Medical Dictionary

Acquired Hydrocephalus - Resulting from an outside factor; not inherited nor congenital
Aqueductal Stenosis - A blockage or narrowing of the path from the third to the fourth ventricle
Arachnoid Villi - See Arachnoid Granulations
Arachnoid Granulations - Protrusions of the arachnoid membrane of the brain. The arachnoid villi (or granulations) are very similar to a one-way valve, as they allow the CSF to drain from the subarachnoid space into the superior sagittal sinus, where it can be reabsorbed into the blood system
Benign External Hydrocephalus - (Also referred to as External Hydrocephalus.) An accumulation of CSF found on the outside of the brain, which usually presents itself at birth or soon thereafter. The child's head size will increase, but scans show no internal problems in the ventricles or pathways. The condition corrects itself within about 18 months of age (of the child)
Cerebrospinal Fluid (CSF) - The water-type fluid that bathes the brain and spinal cord
Communicating Hydrocephalus - A type of hydrocephalus where the pathways and the ventricular system are not obstructed, however, the problem appears to be that of re-absorption of the used CSF
Congenital Hydrocephalus - A child diagnosed in utero or at the time of birth as having hydrocephalus
Distal (Catheter) - The catheter connected to the shunt valve and directed to the point where the CSF can drain and be re-absorbed
Endoscopic Third Ventriculostomy - A surgery in which a hole is punctured in the floor of the third ventricle. This allows a new pathway for the CSF to be absorbed by the body
External Hydrocephalus - See Benign External Hydrocephalus
Fixed Shunt - A type of shunt that comes with a valve for either high, medium, or low pressure
Intraventricular Hemorrhage (IVH) - A bleed within the ventricular system of the brain (also referred to as a brain bleed)
Lateral Ventricles - There are two, one on each side of the brain
Lumbar Tap - (Also called Lumbar Puncture and/or a Spinal Tap.) The insertion of a hollow needle to remove some of the CSF either for pathological testing (i.e. for infection), or to relieve some pressure and see if the patient improves
Non-Communicating Hydrocephalus - Hydrocephalus that is caused by an obstruction in the flow of the CSF
Normal Pressure Hydrocephalus - Type of hydrocephalus, where the ventricles are enlarged but there is no obstruction in the ventricular system. The cause appears to be that the CSF is not being absorbed
Programmable Shunt - Type of shunt where the physician can raise or lower the amount of CSF taken from the brain
Proximal (Catheter) - A catheter that is placed in the ventricle of the brain
Reservoir - Part of the shunt where the CSF is stored and then released periodically
Revision - When an operation is needed to replace part or all of the shunt
Subarachnoid - Space where CSF travels over the surface of the brain and the spinal cord
Valve - That which controls how much CSF is taken from the brain
Ventricles - Four chambers of the brain that produce the CSF - lateral ventricles (2), one on each side of the hemispheres which then flows into the third ventricle, which is located in the center of the brain, and onto the fourth ventricle, which is located in the lower back of the skull
Ventriculo-Artial (VA) Shunt - Type of shunt where the distal catheter tip lies in the right atrium of the heart. This allows the CSF to enter the bloodstream directly
Ventriculo-Pleural Shunt - Type of shunt where the distal catheter is located in the pleural space that surrounds the lungs
Ventroperitional (VP) Shunt - Type of shunt where the distal catheter is located in the lower part of the abdomen