Hydrocephalus & Infant Brain Damage
Hypoxia and brain trauma can lead to bleeding inside brain ventricles, which can cause ventricular swelling due to excessive cerebrospinal fluid (CSF). This damages white matter in the brain and impairs the growth of the cerebral cortex, significantly impacting memory, attention, perception, thought, language, and consciousness. Hydrocephalus occurs as a secondary result of other brain injuries. This brain damage occurs in a feedback loop to cause more damage. This is usually treated using a shunt system to relieve pressure on the brain from CSF.
Babies are often admitted to the NICU when they show signs of brain injury. Permanent damage to a baby’s brain can occur when a baby experiences a lack of oxygen (hypoxia), head trauma, or other complications around the time of birth. Brain trauma in turn can lead to bleeding inside brain ventricles (intraventricular hemorrhage), which can cause ventricular swelling due to an excess of cerebrospinal fluid (CSF). This type of newborn injury is called hydrocephalus.
Ventricular Injury in Hydrocephalus
The brain has four ventricles. The walls of each ventricle have a structure called a choroid plexus, which constantly produces cerebrospinal fluid (CSF). This liquid acts as a shock absorber for the brain and spinal cord tissue, protecting them from impacts. Cerebrospinal fluid circulates from the ventricles through the brain and spinal cord. It is eventually reabsorbed back into the blood.
Normally, the volume of CSF being absorbed is equal to the volume being produced. Hydrocephalus occurs when this normal circulation is blocked (i.e. when the outflow of CSF into the brain does not match the inflow of CSF). Usually, this is because CSF is not adequately absorbed, or because the circulation of CSF is blocked in some way. This causes CSF to build up in the ventricles (or in the subarachnoid space, an area near the ventricles) instead of being reabsorbed normally.
There are two types of hydrocephalus:
- Communicating hydrocephalus, in which something outside the ventricular system obstructs CSF flow.
- Obstructive hydrocephalus, in which an obstruction within the ventricular system itself obstructs CSF flow.
These CSF imbalances are caused by insults to the brain (like oxygen deprivation, trauma, or infection) that cause brain swelling. While the initial swelling may subside, the injury can damage the ventricles, either by directly damaging the tissues that reabsorb CSF or indirectly by causing a blockage. Since the body is constantly making CSF, any delayed absorption or obstruction results in fluid buildup and ventricular swelling. This leads to pressure on surrounding brain matter, pushing aside the soft tissue of the brain and leading to further brain damage.
The progression of hydrocephalus is as follows:
- IVH (or other brain insult)
- Disturbance in CSF dynamics
- Swelling of the ventricles
Intracranial Pressure and Hydrocephalus
When CSF builds up, the pressure inside the baby’s head increases (intracranial pressure), causing the ventricles to get bigger. The ventricles then press up against other parts of the baby’s brain. In many cases, the increased pressure can make the baby’s head enlarged.
In cases of hydrocephalus, the CSF must be drained, or the baby’s brain may become permanently damaged. Built-up CSF can put pressure on the baby’s delicate brain structures, causing white and grey matter damage, gliotic scarring, and brain tissue damage. Improperly treated hydrocephalus can cause disabilities, including seizures, cerebral palsy, and developmental delays.
Which babies are at risk for hydrocephalus?
Preterm babies are more susceptible to hydrocephalus. This is because preterm babies have fragile brains and blood vessels that are more susceptible to brain bleeds, one of the main factors that can trigger hydrocephalus. Conditions that can cause IVH include:
- Hypoxic-ischemic encephalopathy (HIE)
- Trauma from prolonged labor, macrosomia, face or breech presentation, cephalopelvic disproportion, or the improper use of forceps or vacuum extractors
- Brain infections
- Intrauterine infections (such as syphilis, CMV, rubella, or toxoplasmosis)
- Subarachnoid hemorrhage (described here)
- Germinal matrix hemorrhage (a type of brain bleed seen primarily in preterm babies)
- Misuse of Pitocin or Cytotec during labor
How Does Hydrocephalus Damage a Baby’s Brain?
Germinal Matrix Hemorrhage (GMH) and Hydrocephalus
Hypoxia (a lack of oxygen to the baby’s brain) or other brain injuries can cause brain bleeds into the ventricles (intraventricular hemorrhage, or IVH). Premature babies are especially susceptible to IVH because their brains are fragile. In premature babies, one type of IVH is called a germinal matrix hemorrhage (GMH), also known as a periventricular-intraventricular hemorrhage. Generally, GMHs are benign unless they grow very large. GMH is the most common cause of acquired hydrocephalus in babies.
The germinal matrix is a key component of brain growth in the fetus – cells develop and grow out of the germinal matrix as the brain develops. In GMH, there is bleeding into the part of the germinal matrix that connects the the lateral ventricles. As bleeding continues, there can be rupture into the lateral ventricles; the ventricles fill with blood and other cellular products, which cause them to swell.
Mechanisms of Damage in Hydrocephalus
Hydrocephalus and brain damage can occur due to:
- The front and back horns of the ventricles typically enlarge most and enlarge first, causing uneven ventricle dilation. This enlargement disrupts the ventricles’ lining, allowing CSF to move directly into brain tissue. This reduces CSF pressure significantly, but it also leads to fluid leaking into the spaces between the membranes that cover the brain. This progressively damages white matter.
- Accumulated CSF can directly damage the brain’s white matter (WM) by penetrating the WM tissues that surround the ventricles (periventricular brain tissue). When CSF penetrates these tissues, it decreases blood flow to those areas, causing ischemia and tissue damage.
- With further progression, the membrane that covers the brain can become obliterated over the brain hemispheres. The gray brain matter at the cortex may be reduced, but gray matter is better preserved than white matter. This eventually leads to vascular system compression, and pressure in the veins increasing in certain areas.
- As hydrocephalus progresses, blood vessels in the brain weaken, compromising blood supply to critical areas. Damage to the white matter is also caused by changes in cells that are part of the central nervous system.
Why Is It Important to Treat Hydrocephalus Promptly?
Treatment of hydrocephalus must occur immediately because hydrocephalus can cause injury to blood vessels in the brain, damage white matter, and impair the growth of the cerebral cortex (the outer layer of neural tissue, or gray matter, which plays a critical role in thinking, attention, memory, perceptual awareness, language, and consciousness). White matter is important because it helps transmit messages throughout the largest part of the brain and is more commonly damaged than gray matter. Damage to the white and gray matter, along with delayed diagnosis of hydrocephalus, can cause:
- Cerebral palsy
- Developmental delays that affect reasoning, memory, speech, or other learning and communication abilities.
How Is Hydrocephalus Diagnosed?
Babies are sometimes diagnosed with hydrocephalus in utero. This can be detected using ultrasound at or after 24 weeks of gestation. After 32-34 weeks of gestation, the baby’s head size begins to increase as ventricular dilation increases.
In other cases, hydrocephalus is detected only once a baby is born. The following infants should have frequent head measurements and be checked for hydrocephalus:
- Babies with a larger-than-normal head circumference at birth
- Babies whose head measurements after birth indicate excessive head growth
- Babies with a traumatic birth
- Babies born prematurely
- Babies with increased intracranial pressure
If a baby’s hydrocephalus is due to birth trauma or birth asphyxia, hydrocephalus usually begins 1-3 weeks after the baby is born. Babies at risk for brain bleeds should have routine (serial) ultrasounds performed by and on day 5 of life, since most cases of IVH occur within the first 5 days of life.
If the baby has symptoms of brain bleeds, like IVH, medical staff should confirm the brain bleed using head imaging (although treatment of IVH usually should begin prior to confirmation). Once IVH is diagnosed, routine head imaging should continue in order to identify potential hydrocephalus, its progression, and distinguish between obstructive vs. communicating hydrocephalus to help guide medical providers in making medical decisions. Usually, head imaging takes the form of an ultrasound (which cannot be used once the anterior fontanelle closes), but MRIs are the most accurate way to image the brain.
If the baby has signs or symptoms of hydrocephalus, head imaging must be immediately performed.
Cerebral angiography, CSF analysis, an EEG and an external pressure transducer that measures the baby’s intracranial pressure are all tools that can assist in the diagnosis of hydrocephalus.
What Are the Symptoms of Hydrocephalus?
When birth trauma results in hydrocephalus, evidence of fluid buildup may be present within days. Possible signs and symptoms can include:
- Puffiness/swelling at the temples, the bridge of the nose, or around the eyes
- Enlarged head (sign of increased intracranial pressure)
- Abnormally fast head growth
- Inability to look upward
Rapid head growth occurs in an attempt to decrease pressure on the brain. In babies, the bones of the skull are not yet fused, so the head can stretch and grow in an attempt to decrease the pressure in the brain.
Long-Term Outcomes of Hydrocephalus
Outcomes of hydrocephalus can vary. If hydrocephalus is diagnosed early and treated quickly, long-term problems can be avoided. The severity of the effects of hydrocephalus depend on several factors:
- The cause of the hydrocephalus
- How severe fluid buildup is
- How the baby responds to treatment
- How quickly treatment is instituted
If left untreated, hydrocephalus can cause a compressed brain stem, which can stop a baby’s breathing and/or heartbeat. Hydrocephalus can also cause cerebellum compression, which may lead to problems with swallowing, speaking, and breathing, or it can cause cerebral palsy in fetuses or infants.
Legal Help for Hydrocephalus and Birth Injuries
If your child has a condition such as a seizure disorder, cerebral palsy, or developmental delays due to a birth injury like hydrocephalus, call the law offices of Reiter & Walsh ABC Law Centers for a free consultation. We focus solely on birth injury – unlike other firms that say they take on birth injury cases, but amid caseloads of dog bites, medical device malfunctions, and car accidents.
Birth injury is a complex field that requires deep content knowledge of birth injury, medicine, law, and life care planning. The birth injury attorneys at Reiter & Walsh ABC Law Centers have over 100 years of combined experience in birth injury, and would be happy to speak with you and your family about pursuing a case.
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