Re-inventing the Wheel or Third Ventriculostomy
Michael Vloeberghs MD
Senior Lecturer in Paediatric Neurosurgery & Honorary Consultant Paediatric Neurosurgeon, Queens Medical Centre, University of Nottingham
Why re-invent the wheel? There was nothing wrong with the old ones. This may be true for wheels but not when it comes to the treatment of hydrocephalus. It wasn't until the 1960s, with the development of implants. that the treatment of hydrocephalus became possible and shunts (the diversion of fluid from brain to chest, the heart, or usually the belly with silicone tubing) became a routine procedure for neurosurgeons and others. Apart from technical advances in structure and shape, the concept has remained the same. The problems associated with shunts haven't changed either. Shunts still fail mechanically, block, overdrain and infect. Very little can be done on this front and if shunts were kitchen appliances, the manufacturers would recall them.
There is an alternative which is endoscopic third ventriculostomy. This very old procedure (dating back to the 1900s) was abandoned because of outrageous complications due to poor anaesthetics and inappropriate equipment. Technical progress in optics, electronics and image processing have made endoscopy (which means looking inside something) accessible to all medical disciplines. In the 1980s endoscopic instruments were purpose-built for neurosurgery and an increasing number of applications were found. Currently in our department two or three neuroendoscopies are performed per week for a variety of indications, mostly for the treatment of hydrocephalus but also in tumour surgery.
Endoscopic ventriculostomy, which means opening the floor of the brain using a miniaturised telescope, was one of the first applications. Because of the position of the cavities of the brain, specifically in hydrocephalus, you can navigate from the top of the skull through the brain to the floor of the brain. The floor is very thin and can be opened using a laser fibre or another cutting device. This allows the fluid to flow out of the brain via a natural bypass. The risk of this procedure is very low and there are very few potential side effects, there is no overdrainage, no blockage, the risk of infection is very small and, most important of all, there is no foreign material left behind that can cause difficulties at a later date.
The success of this treatment is determined by what caused the hydrocephalus in the first place. If the natural outflow of fluid is blocked by a tumour or from birth (obstructive hydrocephalus) the success rate is 85%, when there has been an infection (meningitis) or a bleed in the brain the success rate is about 50%. The overall success rate for endoscopic ventriculostomy in hydrocephalus is two-thirds. The advantage is that once a ventriculostomy functions and the hydrocephalus is relieved there is no need for further surgery. Ventriculostomy, when successful, is a one-off procedure with permanent result. We now treat an increasing number of patients with shunt complications with the same overall success rate. Having a shunt in place does not preclude endoscopic treatment.
This compares favourably with the 'classic' treatment of hydrocephalus, ie shunts, since 70% will fail within a 10-year period and a child needs a mean of five to six shunts before reaching adult age. We have come to the point that we offer endoscopic treatment for every new case of hydrocephalus and for every shunt blockage.
But what if the endoscopic treatment does not work? Overall there remains one-third of the patients in whom the procedure will not relieve the hydrocephalus. In those patients the only option is to divert the fluid with a shunt. A prior ventriculostomy does not influence the procedure. Up to now there is no way of predicting which patient will benefit from the procedure so we must remain honest about the results and it is only after a lengthy and informative talk with the parents that we proceed.
Unfortunately, we can't take any credit for either the operation or the equipment, but we may have re-invented the wheel in the sense that we are rediscovering an old procedure using the latest technology and improving the results.