Brain & Nervous System What Is Hydrocephalus? "Water" or, Rather, Cerebrospinal Fluid on the Brain By Colleen Doherty, MD Colleen Doherty, MD Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis. Learn about our editorial process Published on January 05, 2023 Medically reviewed by Lyndsey Garbi, MD Medically reviewed by Lyndsey Garbi, MD LinkedIn Lyndsey Garbi, MD, is a pediatrician who is double board-certified in pediatrics and neonatology. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Types Symptoms Causes Diagnosis Treatment Prognosis Hydrocephalus is the buildup of cerebrospinal fluid (CSF) within the brain's hollow spaces (ventricles). The excessive fluid increases pressure inside the skull, affecting the brain's ability to function normally. CSF is a clear fluid that bathes and cushions the brain, protecting and providing it with vital nutrients. CSF flows around the spinal cord and through the brain's ventricles before being reabsorbed into the bloodstream. This article reviews key facts about hydrocephalus, including its types, symptoms, causes, diagnosis, treatment, and outlook. undefined undefined / Getty Images Types of Hydrocephalus Hydrocephalus can occur at any age but is most common in babies and older adults. The two main types are: Noncommunicating (obstructive) hydrocephalus develops when a blockage occurs along one or more of the passages connecting the ventricles. As a result, CSF cannot flow freely among the ventricles.Communicating hydrocephalus occurs when CSF cannot adequately be reabsorbed into the bloodstream. It's called "communicating" because the CSF can still flow normally within the ventricles. Hydrocephalus is also sometimes categorized as congenital or acquired hydrocephalus. Congenital hydrocephalus is present at birth, whereas acquired hydrocephalus develops after birth. The following two forms of acquired hydrocephalus can develop in adults: Normal pressure hydrocephalus (NPH) is a communicating hydrocephalus that can strike at any age but is more common in adults 60 or older. It's characterized by widened ventricles but normal CSF pressure. Hydrocephalus ex vacuo is usually seen in older individuals. It develops when the brain tissue surrounding the ventricles shrinks. CSF volume increases within the ventricles to try and fill the extra space. Hydrocephalus Symptoms Hydrocephalus symptoms often occur due to increased pressure within the skull (increased intracranial pressure). In congenital hydrocephalus, symptoms may include: A head that is larger than normal A bulge at the soft spot on top of the head (fontanelle) Eyes that stay looking down Vomiting Problems feeding Sleepiness or unusual fussiness Seizures In older children and adults, hydrocephalus symptoms include: Headache (usually worse when lying down, coughing, or having a bowel movement) Vision problems (e.g., double vision) Nausea or vomiting Poor balance or coordination Drowsiness Loss of previously acquired skills (e.g., walking) Change in personality or behavior There are also symptoms specific to the type of hydrocephalus, especially regarding normal pressure hydrocephalus. The three hallmark symptoms of NPH include: Gait (manner of walking) disturbance: People move slowly with a broad base. They often have trouble picking up their feet, as if they were glued to the ground. Mild dementia: Diminished concentration, short-term memory loss, and apathy (a lack of emotion) may occur. Bladder dysfunction: A strong urge to urinate (urgency), an increased need to urinate (frequency), and in severe cases, loss of bladder control (urinary incontinence) can develop. Causes Hydrocephalus has many potential causes, depending on the type. Congenital hydrocephalus can be caused by inherited genetic abnormalities or developmental disorders affecting the brain's CSF flow. Acquired hydrocephalus in babies is most commonly caused by a brain bleed, often due to prematurity. Other causes of hydrocephalus in babies include: Brain tumor or infection, usually bacterial meningitis (infection of the membranes that surround the brain/spinal cord) Unrecognized infections during pregnancy (e.g., cytomegalovirus (CMV) or toxoplasmosis) Exposure to certain medications during pregnancy (e.g., misoprostol) Normal pressure hydrocephalus may be caused by a brain bleed or tumor, head trauma, or meningitis. In around half of NPH cases, the cause remains unknown. Hydrocephalus ex-vacuo is usually caused by a stroke or an injury to the brain. It may also occur in older individuals whose brain shrinks with age or in those with Alzheimer's disease. Diagnosis The diagnosis of hydrocephalus starts with a detailed medical history and neurological exam. Imaging tests and a spinal tap are also vital diagnostic tools. In some cases, intracranial pressure monitoring may be required. Imaging Tests The type of imaging test used to evaluate hydrocephalus depends on the age of the patient: An ultrasound is used for newborns or young infants to take brain pictures. Fetal ultrasound is used to detect hydrocephalus before birth. More advanced brain imaging tests, such as computed tomography (CT) scan or magnetic resonance imaging (MRI), are used for older children or adults. MRI: Preferred Diagnostic Test for Hydrocephalus An MRI is often the preferred test for diagnosing hydrocephalus. Using magnetic fields and radio waves, an MRI can help assess CSF flow and reveal whether the ventricles are enlarged. Spinal Tap A spinal tap (lumbar puncture) is performed in a healthcare provider's office or a hospital. A thin needle is placed into the person's lower back. The pressure of the CSF is measured, and then up to 50 cubic centimeters (cc) of CSF is removed for analysis. Spinal taps can also be therapeutic because they often temporarily relieve a person's hydrocephalus symptoms. Intracranial Pressure Monitoring In some cases, such as after severe head trauma, intracranial pressure (ICP) monitoring may be used to detect and measure CSF pressure. ICP monitoring is performed in the hospital by a neurosurgeon (a surgeon who treats nervous system conditions). It requires the placement of a catheter (a thin tube) through the skull into the brain. The catheter measures the CSF pressure. If the pressure gets too high, the CSF may need to be drained to ensure adequate oxygenation to the brain. Treatment Hydrocephalus is a serious condition that is treated with brain surgery. That said, surgery is not a cure. Instead, it helps relieve symptoms and lower the pressure in the skull. Ommaya Reservoir An Ommaya reservoir is a device that's implanted under the skin of the scalp and attached to a catheter that extends into a brain ventricle. This allows CSF to be aspirated from the reservoir rather than by lumbar puncture. Shunt surgery may still required after initially managing hydrocephalus with an Ommaya reservoir. Shunt Surgery The most common surgery for hydrocephalus involves placing a shunt (a thin, hollow tube) to reroute the extra CSF away from the brain, lowering the pressure within the skull. During shunt surgery, a neurosurgeon places the shunt through an opening in the skull into the ventricle. The shunt tubing is then passed under the skin into another area of the body (usually the abdominal cavity), where the CSF drains. Are Shunts Permanent? Shunts often remain in place for the duration of a person's life, but that is not always necessary. Additional shunt surgery may be needed if the shunt malfunctions. Children with hydrocephalus who receive a shunt will need multiple surgeries over their lifetime as they grow. Endoscopic Third Ventriculostomy Sometimes, a surgery called endoscopic third ventriculostomy is performed. During this surgery, an endoscope (a long, thin device attached to a tiny camera) and special surgical tools inserted through the endoscope are used to make a small hole in the brain's third ventricle. This hole creates a pathway for the excess CSF to flow in and around the brain. Prognosis The outlook for those living with hydrocephalus depends on factors like the hydrocephalus cause, severity, type of symptoms, and promptness of treatment. As an example, after shunt placement, adults with normal pressure hydrocephalus may notice an improvement in their cognitive (thinking and memory) skills, walking, and bladder problems within days after surgery. Others may not experience improvement for weeks or months. For some people, one or more symptoms may persist or recur. Ultimately, there is no way to predict precisely how beneficial surgery will be for anyone. Generally speaking, though, the sooner hydrocephalus is diagnosed and treated, the better the chances for a successful outcome. Ongoing Care for Children With Hydrocephalus Children with hydrocephalus may experience delays in reaching milestones like sitting, crawling, standing, walking, and talking. Early rehabilitation therapy can help children improve, adapt, and cope with development or physical impairments. Summary Hydrocephalus is associated with the abnormal buildup of cerebrospinal fluid within the brain's ventricles. Babies with hydrocephalus may have unusually large heads. Older children and adults typically develop symptoms like headaches and vision problems. The diagnosis of hydrocephalus involves a brain imaging test, like an ultrasound or MRI. Treatment consists of brain surgery, typically placing a shunt in the brain to drain the excess CSF. A Word From Verywell Hydrocephalus is a complex, lifelong condition. The upside is that a good, if not great, recovery is possible with early diagnosis and treatment. If you or a loved one are being treated for hydrocephalus, consider seeking support from an organization like Hydrocephalus Association. Support resources, whether a helpline, community network, or pen pal program for children, can be a tremendous source of comfort and emotional guidance. 9 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. National Institute of Neurological Disorders and Stroke. Hydrocephalus fact sheet. American Association of Neurological Surgeons. Adult-onset hydrocephalus. National Organization of Rare Diseases. Hydrocephalus. Tully HM, Dobyns WB. Infantile hydrocephalus: a review of epidemiology, classification and causes. Eur J Med Genet. 2014;57(8):359-68. doi:10.1016/j.ejmg.2014.06.002 Auffret M, Bernard-Phalippon N, Dekemp J, et al. Misoprostol exposure during the first trimester of pregnancy: Is the malformation risk varying depending on the indication? Eur J Obstet Gynecol Reprod Biol. 2016;207:188-192. doi:10.1016/j.ejogrb.2016.11.007 Oliveira LM, Nitrini R, Román GC. Normal-pressure hydrocephalus: a critical review. Dement Neuropsychol. 2019;13(2):133-143. doi:10.1590/1980-57642018dn13-020001 Palpan Flores A, Saceda Gutiérrez J, Brin Reyes JR, Sierra Tamayo J, Carceller Benito F. Risk factors associated with conversion of an Ommaya reservoir to a permanent cerebrospinal fluid shunt in preterm posthemorrhagic hydrocephalus. J Neurosurg Pediatr. 2020:1-8. doi:10.3171/2019.11.PEDS19320 Giordan E, Palandri G, Lanzino G, Murad MH, Elder BD. Outcomes and complications of different surgical treatments for idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis. J Neurosurg. 2018:1-13. doi:10.3171/2018.5.JNS1875 Tully HM, Ishak GE, Rue TC, et al. Two hundred thirty-six children with developmental hydrocephalus: causes and clinical consequences. J Child Neurol. 2016;31(3):309-320. doi:10.1177/0883073815592222 By Colleen Doherty, MD Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis. 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