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Diffuse Axonal Injury and Concussion

Due to stretching forces placed on individual nerve cells
Pathology distributed throughout brain
Types
Concussion
Diffuse Axonal Injury (Moderate to Severe)

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Diffuse Axonal Injury and Concussion

  1. 1. Diffuse Axonal Injury and Concussion Dr Amit Agrawal, MCh
  2. 2. ∗ Due to stretching forces placed on individual nerve cells ∗ Pathology distributed throughout brain ∗ Types ∗ Concussion ∗ Diffuse Axonal Injury (Moderate to Severe) Diffuse Brain Injury
  3. 3. ∗ Accidental Falls ∗ Vehicular accidents ∗ Child Abuse ∗ Assaults ∗ Gunshots ∗ Violent shaking of a child ∗ Sports related injuries Causes
  4. 4. ∗ Diffuse axonal injury (DAI) is the predominant mechanism of injury in 40% to 50% of traumatic brain injuries (TBIs) requiring hospital admission in the United States. ∗ A component of DAI is believed to be present in all motor vehicle crashes (MVCs) where the patient has lost consciousness ∗ Widespread axonal damage occurring after a mild, moderate, or severe TBI ∗ Process takes approximately 12-24 hours ∗ One of the major causes of unconsciousness and persistent vegetative state after head trauma Diffuse Axonal Injury
  5. 5. ∗ Due to acceleration/deceleration to whtie matter + hypoxia ∗ Significant mechanical disruption of nerve cells ∗ Cerebral hemispheres and brainstem ∗ High mortality rate Diffuse Axonal Injury
  6. 6. ∗ Mostly microscopic damage, and it is often not visible on imaging studies ∗ The main mechanical force that causes DAI is rotational acceleration of the brain, resulting in unrestricted head movement ∗ Rotational acceleration produces shearing and tensile forces, and axons can be pulled apart at the microscopic level ∗ Microscopic evaluation of the brain tissue often shows numerous swollen and disconnected axons ∗ Rapid stretching of axons is thought to damage the axonal cytoskeleton and, therefore, disrupt normal neuron function Diffuse Axonal Injury:Pathological feature
  7. 7. ∗ Varies from mild to profound ∗ May be permanent or temporary ∗ Symptoms may appear immediately or over weeks, months, years ∗ Diffuse axonal injury (DAI) ∗ Clinical signs: ∗ ↓ LOC ∗ ↑ ICP ∗ Decerebration or decortication ∗ Global cerebral edema Diffuse Axonal Injury: Clinical features
  8. 8. Diffuse Axonal Injury: Grading
  9. 9. ∗ Defined as the result of the forceful motion of the head causing a brief change in mental status for less than 30 minutes. Concussion
  10. 10. ∗ Concussion may be caused either by a direct blow to the head, face, neck or elsewhere on the body with an ‘‘impulsive’’ force transmitted to the head. ∗ Concussion typically results in the rapid onset of short- lived impairment of neurologic function that resolves spontaneously. However in some cases symptoms and signs may evolve over a number of minutes to hours. ∗ Concussion may result in neuropathological changes but the acute clinical symptoms largely reflect a functional disturbance rather than a structural injury and as such, no abnormality is seen on standard structural neuroimaging studies. ∗ Concussion results in a graded set of clinical symptoms that may or may not involve loss of consciousness. Resolution of the clinical and cognitive symptoms typically follows a sequential course. However it is important to note that in some cases, post-concussive symptoms may be prolonged. Concussion
  11. 11. ∗ Level of consciousness ∗ Variable period of unconsciousness or confusion ∗ Followed by return to normal consciousness ∗ Retrograde short-term amnesia ∗ May repeat questions over and over ∗ Associated symptoms ∗ Dizziness, headache, ringing in ears, and/or nausea Concussion Head Trauma -
  12. 12. ∗ No structural injury to brain ∗ Mild to moderate form of Diffuse Axonal Injury (DAI) ∗ Nerve dysfunction without anatomic damage ∗ In a concussion, certain chemical levels are altered at the cellular level ∗ Blood supply to the brain decreases ∗ The brain’s demand for glucose increases ∗ Mismatch in fuel supply and demand ∗ Neuronal tissue vulnerability ∗ Brain needs time to recover Concussion: Pathophysiology
  13. 13. Classification/Grading Guides Guideline Grade 1 Grade 2 Grade 3 Cantu 1. No LOC 2. Posttraumatic amnesia <30 min 1. LOC > 5 min OR 2. Posttraumatic amnesia > 30 min 1. LOC > 5 min OR 2. Posttraumatic amnesia >24˚ Colorado 1. Confusion w/out amnesia 2. No LOC 1. Confusion w/ amnesia 2. No LOC 1. LOC (of any duration) AAN 1. Transient confusion 2. No LOC 3. Concussion syx, ms change resolve w/in 5 min 1. Transient confusion 2. No LOC 3. Concussion syx, ms change >15 min 1. LOC (brief or prolonged) Cantu (Revised) 1. No LOC OR 2. Posttraumatic amnesia signs/syx < 30 min 1. LOC < 1 min OR 2. Posttraumatic amnesia >30 min, <24˚ 1. LOC > 1min OR 2. Posttraumatic amnesia >24˚ OR 3. Post concussion signs/syx > 7d
  14. 14. ∗ Neurological examination and assigning a GCS Score. ∗ Neuroimaging helps in determining the diagnosis and prognosis and proposed treatment ∗ Neuropsychological assessment Diagnosis
  15. 15. ∗ Computed tomography (CT) ∗ Rarely detected on CT ( 20% of DAI lesions are hemorrhagic) ∗ Magnetic resonance imaging (MRI) ∗ Can show more details than CT as detecting injury characteristics such as diffuse axonal injury ∗ However, MRI is not used in the emergency setting ∗ X-rays: ∗ Not much role ∗ Angiography: ∗ May be used to detect blood vessel pathology. ∗ Electroencephalography and transcranial doppler may also be used. Investigations
  16. 16. ∗ ABCD ∗ Pharmacotherapy ● Prolonged symptoms (sleep disturbance, anxiety) ● Modify underlying pathophysiology ∗ Upon return to play should not be on medication that could mask symptoms ● Antidepressants? ● Physical Rest ● No training, playing, exercise, weights ● Beware of exertion with activities of daily living ● Cognitive Rest ● No television, extensive reading, video games? ● Caution re: daytime sleep Management
  17. 17. ∗ Mild cases: Gradual resolution within 7-10 days ∗ Gradual return to work and social activities that does not result in significant exacerbation of symptoms Management
  18. 18. ∗ Intracranial Hemorrhage ∗ Skull Fracture ∗ Epidural Hemorrhage ∗ Subdural Hemorrhage ∗ Intracerebral Hemorrhage ∗ Cerebral Hyperemia ∗ Cerebral Edema ∗ Seizures ∗ Migraine Headaches Associated Secondary Conditions
  19. 19. ∗ Majority (80-90%) resolve in short (7-10 day) period ∗ May take longer in children and adolescents Recovery
  20. 20. ∗ Alzheimer's Disease: recent research suggests correlation between head injury in early adulthood and AD later in life ∗ Parkinson's Disease: rare, but may occur ∗ Dementia Pugilistica: also known as chronic traumatic encephalopathy, usually acquired from repetitive blows to the head (boxers) ∗ Post-traumatic Dementia: long term memory problems, caused by single, severe traumatic brain injury resulting in a coma Long Term Effects
  21. 21. • In the car... o Wear seatbelt o Head rest in proper position o Children under the age of 13 should ride in the back seat • Activities o Wear a helmet • Sports o Wear protective gear Prevention
  22. 22. ∗ Traumatic injuries affect more patients than all other neurological conditions COMBINED ∗ At present, the best treatment is PREVENTION Conclusion
  23. 23. 1.6 to 2.3 million sports concussions per year Center for Disease Control 2006

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