The signs and symptoms of hydrocephalus vary somewhat by age of onset.

Infants

Common signs and symptoms of hydrocephalus in infants include:

Changes in the head

• An unusually large head
• A rapid increase in the size of the head
• A bulging or tense soft spot (fontanel) on the top of the head

Physical signs and symptoms

• Vomiting
• Sleepiness
• Irritability
• Poor feeding
• Seizures
• Eyes fixed downward (sunsetting of the eyes)
• Deficits in muscle tone and strength
• Poor responsiveness to touch
• Poor growth

Toddlers and older children

Among toddlers and older children, signs and symptoms may include:

Physical signs and symptoms

• Headache
• Blurred or double vision
• Eyes fixed downward (sunsetting of eyes)
• Abnormal enlargement of a toddler's head
• Sleepiness or lethargy
• Nausea or vomiting
• Unstable balance
• Poor coordination
• Poor appetite
• Seizures
• Urinary incontinence

Behavioral and cognitive changes

• Irritability
• Change in personality
• Decline in school performance
• Delays or problems with previously acquired skills, such as walking or talking

Young and middle-aged adults

Common signs and symptoms in this age group include:

• Headache
• Lethargy
• Loss of coordination or balance
• Loss of bladder control or a frequent urge to urinate
• Impaired vision
• Decline in memory, concentration and other thinking skills that may affect job performance

Older adults

Among adults 60 years of age and older, the more common signs and symptoms of hydrocephalus are:

• Loss of bladder control or a frequent urge to urinate
• Memory loss
• Progressive loss of other thinking or reasoning skills
• Difficulty walking, often described as a shuffling gait or the feeling of the feet being stuck
• Poor coordination or balance

Hydrocephalus is caused by an imbalance between how much cerebrospinal fluid is produced and how much is absorbed into the bloodstream.

Cerebrospinal fluid is produced by tissues lining the ventricles of the brain. It flows through the ventricles by way of interconnecting channels. The fluid eventually flows into spaces around the brain and spinal column. It's absorbed primarily by blood vessels in tissues near the base of the brain.

Cerebrospinal fluid plays an important role in brain function by:

• Keeping the brain buoyant, allowing the relatively heavy brain to float within the skull
• Cushioning the brain to prevent injury
• Removing waste products of the brain's metabolism
• Flowing back and forth between the brain cavity and spinal column to maintain a constant pressure within the brain — compensating for changes in blood pressure in the brain

Excess cerebrospinal fluid in the ventricles occurs for one of the following reasons:

• Obstruction. The most common problem is a partial obstruction of the normal flow of cerebrospinal fluid, either from one ventricle to another or from the ventricles to other spaces around the brain.
• Poor absorption. Less common is a problem with the mechanisms that enable the blood vessels to absorb cerebrospinal fluid. This is often related to inflammation of brain tissues from disease or injury.
• Overproduction. Rarely, cerebrospinal fluid is created more quickly than it can be absorbed.

In many cases, the exact event leading to hydrocephalus is unknown. However, a number of developmental or medical problems can contribute to or trigger hydrocephalus.

Newborns

Hydrocephalus present at birth (congenital) or shortly after birth may occur because of any of the following:

• Abnormal development of the central nervous system that can obstruct the flow of cerebrospinal fluid
• Bleeding within the ventricles, a possible complication of premature birth
• Infection in the uterus during a pregnancy, such as rubella or syphilis, that can cause inflammation in fetal brain tissues

Other contributing factors

Other factors that can contribute to hydrocephalus among any age group include:

• Lesions or tumors of the brain or spinal cord
• Central nervous system infections, such as bacterial meningitis or mumps
• Bleeding in the brain from a stroke or head injury
• Other traumatic injury to the brain

Long-term complications of hydrocephalus can vary widely and are often difficult to predict.

If hydrocephalus has progressed by the time of birth, it may result in significant intellectual, developmental and physical disabilities. Less severe cases, when treated appropriately, may have few, if any, serious complications.

Adults who have experienced a significant decline in memory or other thinking skills generally have poorer recoveries and persistent symptoms after treatment of hydrocephalus.

The severity of complications depends on:

• Underlying medical or developmental problems
• Severity of initial symptoms
• Timeliness of diagnosis and treatment