Hydrocephalus is an excessive accumulation of CSF in the ventricles resulting in increased intracranial pressure and its symptoms. There are two types of hydrocephalus -- obstructive and non-obstructive. While endoscopy is favoured in obstructive type, in the other variety, Ventriculo-peritoneal shunting is preferred.
1. Obstructive hydrocephalus -- Whenever there is obstruction to the CSF pathways of the ventricular system, it is labelled as obstructive hydrocephalus. Causes include congential like aqueductal stenosis, fourth ventricular outlet obstruction, intraventricular lesions as colloid cyst, cysticercal cyst, extraventricular lesions as tumors of thalamus, posterior third ventricle, fourth ventricular tumor. In majority of these patients, "Endoscopic Third Ventriculostomy" can be performed with good results. In this procedure, an internal communication is made between the obstructed ventricles and cistern from where CSF can be absorbed. The benefits include avoiding a foreign body as shunt and its associated complications. In some patients with tumors as in thalamus and posterior third ventricle, biopsy can be taken simultaneously to arrive at a histological diagnosis also.
2. Non-obstructive hydrocephalus -- This is more often in situations wherein absorption of CSF is reduced like in post-meningitic states (following tuberculosis, bacterial meningitis) and following subarachnoid hemorrhage. In these patients, Endoscopic methods are not very helpful and treatment is by Ventriculoperitoneal shunt. A variety of shunts are available. Most common include fixed pressure shunts like the Chabbra Shunt. Programmable shunts are also available. These have a magnetic valve whose opening pressure (at which the CSF will start draining) can be adjusted easily in OPD using a programmar. These are commonly used in Normal Pressure Hydrocephalus wherein one is not sure of the pressure in the ventricles and using a fixed pressure shunt could result in under-drainage or over-drainage of CSF. The pressure can be adjusted easily in OPD without the need to undergo another surgery.