Neurosurgical Critical Care and Perioperative Management
What you must own
Understand the principles of neurocritical care. Raised intracranial pressure: Monroe-Kellie doctrine, CPP = MAP - ICP, and tiered management (head elevation, sedation, normocapnia, osmotic therapy with mannitol or hypertonic saline, and decompressive craniectomy in selected cases). Avoid hypoxia, hypotension, hyperthermia and hyperglycaemia.
Fluid and electrolyte: recognise SIADH (euvolaemic hyponatraemia) versus cerebral salt wasting (hypovolaemic hyponatraemia), and the risk of osmotic demyelination with rapid correction. Manage diabetes insipidus after pituitary surgery.
Perioperative: seizure prophylaxis (e.g. levetiracetam), venous thromboembolism prophylaxis, and steroid use for vasogenic oedema. Understand the complications of prolonged immobilisation and the importance of early rehabilitation. Recognise the signs of herniation syndromes and the need for urgent intervention.
Sedation and ventilation: avoid hypercapnia (which raises ICP) and hypocapnia (which causes ischaemia).
Traps
Questions test SIADH versus cerebral salt wasting (both cause hyponatraemia, but volume status differs). Another trap: over-ventilating a patient with raised ICP and causing cerebral ischaemia.
Rule of thumb
In raised ICP, optimise CPP, avoid hypoxia and hypotension, and use osmotherapy for acute deterioration.
Worked example
A patient after SAH develops hyponatraemia with low central venous pressure and polyuria. This suggests cerebral salt wasting, and treatment is volume replacement rather than fluid restriction.