Intracranial Hypertension Resident Survival Guide
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# Overview
Intracranial pressure, (ICP), is the pressure exerted by three structures inside the cranium; brain parenchyma, CSF and blood. The norma ICP is 10-15 mmHg and is usually maintained by equilibrium of the intracranial contents. Intracranial hypertension ( IH), is elevation of the pressure in the cranium. It typically occurs when the ICP is >20 mmHg. Hans Queckenstedt's was the first person to use lumbar needle for ICP monitoring. Intracranial hypertension is generally categorized as acute or chronic. The Monro-Kellie hypothesis explains the relationship between the contents of the cranium and intracranial pressure. It explains the underlying pathophysiology of elevated intracranial pressure or intracranial hypertension. Several pathophysiologic mechanisms are thought to be involved in the pathogenesis of Increased Intracaranial pressure (ICP) or Intracranial hypertension (ICH). All mechanisms eventually lead to brain injury from brain stem compression and decreased cerebral blood supply or ischemia. Increased Intracaranial pressure (ICP) or Intracranial hypertension (ICH) must be differentiated from other diseases that cause headache, nausea, vomiting and neurologic deficits such as tumor, abscess or space occupying lesion, venous sinus thrombosis, neck surgery, Obstructive hydrocephalus, meningitis, subarachnoid hemorrhage, choroid plexus papilloma, and Malignant systemic hypertension. The diagnosis of Increased Intracaranial pressure (ICP) or Intracranial hypertension (ICH) is made when ICP is >20 mmHg. CT scan or MRI may be considered initial diagnostic investigations.  Intracranial hypertension is considered to be emergency condition.  Treatment includes resuscitative measures and specific directed therapy.  Resuscitative measures include oxygen, blood pressure and ICP monitoring, osmotic diuresis, head elevation up to 30 degrees, therapeutic hypothermia and seizure prophylaxis.

# Causes

## Life Threatening Causes
Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated. If intracranial hypertension left untreated, may cause:
- Transtentorial herniation
- Respiratory depression
- Coma
- Brain death

## Common Causes
- Aneurysm
- Arnold-chiari malformation
- Behcet's disease
- Brain tumor
- Cerebral edema
- Cerebral venous sinus thrombosis
- Choroid plexus tumor
- Chronic kidney disease
- Colloid cyst of third ventricle
- Contusions
- Crouzon craniofacial dysostosis
- Cushing's syndrome
- Dural arteriovenous fistula
- Encephalitis
- Epidural haemorrhage
- Epidural hematoma
- Erdheim-chester disease
- Excess cerebrospinal fluid
- Head trauma
- Hydrocephalus
- Hypertensive brain hemorrhage
- Hypertensive encephalopathy
- Idiopathic intracranial hypertension
- Intracranial granuloma
- Intracranial haemorrhage
- Intraventricular hemorrhage
- Meningioma
- Meningitis
- Meningoencephalitis
- Obstruction of superior mediastinal veins
- Obstruction of jugular veins
- Status epilepticus
- Stroke
- Subarachnoid haemorrhage
- Subdural haemorrhage
- Subdural hematoma
- Vasculitis
- Venous sinus thrombosis

# Diagnosis and Treatment

# Do's
- Maintain oxygen
- Head elevation
- Hyperventilation to achieve a PaCO2 of 26-30 mmHg
- Osmotic diuresis with intravenous mannitol and Lasix
- Appropriate sedation, if patient requires intubation. Propofol is considered to be the preferred agent.
- Therapeutic hypothermia to achieve a low metabolic state
- Appropriate choice of fluids to achieve euvolemic state. Avoid hypotonic agents
- Allow permissive hypertension. Treat hypertension only when CPP >120 mmHg and ICP >20 mmHg
- Seizure prophylaxis with anticonvulsant therapy.

# Don'ts
- Don't give hpyotonic fluids
- Don't aggresively treat hypertension