Intracranial Hypertension Resident Survival Guide

Intracranial Hypertension Resident Survival Guide Microchapters
Overview
Causes
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sabeeh Islam, MBBS[2]

Synonyms and keywords:

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
• Behçet'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

Signs and symptoms of Intracranial Hypertension Headache Nausea Vomiting Hyperventilation Ocular palsies (abducens palsy) Periorbital bruising Altered level of consciousness Papilledema Pupillary dilatation Cushing's triad ( Elevated systolic blood pressure, a widened pulse pressure, bradycardia, and an abnormal respiratory pattern. Cheyne-Stokes respiration Bulging of fontanels in infants

CT scan/MRI to rule out tumor, hematoma etc

Monitor Intracranial pressure (ICP >20mmHg), Low Pao2, High Paco2 Invasive ICP monitoring sites Intraventricular Intraparenchymal Subarachnoid Epidural

Surgical evacuation if + for mass

Increased Intracranial pressure ICP>20mmHg

Resuscitation Maintain oxygen Head elevation at 30 Hyperventilation to achieve a PaCO2 of 26-30 mmHg Osmotic diuresis with intravenous mannitol Appropriate sedation, if patient requires intubation Therapeutic hypothermia to achieve a low metabolic state Appropriate choice of fluids to achieve euvolemic state. Allow permissive hypertension. Treat hypertension only when CPP >120 mmHg and ICP >20 mmHg Seizure prophylaxis with anticonvulsant therapy

If ICP is stable and patient is responding well to resuscitation measures Continue aggressive osmotic diuresis with IV mannitol and furosemide Glucocorticoids when underlying etiology is brain tumor or CNS infection Phenobarbital (Barbiturates)

Persistently elevated Intracranial pressure ICP>20mmHg despite above mentioned measures

*Surgical evacuation CSF drainage via ventriculostomy CSF is usually drained at a rate of 1 to 2 mL/minute for 2 to 3 minutes. The procedure is repeated after every 2 to 3 minutes, until ICP is less than 20mmHg Decompressive craniectomy

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.