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Define Diffuse Axonal Injury
An immediate disruption of the axons due to acceleration-deceleration and rotational forces that cause shearing upon impact.
You are following a patient who recently sustained a traumatic brain injury. His nurse tells you that he keeps trying to pull out his NG tube and his IV line. He thinks he is on a spaceship. What Ranchos Los Amigos level is he?
Level IV.
I - no response
II - generalized response
III - localized response
IV - confused, agitated
V - confused, inappropriate
VI - confused, appropriate
VII - automatic, appropriate
VIII - purposeful, appropriate
Of the three items in GCS, which one is the best predictor of outcome?
Motor response.
In TBI, which joints are highest risk for developing heterotopic ossification?
1. Hips
2. Elbows/shoulders
3. Knees
Which posture has a worse prognosis: decerebrate or decorticate?
Decerebrate
What are common locations for Diffuse Axonal Injury to occur?
Corpus callosum
Central white matter
Midbrain
A moderate brain injury is defined as a GCS of __ to __:
GCS 9-12
Severe TBI: 3-8
Moderate TBI: 9-12
Mild TBI: 13-15
Which measure is commonly used to assess the end of post traumatic amnesia? What score defines the end of PTA on this measure?
A score of 75 or higher on the Galveston Orientation and Amnesia Test (GOAT) for two consecutive days defines the end of PTA.
What is the oculocardiac reflex?
Bradycardia induced by increasing pressure on the eyeball.
You are following a patient with a traumatic brain injury on the rehab unit. Therapists have noted that for the past few days, he has not been progressing adequately. He has a normal BMP, CBC and UA. What would you check next?
CT head to evaluate for hydrocephalus.
Typical symptoms of dementia, ataxia and urinary incontinence are difficult to evaluate for in TBI patients.
Define Diaschisis
Lesions to one region of the CNS can produce altered function in other areas of the brain (at a distance from the original site of injury) that were not severed. Function is lost in both the injured and morphologically intact brain tissue.
Which cranial nerve is commonly injured with uncal herniation of the medial temporal lobe?
CN III
A patient that does not demonstrate a sleep wake cycle, follow commands, or open their eyes is in what state of consciousness?
Coma: Lake of sleep/wake cycle on EEG, no spontaneous purposeful movement, eyes closed.
VS: Resumption of sleep/wake cycle on EEG, no purposeful behavior.
MCS: Inconsistent but reproducible purposeful behaviors, shows evidence of self or exhibits environmental awareness.
74 yo M in your inpatient rehabilitation unit after sustaining traumatic brain injury six weeks prior seems more lethargic. On exam, he has dry mucous membranes and a delayed capillary refill. His serum sodium is 121. What diagnosis do you suspect?
Cerebral salt wasting.
Hyponatremia with isovolemia=SIADH.
Hyponatremia with hypovolemia=CSW.
Which medications can you use to treat diabetes insipidus?
DDAVP (ADH analog) or chlorpropamide (potentiates the effects of ADH on the renal tubules).
Name two mechanisms by which Plasticity occurs.
1. Neuronal regeneration/collateral sprouting: Intact axons establish synaptic connections through sprouting.
2. Functional reorganization/unmasking neural reorganization: Healthy neural structures not formerly used for a given purpose are developed or reassigned.
Which cranial nerve is most often damaged by blunt head trauma?
CN I due to tearing of the olfactory nerve filaments in or near the cribriform plate through which they traverse.
What area of the brain affects arousal?
Reticular-thalamic, thalamocortical, reticular-cortical networks.
Name three prophylactic treatments for heterotopic ossification.
1. NSAIDS
2. Radiation
3. Bisphosphonates
After how many weeks can you see HO on an x-ray?
3 weeks to 2 months post-injury
Define Vicariation.
Functions taken over by brain areas not originally managing that function.
You are consulted on a patient who sustained a traumatic brain injury after a MVA. He opens his eyes to painful stimuli, says inappropriate words, and withdraws to painful stimuli. What is his GCS?
GCS 9
Opens eyes to pain=2
Inappropriate words=3
Withdraws to pain=4
How do you calculate the Cerebral blood perfusion pressure?
What should the CPP be to ensure cerebral blood flow?
Cerebral perfusion pressure = Mean arterial pressure - intracranial pressure
CPP>60
How many months after a brain injury should patients undergo an endocrine evaluation?
Name at least 3 labs that should be checked.
3 months and 12 months, regardless of injury severity.
AM cortisol, IGF-I, FSH, LH, testosterone, estradiol, prolactin, urinary free cortisol, TSH
Define the 3 classifications of diffuse axonal injury (grade I-III).
I: Widespread white matter/axonal damage but no focal abnormalities on imaging.
II: Widespread white matter/axonal damage, and focal findings (most common in the corpus callosum).
III: Damage involving the brainstem.