Concussion and traumatic brain injury

18,160views

00:00 / 00:00

High Yield Notes

5 pages

Flashcards

Concussion and traumatic brain injury

of complete

Questions

USMLE® Step 1 style questions USMLE

of complete

A 30-year-old woman is brought to the emergency department following a fall during a climbing trip. Her partner, who accompanied her, reports that the patient fell from a 4-meter height and hit her head. En route to the hospital, the patient is comatose and unresponsive. Glasgow Coma Score is 3. She is sedated and intubated. On arrival, her temperature is 36.0°C (96.8°F), pulse is 43/min, respirations are 7/min and irregular, and blood pressure is 200/70 mmHg. On physical examination, her arms are stiff and bent, with clenched fists and outstretched legs. Both pupils are fixed and dilated. A non-contrast CT is obtained and shows a large biconvex-shaped lesion. Which of the following additional findings is most likely to be present?  

Transcript

Watch video only

Concussion, also called a mild traumatic brain injury, usually starts with a hit to the head.

But what makes it a concussion is that the hit results in diffuse brain injury--meaning a large part of the brain is affected rather than a small specific area.

Also, concussions don’t cause obvious brain trauma that can be seen on imaging--like bleeding.

Most concussions are the result of injuries from things like motor vehicle accidents, falling down the stairs, recreational activities - like getting hit in boxing or getting tackled in a football game, or even violence in the home.

Now, the brain is made up of neurons--the functional cells of the nervous system.

Neurons are made up of three main parts. The dendrites, which are little branches off of the neuron that receive signals from other neurons, the soma, or cell body, which has all of the neuron’s main organelles like the nucleus, and the axon which is intermittently wrapped in fatty myelin.

When an electrical impulse called an action potential flows through a neuron, it causes the release of stored neurotransmitters into the gap between two neurons called the synapse.

This first neuron is called the presynaptic neuron.

And the next neuron, called the postsynaptic neuron, has receptors for the neurotransmitters on its dendrites which trigger the opening of ion channels in the postsynaptic neuron.

When the neurotransmitter glutamate binds to a postsynaptic neuron, it causes ion channels to open, and positively charged ions like sodium, potassium, and calcium enter the cell.

This is called an excitatory postsynaptic potential, or EPSP, because more positive charge inside the cell causes a depolarization to happen.

If the overall charge of the cell increases enough, it triggers an action potential, which is an electrical signal that races down the axon at speeds of up to 100 meters per second, triggering the release of more neurotransmitter at the next synapse.

In contrast to glutamate, neurotransmitters like GABA, or gamma-aminobutyric acid, binds to postsynaptic neurons and open ion channels that lets in negatively charged chloride ions, creating an inhibitory postsynaptic potential, or IPSP, which make the cell potential more negative by repolarizing it.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Assessment, Management and Knowledge of Sport-Related Concussion: Systematic Review" Sports Medicine (2014)
  6. "The New Neurometabolic Cascade of Concussion" Neurosurgery (2014)
Elsevier

Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.

RELX