Hydrocephalus Birth Injuries
Hydrocephalus is a very serious type of infant brain injury in which the ventricle spaces inside the brain become flooded by a backup of cerebrospinal fluid (CSF).
Hydrocephalus can occur in adults but it is most common in newborn infants who experience some type of external trauma to the head during childbirth. Hydrocephalus in newborns is typically attributable to a specific event that caused the birth injury. In older patients, the cause is often more difficult to ascertain. The focus of this page is birth injuries from hydrocephalus.
Hydrocephalus means "water in the brain" ("hydro" is a Greek word for water and "cephalus" refers to the head). Hydrocephalus is a medical condition that occurs when cerebrospinal fluid (CSF) becomes blocked and starts to build up within the brain eventually flooding into the ventricle cavities. So a child with hydrocephalus will have a pressure difference from the ventricles and a space exterior to the brain.
CSF is a vital fluid that is constantly produced inside the ventricles of the brain. As the CSF is produced it gets released from the ventricles and it is supposed to circulate down to the spinal cord before getting absorbed into the blood. Hydrocephalus occurs when this normal outflow of CSF from the brain down to the spine gets blocked.
The blockage prevents the release of CSF but the brain continues to produce it so it begins to back up, like water in a clogged plumbing system. As the CSF accumulates it eventually floods into the brain ventricles. The flooding within the ventricles creates internal outward pressure inside the brain which can cause devastating internal damage.
Hydrocephalus is usually a birth injury resulting from external head trauma during delivery. This can often be caused by forceps or a vacuum during childbirth. It can also be caused by a congenital defect. Congenital hydrocephalus is triggered by a developmental abnormality that occurs during fetal growth and can be passed genetically.
The most common abnormalities that cause congenital hydrocephalus is aqueductal stenosis. Abnormalities that can trigger congenital hydrocephalus can sometimes be diagnosed during pregnancy. When properly diagnosed these conditions can be managed so good prenatal care is an important preventative measure. When hydrocephalus is the result of head trauma (or another perinatal event) during labor and delivery, it is often described as "acquired" rather than congenital.
Whether acquired or congenital, hydrocephalus is classified into one of two different types based on exactly where the cerebrospinal fluid is being blocked within its circulatory path:
- Communicating Hydrocephalus: communicating hydrocephalus (also called "non-obstructive") occurs when the CSF circulation is being blocked somewhere outside of the brain.
- Non-Communicating Hydrocephalus: when the outflow of CSF is blocked inside the brain and ventricles, the condition is classified as non-communication or "obstructive" hydrocephalus.
A positive cisternogram may be an indication of active hydrocephalus. A cisternogram looks at the spinal fluid flow surrounding the spinal cord.
The most common developmental abnormality that causes congenital hydrocephalus is aqueductal stenosis. It occurs when the narrow pathway connecting the 4th and 3rd ventricles (called the aqueduct of Sylvius) becomes compressed and blocked. The compression is usually the result of either an infection or a tumor. A neural tube defect is another common cause of congenital hydrocephalus. This occurs when the spinal cord is exposed during fetal development and CSF leaks out.
Acquired hydrocephalus is caused by external trauma or another event that occurs during labor and delivery that triggers a blockage of normal CSF flow and absorption. External trauma to the head during a difficult vaginal delivery is the leading cause of acquired hydrocephalus.
When the baby's delicate head is subjected to excessive pressure during childbirth it can rupture blood vessels and cause swelling within the. The internal inflammation in the brain can obstruct pathways and block or restrict the outflow of CSF. The blockage causes a buildup of CSF that eventually floods into the ventricles.
Hydrocephalus can also be caused by intraventricular hemorrhage which occurs when blood vessels around the brain ventricles rupture and block CSF flow. This frequently occurs in premature babies with underdeveloped blood vessels.Hydrocephalus Treatment and Prognosis
Sadly there is no effective cure or treatment for hydrocephalus and it is often difficult to prevent. But it is important to get the baby to a pediatric neurosurgeon as soon as possible after the diagnosis of intracerebral bleed, hydrocephalus, or increased intracranial pressure is made. When an early diagnosis is made, surgery is an option for the treatment of hydrocephalus.
The surgery is complex. The goal is to clear the blockage of CSF. This will hopefully restore normal circulation of the fluid out of the brain. This is typically accomplished by surgically implanting a ventriculoperitoneal shunt inside the head. Any type of major brain surgery like this is always a difficult and very high risk. But this is particularly true for newborn infants.
There are a host of potential post-surgical complications. The biggest risk is probably infection. You are putting in plastic tubing in the brain which risks introducing bacteria into the bloodstream. Another great risk is that, like any foreign object, the immune system attacks it and so it can become clogged. So the life expectancy on the shunt is about 4 or 5 years, with a 30% risk of failure in the first year.
The bottom line is that this is dangerous surgery fraught with perils. But a successful surgery might prevent the permanent destruction of the periventricular white matter that is so important for the child's development.
In sum, hydrocephalus is an extremely dangerous medical condition that can be potentially fatal. The internal pressure caused by a buildup of CSF within the brain can do extensive internal damage as well as disrupt normal brain development. Hydrocephalus is also a progressive condition which means it can and often does get worse over time. If left undiagnosed and untreated, the pressure within the brain from hydrocephalus can cause damage that can lead to to cause seizures, cognitive and physical delays, and death.