Post-hemorrhagic hydrocephalus (PHH) is a neurological condition that primarily affects infants, particularly those born prematurely. It develops when there is an abnormal accumulation of cerebrospinal fluid (CSF) within the brain’s ventricles following a brain hemorrhage. This buildup of fluid can exert pressure on surrounding brain tissue, potentially leading to damage.
Understanding Post-Hemorrhagic Hydrocephalus
Hydrocephalus is an excess of cerebrospinal fluid (CSF) in the brain’s ventricles. The brain and spinal cord are bathed in CSF, a clear fluid that cushions the brain, delivers nutrients, and removes waste. This fluid is continuously produced within the ventricles, a connected system of four fluid-filled chambers deep within the brain.
Normally, CSF flows through these ventricles and then circulates around the brain and spinal cord before being reabsorbed into the bloodstream. In PHH, a brain hemorrhage disrupts this balance. Blood from the hemorrhage can block the normal pathways for CSF flow or impair its reabsorption, similar to how a clogged drain prevents water from flowing away.
The presence of blood and its breakdown products within the ventricular system can also trigger an inflammatory response. This inflammation can damage the ependymal cells lining the ventricles, which have small, hair-like structures called cilia that help move CSF. When these cells are damaged, the fluid movement slows, contributing to the fluid accumulation.
The increasing fluid volume puts pressure on brain tissue, causing compression and potential injury. This sustained pressure can impact brain development, learning, memory, and motor control.
Causes and Recognition
PHH is linked to intraventricular hemorrhage (IVH), bleeding into the brain’s fluid-filled ventricles. Premature infants are susceptible to IVH due to the germinal matrix, a region of fragile blood vessels unique to preterm infants. This delicate area is vulnerable to fluctuations in blood pressure, common in premature babies whose systems are not fully developed to maintain stable blood pressure.
IVH severity is graded, with higher grades (e.g., III or IV) more likely to lead to PHH. Approximately 25% to 35% of preterm infants who experience severe IVH may develop PHH. The younger and more premature an infant is, the higher the chance of developing this condition.
PHH is recognized through specific symptoms and diagnostic imaging. In infants, common signs include an unusually large head or a rapid increase in head circumference. A bulging fontanelle (soft spot) also indicates increased intracranial pressure.
Other symptoms may include irritability, a high-pitched cry, frequent vomiting, excessive sleepiness, and difficulty looking upwards.
Diagnosis uses imaging like cranial ultrasound for neonates and young infants, or CT scans and MRI for older children, to visualize the brain and assess ventricular size.
Treatment Options
PHH treatment aims to manage CSF flow and reduce brain pressure. Initial interventions often involve temporary measures to drain excess fluid. These may include serial lumbar punctures, where fluid is removed from the spinal canal, or the placement of external ventricular drains (EVDs) or ventricular access devices (VADs). A VAD, such as an Ommaya or Rickham reservoir, is a small device surgically placed under the scalp that allows for repeated aspiration of CSF.
For long-term management, the most common surgery is a ventricular shunt, typically a ventriculoperitoneal (VP) shunt. A shunt is a thin, flexible tube surgically inserted into one of the brain’s ventricles. It then tunnels under the skin, usually to the abdominal cavity (peritoneum), where excess CSF is reabsorbed by the body. A one-way valve within the shunt regulates fluid flow, ensuring only the appropriate amount is drained and preventing backflow. While shunts are widely used, they can have complications like infection or malfunction, requiring revisions.
Another surgical option, especially for obstructive hydrocephalus, is endoscopic third ventriculostomy (ETV). This minimally invasive procedure creates a small opening in the floor of the third ventricle, allowing trapped fluid to bypass the blockage and flow into its normal pathways. Sometimes, ETV is combined with choroid plexus cauterization (CPC), a procedure that reduces CSF production by the choroid plexus, a tissue within the ventricles responsible for CSF formation.
Long-Term Considerations
The long-term outlook for children with PHH varies considerably, influenced by hemorrhage severity and intervention timeliness. Ongoing monitoring by neurosurgeons and neurologists is often required to ensure proper shunt function and assess neurological development. Regular follow-up appointments are necessary to detect and address any potential complications, such as shunt malfunctions or infections, which may require additional surgeries.
Children with PHH may face a range of developmental outcomes, including motor dysfunction, intellectual disability, and behavioral challenges. They might benefit from various therapies, such as physical therapy to improve motor skills, occupational therapy to assist with daily activities, and speech therapy to address communication difficulties. Educational support tailored to their individual needs is also often provided to help them reach their full potential. While some children may experience significant challenges, others achieve favorable outcomes, emphasizing the wide spectrum of possibilities.