[2] In general, symptoms and signs that suggest a rise in ICP include headache, vomiting without nausea, ocular palsies, altered level of consciousness, back pain and papilledema.

The brain is relatively poorly supplied by oxygen as a result of mild hypoventilation during the sleeping hours leading to hypercapnia and vasodilation.

[citation needed] Intracranial hypertension syndrome is characterized by an elevated ICP, papilledema, and headache with occasional abducens nerve paresis, absence of a space-occupying lesion or ventricular enlargement, and normal cerebrospinal fluid chemical and hematological constituents.

[citation needed] In infants and small children, the effects of ICP differ because their cranial sutures have not closed.

In infants, the fontanels (soft spots on the head where the skull bones have not yet fused) bulge when ICP gets too high.

[17] Spontaneous intracranial hypotension may occur as a result of an occult leak of CSF at the level of the spine, into another body cavity.

[citation needed] If persistent intracranial hypotension is the result of a lumbar puncture, a blood patch may be applied to seal the site of CSF leakage.

[21] The pressure–volume relationship between ICP, volume of CSF, blood, and brain tissue, and cerebral perfusion pressure (CPP) is known as the Monro–Kellie doctrine or hypothesis.

[24] *This concept only applies to adults, as the presence of fontanelles and open suture lines in infants that have not yet fused means there is potential for a change in size and intracranial volume.

For example, an increase in lesion volume (e.g., epidural hematoma) will be compensated by the downward displacement of CSF and venous blood.

A catheter can be surgically inserted into one of the brain's lateral ventricles and can be used to drain CSF (cerebrospinal fluid) in order to decrease ICPs.

[citation needed] For long-term or chronic forms of raised ICP, especially idiopathic intracranial hypertension (IIH), a specific type of diuretic medication (acetazolamide) is used.

[30] In people who have high ICP due to an acute injury, it is particularly important to ensure adequate airway, breathing, and oxygenation.

[10] Conversely, blood vessels constrict when carbon dioxide levels are below normal, so hyperventilating a person with a ventilator or bag valve mask can temporarily reduce ICP.

Venous drainage may also be impeded by external factors such as hard collars to immobilize the neck in trauma patients, and this may also increase the ICP.

[32] Since hypertension is the body's way of forcing blood into the brain, medical professionals do not normally interfere with it when it is found in a person with a head injury.

[6] When it is necessary to decrease cerebral blood flow, MAP can be lowered using common antihypertensive agents such as calcium channel blockers.

[31][36] Analgesia and sedation are used to reduce agitation and metabolic needs of the brain, but these medications may cause low blood pressure and other side effects.

[citation needed] A drastic treatment for increased ICP is decompressive craniectomy,[37] in which a part of the skull is removed and the dura mater is expanded to allow the brain to swell without crushing it or causing herniation.

Alternatively a synthetic material may be used to replace the removed bone section (see cranioplasty)[citation needed] Creutzfeldt–Jakob disease