Commonly known as “accumulation of water in brain”.
It is a condition in which due to accumulation of the brain water there is an increase in the intra cranial pressure.
Physiologically, there is a continuous formation of water inside our brain in the ventricles, from where it circulates in and around the brain and spinal cord, and finally resorbed in the brain itself through the arachnoid villi. Approximately, it forms around 450 ml of cerebrospinal fluid per day.
This fluid keeps the brain and the spinal cord floating, provide padding and helps in the circulation of various nutrients.
Hydrocephalus results when there is any obstruction to this CSF pathway or there is some pathology in the absorption mechanism. This results in accumulation of fluid inside the ventricles, increasing the intracranial pressure and producing symptoms. This can occur in any age group.
We usually classify hydrocephalus into two subgroups:
- Obstructive Hydrocephalus: In which there is an obstruction to the CSF flow secondary to a tumor or a cyst near the foramen of monro or at the aqueduct. At times in pediatric age group, there may be a thin membrane at the aqueduct causing aqueductal stenosis.
- Communicating Hydrocephalus: In this subtype, the CSF is not adequately absorped hence causing hydrocephalus. It may be secondary to infections, tuberculosis or heamorrhage.
Rarely, pressure can be built in our brain without enlargement of ventricular size. A condition known as “Idiopathic Intracranial Hypertension or Pseudo tumor cerebri”. It is most often found in fatty, middle aged females. This has a high ICP but ventricles are slit like.
Hydrocephalus always does not require treatment. Many times we see a number of patients with enlarged ventricles since many years, but they do not manifest any symptoms. It is called arrested hydrocephalus.
Most of symptomatic require treatment, and if left untreated can result into a permanent neurological damage. There are some medication which can reduce the formation of CSF, but cannot stop fully, so treatment is usually surgical.
- Communicating Hydrocephalus: There is some pathology with the reabsorption of CSF. Hence, shunting is done in symptomatic patients.
- Obstructive Hydrocephalus: In this, there is obstruction to CSF flow. In such patients either shunting or removing the obstruction or creating a bypass is done.
Whenever, there is a mass or a cyst in the ventricles, removal of the lesion may resolve the hydrocephalus and allows the CSF to flow normally.
In aqueduct stenosis, there is an obstruction at the proximal portion of the duct.
- Shunting is done in such cases, where we put a catheter into the ventricles and bypasses the fluid in the belly, from where it is absorbed
- Endoscopic third ventriculostomy (ETV): in this we divert the obstructive site by doing a small opening in the floor of third ventricle.
In this we place one end of plastic (latex) catheter inside the ventricles of the brain, by making a very small opening in the skull to pass the catheter through it usually in the parietal region. The other end of the catheter is placed inside the belly through a subcutaneous tunnel made, so that the fluid from the ventricle directly goes into the belly, from where it can be absorbed easily. Between the catheters, there is a valve which maintains the flow of CSF and stops it’s over drainage into the belly. This type of shunt is called a ventriculo-peritoneal shunt. Sometimes, we can drain the CSF in the heart or lungs as well. The whole shunt is lying below the skin and nothing is visible outside.
These shunts can sometimes malfunction because of the obstruction of catheter or disconnection. In such cases we need to do a shunt revision surgery.
ETV (Endoscopic Third Ventriculostomy):
Done mainly in the cases of obstructive hydrocephalus. In this we do a small opening in the frontal region, and pass a camera inside the ventricles directly with working channels. Then from the opening of the lateral ventricle, is passed to the third ventricle. Then a small opening is created in the floor of the third ventricle, through which the CSF directly enters the base of the skull, bypassing the obstruction. Then it circulates and absorbed normally.