An External Ventricular Drain is placed into which structure to monitor ICP and drain CSF?

An External Ventricular Drain is placed into which structure to monitor ICP and drain CSF?

• A. Lateral ventricle.
• B. Third ventricle.
• C. Subarachnoid space.
• D. Cerebellar hemisphere.

Answer: (A)

The key idea is that an external ventricular drain provides both continuous ICP monitoring and CSF drainage by entering the ventricular system. The lateral ventricle is the usual entry point because it offers direct access to CSF and allows the catheter tip to sit in the frontal horn near the foramen of Monro, giving an accurate intraventricular pressure reading and a reliable drainage path. Draining from the ventricular system makes the ICP measurement reflect true intracranial pressure and enables effective CSF removal to prevent or treat hydrocephalus. Placing the catheter in the third ventricle is technically possible but much less common and more risky; the subarachnoid space drains CSF but does not provide as precise, reliable ICP monitoring with an external drain; the cerebellar hemisphere is not part of the ventricular CSF pathway and isn’t used for EVD.

The key idea is that an external ventricular drain provides both continuous ICP monitoring and CSF drainage by entering the ventricular system. The lateral ventricle is the usual entry point because it offers direct access to CSF and allows the catheter tip to sit in the frontal horn near the foramen of Monro, giving an accurate intraventricular pressure reading and a reliable drainage path. Draining from the ventricular system makes the ICP measurement reflect true intracranial pressure and enables effective CSF removal to prevent or treat hydrocephalus. Placing the catheter in the third ventricle is technically possible but much less common and more risky; the subarachnoid space drains CSF but does not provide as precise, reliable ICP monitoring with an external drain; the cerebellar hemisphere is not part of the ventricular CSF pathway and isn’t used for EVD.