CSF Diversion (Shunt Variants, Revision, EVD, ETV)
Updated On: July 23, 2026
Anesthetic Approaches
Four operations, one booking - a first ventriculoperitoneal shunt in an infant, a revision in a child on their eighth, an emergency drain in a deteriorating adult, and an endoscopic third ventriculostomy share a diagnosis and almost nothing else. Plan to the variant in front of you.
Raised ICP on arrival - headache, vomiting, drowsiness, and hypertension with bradycardia mean the compliance curve is exhausted and a small rise in intracranial volume buys a large rise in pressure. Treat as high pressure until decompressed, not until imaged.
The induction surge - an intravenous induction deep enough for laryngoscopy avoids the hypertensive spike that herniates a tight brain. Coughing, straining and a light airway are what cause harm here, so time the relaxant and the tube rather than hurrying them.
Ventilation targets - hypercapnia raises cerebral blood volume, and a tight tie, hard collar or sharply turned head obstructs jugular outflow and does the same. Keep the neck free, and set ventilation targets against current neuroanaesthesia guidance.
Against deep hypocapnia - driving the CO2 down shrinks the ventricles and makes the surgeon's cannulation pass harder, so the reflex to hyperventilate a tight brain works against the operation. Hold normocapnia unless the surgeon asks for something else.
The revision child - expect many previous anesthetics, scarred veins, developmental disability, and a spina bifida history that makes latex sensitization likely. Confirm the room is latex-free, and ask the parent rather than the chart which induction went badly.
Third ventricular floor - fenestrating the floor next to the basilar artery produces abrupt bradycardia or asystole with a pressure surge. Say it out loud the moment the rhythm changes so the instrument comes off the floor, which is usually what restores it.
Continuous irrigation - warmed fluid runs through a closed ventricular system throughout the endoscopic work and can raise pressure, cool a small child, or disturb sodium. Watch outflow, temperature and volume balance, not only the screen.
Subcutaneous tunneling - passing the catheter from scalp to abdomen is the most stimulating part of a case that looks minor. Deepen ahead of it, because that is where movement and hypertension appear in an otherwise quiet case.
Airway inside the field - head, neck, chest and abdomen are prepped as one field and the table is turned away, so the tube sits under drapes and out of reach. Secure it and recheck it before draping, since a disconnection means a re-prep.
The distal end - a peritoneal end adds an abdominal incision, an atrial end threads a catheter into the venous circulation with air entrainment and arrhythmia risk, and a pleural end can produce a pneumothorax.
Implanted hardware - a foreign body that fails infected costs the patient another operation and an externalized drain, so timing the antibiotic to be at tissue level at incision is part of the operation, not a checklist item.
Ex-premature infant - a low post-conceptual age means postoperative apnea monitoring and no discharge to an unmonitored bed. Confirm the threshold your institution uses, because it is the single factor that changes where this patient goes afterwards.
An examinable emergence - the surgeon wants a neurological examination, so plan a smooth early wake-up without coughing on a fresh tract. A patient who will not wake, vomits, or has a headache that worsens lying flat is a blocked or overdraining system until proven otherwise.
Tucked Arms (general considerations): Consider a second IV – once the procedure has started, it's going to be VERY difficult to handle IV issues – especially if your only IV has problems. Ensure the IV is running and monitors are still functioning after tucking the patient's arms.
180-degree turns (general considerations): Arrange lines and monitor cords in anticipation to turn. If turning right, keep cords and lines draped to the left. If turning left, keep cords and lines draped to the right. Have a circuit extension connected. Disconnect the circuit when turning and immediately reconnect.
Fluoroscopy / Xray (general considerations): Have lead aprons and thyroid shields available. Alternatively, distancing yourself 3 to 6 feet will reduce scatter radiation to 0.1% to 0.025% respectively. Occupational maximum exposure to radiation should be limited to a maximum average of 20 Sv (joules per kilogram - otherwise known as the Sievert/Sv) per year over a 5 year period. Limits should never exceed 50 Sv in a single year.
Arterial line (general considerations): Preoperatively check pulses to gauge the best side to attempt the A-line. Perform an Allen test to ensure adequate blood flow. Have the A-line equipment set up and ready in the room.
Bispectral Index Scale (BIS) monitor (general considerations): The recommended values under general anesthesia are 40-65. Values of 65-85 are recommended for sedation.
Hydrocephalus is a mismatch between CSF production and absorption, and the ventricles enlarge because the fluid has nowhere to go. Congenital forms present in the newborn, while posthaemorrhagic, infectious and neoplastic obstruction present at any age. Once the intracranial compliance curve is exhausted, a small further rise in volume produces a large rise in pressure, which is why these patients decompensate quickly and why headache, vomiting, drowsiness and papilloedema are late rather than early signs. Diversion either reroutes CSF through implanted hardware to the peritoneum, right atrium or pleura, or restores an internal pathway by fenestrating the floor of the third ventricle. Implanted systems obstruct, disconnect, overdrain and become infected, so a large share of this work is revision rather than first placement.
Indication - imaging shows enlarging ventricles or a failing existing system, and the choice is between a first shunt, a revision, a temporary external drain, or an endoscopic fenestration.
Positioning and prep - supine with a bolster under the operative shoulder and the head turned, then the scalp, neck, chest and abdomen prepped as one continuous field with the table turned away.
Ventricular access - a burr hole is made over the frontal or parietal region and a catheter passed into the lateral ventricle, with CSF egress confirming placement.
Tunneling - the distal catheter is passed subcutaneously from the scalp down the neck and chest wall to its destination in a single long pass.
Distal placement - peritoneal through a small abdominal incision, atrial through the internal jugular or facial vein with the tip positioned radiographically, or pleural.
Valve - a fixed-pressure or programmable valve is interposed and its setting recorded, since some designs can be reset by subsequent magnetic imaging.
Revision - the existing system is exposed and tested and the failed component replaced; a system that has become infected is removed in full and replaced temporarily by an external drain.
Endoscopic third ventriculostomy - an endoscope is passed through a frontal burr hole and the foramen of Monro under continuous irrigation, and the floor of the third ventricle is fenestrated to restore flow without hardware.
External ventricular drain - a burr hole and ventricular catheter left externalized, used to drain CSF and measure pressure as a temporising or diagnostic step.
Handover carries the pressure - state the baseline neurological status, what the pressure and rhythm did during fenestration or cannulation, and whether any drain is open or clamped for transfer. The team receiving the patient judges new deficits against your last examination.