What is Hydrocephalus?
The primary characteristic of hydrocephalus is an excessive accumulation of cerebrospinal fluid (CSF) on the brain. CSF is a clear fluid that surrounds the brain and spinal cord. It typically flows through ventricles before exiting into cisterns at the base of the brain, where it bathes the surfaces of the spinal cord and brain before being reabsorbed into the bloodstream. CSF’s functions include keeping the brain tissue buoyant in the manner of a cushion; being a means to deliver nutrients to the brain and remove waste; and flowing between the spine and skull to offset changes in intracranial blood volume. An excessive accumulation of CSF results in an abnormal widening of the brain’s ventricles, creating potentially harmful pressure that can damage brain tissue and impair the brain’s function.
Causes of Hydrocephalus
Excess CSF in the ventricles can occur because of an obstruction of its normal flow, the blood vessels’ inability to absorb it, or overproduction. Though its causes are not well understood, hydrocephalus may be associated with developmental disorders such as spina bifida and encephalocele. In rare cases, the condition may be inherited genetically. Additional possible causes include tumors, a traumatic head injury, meningitis, a subarachnoid hemorrhage, or complications from premature birth. Congenital hydrocephalus may occur as a result of abnormal development of the central nervous system obstructing the flow of CSF, bleeding within the ventricles, or a uterine infection during pregnancy. Some data suggests that one to two of every 1,000 babies in the United States are born with hydrocephalus. However, the condition can develop later in life. Normal pressure hydrocephalus (NPH) mainly occurs in adults aged 60 or older and involves little or no pressure on the brain despite enlarged ventricles.
Symptoms of Hydrocephalus
The symptoms of hydrocephalus vary based on age, severity, and individual tolerance differences. An infant’s skull can expand to relieve the pressure from CSF buildup and compensate for the enlargement of ventricles because its sutures have yet to close. For infants, the most apparent symptom of hydrocephalus is a rapid enlargement of the head, though other symptoms include downward deviation of the eyes, seizures, and vomiting. The hydrocephalus symptoms evident in older children and adults differ because their skulls cannot expand to ease the pressure created by a buildup of CSF. Toddlers and children may experience headaches, nausea, blurred or double vision, lack of balance, personality changes, loss of motor functions, an inability to remain awake, irritability, and delayed development or poor learning ability. In addition to the symptoms experienced by toddlers and children, young and middle-aged adults are also prone to bladder control problems and impaired cognitive skills. Adult-onset NPH is often misdiagnosed as Alzheimer’s or dementia because it can also cause memory loss.
Hydrocephalus is typically diagnosed following an amalgamation of a general physical, neurological exam, and brain imaging tests. A physician may conduct a clinical neurological evaluation to determine the severity of one’s condition by performing an MRI, CT scan, or pressure-monitoring. For infants, ultrasound imaging may be used for an initial assessment because of its relatively low risk. A physician will select the appropriate course of action after considering an individual’s clinical presentation, age, and whether abnormalities of the brain or spinal cord are known. Magnetic resonance imaging is typically the preferred option due to the detail of its images. CT scans are usually reserved for emergency exams.
The most common treatment for hydrocephalus is the surgical insertion of a shunt system. The system uses a sturdy plastic tube, known as the shunt, as well as a catheter and valve to divert the flow of CSF from the central nervous system (CNS) to an area of the body where it can be absorbed through the normal circulatory process. The system usually routes the excess CSF to the abdominal cavity, though other options for the fluid include areas around the lung or a chamber of the heart. Another treatment option for a select number of individuals diagnosed with hydrocephalus is a third ventriculostomy. For this procedure, a doctor uses a neuroendoscope to view the ventricular surface. Upon assessing the brain, a surgeon uses a tool attached to the instrument to make a small hole in the floor of the third ventricle. The hole creates a path allowing CSF to circumvent any obstructions and flow toward a resorption site near the surface of the brain.
The prognosis for those afflicted with hydrocephalus varies based on factors such as the presence of associated disorders, early detection of the condition, and the treatment’s success. Rehabilitation therapies and educational interventions can help children diagnosed with the disorder live healthy lives. However, symptoms can get progressively worse if untreated. Though the success of treatment with the shunt system varies, it can lead to a nearly complete recovery for some individuals. Early diagnosis and treatment improve the chances of success.