EMS Neurological Emergencies - The Monro-Kellie Doctrine

The Monro-Kellie Doctrine is a fundamental concept in neurology and emergency medicine that EMS providers should be familiar with.

Essentially, it states that the skull is a rigid container that houses the brain, blood, and cerebrospinal fluid (CSF), and that the total volume inside the skull must remain relatively constant to maintain normal intracranial pressure (ICP).

Here are some key points that EMS providers should know about the Monro-Kellie Doctrine:

Components of Intracranial Contents: The doctrine describes the three main components inside the skull - brain tissue, blood, and cerebrospinal fluid.

Any increase in the volume of one of these components must be compensated by a decrease in the volume of another to maintain a relatively constant intracranial pressure.

Implications for Traumatic Brain Injury (TBI): In cases of TBI, such as intracranial hemorrhage or cerebral edema (swelling of the brain tissue), the Monro-Kellie Doctrine helps EMS providers understand the potential consequences.

An increase in the volume of blood or swelling of the brain tissue can lead to increased intracranial pressure, which can compromise cerebral perfusion and cause further damage.

Clinical Assessment: EMS providers should be vigilant for signs and symptoms of increased intracranial pressure in patients with head injuries, such as altered level of consciousness, headache, vomiting, pupillary changes, and changes in vital signs.

These indicators may prompt the need for urgent intervention and transport to a higher level of care.

Treatment Implications: Understanding the Monro-Kellie Doctrine guides treatment strategies for patients with traumatic brain injury.

Interventions aimed at reducing intracranial pressure may include elevating the head of the bed, administering hyperosmolar therapy (such as mannitol or hypertonic saline) to reduce cerebral edema, ensuring adequate oxygenation and ventilation, and potentially performing interventions to control bleeding or relieve pressure, such as craniotomy or burr hole evacuation.

Importance of Monitoring: Continuously monitoring vital signs, neurologic status, and intracranial pressure in patients with head injuries is crucial for early detection of deteriorating conditions and timely intervention.

EMS providers should be trained in the use of appropriate monitoring devices and interpretation of data.

Overall, a solid understanding of the Monro-Kellie Doctrine is essential for EMS providers caring for patients with traumatic brain injury or other intracranial pathology.

It helps guide clinical assessment, treatment decisions, and ongoing management to optimize outcomes for these patients.

Further Reading:

Cowburn, R. & Cadogan, M (2020) Monro-Kellie Doctrine. Life in the Fast Lane https://litfl.com/monro-kellie-doctrine/ Accessed April 14, 2024

Mokri B (2001) The Monro-Kellie Hypothesis: Applications in CSF Volume Depletion. Neurology 56 (12): 1746-8