====== Intracranial hypertension ======

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Intracranial [[hypertension]], commonly abbreviated IH, IICP or [[raised intracranial pressure]] (ICP), is elevation of the pressure in the [[cranium]] greater than 20 cmH2O.

ICP is normally 7–15 mm Hg; at 20–25 mm Hg, the upper limit of normal, treatment to reduce ICP may be needed.

===== Classification =====
**Intracranial hypertension (IH)** refers to elevated pressure inside the skull, and it can be classified based on its underlying cause or etiology. 

### 1. **Primary Intracranial Hypertension ([[Idiopathic Intracranial Hypertension]] 

  
### 2. **Secondary Intracranial Hypertension**
- **Definition**: This occurs when the increase in intracranial pressure is due to an identifiable cause or underlying pathology.
- **Causes**:
  - **Cerebral masses or lesions** (tumors, abscesses, hematomas)
  - **Hydrocephalus** (accumulation of excess CSF)
  - **Cerebral venous sinus thrombosis** (blockage of venous drainage)
  - **Traumatic brain injury** or hemorrhage (subarachnoid or subdural hemorrhage)
  - **Infections** (meningitis, encephalitis)
  - **Toxins or drugs** (e.g., tetracyclines, vitamin A toxicity, steroids)
  - **Systemic conditions** (severe hypertension, renal failure, obstructive sleep apnea)
  
### 3. **Acute Intracranial Hypertension**
- **Definition**: Rapid increase in intracranial pressure over a short period of time, typically due to traumatic brain injury, stroke, or hemorrhage.
- **Symptoms**: Severe headache, altered consciousness, rapid neurological deterioration.
- **Treatment**: Immediate interventions to reduce pressure, such as osmotic therapy (mannitol, hypertonic saline), mechanical ventilation, or surgical decompression.

### 4. **Chronic Intracranial Hypertension**
- **Definition**: Gradual and sustained elevation of intracranial pressure over a longer period of time, usually due to a chronic underlying condition (e.g., long-standing hydrocephalus, tumors, chronic idiopathic intracranial hypertension).
- **Symptoms**: More subtle over time, with progressive headache, vision problems, and cognitive decline.

### 5. **Malignant Intracranial Hypertension**
- **Definition**: This term is often used to describe rapidly progressing and life-threatening increases in intracranial pressure, typically secondary to brain tumors, infections, or severe head trauma.
- **Symptoms**: Rapid progression to coma or death without intervention due to herniation (downward displacement of brain tissue).

### Classification Based on **Severity**:
- **Mild**: ICP slightly elevated, typically less than 20 mmHg.
- **Moderate**: ICP between 20–40 mmHg.
- **Severe**: ICP greater than 40 mmHg, which requires urgent intervention to prevent brain damage or death.

### Clinical Relevance:
- **Idiopathic Intracranial Hypertension** is a diagnosis of exclusion, meaning secondary causes of elevated ICP must be ruled out.
- **Secondary Intracranial Hypertension** requires treatment of the underlying cause in addition to measures to lower intracranial pressure.

Management is aimed at addressing the cause, reducing intracranial pressure, and preventing complications such as brain herniation or vision loss.

===== Etiology =====

[[Intracranial Hypertension Etiology]].

===== Pathogenesis =====

[[Intracranial Hypertension Pathogenesis]].

===== Clinical features =====

[[Intracranial hypertension clinical features]]

===== Diagnosis =====

[[Intracranial hypertension diagnosis]].

===== Outcome =====

[[Intracranial hypertension]] is the largest cause of [[death]] in young patients with [[severe traumatic brain injury]]
((Alvis-Miranda H, Castellar-Leones SM, Moscote-Salazar LR. Decompressive
Craniectomy and Traumatic Brain Injury: A Review. Bull Emerg Trauma. 2013
Apr;1(2):60-8. Review. PubMed PMID: 27162826; PubMed Central PMCID: PMC4771225.
)).

===== Complications =====
[[Autonomic impairment]] after acute [[traumatic brain injury]] has been associated independently with both increased [[morbidity]] and [[mortality]]. Links between autonomic impairment and [[increased intracranial pressure]] or impaired cerebral [[autoregulation]] have been described as well. However, relationships between autonomic impairment, intracranial pressure, impaired cerebral autoregulation, and outcome remain poorly explored. 

If intracranial pressure gets too high, it can lead to deadly [[brain herniation]], in which parts of the brain are squeezed past structures in the skull.

===== Treatment =====

see [[Intracranial hypertension treatment]].