Week 5 - Concussion and SCI

Question 1

what are the 2 main types of concussion injuries?

Answer 1

1. Coup-contrecoup injury
2. torque (rotational) injury

Question 2

Coup-contrecoup injury

Answer 2

contusion from impact (coup) causes a movement of the brain to impact the opposite side of the skull (contrecoup)

Question 3

Torque (rotational) injury

Answer 3

• head and neck twists, causing shear stress on neurons
• neurons of the reticular formation most often affected

Question 4

Concussion pathophysiology

Answer 4

• many neurons injured due to blow and/or shearing
• spontaneous AP firing (axons begin to leak ions)
• excess excitatory NT release (glutamate)
• many neurons stimulated (EPSP)
• massive increase in metabolic activity
• increased demand for blood (glucose) but also a transient decrease in blood to the brain after a concussion
• imbalance of nutrient supply and demand (hours-days)
• neurons are damaged; remain in a low metabolic state for a period of time

Question 5

Acute concussion symptoms

Answer 5

• confusion
• memory loss
• loss of consciousness

Question 6

Chronic concussion symptoms

Answer 6

• headache
• dizziness
• nausea
• sensitivity to noise or light
• fatigue
• vision disturbances
• emotional disturbances
• sleep disturbances

Question 7

Concussion treatment

Answer 7

• rest completely
• avoid activity that could cause excess brain movement
• rehab with support
• avoid repeated concussion

Question 8

Chronic Traumatic Encephalopathy

Answer 8

• from repeated concussion
• damage build up
• neuronal death
• brain atrophy
• dementia

Question 9

Spinal Cord Injury (SCI)

Answer 9

• obstructs the transmission of neural messages through the spinal cord; loss of somatic and autonomic control of the trunk, limbs, and viscera below the site of the injury

Question 10

Phases of SCI: primary injury

Answer 10

• sudden trauma to the spine
• acute spinal cord compression, shear stress, severing (partial vs complete)
• acute impact to neurons, glial cells, and neural parenchyma

Question 11

Phases of SCI: secondary injury

Answer 11

Primary injury triggers secondary
- involves cascade of biochemical/metabolic and mechanical changes within the neural tissues
- secondary injury is a consequence of these downstream effects (hemorrhage and inflammation)

Question 12

SCI secondary injury sub-classifications

Answer 12

1. acute phase
2. sub-acute phase
3. chronic phase

Question 13

SCI secondary injury: acute phase

Answer 13

(0-48hrs)
- hemorrhage, inflammation and edema result in local ischemia
- neural toxicity induces cellular damage
- demyelination and cell death begins

Question 14

SCI secondary injury: sub-acute phase

Answer 14

(first two-weeks)
- further neurotoxicity, inflammation, cell death, scar tissue formation
- any undamaged tracts begin to resume function (incomplete injury)
- axonal regrowth and sprouting begins if possible

Question 15

SCI secondary injury: chronic phase

Answer 15

( days to years)
- continued cell death and scar tissue formation
- cyst development
- axonal degeneration and demyelination
- continued regrowth and sprouting if possible

Question 16

Systemic effects of SCI

Answer 16

• bradycardia in response to acute cervical and upper thoracic SCI
• hypotension
• pulmonary: ventilation severely impaired in injuries above C5
• bowel and bladder function
• Hyperreflexia (spasticity): disinhibition of spinal reflex arcs
• thermoregulation
• autonomic dysreflexia

Question 17

Autonomic dysreflexia

Answer 17

uncontrolled SNS response to an afferent stimulus below the level of the SCI

Question 18

Autonomic dysreflexia result

Answer 18

widespread vasoconstriction BELOW the level of the injury;
- increased BP
- baroreceptors sense and send signal to medulla
- parasympathetic response ABOVE level of injury; decreased HR and vasodilation