Causes of Raised Intracranial Pressure
| Mechanism | Pathologies | Comment |
|---|---|---|
| Vascular | Haemorrhagic stroke Subarachnoid haemorrhage Cerebral venous sinus thrombosis Ischaemic stroke with mass effect (‘malignant MCA (middle cerebral artery) syndrome’) | Vascular causes typically present suddenly, with headache, vomiting and neurological deficit. Patients with raised ICP secondary to ischaemic stroke present with pressure symptoms usually over 24h following the infarct, with severe headache and progressive reduction in conscious level. |
| Disorders of CSF hydrodynamics | Obstructive hydrocephalus Communicating hydrocephalus Idiopathic intracranial hypertension | Obstructive hydrocephalus due to a mass lesion such as a tumour presents subacutely, but conscious level may deteriorate very rapidly. Such patients, particularly if young, may lose the ability to look upwards, due to dorsal midbrain compression. Communicating hydrocephalus usually occurs due to disruption of CSF reabsorption, such as following subarachnoid haemorrhage, or meningitis. Idiopathic intracranial hypertension (previously known as benign intracranial hypertension) occurs almost exclusively in young, obese females. It is characterized by headache, papilloedema, and markedly raised CSF pressures on lumbar puncture. |
| Infection | Brain abscess Subdural empyema Meningitis | Brain abscess and empyema present with headache, confusion and seizures. There is usually a source such as sinusitis, dental abscess or infective endocarditis. Meningitis and encephalitis cause raised intracranial pressure secondary to cerebral inflammation, venous congestion and thrombosis, and secondary hydrocephalus. |
| Trauma | Severe head injury with traumatic haematoma (e.g. subdural or extradural haematoma) Chronic subdural haematoma | Acutely raised intracranial pressure secondary to trauma presents with a clear history in a usually comatose patient. Chronic subdural haematoma is a common presentation to medicine, usually in elderly patients with a great variety of presentations. Most commonly it presents with deterioration in mobility, headache, confusion, and occasionally focal deficit. |
| Neoplasia | Primary brain tumour Brain metastasis Extra-axial tumour (e.g. meningioma) | Brain tumours present subacutely with headache, nausea and vomiting, and focal deficits. There may be a history of previous cancer in patients presenting with brain metastasis. A small number of patients, usually with cerebellar metastasis, present in extremis with obstructive hydrocephalus. |
| Metabolic disorder | Acute liver failure Diabetic ketoacidosis Hypoxic-ischaemic brain injury Severe hyponatraemia Acute mountain sickness | Metabolic presentations of raised ICP are varied, and the diagnosis is often suspected by the systemic condition of the patient, for example cerebral oedema in a young patient with diabetic ketoacidosis following fluid administration. |