Level 2 of 6Must-remember
Raised intracranial pressure
Assess, manage and stay safe — enough on its own
The card — assess, manage, caution
Assessment— look, ask, measure
- Know the normal numbers: intracranial pressure in a resting supine adult is about 7–15 mmHg (Kumar & Clark) or less than 10–15 mmHg (Davidson's), lower in children (roughly 3–7 mmHg) and lower still in infants (1.5–6 mmHg) — so a "normal adult" pressure may be pathological in a toddler.
- Treat above 20 mmHg and keep cerebral perfusion pressure at least 60 mmHg, where CPP = mean arterial pressure − ICP: 25 mmHg with a MAP of 100 mmHg is a nuisance, the same pressure with a MAP of 65 mmHg is an infarct in progress; sustained pressures above 20–25 mmHg, and particularly above 40 mmHg, are strongly associated with death and severe disability.
- Drowsiness and a falling conscious level are the crucial early features and the ones most often dismissed — the patient who was conversing and is now "just tired", who needs a louder voice, or who dozes between questions, is decompensating now; this is the sign that permits pre-emptive treatment, and a fixed dilated pupil does not.
- The headache pattern: worse on waking, worse on coughing, sneezing, straining or bending forward, and progressive over days to weeks; a thunderclap onset points instead to subarachnoid haemorrhage, dissection, venous sinus thrombosis or pituitary apoplexy.
- Vomiting often occurs without preceding nausea and may briefly relieve the headache; in children it frequently dominates and is mistaken for gastroenteritis.
- Record an itemised GCS (E, V and M separately) with a clock time — the trend matters far more than any single value and the motor score carries most of the prognostic weight; 13–15 mild, 9–12 moderate, 8 or less severe, and GCS 8 or less generally mandates a definitive airway. Below about 5 years use the paediatric GCS; on AVPU "P" is approximately GCS 8.
- Examine the pupils one at a time with a bright light in a darkened room, recorded in millimetres with the reaction: a progressively enlarging, then sluggish, then fixed and dilated pupil on one side is third nerve compression from uncal herniation.
- The pupil tells you which side, and the conscious level tells you how much time is left.
- Transient visual obscurations — grey-outs or black-outs lasting seconds, in one eye or both simultaneously, typically provoked by abrupt shifts in posture — are the classic symptom of papilloedema, and when prolonged or spontaneous the papilloedema is more threatening.
- Papilloedema shows blurred and elevated disc margins, loss of spontaneous venous pulsation and peripapillary haemorrhages, with an enlarged blind spot and peripheral field constriction; acuity is not affected unless it is severe, long-standing or accompanied by macular oedema and haemorrhage, and it takes hours to days to develop, so its absence never excludes acutely raised pressure.
- The Cushing response — hypertension with bradycardia and an irregular respiratory pattern — is late and pre-terminal. Posturing may be decorticate (flexion, M3) or decerebrate (extension, M2, worse); asymmetry lateralises.
- The respiratory pattern degrades from Cheyne–Stokes through central neurogenic hyperventilation and apneusis to ataxic breathing and apnoea as failure descends the brainstem.
- A sixth nerve palsy causing horizontal diplopia is a false localising sign — it confirms raised pressure but says nothing about the site of the lesion; so is Kernohan's notch phenomenon, hemiparesis ipsilateral to the blown pupil.
- In infants: an open fontanelle and unfused sutures let the calvarium expand, so look for a tense bulging fontanelle (palpated with the infant calm and held upright, since crying causes bulging), splayed sutures, an accelerating head circumference and "sunsetting" eyes, with irritability alternating with lethargy, a high-pitched cry, poor feeding, persistent vomiting and a new squint. Bradycardia in a drowsy child is a pre-terminal sign, not a vagal quirk.
- Red flags mandating treatment rather than observation: a fall in GCS of 2 or more points or any GCS of 8 or less; a new, enlarging, sluggish or fixed pupil; decorticate or decerebrate posturing; the Cushing response; new or repeated seizures or failure to wake after one; prolonged or spontaneous visual obscurations or falling visual acuity with papilloedema; a rising PaCO₂; and in an infant a tense bulging fontanelle or bradycardia.
- Always check the capillary glucose — hypoglycaemia mimics every neurological emergency, and failure to wake after normoglycaemia suggests cerebral oedema.
Management— do this, in order
- Tier 0 costs nothing and works within seconds: position the patient head-up at 30°, head in the midline, and the neck completely free — head rotation kinks the internal jugular vein, so turn the whole patient rather than the head alone, and remove any tight cervical collar, tube ties or tracheostomy tape.
- Do not elevate beyond 30°, which lowers cerebral perfusion pressure and is counterproductive.
- Treat fever — in raised ICP euthermia is mandatory: paracetamol 1 g IV/PO/PR 6-hourly (maximum 4 g/day) in adults, 15 mg/kg 6-hourly (maximum 60 mg/kg/day) in children, with surface cooling.
- Stop seizures, which double cerebral metabolic rate: lorazepam 4 mg IV (paediatric 0.1 mg/kg, maximum 4 mg), diazepam 5–10 mg IV (paediatric 0.3 mg/kg IV, 0.5 mg/kg per rectum), or buccal midazolam 10 mg (paediatric 0.3 mg/kg) without access; then phenytoin 20 mg/kg IV at no more than 50 mg/min with cardiac monitoring, or levetiracetam 60 mg/kg (maximum 4.5 g).Doctor / Nurse
- Treat pain and agitation, suppress cough and straining, give an antiemetic, catheterise the bladder and relieve constipation — each raises intrathoracic or intra-abdominal pressure and therefore ICP — and maintain normoglycaemia, roughly 6–10 mmol/L, never below 4 mmol/L.
- Intubate and ventilate for a GCS of 8 or less, a falling GCS, absent airway reflexes, or inadequate respiratory effort; laryngoscopy produces a sympathetic surge and a rise in ICP, so induction must be smooth and complete with adequate depth and neuromuscular blockade.Doctor / NurseNot available at your setup — Endotracheal intubation kit, Mechanical ventilator.
- Ventilation targets: SpO₂ above 94% and PaCO₂ 4.5–5.0 kPa (35–38 mmHg) — normocapnia, not hyperventilation, as the routine target.Not available at your setup — Arterial blood gas, Mechanical ventilator.
- Aim for euvolaemia with a high-normal blood pressure using isotonic fluid only, with vasopressor support to hold CPP at least 60 mmHg once the patient is volume-replete.Doctor / NurseNot available at your setup — Infusion pump.
- Osmotherapy is indicated for a new unilateral dilating or fixed pupil, a fall in GCS of 2 or more points, posturing, the Cushing response, or imaging showing significant mass effect, midline shift or herniation — and in a patient who is actively herniating it is given immediately, without waiting for imaging.Doctor / Nurse
- Mannitol 20%: 0.5–1 g/kg IV over 15–20 minutes (2.5–5 mL/kg; 35–70 g for a 70 kg adult); for established herniation CMDT gives 1.5 g/kg over about 30 minutes, and Harrison's maintenance dosing is 25–100 g every 4 hours as needed; paediatric 0.5–1 g/kg IV over 20 minutes, repeat 0.25–0.5 g/kg.Doctor / Nurse
- Give mannitol into a large vein through a filtered giving set (it crystallises), catheterise because a brisk osmotic diuresis follows, keep serum osmolality below 320 mosmol/kg, and replace the diuresis with isotonic fluid.Doctor / NurseNot available at your setup — Serum electrolytes.
- Hypertonic saline 3%: 3–5 mL/kg IV over 10–20 minutes in adults and children; for symptomatic hyponatraemic cerebral oedema 100–150 mL over 10–20 minutes, repeated up to twice; target sodium 145–155 mmol/L. It expands intravascular volume rather than depleting it, so prefer it if the patient is hypotensive, hypovolaemic, oliguric or renally impaired.Doctor / NurseNot available at your setup — Serum electrolytes.
- Hypertonic saline 23.4%: a 30 mL bolus as a rescue for herniation in a monitored environment — central access only.Doctor / NurseNot available at your setup — Central venous access.
- A rise in serum sodium of only 4–5 mmol/L is generally sufficient to reverse severe neurological symptoms promptly and to decrease intracranial pressure; in chronic hyponatraemia correction must not exceed 8–10 mmol/L in 24 hours.Not available at your setup — Serum electrolytes.
- Corticosteroids only for vasogenic oedema around a tumour or abscess: for herniation from a mass lesion CMDT gives dexamethasone 10–20 mg IV as a bolus followed by 4 mg every 6 hours with intravenous mannitol; for tumour-associated oedema generally, dexamethasone 4–25 mg four times daily IV or orally depending on severity, then tapered; paediatric 0.25–0.5 mg/kg IV then 0.25 mg/kg 6-hourly. Co-prescribe gastric protection and monitor capillary glucose.Doctor / Nurse
- CSF drainage through a ventricular drain is more effective than any drug when hydrocephalus is present — and in a shunted patient with vomiting and headache, palpate the reservoir and arrange a shunt tap or revision.Doctor / Nurse
- Controlled hyperventilation is the emergency brake: target PaCO₂ 4.0–4.7 kPa (30–35 mmHg) and no lower, in an intubated sedated patient, guided by blood gas or capnography, and only as a bridge of minutes to an hour; wean slowly because abrupt discontinuation causes rebound intracranial hypertension.Doctor / NurseNot available at your setup — Mechanical ventilator, Arterial blood gas.
- Treat the cause, because every medical measure is temporising: evacuate the clot, drain the CSF, remove the mass, kill the organism, correct the sodium — and in suspected bacterial meningitis give ceftriaxone 2 g IV 12-hourly immediately (child ceftriaxone 75–100 mg/kg/day, maximum 4 g/day, in one or two divided doses, or cefotaxime 200 mg/kg/day, maximum 8 g/day, in four).Doctor / Nurse
Caution— what harms
- Never give hypotonic fluid — 5% dextrose alone, 0.45% saline, or any hypotonic maintenance solution — because free water crosses into the brain and worsens oedema; this is the commonest fluid error in these patients.
- Equally, do not dehydrate the patient: hypovolaemia must be avoided because it contributes to hypotension and worsening infarction. A single episode of hypotension or hypoxia measurably worsens outcome after any brain insult.
- Do not treat the hypertension of the Cushing response — it is the brain defending its own perfusion; where blood pressure must be lowered for a separate reason use labetalol or nicardipine, which are non-sedating and do not appear to raise cerebral blood flow or ICP, and avoid nitroprusside, which raises intracranial pressure.
- Clinical features of raised pressure contraindicate lumbar puncture regardless of the scan — a normal CT does not exclude raised intracranial pressure, and neither does a normal fundus. The other contraindications are uncorrected shock, disordered coagulation, thrombocytopenia, respiratory insufficiency, local infection at the site and ongoing convulsions.
- But the withheld tap must never mean a withheld antibiotic — herniation precipitated by lumbar puncture is the most preventable complication in the subject, and delayed antibiotic is the second.
- Dexamethasone does not treat cytotoxic oedema and causes harm: it must not be given for traumatic brain injury (large randomised evidence shows increased mortality), ischaemic stroke, or intracerebral haemorrhage.
- Do not blindly or vigorously bag-ventilate "to blow off the CO₂" — it is harmful; and sustained hyperventilation causes ischaemia in a brain already marginally perfused, wanes over hours as CSF bicarbonate re-equilibrates, and rebounds on abrupt withdrawal.
- Mannitol hazards: anticipate hypotension after the diuresis and acute kidney injury with repeat dosing; avoid it in anuric renal failure, pulmonary oedema and hypovolaemia; an osmolar gap above about 20 mosmol/kg suggests accumulation and predicts renal injury.Not available at your setup — Serum electrolytes, Renal function (creatinine/urea).
- Hypertonic saline extravasation causes necrosis, and 23.4% saline requires central access.Not available at your setup — Central venous access.
- Never correct sodium faster than 8–10 mmol/L in 24 hours in chronic hyponatraemia — irreversible osmotic demyelination follows.Not available at your setup — Serum electrolytes.
- Do not be reassured by a normal CT, a normal fundus, or an alert-looking patient: compensation is silent until exhausted, after which each further millilitre produces a very large rise in pressure — "he was talking to me ten minutes ago" is the natural history, not evidence against it.
- Do not be talked out of the diagnosis because the signs "do not fit": the sixth nerve palsy and Kernohan's notch hemiparesis are false localising signs, and a reduction in optic disc swelling in chronic papilloedema is an ominous sign of a dying nerve, not resolving papilloedema.
- Beware the other causes of a unilateral fixed dilated pupil — posterior communicating artery aneurysm (painful third nerve palsy with ptosis, conscious level preserved), pharmacological mydriasis from nebulised ipratropium or topical agents in a fully alert patient, ocular trauma and post-ictal anisocoria. Conscious level is the discriminator.
- Do not skip observations when there is no monitor: without invasive monitoring the patient is the monitor — record the itemised GCS, pupils, limb power, blood pressure, heart rate, respiratory pattern and temperature at short fixed intervals, comparing each set with the written previous entry, and recheck the blood pressure after osmotherapy because the diuresis will lower it.
Refer / escalate
Refer urgently for neurosurgery and critical care as soon as there is a fall in GCS of 2 or more points, GCS 8 or less, a new or fixed pupil, posturing, the Cushing response, or imaging showing haematoma, hydrocephalus, midline shift over 5 mm or effaced basal cisterns — because the definitive treatments are almost all surgical and everything medical exists only to buy time.
Read the full lesson free
Create a free account to unlock every page, the level exams, and progress tracking.
Sign up freeLog in