|Year : 2014 | Volume
| Issue : 4 | Page : 456-457
Treatment of hydrocephalus: Challenges and the way ahead
V Bhadri Narayan
Professor of Neuroanaesthesia, National Institue of Mental Health and Neuro Sciences, Bangalore, Karnataka, India
|Date of Web Publication||17-Aug-2014|
Prof. V Bhadri Narayan
National Institute of Mental Health and Neurosciences, Bengaluru - 560 029, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Narayan V B. Treatment of hydrocephalus: Challenges and the way ahead. Indian J Anaesth 2014;58:456-7
Hydrocephalus is a common clinical condition which occurs as a result of cerebrospinal fluid (CSF) accumulation resulting from complex mechanisms, and cerebrospinal shunt procedures are life-saving. Even though, significant progress has been made, multiple interventions and lifelong care are required. Management of patients presenting for shunt surgery can be challenging, especially in children with congenital abnormalities and will require thorough planning and execution. The anaesthetic management can be particularly challenging with varied, complex issues ranging from difficulties related to airway management, cardiovascular dysfunction, age-related needs of positioning and coagulation abnormalities.
There is an urgent need to resolve this issue as failure rates are high particularly for complex shunt systems. Major complications of shunt surgery are blockage, infection, or shunt malfunction and hence the need for shunt revisions. Shunt failures occur due to catheter obstruction proximally or distally, migration of the catheter, catheter fracture, disconnection, valve malfunction, haematomas, and infection. The problems related to the catheter could be from the materials used, size of the holes, the number, the inflammatory reactions it may induce and changes in and on the catheter over time. The typical ventricular catheter has 32 holes of 500-μm diameter arranged in four rows to allow CSF outflow from the ventricle, this may vary with different manufacturers. The consistency in the size and number of the holes in the catheter, the distance between each one and hole calibre may play an important role for the survival of the catheter.  There are a variety of different valves at present like high, medium and low-pressure valves to differential pressure valves, siphon-resistant valves, flow-regulating valves, and externally adjustable valves. However, failures continue to occur which is a concern and calls for reflection and further improvement. 
Ventriculo-peritoneal, ventriculo-atrial, ventriculo-pleural shunts were the mainstay of surgical management till the advent of endoscopic third ventriculostomy (ETV), which has made a significant qualitative difference to patient's outcomes. Third ventriculostomy creates a physiological shunt between the obstruction and the arachnoid space and ensures CSF circulation and absorption. The biggest advantage of creating a functioning physiological shunt is it will completely eliminate catheter-related problems which are a major cause of failure. Improved surgical skill, imaging and better visualisation have improved with advances. Recently, a modified technique of ETV by using a transendoscopic pulse-waved microvascular Doppler probe and videoscope head has been described to avoid vascular injury, which is a significant advance and may contribute to better patient outcomes. 
The anaesthetic management needs careful planning and can be challenging given the fact that many procedures are done as emergencies, and expert help may not be available. A thorough pre-operative examination is very essential in planning the anaesthetic. Induction of anaesthesia depends on the medical condition and intravenous access; if intravenous access is available then thiopentone or propofol can be used. If not, then a volatile induction may be necessary. An appropriate choice of tube size is made and should be carefully fixed as endobronchial migration can occur easily in young children with changes in position. The challenges posed are related to the age of patients. Children with congenital disorders may present with airway abnormalities, which is of concern as these patients may have altered respiratory patterns. The resulting hypoxia or hypercarbia will affect cerebral dynamics and get aggravated if airway access fails. Equipment to handle this may not be able available in all centres. Cardiac function can be altered by hypovolemia resulting in hypotension from persistent vomiting, hyponatremia is also often present that needs attention. Resuscitation must be adequate to avoid the adverse effects of anaesthetic induction agents. Temperature management intraoperatively is essential as young children are vulnerable to hypothermia from infusion of cold fluids, open abdomen and temperature loss with its attendant problems like decreased metabolism of drugs, prolonged neuromuscular blockade, and delayed recovery. Warming fluids intraoperatively is a good solution. The goals of fluid management will be to maintain cerebral perfusion and normovolemia with isotonic fluids and avoid hyperglycaemia. Repeated glucose measurements will guide fluid management. Small children will require extended monitoring in the post-operative period to identify problems early to enable early treatment.  In patients presenting for repeated procedures, intravenous access may be difficult and abdominal adhesions may increase the risk of bowel injury.
The technical challenges hydrocephalus poses are great and are apparent from the high-failure rates, which will need further understanding. Solutions have to be found in terms of modifications to the catheter, valves and indications for placement of the right materials. Then are we looking at a smart shunt in the future? The smart shunt will need to possess technical attributes to overcome present difficulties, be cost-effective, easily available and have good regulatory control with low risk to be successful.  When this balance is struck, it may greatly influence patient care in the future. When technology can mimic the complex cerebral physiological function, the survival of shunts may increase and improve outcomes.
| References|| |
|1.||Harris CA, McAllister JP 2 nd . What we should know about the cellular and tissue response causing catheter obstruction in the treatment of hydrocephalus. Neurosurgery 2012;70:1589-601. |
|2.||Piatt JH Jr, Carlson CV. A search for determinants of cerebrospinal fluid shunt survival: Retrospective analysis of a 14-year institutional experience. Pediatr Neurosurg 1993;19:233-41. |
|3.||Eguchi S, Aihara Y, Tsuzuki S, Omura Y, Kawamata T, Okada Y. A modified method to enhance the safety of endoscopic third ventriculostomy (ETV): Transendoscopic pulse-waved microvascular Doppler-assisted ETV, technical note. Childs Nerv Syst 2014;30:515-9. |
|4.||Nienaber J. Anaesthesia for ventriculoperitoneal shunts. South Afr J Anaesth Analg 2011;17:73-5. |
|5.||Lutz BR, Venkataraman P, Browd SR. New and improved ways to treat hydrocephalus: Pursuit of a smart shunt. Surg Neurol Int 2013;4:S38-50. |