**Abstract**

It is now recognised that infections in CSF shunts and external ventricular drains (EVDs) are biofilm infections, and the scientific basis of these infections is better understood. Infection rates in shunts have now fallen but remain unacceptably high. There is an increase in infections due to multi-drug-resistant bacteria in EVDs. Reliance on antimicrobial prophylaxis has potential lifethreatening consequences and safer more effective measures are available. These consist of well-founded "bundles" or surgical protocols that have been shown to reduce infection by application of well known but not universally applied principles. New developments in antimicrobial technology have now been shown to be clinically effective and have reduced healthcare costs. The reduction in antibiotic use has led to fewer adverse effects. Problems with multidrug resistance in EVD infections remain and technology to address these has been developed but is not yet clinically available.

**Keywords:** CSF shunt, external ventricular drainage, antimicrobial prophylaxis, antimicrobial catheters, intracranial pressure management

## **1. Introduction**

Intracranial pressure needs to be controlled in cases of hydrocephalus, or after cranial trauma, or cerebral oedema due to, for example, tumour. In hydrocephalus, the most common treatment involves placement of a shunt to drain cerebrospinal fluid (CSF) from the cerebral ventricles to a body cavity such as the peritoneum (ventriculoperitoneal, VP, shunt) or the right cardiac atrium (ventriculaoatrial, VA shunt). Sometimes other sites are used, such as the pleural space. Where there is free communication with the spinal theca and the ventricular system, a lumbar-peritoneal (LP) shunt can be used. Shunts are totally internal and are intended to be in place permanently, though they often require revision due to obstruction. In cases where the need for control of intracranial pressure is temporary, such as following cranial trauma or haemorrhage, or as part of the management of a shunt infection, an external ventricular drain (EVD) is used. This drains CSF from the cerebral ventricles, exiting through a burr hole to an external collecting system. It might be in place for a few days or a few weeks depending on the patient's condition. The collecting bag is changed when approximately 75% full. Another temporary means of controlling CSF pressure is insertion of a reservoir,

typically Ommaya or Rickham. As these are "blind" with no drainage tube, it is necessary to aspirate CSF percutaneously, typically daily. Reservoirs are also commonly used as access ports for administration of drugs to the ventricular system.
