Hydrocephalus

Hydrocephalus Overview

Aspect	Details
Definition	Accumulation of cerebrospinal fluid (CSF) within the brain, leading to ventricular dilatation.
Normal CSF Volume	About 150 cc.
CSF Production	80% by choroid plexus, 20% in interstitial areas.
CSF Flow	Lateral ventricles -> Foramen of Monro -> 3rd ventricle -> Aqueduct of Sylvius -> 4th ventricle -> Foramen of Magendie & Luschka -> Bathes external surfaces & reabsorbed via arachnoid villi.
Causes	Obstruction (non-communicating or communicating), Oversecretion (rare, choroid plexus tumor).
Clinical Manifestation	Infants: Bulging fontanelles, head enlargement, vomiting. Adults: Acute - Increased ICP symptoms; Chronic - Dementia, gait ataxia, urinary incontinence.
Investigation	CT Scan, Ventriculography.
Treatment	Shunt Surgery (e.g., ventriculoperitoneal shunt), Tumor Resection.

Hydrocephalus is characterized by cerebrospinal fluid (CSF) accumulation within the brain, leading to ventricular dilatation. Normally, the body contains about 150 cc of CSF, with a portion of it residing within the ventricles. About 80% of CSF is produced by the choroid plexus, with the rest being generated in the interstitial areas of the brain.

CSF Flow

The flow of CSF begins in the lateral ventricles, moves through the foramen of Monro into the 3rd ventricle, then flows into the 4th ventricle via the aqueduct of Sylvius. From there, it passes through the foramen of Magendie (midline) and the foramina of Luschka (lateral) to bathe the external surfaces of the brain and spinal cord. Finally, CSF is reabsorbed into the bloodstream through the arachnoid villi located at the superior sagittal sinus.

Causes of Hydrocephalus

Obstruction:
Non-communicating hydrocephalus: Obstruction within the ventricular system, often due to aqueduct stenosis, prevents CSF from exiting the ventricles.
Communicating hydrocephalus: Obstruction outside the ventricles, typically within the subarachnoid space, caused by conditions like arachnoid granulomas, scarring, or blockages from blood clots or tumors.
Oversecretion: Rarely, a tumor in the choroid plexus can lead to excessive CSF production.

Clinical Manifestation

In infants, signs include bulging fontanelles, head enlargement, vomiting.
In adults:
Acute: Symptoms of increased intracranial pressure, such as headache, nausea, vomiting, blurred vision, and altered consciousness, indicating high-pressure hydrocephalus.
Chronic: Common in older adults (>60 years), characterized by ventricular enlargement without significant raised intracranial pressure. Symptoms include the classic triad of dementia, gait ataxia, and urinary incontinence, known as normal pressure hydrocephalus.

Investigation

CT Scan: Shows ventricular enlargement.
Ventriculography: Identifies the exact location of duct obstruction.

Treatment

Shunt Surgery: The most common treatment involves the placement of an extracranial shunt, such as a ventriculoperitoneal shunt, which diverts CSF from the brain to the peritoneal cavity. Shunts have the advantage of being easier to correct in case of obstruction or malfunction compared to internal shunts, which require cranial surgery for correction.
Tumor Resection: If a tumor causes hydrocephalus, surgical removal of the tumor may be necessary.

This comprehensive overview explains hydrocephalus in detail, focusing on the pathophysiology, causes, clinical manifestations, diagnostic methods, and treatment options.