors, traumatic head injury, or subarachnoid hemorrhage, which block the exit of cerebrospinal fluid (CSF) from the ventricles to the cisterns or eliminate the passageway for CSF within the cisterns.
Congenital Hydrocephalus
Affecting one out of every 1,000 newborns, congenital hydrocephalus is the type that is present at birth. Congenital hydrocephalus is a buildup of excess cerebrospinal fluid (CSF). The extra fluid can increase pressure in the baby’s brain, which then causes brain damage and physical as well as mental problems. Discovering the condition early and treating it quickly can help limit any long-term problems. But long-term effects greatly depend on the cause of the fluid buildup, how bad it gets, and how the baby responds to treatment. Early treatment (before age 4 months) is important to help limit or prevent brain damage. However, congenital hydrocephalus is now often diagnosed before birth through routine ultrasound. Treatment focuses on reducing the amount of fluid in the brain to relieve pressure.
Congenital hydrocephalus is caused by a complex interaction of genetic and environmental factors during fetal development. One of the most common causes of congenital hydrocephalus is “aqueductal stenosis” (a narrowing of the aqueduct of Sylvius, a cerebral aqueduct). Another common cause of hydrocephalus is a neural tube defect (NTD).
Other Causes of Congenital Hydrocephalus
-
-
-
- Birth defect (such as spina bifida)
- Genetic defect
- Mother’s infections during pregnancy (such as rubella, mumps, toxoplasmosis, or syphilis)
-
-
Acquired Hydrocephalus
Acquired hydrocephalus develops at the time of birth or at some point afterward. This type of hydrocephalus can affect individuals of all ages and may be caused by injury or disease. The following conditions may cause CSF obstruction and subsequently acquired hydrocephalus:
-
-
-
-
- Bleeding (hemorrhage)
- Brain trauma (i.e., a result of injury)
- Brain tumor
- Cyst (i.e., a fluid-filled sac)
- Infection (e.g., cerebral abscess, bacterial meningitis)
-
-
-
Premature births may be a risk factor for hydrocephalus. Hemorrhaging, traumatic brain injury, and infection are seen in some premature births.
Pseudotumor Cerebri
Pseudotumor cerebri (PTC) is caused by high pressure in the fluid surrounding the brain. Pseudotumor cerebri means “false brain tumor” because it mimics a tumor or hydrocephalus.
The difference between pseudotumor cerebri and hydrocephalus is that PTC fluid is encased in the extracellular space (located around each brain cell) rather than in the ventricles. In essence, then, the ventricles are compressed with PTC and expanded in the case of hydrocephalus.
PTC is often associated with overweight adolescents or sudden weight gain (such as in pregnancy). It is sometimes treated with shunting.
Diagnosis
Once a physician suspects hydrocephalus, he/she performs a thorough clinical evaluation, including reviewing and recording a detailed patient history and performing a physical exam to assess the condition. A complete neurological examination, including one or more of the following tests, is usually recommended to confirm the diagnosis and assess for treatment options:
The tests may reveal useful information about the severity of the condition and its likely cause. Once hydrocephalus is suspected, it is important that a neurosurgeon and/or neurologist become part of the medical team for their expertise in interpreting test results and treating the condition.
Because the symptoms of normal pressure hydrocephalus are similar to Alzheimer’s disease, Parkinson’s disease, and Creutzfeldt-Jakob disease, normal pressure hydrocephalus is often overlooked or misdiagnosed. The three hallmark normal pressure hydrocephalus symptoms are considered the “classic” clinical picture, but not everyone with normal pressure hydrocephalus experiences all three symptoms.
In a Mayo Clinic study, among 41 older adults with suspected normal pressure hydrocephalus, all had difficulty walking, 30 experienced cognitive decline, and 14 reported loss of bladder control. Only 12 of the 41 had all three symptoms.
To confirm a diagnosis of normal pressure hydrocephalus, one or more of the following tests are done:
-
-
- Brain imaging: Imaging of the brain’s structure to detect enlargement of the ventricles, often with magnetic resonance imaging (MRI) or CT scan, plays a key role in diagnosing normal pressure hydrocephalus. Several brain disorders, including Alzheimer’s disease, can cause overall brain tissue shrinkage that makes the ventricles look larger than normal. In normal pressure hydrocephalus, brain tissue may not appear shrunken even though the ventricles are enlarged.
- Clinical examination: Because the clinical picture for normal pressure hydrocephalus may vary and symptoms may overlap with those of Alzheimer’s and other dementias, experts recommend that a person with suspected normal pressure hydrocephalus undergo examination by a neurologist with extensive experience evaluating brain disorders that affect movement, thinking skills, and physical functions.
- Cerebrospinal fluid tests: CSF tests to predict shunt responsiveness and/or determine shunt pressure include lumbar puncture, external lumbar drainage, measurement of CSF outflow resistance, intracranial pressure (ICP) monitoring, and isotopic cisternography.
-
Types of Hydrocephalus
Hydrocephalus is a defect that causes excess cerebrospinal fluid (CSF) to build up in the brain. The brain is surrounded and cushioned by this fluid, which also fills open structures deep in the brain, called ventricles. With hydrocephalus, the fluid becomes trapped in the brain ventricles, which causes them to enlarge. We explain more about hydrocephalus here.
For most types of hydrocephalus, surgery is the only treatment option. On this page, we discuss the different types of hydrocephalus, which are classified according to the cause and symptoms of hydrocephalus.
Communicating vs Non-Communicating Hydrocephalus
There are two main classifications for hydrocephalus:
-
-
-
- Communicating hydrocephalus (or non-obstructive) – after the brain fluid becomes blocked, it can still flow between the ventricles.
- Non-communicating hydrocephalus (or obstructive) – the brain fluid becomes blocked in one or more of the narrow passages that connect the ventricles.
-
-
Both communicating and non-communicating hydrocephali can be subdivided into:
-
-
-
- congenital hydrocephalus (present at birth)
- acquired hydrocephalus (occurs following birth).
-
-
Communicating hydrocephalus can also be subdivided into:
-
-
-
- normal pressure hydrocephalus (NPH)
- hydrocephalus ex-vacuo.
-
-
The below image illustrates the two main types of hydrocephalus:
-
-
-
- non-communicating hydrocephalus is shown in the left scan;
- the right shows communicating, normal pressure hydrocephalus (NPH).
-
-
In a brain without hydrocephalus, the blue areas – which are fluid on the brain – would be less visible.
Non-Communicating Hydrocephalus
Non-communicating hydrocephalus — also called obstructive hydrocephalus — occurs when the flow of cerebrospinal fluid (CSF) is blocked along one or more of the narrow passages connecting the ventricles.
Communicating Hydrocephalus
Also known as non-obstructive hydrocephalus, communicating hydrocephalus occurs when the flow of cerebrospinal fluid (CSF) is blocked after it exits the ventricles. This form is called communicating because the CSF can still flow between the ventricles, which remain open.
Normal Pressure Hydrocephalus (NPH)
This type only affects people ages 50 years or older. It may develop after a stroke or injury. As opposed to other types of hydrocephalus, NPH develops slowly due to the gradual blocking of CSF drainage, which subsequently causes slow fluid buildup over time. The enlarged ventricles then press on the brain and cause symptoms. These include dementia-like signs similar to Alzheimer’s disease, and walking difficulties that resemble Parkinson’s disease. That’s why the diagnosis is often problematic. The good news, however, is that, unlike those conditions, NPH can be resolved.
Since diagnosis is complicated by the fact that many people assume the symptoms of NPH (difficulty walking/gait disturbances, cognitive challenges/mild dementia, urinary urgency, or incontinence) are related to aging, it is important to recognize that those symptoms may be part of NPH, which is a treatable condition.
Hydrocephalus Ex-Vacuo
Hydrocephalus ex-vacuo occurs from brain damage caused by stroke or injury. In this condition, there may be an actual shrinkage of brain substance. Although there is more cerebrospinal fluid (CSF) than usual, and the ventricles are enlarged, the CSF pressure may or may not be elevated in hydrocephalus ex-vacuo.
This dilation of the cerebral ventricles, which is due to loss of brain tissue, is a common result of brain diseases such as leukodystrophies (a group of rare genetic disorders that affect the central nervous system), multiple sclerosis, multiple strokes, Alzheimer’s disease, Huntington’s disease, and other related diseases.
In adults, there are four different types; obstructive, communicating, hypersecretory, and normal pressure hydrocephalus (NPH). Congenital or developmental hydrocephalus is often present at birth and is often part of a genetic syndrome or spinal dysraphism.
Obstructive hydrocephalus develops from a block in CSF pathways. The obstruction most commonly occurs at the foramina Monro, the aqueduct of Sylvius, the fourth ventricle, and the foramen magnum, but most tumors with a significant size can obstruct at any point of CSF pathways. Some of the most frequent tumors associated with hydrocephalus are ependymoma, subependymal giant cell astrocytoma, choroid plexus papilloma, craniopharyngioma, pituitary adenoma, hypothalamic or optic nerve glioma, hamartoma, and metastatic tumors. Posterior fossa tumors are commonly associated with the development of hydrocephalus.
Communicating hydrocephalus is caused by impaired absorption of CSF. The most common causes are post-hemorrhagic or post-inflammatory changes. Subarachnoid hemorrhage accounts for one-third of these cases by blocking CSF absorption at the arachnoid granulations.[3] Meningitis, especially bacterial, can be complicated with hydrocephalus. Head trauma in the industrial world is a significant contributor to hydrocephalus in adulthood.
Hypersecretory hydrocephalus is caused by an overproduction of CSF, most likely due to plexus papilloma or rarely a carcinoma. These tumors are more common in children.
Normal-pressure hydrocephalus (NPH) is a type of communicating hydrocephalus with increased incidence in older age with a not fully understood pathogenesis. Impaired CSF dynamics cause it with a slight or no increase in intracranial pressure (ICP).[4]
Prognosis
The prognosis for hydrocephalus depends on the cause, the extent of symptoms, and the timeliness of diagnosis and treatment. Some patients show a dramatic improvement with treatment, while others do not. In some instances of normal pressure hydrocephalus, dementia can be reversed by shunt placement. Other symptoms, such as headaches, may disappear almost immediately if the symptoms are related to elevated pressure.
In general, the earlier hydrocephalus is diagnosed, the better the chance for successful treatment. The longer the symptoms have been present, the less likely it is that treatment will be successful. Unfortunately, there is no way to accurately predict how successful surgery will be for each individual. Some patients will improve dramatically, while others will reach a plateau or decline after a few months.
Shunt malfunction or failure may occur. The valve can become clogged or the pressure in the shunt may not match the needs of the patient, requiring additional surgery. In the event of an infection, antibiotic therapy may be needed, and likely temporary removal of the shunt and replacement by a drain until the infection clears. The shunt can then be re-implanted. A shunt malfunction may be indicated by headaches, vision problems, irritability, fatigue, personality change, loss of coordination, difficulty in waking up or staying awake, a return of walking difficulties, mild dementia, or incontinence. In infants, the symptoms of shunt malfunction can include the above as well as vomiting, inappropriate head growth, and/or sunsetting eyes. When a shunt malfunctions, surgery is often needed to replace the blocked or malfunctioning portion of the shunt system. Fortunately, most complications can be dealt with successfully.
Normal pressure hydrocephalus primarily affects people in their 60s and 70s. The Hydrocephalus Association estimates that nearly 700,000 adults have normal pressure hydrocephalus, but it is often misdiagnosed as Alzheimer’s or Parkinson’s disease. In fact, less than 20 percent of people with the disease are properly diagnosed.
Learn more: Key Types of Dementia
Few studies have explored the benefits of shunt insertion. Most of these studies were small and followed participants for a limited time. The SINPHONI-2 trial results, published in the June 2015 issue of Lancet, found that people with normal pressure hydrocephalus might benefit from lumboperitoneal shunt surgery but further studies need to be done to confirm the findings. Available data suggest that difficulty walking is the symptom most likely to improve. Several studies found a significant rate of postsurgical complications and also showed that the short-term benefits of shunt insertion tend to decline over time.
Does hydrocephalus ever go away?
Hydrocephalus is a chronic condition. It can be controlled, but usually not cured. With appropriate early treatment, however, many people with hydrocephalus lead normal lives with few limitations. Hydrocephalus can occur at any age but is most common in infants and adults age 60 and older.
Treatment
Hydrocephalus can be treated in a variety of ways. Based on the underlying etiology, the condition may be treated directly by removing the cause of CSF obstruction or indirectly by diverting the excess fluid. Hydrocephalus is most commonly treated indirectly by implanting a device known as a “shunt” to divert the excess CSF away from the brain. The shunt is a flexible tube that, along with a catheter and a valve, is placed under the skin to drain excess CSF from a ventricle inside the brain to another body cavity such as the peritoneal cavity (the area surrounding the abdominal organs).
Once inserted, the shunt system usually remains in place for the duration of a patient’s life (although additional operations to revise the shunt system are sometimes needed). The shunt system continuously performs its function of diverting the CSF away from the brain, thereby keeping the intracranial pressure within normal limits. In some cases, two procedures are performed, the first to divert the CSF and another at a later stage to remove the cause of obstruction (e.g. a brain tumor).
A limited number of patients can be treated with an alternative operation called endoscopic third ventriculostomy. In this procedure, a surgeon utilizes a tiny camera (endoscope) with fiber optics to visualize the ventricles and create a new pathway through which CSF can flow.
Neurological function will be evaluated after surgery. If any neurological problems persist, rehabilitation may be required to further improvement. However, recovery may be limited by the extent of the damage already caused by the hydrocephalus and by the brain’s ability to heal.
Because hydrocephalus is an ongoing condition, long-term follow-up by a doctor is required. Follow-up diagnostic tests, including CT scans, MRIs, and X-rays, help determine if the shunt is working properly. A physician should be contacted if any of the following postoperative symptoms are experienced:
-
-
- Redness, tenderness, pain, or swelling of the skin along the length of the tube or incision
- Irritability or drowsiness
- Nausea, vomiting, headache, or double vision
- Fever
- Abdominal pain
- Return of preoperative neurological symptoms
-
Normal pressure hydrocephalus can sometimes be treated with surgical insertion of a shunt, a long, thin tube that drains excess CSF from the brain to the abdomen. Surgery is most likely to help correct difficulties walking, but thinking changes and loss of bladder control are less likely to improve. Shunting doesn’t help everyone with normal pressure hydrocephalus, and there’s uncertainty about how best to identify those most likely to benefit. There’s also a lack of data showing how long the benefit of shunting may last for those whose symptoms improve.
Normal pressure hydrocephalus is one of the few causes of dementia that can be controlled or reversed with treatment. If symptoms and results from an evaluation and MRI point to normal pressure hydrocephalus, a high-volume spinal tap may be used to identify if an individual has the potential to benefit from the surgical insertion of a shunt. In this procedure, doctors remove a large amount of spinal fluid and observe the individual for 30 to 60 minutes, looking for any improvements in walking or thinking, and reasoning. Most people originally suspected of having normal pressure hydrocephalus do not improve following a cerebrospinal fluid removal test.
Researchers have not found effective nonsurgical treatments for normal pressure hydrocephalus. Drugs that remove excess fluid throughout the body, such as diuretics, don’t appear to improve symptoms of normal pressure hydrocephalus. More research is needed to:
-
-
-
-
- Understand the prevalence of normal pressure hydrocephalus.
- Show how the excess CSF involved in normal pressure hydrocephalus causes symptoms affecting movement, thinking, and bodily functions.
- Clarify the possible benefits and ideal targets of shunt insertion.
-
-
-
Arachnoid cysts
A brain cyst is a balloon-like sphere found in the brain. The most common—the arachnoid cyst—is full of cerebrospinal fluid. Other types can contain pus, hair follicles, or skin cells. They are not considered tumors, and are usually non-cancerous.
Arachnoid cysts are the most common type of brain cyst. They get their name from the arachnoid membrane that covers the brain and spinal cord. The cysts can occur in the brain or spinal canal. Arachnoid cysts affect approximately 3 in 100 people, but most will never know they have one because they often go undetected.
They are often congenital or present at birth (primary arachnoid cysts). Head injury or trauma can also result in a secondary arachnoid cyst. The cysts are fluid-filled sacs, not tumors.
Arachnoid cysts often have no symptoms and may go undetected for years if they remain small. When arachnoid cysts grow, they can apply pressure on the spinal cord, cranial nerve, or brain, which may cause symptoms.
If arachnoid cysts are not treated, they may cause serious, permanent nerve damage if the cyst(s) injures the brain or spinal cord. This can happen if the cyst(s) get larger or if there is bleeding into the cyst. Treating the symptoms of arachnoid cysts usually makes the symptoms go away or improve.
Arachnoid cyst symptoms may include:
-
-
-
- Headaches
- Nausea
- Dizziness
- Vision problems
- Impaired balance
- Behavior problems
- Impaired brain function
-
-
-
-
-
- bleeds or oozes.
- changes color.
- grows quickly.
- itches.
- ruptures.
- looks red or swollen.
-
-
When symptoms do occur, they depend on the location and size of the arachnoid cyst and what brain regions it presses against, affecting function.
DIAGNOSIS
Many times, arachnoid cysts are found incidentally, when a child has a test such as an MRI or CT scan for another reason like head trauma.
While most cysts can be monitored clinically, there are times when the cyst grows and treatment becomes necessary. Because an arachnoid cyst is a fluid-filled sac, the goal in treatment is to fenestrate or create very small openings, in the wall of the cyst so the fluid can drain into a location where the body has built-in abilities to re-absorb the fluid. This procedure relieves the pressure that is created by the cyst and alleviates symptoms.
-
-
- Endoscopic fenestration ‒ At CHOC, our doctors typically use a minimally invasive procedure called endoscopic fenestration. Endoscopic tools are inserted through a small incision into the cyst. Holes are created in the wall of the cyst, allowing the liquid to drain and safely absorb into the brain.
- Craniotomy ‒ In cases where an endoscopic procedure isn’t successful, a small craniotomy may be performed, in which a small part of the skull is removed and the wall of the cyst is opened up so that the fluid can drain.
- Shunt – When endoscopy or craniotomy is unsuccessful, which is rare, a shunt may be inserted with tubing that runs beneath the skin and allows the fluid to drain and be absorbed by the abdominal wall.
-
Arachnoid cyst recovery and follow-up care
Depending on the course of treatment, you will likely have follow-up visits with your child’s doctor at CHOC. CHOC will follow your child throughout their life, from birth to surgery to recovery and beyond, with regular checkups to ensure the best possible outcome for your child.
-
-
-
- Soak a clean towel or washcloth in warm water.
- Wring the water from the cloth.
- Place it gently on the cyst. Leave it in place for up to 10 minutes.
- Repeat the treatment 3–4 times each day, using a clean washcloth each time.
-
-
Other brain cysts in children
Besides arachnoid cysts, there are several other types of brain cysts that can commonly occur in children. These include colloid and dermoid cysts:
-
-
- Colloid cysts ‒ These cysts likely begin during fetal growth as part of the development of the central nervous system but often do not present any symptoms until later in life. These cysts are filled with gelatinous material and can cause headaches, nausea, or excessive cerebrospinal fluid, known as hydrocephalus.
- Dermoid and epidermoid cysts ‒ Dermoid cysts occur when skin and related cells become trapped during development. They may occur on the brain, but can also be found elsewhere in the body. These cysts often contain hair follicles, cartilage, or glands.
-
They are fluid-filled cysts that form from a hair follicle and usually develop on the scalp.
References: 
