What exactly is hydrocephalus and why does it occur?
Hydrocephalus is an accumulation of cerebrospinal fluid in the ventricular cavities, causing dilatation of the ventricular cavities. It can occur for multiple causes and in any age range:
- Obstructive cause: a hemorrhage, a tumor or a congenital stenosis of the aqueduct, which compresses any of the ventricular cavities preventing the correct circulation of CSF.
- Arresorptive cause: due to altered physiological reabsorption of CSF as a result of age (chronic adult hydrocephalus), having suffered a brain hemorrhage or traumatic brain injury (post-hemorrhagic or post-traumatic hydrocephalus), after resection of a brain or intraventricular tumor.
Can hydrocephalus be detected during pregnancy when it affects infants?
If it is a congenital cause, or an alteration in the formation of the ventricles during embryonic development, it can be detected by the control ultrasounds performed during pregnancy. When it is detected, a magnetic resonance imaging (MRI) scan is usually performed on the pregnant woman to better visualize the brain of the fetus and try to find out what is causing the hydrocephalus.
How likely is hydrocephalus to occur in adults, and why does it occur in such cases?
The overall incidence of hydrocephalus is 1 in 1,000. It is not a frequent pathology, but it is necessary to think about it in order to diagnose it. Sometimes the diagnosis in adults, in the absence of any risk factor such as those mentioned above (traumatic brain injury, cerebral hemorrhage or brain tumor), is delayed because the symptomatology of chronic adult hydrocephalus is mixed with that of other neurodegenerative disorders such as dementia or Parkinson’s disease.
Are there any risk factors that influence its onset? What are the symptoms of hydrocephalus?
Patients who have suffered previous brain pathology, such as cerebral hemorrhage, cranioencephalic trauma or brain tumor have more predisposing factors for hydrocephalus.
For chronic adult hydrocephalus, there is no clearly established risk or predisposing factor. The typical symptomatology is mild cognitive impairment, gait disturbance and urinary incontinence, which is known as Hakim’s triad. Diagnosis is sometimes difficult because it involves patients of a certain age who may have this symptomatology due to other causes.
In the case of acute obstructive hydrocephalus, the diagnosis is clearer because it presents with intense headache, vomiting and deterioration of the level of consciousness up to coma. It is an emergency, since at that moment there is a sudden increase in intracranial pressure and can lead to the death of the patient if it is not treated.
How can hydrocephalus be treated surgically? Is it a complex intervention?
There are 3 types of surgical treatment, depending on the cause and type of hydrocephalus, which can be applied to all ages:
- Placement of ventricular drainage (transient).
- Placement of ventriculoperitoneal shunt (permanent)
- Endoscopic ventriculostomy (permanent)
Acute hydrocephalus is an emergency that is treated by placing a ventricular drainage, i.e. a thin silicone catheter that is inserted through a small hole in the skull, under local anesthesia and channeling the ventricle. This catheter is connected to an external reservoir system through which, in the following hours and days, fluid is extracted in a regular and controlled manner. Subsequently, and once the diagnosis has been made and the cause resolved, if the hydrocephalus persists, a permanent drainage of liquid is established, which is known as ventriculoperitoneal shunt.
Hydrocephalus is generally treated by the implantation of a cerebrospinal fluid shunt. It consists of placing a silicone catheter at the level of the cerebral ventricle and connecting it to a valve that is lodged under the skin. This valve, in turn, is connected to another subcutaneous catheter that can be placed in different cavities, most commonly in the peritoneal cavity (abdomen), ventriculoperitoneal shunt. If, for some reason, it is not possible to place the distal catheter there, it is placed in the heart (atrium), known as ventriculo-atrial shunt.
When it is an obstructive hydrocephalus due to a tumor, the treatment is to operate on the tumor (the cause of the obstruction), and the hydrocephalus may be resolved without the need to place a shunt.
In cases of obstruction at ventricular level, due to intraventricular tumor or congenital stenosis of the aqueduct, for example, hydrocephalus can be resolved by endoscopic treatment. This surgical treatment consists of making a hole in the skull and introducing a camera that takes us to the ventricular cavities. Through this intervention, we can resect a tumor or intraventricular cyst, and also perform an extra communication at the level of the floor of one of the ventricles, which is known as endoscopic ventriculostomy.
Any of the surgical treatments for hydrocephalus are not technically complex. What is complex is actually the correct diagnosis of hydrocephalus, choosing the type of valve that may be most appropriate for each patient and being able to follow up correctly.