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External Ventricular Drain

Last Updated: October 1, 2018

Placement of an External Ventricular Drain

The external ventricular drain (EVD) is one of the most basic and essential procedures that the junior resident must master but even the most experienced can face difficulties if the technical principles are not respected. This technique is lifesaving for patients suffering from life-threatening hydrocephalus and intraventricular hemorrhage.

Whereas other intraparenchymal pressure monitoring devices are limited to measuring the intracranial pressure (ICP), the EVD is both diagnostic and therapeutic. The EVD drains cerebrospinal fluid (CSF) and relieves intracranial hypertension related to disorders of CSF overproduction and underabsorption. However, compared to intraparenchymal pressure monitoring devices, the EVD is more invasive and associated with a higher risk of intracranial hemorrhage and infection (ventriculitis).

Insertion of the EVD is a “blind procedure” based on approximate external anatomic landmarks. Frequently, the ventricular anatomy is distorted by the mass effect of the underlying pathology, so the catheter trajectory must be adjusted based on the ventricular disto...