Basics of Increased Intracranial Pressure: Explained

What is increased intracranial pressure?

Increased intracranial pressure (ICP) happens when there’s a rise in the pressure within your cranial vault. It can be sudden (acute) or develop slowly over time (chronic) and has several possible causes.

Your cranial vault is a rigid compartment for:

• Your brain.
• Cerebrospinal fluid (CSF). This is the fluid that cushions your brain and spinal cord.
• Blood.

Any increase in the volume of one of these three components will increase the overall pressure within your cranial vault.

Increased intracranial pressure typically leads to a decrease in blood flow in your brain, or to brain herniation (when brain tissue moves). Both of these are serious, life-threatening conditions.

Elevated pressure within the cranial vault, exceeding 20 mmHg.

Normal ICP: 5-15 mmHg.

Causes:

1.Causes of an increase in brain volume

Generalized (all over) brain swelling (cerebral edema) can happen from:

• Traumatic brain injury.
• Blood flow issues in your brain (ischemia).
• High levels of ammonia in your blood (hyperammonemia).
• Decreased brain function due to a buildup of toxins in your blood from decreased kidney function (uremic encephalopathy).
• Low sodium levels in your blood (hyponatremia).

Swelling can also develop in specific parts of your brain from:

• Intracerebral or subdural hematomas (types of brain bleeds).
• Brain tumor.
• Brain abscess.
• Stroke.

2.Causes of an increase in cerebrospinal fluid

The amount of CSF in your brain can increase due to:

• Hydrocephalus.
• Choroid plexus tumor (a rare type of brain tumor).
• Meningitis.
• Granulomas on your meninges.

3.Causes of an increase in brain blood volume

You can develop increased brain blood volume from:

• Ruptured brain aneurysms or hypercapnia (increased blood carbon dioxide levels).
• Cerebral venous sinus thrombosis.
• Heart failure.

4.Other causes of increased intracranial pressure

Other causes of ICP include:

• Benign or idiopathic intracranial hypertension.
• Skull deformities, like craniosynostosis.
• Too much vitamin A in your body.
• Tetracycline (an antibiotic) use.

Signs and Symptoms:

1. Signs and symptoms of increased intracranial pressure in children and adults include:
2. Headaches. They’re typically worse in the morning or when you’re lying down.
3. Nausea and vomiting.
4. Altered mental status, which can range from drowsiness to coma.
5. Vision changes, like blurred vision, double vision and/or sensitivity to light (photophobia).
6. Eye movement problems.
7. Muscle weakness.
8. Numbness.
9. Seizures.

Signs of ICP in infants include:

1. Drowsiness.
2. Bulging of the soft spot (fontanelle) on the top of their head.
3. Vomiting.
4. Increased intracranial pressure is a medical emergency.

Late signs of increased intracranial pressure

1. Cushing’s reflex — a collection of three conditions that happen together — is a late sign of increased intracranial pressure. It includes:
2. High blood pressure (hypertension).
3. Slow heart rate — fewer than 60 beats per minute (bradycardia).
4. Irregular breathing — mainly, gasping for air (agonal breathing).
5. These signs mean that brain herniation is about to happen.

Stages:

1. Mild (20-30 mmHg): Minimal symptoms
2. Moderate (30-40 mmHg): Progressive symptoms
3. Severe (>40 mmHg): Life-threatening

Diagnosis:

1. Computed Tomography (CT) scan
2. Magnetic Resonance Imaging (MRI)
3. Lumbar puncture (LP)
4. Intracranial pressure monitoring (ICPM)

ICP Monitoring Techniques:

1.Invasive Methods:

1. Intraventricular Catheter (IVC): Gold standard for ICP monitoring.
2. Subdural Catheter: Placed between dura and brain cortex.
3. Epidural Catheter: Placed between skull and dura.
4. Parenchymal Catheter: Placed within brain tissue.

2.Non-Invasive Methods:

1. Transcranial Doppler Ultrasonography (TCD): Measures blood flow velocity.
2. Near-Infrared Spectroscopy (NIRS): Measures cerebral oxygenation.
3. Magnetic Resonance Imaging (MRI): Measures brain volume and CSF flow.
4. Optic Nerve Sheath Diameter (ONSD) Ultrasound: Estimates ICP.

3.Semi-Invasive Methods:

1. Lumbar Puncture (LP): Measures CSF pressure.
2. Bolus Injection Test: Assesses cerebrospinal fluid dynamics.

Monitoring Devices:

1. Camino ICP Monitor
2. Codman ICP Monitor
3. Integra ICP Monitor
4. Medtronic ICP Monitor

Advantages and Disadvantages:

Invasive Methods:

Advantages:

Accurate, reliable, real-time data.

Disadvantages:

Risk of infection, haemorrhage, and brain damage.

Non-Invasive Methods:

Advantages:

Safe, easy to use, no risk of infection.

Disadvantages:

Less accurate, indirect measurements.

Clinical Considerations:

1. Patient selection and contraindications.
2. Monitoring frequency and duration.
3. Data interpretation and integration with clinical assessment.
4. Calibration and maintenance of monitoring devices.

ICP Monitoring in Specific Patients:

1. Traumatic Brain Injury (TBI) Patients:
   • Indications: Severe TBI (GCS ≤ 8), intracranial hypertension.
   • Monitoring goals: Maintain ICP < 20 mmHg, CPP > 60 mmHg.
2. Stroke Patients:
   • Indications: Ischemic or hemorrhagic stroke, cerebral edema.
   • Monitoring goals: Maintain ICP < 20 mmHg, CPP > 60 mmHg.
3. Subarachnoid Hemorrhage (SAH) Patients:
   • Indications: Aneurysmal SAH, vasospasm.
   • Monitoring goals: Maintain ICP < 20 mmHg, CPP > 60 mmHg.
4. Pediatric Patients:
   • Indications: TBI, hydrocephalus, brain tumors.
   • Monitoring goals: Maintain ICP < 15 mmHg, CPP > 50 mmHg.
5. Neonatal Patients:
   • Indications: Perinatal asphyxia, intraventricular hemorrhage.
   • Monitoring goals: Maintain ICP < 10 mmHg, CPP > 40 mmHg.
6. Spinal Cord Injury Patients:
   • Indications: Acute spinal cord injury, spinal cord compression.
   • Monitoring goals: Maintain ICP < 20 mmHg, CPP > 60 mmHg.
7. Liver Transplant Patients:
   • Indications: Fulminant hepatic failure, cerebral edema.
   • Monitoring goals: Maintain ICP < 20 mmHg, CPP > 60 mmHg.

Management:

1. Maintain adequate cerebral perfusion pressure (CPP)
2. Control ICP with medications (e.g., mannitol, hypertonic saline)
3. Surgical interventions (e.g., craniotomy, CSF diversion)
4. Ventilatory support
5. Sedation and analgesia

Complications:

1. Brain herniation
2. Cerebral ischemia
3. Respiratory failure
4. Cardiac arrest

Preventing Increased ICP & its Complications

Increased ICP is not always preventable, but it is possible to reduce the risk of some underlying conditions that may lead to increased ICP. We explore how below.

1.Stroke

Stroke may cause increased ICP. A person can reduce their risk of stroke in the following ways:

• taking steps to lower high blood pressure
• stopping smoking
• managing blood sugar levels
• controlling cholesterol levels
• exercising regularly

2.High blood pressure

High blood pressure may cause increased ICP. A person can maintain healthy blood pressure by:

• losing weight if overweight or maintaining a healthy weight
• avoiding drugs that increase blood pressure
• eating a healthful, balanced diet
• reducing salt intake
• exercising regularly

3.Head injury

A head injury may cause increased ICP. Some examples of how a person can reduce their risk of head injury include:

• avoiding extreme sports or dangerous activities
• always wearing a helmet for activities such as riding a bike
• always wearing a seatbelt when in a car

Nursing Considerations:

1. Monitor vital signs and neurological status
2. Maintain head elevation (30°)
3. Avoid neck bending or flexion
4. Manage pain and anxiety
5. Provide emotional support to patients and families

Special Considerations:

1. Age-related differences in ICP monitoring.
2. Co-existing medical conditions (e.g., hypertension, diabetes).
3. Medication interactions and side effects.
4. Nutritional and metabolic support.

REFERENCES

1. Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW, eds. Seidel’s Guide to Physical Examination. 10th ed. St Louis, MO: Elsevier; 2023:chap 26.
2. Beaumont A. Physiology of the cerebrospinal fluid and intracranial pressure. In: Winn HR, ed. Youmans and Winn Neurological Surgery. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 69.
3. O’Reilly G, Cameron P. Neurotrauma. In: Cameron P, Little M, Mitra B, Deasy C, eds. Textbook of Adult Emergency Medicine. 5th ed. Philadelphia, PA: Elsevier; 2020: chap 3.2.
4. National Library of Medicine (U.S.). Increased Intracranial Pressure (https://medlineplus.gov/ency/article/000793.htm). Last reviewed 4/29/2023. Accessed 6/19/2024.
5. Pinto VL, Tadi P, Adeyinka A. Increased Intracranial Pressure (https://www.ncbi.nlm.nih.gov/books/NBK482119/). 2023 Jul 31. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Accessed 6/19/2024.
6. Saria MG, Kesari S. Increased Intracranial Pressure: The Use of an Individualized Ladder Approach (https://pubmed.ncbi.nlm.nih.gov/33663885/). Semin Oncol Nurs. 2021;37(2):151133. Accessed 6/19/2024.
7. Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/

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