03 / Neurosurgery · percutaneous
External ventricular drain insertion
A catheter into the lateral ventricle through a frontal burr hole at Kocher's point: the emergency treatment of hydrocephalus and raised intracranial pressure, and the ICU's window on the pressure itself.
Indication: Acute hydrocephalus (haemorrhage, tumour, infection), refractory intracranial hypertension needing CSF drainage, and pressure monitoring with a therapeutic option attached.
On the tray for this operation
Test yourself on the tray
Stage
1 / 4
Kocher's point
The entry is marked about 11 cm back from the nasion and 3 cm from the midline, at the mid-pupillary line, in front of the coronal suture on the non-dominant side where possible.
Watch for: Marking behind the coronal suture toward the motor cortex · Too close to midline and the sagittal sinus
Why are we operating?
The external ventricular drain is a controlled tap into the brain's plumbing: a catheter placed into the lateral ventricle relieves acute hydrocephalus, measures intracranial pressure continuously, and buys controlled time in emergencies from subarachnoid haemorrhage to blocked shunts. It is neurosurgery's most-performed emergency procedure and the physical embodiment of Monro-Kellie: remove CSF, and the pressure curve steps back from its cliff.
Pulls toward surgery
Gives the team pause
Shared foundations
What the surgeon is thinking
Kocher's point
Why Kocher's point, of all the skull's real estate?
It is the address that reaches the frontal horn while avoiding what must be avoided: far enough from the midline to spare the sagittal sinus and bridging veins, anterior enough to stay ahead of the motor strip. The measurements are surface anatomy standing in for the ventricle the surgeon cannot see.
Ventricular cannulation
How is a catheter aimed at a chamber it cannot see?
By trajectory: perpendicular to the skull, aimed in the plane of the ipsilateral medial canthus and the tragus, advanced to a measured depth where the give of the ependyma and the flash of CSF announce arrival. The discipline is depth and pass-count: a catheter that has not found CSF by the expected depth is withdrawn and the trajectory rethought, not pushed deeper.
Tunnelling and levelling
Why tunnel the catheter under the scalp before it exits?
Infection: ventriculitis is the EVD's defining complication, and a subcutaneous tunnel separates the skin's flora from the brain's catheter. The same logic governs everything after: closed system, minimal sampling, and a daily 'does it still need to be in?' question.
Burr hole and dural opening
What makes this burr hole different from any other?
Its economy: a single small opening, dura opened just enough to pass the catheter, because this operation's value is speed and control rather than exposure. It is often done at speed for deterioration, which is exactly why its steps are standardised to the point of ritual.
Decision points
The EVD is in. At what height is it set, and who may change it?
Prescribed level, changed only by instruction
The drain's height against the tragus sets the pressure at which CSF spills: it is a prescription, written, and re-zeroed after every position change.
Adjust freely to symptoms
The error: overdraining collapses ventricles and tears bridging veins; underdraining recreates the hydrocephalus. Neither is a bedside improvisation.
The EVD is a column of physics dressed as a drain: its level is a dose. The wards that run EVDs safely are the ones where 'who may touch it' has a one-name answer per shift.
Day 6: CSF cell counts drifting up, one fever. Change, remove, or treat through?
Sample, treat, and plan the catheter's fate
Suspected ventriculitis means cultures, antibiotics with CSF penetration, and usually a catheter exchange: the plastic is the biofilm's home.
Observe
For the isolated soft signal in a patient with another fever source: but the threshold stays low, because ventriculitis compounds daily.
Every EVD day is a bet against infection: the winning strategy is minimising days (daily necessity review), minimising breaches (closed system), and moving decisively when the CSF starts to argue.
Leaving the OR
The handoff
- Procedure
- Right frontal EVD at Kocher's point for acute hydrocephalus post-SAH
- Placement
- CSF under pressure at expected depth, first pass; tunnelled and secured
- Settings
- Levelled at tragus, set at 10 cmH2O, drained 40 mL first hour
- Watch for
- Hourly volumes, waveform, catheter integrity on every move; clamp only per explicit instruction
A fictional educational patient, handed over the way real ones are.
The postoperative course
- First hoursThe drain's arithmetic watched closely: sudden high volumes mean overdrainage risk, sudden silence means blockage, and both are urgent calls rather than notes.
- DailyCSF surveillance and the necessity question: the weaning plan (raising the level, clamp trials) starts as soon as the underlying problem allows.
- WeaningA clamped drain with a stable patient and acceptable pressures earns removal; failure of the trial reopens the conversation about a permanent shunt.
- After removalThe site watched for leak (a CSF-dripping wound is an open door to infection), and the hydrocephalus question formally answered rather than assumed closed.
Watch it done
External ventricular drain (EVD)
Why the drain goes in, where Kocher's point is, and how the height of the bag sets the pressure.
Source: Cleveland Clinic · Watch on YouTube