- When there is excess of CSF, the condition is known as hydrocephalus.
- External hydrocephalus, in which the excess is mainly in the subarachnoid space, is found in senile atrophy of the brain.
- Internal hydrocephalus refers to dilation of the ventricles.
The increase of pressure within the cranial cavity compresses
the brain and unconsciousness develops.
Hydrocephalus may develop following:
- Increased production (choroids plexus papilloma)
- Reduced rate of absorption (bockage of arachnoid
- Obstruction of flow (mesencephalic aqueduct, Monroe,
Luschka, Magendie foramina, tumors, cysts, developmental).
- Inadequate drainage
The effects of increased CSF include:
- Increased intracranial pressure
- Expansion of sutures
The commonest sites of obstruction include
Hydrocephalous can be eased by treating the cause where possible. When not possible, CFS is drained from the ventricles either to the blood (venticulo auricular shunting) or body cavities (ventriculoperitoneal shunting).
- Cerebral aqueduct
- Exit Foramina from 4th ventricle
- Interventricualr foramen (of Monro)
- CSF flow can also be obstrucated in subarchnoid space following post-infection adhesions
Diseases of the CNS and its membranes are often reflected in alternations of the cells, which are normally found in CSF or in alternations in the concentration of its chemical constituents. The determination of these alternations and variations is of service in diagnosis.
CSF is usually obtained through lumbar puncture. Other areas from which samples of CSF can be obtained include the cerebellomedullary cistern (cisternal puncture) and also in some circumstances the ventricles (ventricular puncture).