Intracranial hypertension syndrome !

Syndrome

Raised pressure inside the skull: headache, vomiting, blurred vision and drowsiness; it can be fatal.

Updated 2026-11-01

See it in 3D: Optic disc · Abducens nerve (VI) · Oculomotor nerve (III) · Lateral ventricles · Tentorium · Cerebellar tonsils

What it is

The skull is a rigid box holding brain, blood and cerebrospinal fluid; if one of them grows (a tumour, a haematoma, oedema or fluid that does not drain), the pressure rises. The syndrome combines headache, vomiting, papilloedema and falling consciousness. If the pressure keeps rising, the brain shifts (herniation) and compresses the brainstem.

Key findings

Papilloedema: swollen, blurred optic disc, engorged veins, haemorrhages around the disc; almost always bilateral.
Brief visual obscurations on changing posture.
A normal fundus does not rule out raised intracranial pressure, especially in acute cases.
Nursing: head of the bed raised, frequent neuro and pupil checks and immediate reporting of any change.

Pathophysiology

Monro–Kellie doctrine: the total volume inside the skull is fixed; if one component grows, another must shrink or the pressure rises.
The pressure is passed to the optic nerve sheath and causes swelling of the optic disc.
Cranial nerve VI has a long course over the skull base and is easily stretched.
The temporal uncus can herniate under the tentorium and compress nerve III and the midbrain; the cerebellar tonsils, through the foramen magnum, compress the medulla.

Common causes

Masses: tumours, abscesses, epidural and subdural haematomas, intracerebral haemorrhage.
Oedema: traumatic brain injury, large infarction, hepatic or hypertensive encephalopathy.
Cerebrospinal fluid: hydrocephalus, meningitis.
Venous: cerebral venous sinus thrombosis.
Idiopathic intracranial hypertension: young women with obesity, papilloedema and headache without a mass.

Tests that confirm it

Urgent head CT; MRI and venography as suspicion directs.
Pressure is measured with intracranial monitoring in intensive care, or by lumbar puncture only once imaging has ruled out a mass.

Test yourself

Think of the answer, then tap the question to see it.

What makes up the Cushing triad?

Hypertension with a wide pulse pressure, bradycardia and irregular breathing; it is a late sign of very high intracranial pressure.

Why is a sixth nerve palsy called a 'false localising' sign?

Its palsy can come from raised pressure alone, which stretches the nerve along its long course, rather than from a lesion at its site.

Which signs does uncal herniation produce?

A dilated pupil on the same side from third nerve compression, falling consciousness and hemiparesis on the opposite side.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Increased intracranial pressure (MedlinePlus, U.S. National Library of Medicine, 2024); Papilledema (MSD Manual Professional Edition, 2024); Brain Herniation (MSD Manual Professional Edition, 2024).

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Representative model, for educational purposes only.