Definition: diverse group of conditions which result from impaired circulation and reabsorption of CSF.
CSF is formed by the choroid plexus. Normal csf production: 20 ml/h.
Types of hydrocephalus
Hydrocephalus may be congenital or acquired. Congenital hydrocephalus is present at birth and may be caused by either environmental influences during fetal development or genetic predisposition. Acquired hydrocephalus develops at the time of birth or at some point afterward. This type of hydrocephalus can affect individuals of all ages and may be caused by injury or disease.
Hydrocephalus may also be communicating or non-communicating.
occurs when the flow of CSF is blocked after it exits from the ventricles. This form is called communicating because the CSF can still flow between the ventricles, which remain open. Noncommunicating hydrocephalus – also called “obstructive” hydrocephalus – occurs when the flow of CSF is blocked along one or more of the narrow pathways connecting the ventricles. One of the most common causes of hydrocephalus is “aqueductal stenosis.” In this case, hydrocephalus results from a narrowing of the aqueduct of Sylvius, a small passageway between the third and fourth ventricles in the middle of the brain.
There are two other forms of hydrocephalus which do not fit distinctly into the categories mentioned above and primarily affect adults: hydrocephalus ex-vacuo and normal pressure hydrocephalus.
Hydrocephalus ex-vacuo occurs when there is damage to the brain caused by stroke or traumatic injury. In these cases, there may be actual shrinkage (atrophy or wasting) of brain tissue. Normal pressure hydrocephalus can occur in people of any age, but it is most common in the elderly population. It may result from a subarachnoid hemorrhage, head trauma, infection, tumor, or complications of surgery.
However, many people develop normal pressure hydrocephalus even when none of these factors are present. In these cases the cause of the disorder is unknown.
Causes of hydrocephalus
•Lesions or malformations of the posterior fossa
–Dandy- walker syndrome
•Meningitis: pneumococcal, tb
–In older patients:
•Changes in personality
–Anterior fontanel wide open and bulging, increased head circ.
–Dilated scalp veins
–Setting sun sign
–Brisk tendon reflexes, spasticity
–Macewen sign “cracked pot”
–Prominent occiput (dandy-walker)
•X-ray plain films:
–Separation of sutures
•CT scan, MRI
–V-P shunt placement
•Increased risk for developmental disabilities
•Mean IQ is reduced compared to general population
•Abnormalities in memory
•Some patients show aggressive or delinquent behavior.
–Decreased visual acuity
–Visual field defects
•Patients require long term follow up (multidisciplinary)
•Potential for injury r/t increased ICP
•Potential for infection r/t presence of mechanical drainage system.
•Altered family process r/t child with chronic defect.