- Clinical science
Hydrocephalus refers to the abnormal enlargement of cerebral ventricles and/or subarachnoid space as a result of excess cerebrospinal fluid (CSF) accumulation. There are four types, which include communicating hydrocephalus, non-communicating hydrocephalus, normal pressure hydrocephalus (NPH), and hydrocephalus ex vacuo. Communicating hydrocephalus typically occurs as a result of decreased CSF absorption or increased CSF production, whereas non-communicating hydrocephalus is due to the obstructed passage of CSF from the ventricles to the subarachnoidal space. Both forms lead to an elevated intracranial pressure (ICP), which leads to headache, nausea, and/or vomiting. These symptoms are often accompanied by specific clinical manifestations, such as macrocephaly in congenital hydrocephalus, or changes in vital signs resulting from brainstem compression. In contrast, normal pressure hydrocephalus, which is usually due to decreased CSF absorption in the elderly, manifests with normal ICP because of effective compensation by ventricular dilation. This ventricular distension leads to the classic presentation of urinary incontinence, dementia, and abnormal gait. In hydrocephalus ex vacuo, CSF extension occurs secondary to loss of brain tissue (e.g., cerebral atrophy); this type of hydrocephalus is actually a misnomer as it is not a true hydrocephalus. CT or MRI (and ultrasound for infants) are important diagnostic procedures. Treatment involves surgical insertion of a shunt, which drains excess CSF into another area of the body – usually the peritoneum.
|Type of hydrocephalus|| |
|Non-communicating hydrocephalus|| || || |
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|Hydrocephalus ex vacuo|| || || |
Most types of hydrocephalus are progressive and present a risk of neurological damage. Definitive treatment of hydrocephalus involves the drainage of excess CSF via a cerebral shunt, usually into the peritoneum (e.g., ventriculoperitoneal or VP shunt).
- Indications: hydrocephalus,
- Inflow catheter
- Adjustable one-way pressure valves
- Outflow catheter
- Underdrainage → ↑ ICP
- Symptoms: see
- Variant: Slit ventricle syndrome
- Pathophysiology: Ventricular walls are pulled into the catheter slit by suction and permanently close the slit.
- Shunt infection (∼ 5% of cases)
- Bacterial contamination (e.g., Staphylococcus epidermidis), often associated with biofilm formation
- Therapy: shunt explantation surgery
- Possible interim therapy: diuretics, fibrinolysis, serial lumbar punctures, (acetazolamide)
Alternative surgical procedures
- Endoscopic third ventriculostomy
- Choroid plexectomy (or coagulation)
- Cerebral aqueductoplasty