External Ventricular Drainage

External Ventricular Drainage (EVD) - Overview

An External Ventricular Drainage (EVD) is the temporary drainage of cerebrospinal fluid (CSF) from the fluid filled cavities of the brain (lateral ventricles) to a closed collection system outside the body.

External Ventricular Drainage (EVD) - Indications

• To relieve hydrocephalus ie. the accumulation of brain fluid within the intracranial cavity
• Subarachnoid haemorrhage
• Infection-meningitis
• Obstruction due to tumour
• To reduce intracranial pressure due to brain swelling
• In a setting of head injury, stroke
• Intracranial pressure monitoring
• Head Injury
• To achieve brain relaxation during surgery

External Ventricular Drainage (EVD) - Complications

The cause of this condition is irritation of the fifth cranial nerve (the Trigeminal nerve) which is responsible for providing facial sensation. This irritation is occasionally due to benign tumours or multiple sclerosis, either of which can usually be detected by a high quality MRI of the brain.

In the majority of cases, however, imaging of the brain does not reveal a cause of the nerve irritation. In such cases a small vessel (usually an artery but occasionally a vein) is often found at operation to be compressing the root entry zone of the Trigeminal nerve at the brainstem.