Hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up within the fluid-filled cavities (ventricles) of the brain. When cerebrospinal fluid builds up around the brain, it can cause damaging pressure on the brain tissues within the skull.
There are several categories of hydrocephalus:
- Congenital hydrocephalus
- Acquired hydrocephalus
- Develops at birth or in adulthood
- Usually caused by injury or disease
- Communicating hydrocephalus
- Occurs when there is unobstructed flow of cerebrospinal fluid (CSF) within the ventricular system
- Caused by inadequate absorption or due to an abnormal increase in the quantity of CSF produced
- Normal pressure hydrocephalus
- A form of communicating hydrocephalus
- Can develop at any age, but occurs most commonly in the elderly
- Characterized by dilated ventricles with normal pressure within the spinal column
- Non-communication (obstructive) hydrocephalus
- Occurs when the flow of CSF is blocked along a passage connecting the ventricles, resulting in enlargement of the pathways upstream of the block and an increased pressure within the skull
- Hydrocephalus ex-vacuo
- Mostly affects adults and occurs when a degenerative disease damages the brain and may cause brain tissue to shrink
Symptoms of hydrocephalus can vary depending on the individual and their age.
Symptoms of hydrocephalus in infants may include:
- Head of unusually large size
- Rapidly increasing head circumference
- Bulging and tense fontanelle or soft spot
- Prominent scalp veins
- Eyes looking downward (sunset sign)
- Sleepiness
- Vomiting
- Irritability
- Seizures
Symptoms of hydrocephalus in children and adolescents may include:
- Nausea and vomiting
- Blurred or double vision
- Optic disc swelling (papilledema)
- Balance and gait abnormalities
- Personality changes
- Slowing or loss of developmental progress
- Difficulty concentrating
- Poor appetite
- Urinary incontinence
- Seizures
Symptoms of hydrocephalus in adults may include:
- Headache
- Nausea and vomiting
- Loss of balance or coordination
- Problems walking or gait disturbances
- Frequent falls
- Lethargy
- Vision changes
- Bladder incontinence
- Impaired cognitive skills
- Memory loss
- Mild dementia
What Causes Hydrocephalus?
The causes of hydrocephalus are not always understood. Sometimes the disorder is present at birth, and other times it may develop in childhood or adulthood.
Hydrocephalus present at birth (congenital hydrocephalus) may be caused by certain conditions, such as:
- Spina bifida
- Premature birth, before 37 weeks
- Bleeding in the brain
- A mutation of the X chromosome (X-linked hydrocephalus)
- Rare genetic disorders, such as Dandy Walker malformation
- Arachnoid cysts
Hydrocephalus that develops in children and adults (acquired hydrocephalus) may be caused by:
- Bleeding inside the brain (subarachnoid hemorrhage)
- Blood clots in the brain (venous thrombosis)
- Meningitis
- Brain tumors
- Head injury
- Stroke
- Some people may also be born with narrowed passageways in the brain that restrict the flow of cerebrospinal fluid, but that do not cause symptoms until years later
Hydrocephalus that develops in older people may be caused by:
- Brain injury
- Bleeding in the brain
- Infection
- Other underlying health conditions that affect normal blood flow
How Is Hydrocephalus Diagnosed?
If hydrocephalus is suspected, it is diagnosed with a patient history and physical examination. A neurological examination is also performed along with tests such as:
- Computed tomography scan (CT) scan
- Magnetic resonance imaging (MRI) scan
- Lumbar puncture (spinal tap)
- Intracranial pressure monitoring
- Isotope cisternography
What Is the Treatment for Hydrocephalus?
Treatment for hydrocephalus depends on the underlying cause. It is most commonly treated by removing the cause of cerebrospinal fluid (CSF) obstruction or indirectly by diverting the excess fluid with an implanted device called a shunt that diverts the excess CSF away from the brain, into another body cavity such as the peritoneal cavity (the area surrounding the abdominal organs). A shunt usually remains in place for life although revision surgeries to the shunt may be needed.
Some patients may be treated with a procedure called an endoscopic third ventriculostomy in which a tiny camera (endoscope) is used to visualize the ventricles and create a new pathway through which CSF can flow.
If there is an obstruction such as a brain tumor, that may be removed when possible.
From 
Brain and Nervous System Resources
Image source: iStock Images
https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Hydrocephalus https://www.nhs.uk/conditions/hydrocephalus/causes/