Chapter

Management of raised intracranial pressure

David K. Menon

in Oxford Textbook of Medicine

Fifth edition

Published on behalf of Oxford University Press

ISBN: 9780199204854
Published online May 2012 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.1706

Series: Oxford Textbooks

Management of raised intracranial pressure

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Normal intracranial pressure (ICP) is between 5 and 15 mmHg in supine subjects. Intracranial hypertension (ICP >20 mmHg) is common in many central nervous system diseases and in fatal cases is often the immediate cause of death.

Aetiology and pathogenesis—increases in intracranial volume and hence—given the rigid skull—ICP may be the consequence of (1) brain oedema, (2) increased cerebral blood volume, (3) hydrocephalus, and (4) space-occupying lesions. Brain perfusion depends on the difference between mean arterial pressure and ICP, termed cerebral perfusion pressure (CPP). The normal brain autoregulates cerebral blood flow down to a lower limit of CPP of about 50 mmHg in healthy subjects, and perhaps 60 to 70 mmHg in disease. CPP reduction to below these values results in cerebral ischaemia.

Clinical features—the cardinal symptom of intracranial hypertension is headache, which may be accompanied by vomiting, visual disturbance, and alterations in mental function or conscious state. Papilloedema is the classical sign, but may be absent. Severe elevation of ICP can result in bradycardia and hypertension (Cushing’s response), abnormalities of breathing (Cheyne–Stokes respiration, central neurogenic hyperventilation, ‘ataxia of breathing’), and various forms of cerebral herniation.

Investigation—if clinical features suggest intracranial hypertension, a lumbar puncture must be preceded by CT imaging, and avoided if the basal cisterns are effaced by cerebral oedema.

Management—this involves (1) ensuring normoxia and normocapnia (Pao2 >11 kPa, Paco2 4.5–5 kPa), with tracheal intubation and ventilatory support where required; (2) treating precipitating factors such as fits, pyrexia, and electrolyte abnormalities; (3) treating raised ICP with mannitol, dexamethasone (for tumours), hyperventilation (if pupillary dilatation/clinical picture merits); and (4) monitoring ICP if appropriate (e.g. trauma).

Chapter.  3339 words.  Illustrated.

Subjects: Clinical Medicine

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