Hydrocephalus is a cerebrospinal fluid disorder that can have serious consequences if not treated promptly and properly. Cerebrospinal fluid (CSF) is found inside the brain in cavities called ventricles as well as surrounding the brain in the so-called subarachnoid space.
Cerebrospinal fluid
Every day we produce about 500 ml of cerebrospinal fluid in the lateral ventricles, located on either side of the midline of the brain. From there it passes to a central third ventricle through orifices called Monro’s holes. From there it passes to the fourth ventricle, located inside the cerebellum through a thin duct called the aqueduct of Sylvius, and finally from this ventricle it circulates to the subarachnoid space from where it is reabsorbed and returns to the blood.
Any process that obstructs the free circulation of this fluid or hinders its reabsorption produces an increase of this fluid in the brain called hydrocephalus (obstructive or arreabsorptive, respectively). Tumors located in the ventricles or in the vicinity of the narrowest passage sites cause obstructive hydrocephalus, as well as congenital narrowing of the aqueduct of Sylvius.
Symptoms of hydrocephalus
In neurosurgery we understand different symptoms of hydrocephalus which vary according to the age of the patient and whether the CSF increase is rapid (acute) or slow (chronic):
- In infants in whom the skull bones have not yet closed, there is an increase in head size as well as tension in the fontanelles. If not corrected, irreversible neurological damage may result.
- Acute hydrocephalus is a neurosurgical emergency. It usually begins with headache that increases progressively, usually accompanied by nausea and vomiting. If it is not corrected, it produces a decrease in the level of consciousness that can lead to coma. If maintained, it can also cause inflammation of the optic nerves (papillary edema or papilledema) leading to blindness.
- Chronic hydrocephalus can occur without headache and is sometimes difficult to diagnose. In children it may manifest as school delays or visual impairment. In adults, it manifests with a picture of dementia associated with gait instability and sphincter incontinence, the so-called chronic adult hydrocephalus.
Diagnosis and treatment of hydrocephalus
The diagnosis of hydrocephalus is made by imaging tests, CT or MRI, where an increase in the cerebral ventricles can be seen, but in cases of chronic hydrocephalus other types of tests may be required, such as measurement of intracranial pressure.
The treatment of hydrocephalus is based on correcting the excess fluid to maintain adequate pressure inside the skull. When the cause is obstructive, it can be solved either by eliminating the cause, tumors, or by communicating the ventricles with the subarachnoid space endoscopically through a small hole, endoscopic ventriculostomy. When it is of other origin, it is treated by placing a shunt, a tube associated with a pressure valve, from the ventricles to the peritoneal cavity or, sometimes, to the heart.