46. Hydrocephalus
Definition
Hydrocephalus is a disturbance or interruption of the formation, flow, or absorption of cerebrospinal fluid. All types of hydrocephalus culminate in increased volume of fluid within the central nervous system’s relatively closed spaces.
Types of Hydrocephalus
• Arrested
• Benign external
• Communicating
• Congenital
• Noncommunicating
• Normal pressure
• Obstructive
Incidence
In the United States congenital hydrocephalus occurs at the rate of about 3:1000 live births. The frequency of acquired hydrocephalus is not documented. Internationally there are no estimates on the frequency of congenital or acquired hydrocephalus.
Etiology
Congenital Causes, Infants and Children
• Agenesis of the foramen of Monro
• Arnold-Chiari malformation (Types I and II)
• Congenital toxoplasmosis
• Dandy-Walker malformation∗
• Stenosis of the aqueduct of Sylvius
Acquired Causes, Infants and Children
• Iatrogenic hypervitaminosis A
• Idiopathic
• Increased venous sinus pressure
• Infections (meningitis, cysticercosis)
• Intraventricular hemorrhage
• Mass lesions
 |
| Hydrocephalus. Child with enlarged head caused by hydrocephalus. |
Normal Pressure Hydrocephalus and Causes, Adult
• Congenital aqueductal stenosis
• Head injury
• Idiopathic
• Meningitis
• Previous posterior fossa surgery
• Subarachnoid hemorrhage
• Tumor
Signs and Symptoms
Manifestations are influenced by the following five factors:
1. Cause
2. Duration
3. Obstruction location
4. Patient age
5. Rapidity of onset
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