CNS Injury Flashcards
Types of Skull Fractures
- linear
- depressed
- basilar
- growing
Signs of Skull Base Fracture
- CSF rhinorrhoea
- bilateral peri orbital hematomas (raccoon eyes)
- subconjunctival hemorrhage
- bleeding from external auditory meatus
- CSF otorrhoea
- battle sign
- facial nerve palsy
Epidural Hematoma
- contact phenomena
- intracranial extradural arterial hemorrhage
- associated with skull fracture
- classic lucid interval
- low mortality rate
- lens appearance
Translational Injury
- results from head movement in single plane the instant after impact
- results in stretching and tearing of veins between brain and dura (subdural hematoma) and contusions
Most Common Area of Cerebral Contusion
-frontal and temporal lobes
Subdural Hematoma
- acceleration injury (translational)
- rupture of bridging veins in subdural space
- associated w/ contusions
- high mortality rate
- banana shape
Rotational Injury
- results from head moving in more than one plane
- results in diffuse axonal injury (microscopic tearing of nerve cells)
- no recognizable injury detected w/o microscope
Pathomorphology of Diffuse Axonal Injury (DAI)
- spheroids appear when coma exceeds 6 hrs
- only detectable at LM level after 24 hours
- corpus collosum and brainstem most commonly affected
- invisible on CT/MRI
Intracranial Compensation
- any inc. in intracranial volume dec. CSF (into spinal subarachnoid space) or CBV (in jugular venous system)
- once these mechanisms are exhausted, additional inc. in volume produce extreme inc. in ICP
Exhaustion of Compensation
- once compensation mechanisms are exhausted, small inc. in volume will lead to marked inc. in ICP
- raised ICP may dec. CBF resulting in vicious cycle
Herniation
- ICP inc. not equally distributed leads to pressure gradient
- laterally (cingulate herniation)
- downwards (transtentorial herniation)
Pathophysiologic Changes of TBI
- astrocyte swelling -> cytotoxic edema
- free radicals from excitotoxicity and mechanical trauma to vessels -> vasogenic edema
- swollen brain -> areas of reduced perfusion, ischemia, energy failure, more cytotoxic and vasogenic edema
- areas of hyperperfusion from dysautoregulation
Cytotoxic Edema
- BBB remains intact, but disruption in cell metabolism impairs functioning of NA/K pump in glial membrane leading retention of Na and H2O
- swollen astrocytes occur in grey and white matter
Vasogenic Edema
- BBB is disrupted
- extracellular edema which mainly affects white matter through leakage of fluid out of capillaries
Glasgow Coma Scale
- high score is good (13-15)
- low score is bad (3-8)
- based on eye, motor, and verbal responses
Brainstem Reflexes
- pupillary reflex (CN 2, 3, midbrain)
- corneal blink reflex (CN 5, 7, pons)
- cold caloric testing “doll’s eyes” (CN 8, 6, 3, pons -> midbrain)
- gag reflex (CN 9, 10, medulla)
Normal ICP
3-15 mmHg
Forces Resulting in Cerebral Trauma
- contact phenomena
- acceleration
- penetration
- secondary injury
Anesthesia Definition
-loss of sensation
Paresthesia and Dysesthesia
- numbness, tingling, burning sensation
- dysesthesia are same but more unpleasant
Paresis
-dec. strength
Plegia
-complete loss of strength
Landmark Dermatomes of Arm
- C3: upper neck
- C4: lower neck and top of shoulder
- C5: lateral side of antecubital fossa
- C6: dorsal surface of first finger and thumb
- C7: middle finger
- C8: 4th and 5th fingers
- T1: medical side of antecubital fossa
C5 Cervical Root: motor function, sensory territory, reflex, foramen
- motor function: deltoid, infraspinatus, biceps
- sensory: shoulder, upper lateral arm
- reflex: biceps w/ C6
- foramen: C4-C5
C6 Cervical Root: motor function, sensory territory, reflex, foramen
- motor: wrist extenstion, biceps
- sensory: 1 and 2 digits of hand
- reflex: biceps, brachioradialis
- foramen: C5-C6
C7: motor function, sensory territory, reflex, foramen
- motor: triceps
- sensory: 3rd digit
- reflex: triceps
- C6-C7
L1, L2, L3, L4, L5, S1 dermatomes
- L1: Midway between the key sensory points for T12 and L2
- L2: On the anterior medial thigh
- L3: At the medial epicondyle of the femur
- L4: Over the medial malleolus
- L5: Big tow, and lateral malleolus
- S1: On the lateral aspect of the calcaneus
L4 Lumbosacral Root: motor function, sensory territory, reflex, foramen
- motor: psoas, quads
- sensory: knee, medial leg
- reflex: patellar
- foramen: L4-L5
L5 Lumbosacral Root: motor function, sensory territory, reflex, foramen
- motor: foot dorsiflexion, big toe extension, foot eversion/inversion
- sensory: dorsum of foot, great toe
- reflex: none
- foramen: L5-S1
S1 Lumbosacral Root: motor function, sensory territory, reflex, foramen
- motor: foot plantar flexion
- sensory: lat foot, small toe, sole of foot
- reflex: achilles
- foramen: S1-S2
Clinical Assessment of Reflexes
- 0= reflex absent
- 2+ = normal
- 3+ = brisk
- 4+ = nonsustained clonus
- 5+ = sustained clonus
Clinical Assessment of Strength
0/5= no contraction 1/5= muscle flicker, no movement 2/5= movement possible, but not against gravity 3/5= movement possible against gravity, but not resistance 4/5= movement possible against some resistance 5/5= normal strength
Mild TBI
- concussion
- hallmarks are confusion or amnesia
- no LOC
Pathophysiology of Concussion
- irritation leads to rapid, chaotic electrical depolarization across cortex
- NTs are released in excessive amounts, inc. cellular metabolism and inc. lactic acid levels
- Na/K pump failure and axonal stretch leads to Ca influx and axonal swelling
Second Impact Syndrome
-catastrophic brain swelling occurring if concussion happen too near each other in time
