Concussion and traumatic brain injury


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Concussion and traumatic brain injury

Nervous system

Central nervous system disorders

Spina bifida

Chiari malformation

Dandy-Walker malformation


Tethered spinal cord syndrome

Aqueductal stenosis

Septo-optic dysplasia

Cerebral palsy

Spinocerebellar ataxia (NORD)

Transient ischemic attack

Ischemic stroke

Intracerebral hemorrhage

Epidural hematoma

Subdural hematoma

Subarachnoid hemorrhage

Saccular aneurysm

Arteriovenous malformation

Broca aphasia

Wernicke aphasia

Wernicke-Korsakoff syndrome

Kluver-Bucy syndrome

Concussion and traumatic brain injury

Shaken baby syndrome


Febrile seizure

Early infantile epileptic encephalopathy (NORD)

Tension headache

Cluster headache


Idiopathic intracranial hypertension

Trigeminal neuralgia

Cavernous sinus thrombosis

Alzheimer disease

Vascular dementia

Frontotemporal dementia

Lewy body dementia

Creutzfeldt-Jakob disease

Normal pressure hydrocephalus


Essential tremor

Restless legs syndrome

Parkinson disease

Huntington disease

Opsoclonus myoclonus syndrome (NORD)

Multiple sclerosis

Central pontine myelinolysis

Acute disseminated encephalomyelitis

Transverse myelitis

JC virus (Progressive multifocal leukoencephalopathy)

Adult brain tumors

Acoustic neuroma (schwannoma)

Pituitary adenoma

Pediatric brain tumors

Brain herniation

Brown-Sequard Syndrome

Cauda equina syndrome

Treponema pallidum (Syphilis)

Vitamin B12 deficiency


Friedreich ataxia

Neurogenic bladder


Neonatal meningitis


Brain abscess

Epidural abscess

Cavernous sinus thrombosis

Creutzfeldt-Jakob disease

Central and peripheral nervous system disorders

Sturge-Weber syndrome

Tuberous sclerosis


von Hippel-Lindau disease

Amyotrophic lateral sclerosis

Peripheral nervous system disorders

Spinal muscular atrophy


Guillain-Barre syndrome

Charcot-Marie-Tooth disease

Trigeminal neuralgia

Bell palsy

Winged scapula

Thoracic outlet syndrome

Carpal tunnel syndrome

Ulnar claw

Erb-Duchenne palsy

Klumpke paralysis


Myasthenia gravis

Lambert-Eaton myasthenic syndrome

Autonomic nervous system disorders

Orthostatic hypotension

Horner syndrome

Nervous system pathology review

Congenital neurological disorders: Pathology review

Headaches: Pathology review

Seizures: Pathology review

Cerebral vascular disease: Pathology review

Traumatic brain injury: Pathology review

Spinal cord disorders: Pathology review

Dementia: Pathology review

Central nervous system infections: Pathology review

Movement disorders: Pathology review

Neuromuscular junction disorders: Pathology review

Demyelinating disorders: Pathology review

Adult brain tumors: Pathology review

Pediatric brain tumors: Pathology review

Neurocutaneous disorders: Pathology review


Concussion and traumatic brain injury


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USMLE® Step 1 questions

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High Yield Notes

5 pages


Concussion and traumatic brain injury

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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?  



Marisa Pedron

Vincent Waldman, PhD

Tanner Marshall, MS

Justin Ling, MD, MS

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.

So ultimately it’s a bit of a tug-of-war between stimulation from EPSPs and inhibition from IPSPs that ultimately decides if a neuron fires an action potential.


  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)

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