What is hydrocephalus ?

Hydrocephalus is a neurological disorder in which there is excessive accumulation of cerebrospinal fluid (CSF)within the ventricles of the brain. In hypertensive hydrocephalus the CSF accumulates and causes raised pressure inside the brain. The ventricles swell and the brain tissue is stretched and squashed.
The term 'hydrocephalus' is from two Greek words meaning 'water inthe head'. Hydrocephalus is one of the most frequently seen problems in a busy pediatric neurosurgical practice.

In a normal cases the CSF circulates through the brain, its ventricles and the spinal cord. CSF continuously drained away into the circulatory system. Hydrocephalus occurs when the normal CSF flow pathway becomes obstructed or when there is over-secretion of fluid, an over-secretion ia an imballance between the amount of CSF which is produced and the amout which is reabsorbed into the blood stream. Obstructions can be due to a variety of causes such as tumours, cysts, scarring, blood clots, and developmental abnormalities.

Hydrocephalus in infants is often more severe than in adults because the developing brain is particularly vulnerable to injury and because the immature skull enlarges via the open sutures. Infants and young children with hydrocephalus have abnormally large heads because the pressure of the fluid has caused the individual skull bones to bulge outward at their juncture points. Compression of the brain by the accumulating fluid eventually causes convulsions and mental retardation.

Broadly speaking, there are two types of hydrocephalus, obstructive(Non-communicating) and communicating.
Obstructive hydrocephalus refers to obstruction of the CSF pathways within the interior of the brain or at the tentorial notch. Communication hydrocephalus refers to an inability of the CSF to pass through the arachnoidal villi to get back into the blood stream. This can result when the arachnoidal villi become inflamed by infection or blood with the inflammatory process blocking the microscopic pores through which the CSF must pass from the subarachoidal space into the blood.

Hydrocephalus is also sometimes described as internal or external. Internal hydrocephalus referes to an accumulation of CSF within the ventricles of the brain. External hydrocephalus referes to accumulation of fluid outside the ventricles.
Hydrocephalus may be present at birth ( Congenital Hydrocephalus) or may arise later in life (Acquired Hydrocephalus).
Congenital Hydrocephalus can be due to blockage at the aqueduct (aqueductal stenosis), congenital anomalies such as an Arnold-Chiari malformation or Dandy-Walker malformation or it can be due to an inflammatory process when premature birth has resulted in bleeding within the brain.

Normal Pressure Hydrocephalus (NPH) is the enlargement of the ventricles of the brain, without increased CSF Pressure. NPH causes the symptoms similar to dementia, gait disturbance, deficiencies in short term memory, gradual diminishing of the thought process, and urinary incontinence. Because NPH is most common in patients over the age of 60, its symptoms may be confused with Alzheimer's or Parkinson's diseases. The freatures which distunguish are that the memory loss is not as encompassing that is associated with Alzheimer's disease. Also, apraxia (inability to recognize common objects, or to perform correct movements) or visual loss does not accompany NPH as may be the case in the previously mentioned diseases. A neurological examination with a Computed Tomography (CT) Scan or a Magnetic Resonance Imaging (MRI) will provide anatomic pictures of the ventricles and ensures that the CSF flow is not blocked by a mass.