Flashcards in Clinical - Block 1 Deck (60):
Awake and Aware
Arousal and ability to open eyes
Experience of thoughts, emotions and memories
What lesion most commonly causes locked-in syndrome?
Lesion of bilateral ventral pons
Cortex injury does not usually cause. . .
loss of consciousness
Locked in syndrome
Everything is normal in brain except you cannot move (quadraplegia) except maybe blink or move eyes
Damage to what can result in chronic neuropathic pain?
Function of midbrain:
Vertical eye movements, pupil control, posture, locomotion, non-rapid eye movement, level of arousal
Function of pons:
Conjugate horizontal eye movements, posture, rapid eye movements, facial expressions
Function of medulla:
Blood pressure, breathing, GI motility, Ingestion, Equilibrium
What are the parts of the forebrain?
Cerebral cortex, basal ganglia, thalamus
Not aware but:
-Has sleep-wake cycles, opens eyes
-May smile, grimace, reflexively grip hand
-Does not feel pain or pleasure
-Not aware of self or others
In coma, what might you have?
When are you awake but not aware?
Corneal reflex tests. . .
CN V - wiping cotton on eye of coma patient to look for response of nerve. CN V will detect sensation and CN VII will control the blink reflex.
What will be spared in a central lesion (stroke)?
Hold tuning fork on middle of head
Check air to bone conduction
Stroke (central facial weakness):
Can still raise eyebrows
Cannot raise eyebrows
Peripheral facial weakness:
whole side of face is lateral/weak
Where are things louder in the weber test?
Conductive hearing loss - louder in affected ear
Sensorineural loss - louder in unaffected ear
Where will the tongue deviate when you stick it out?
To the affected side/weak side of CN XII
What is the "clasp knife" tone?
-One direction, better with repetition, worse with speed
-UMN problem, pyramidal
What is the "lead pipe" tone?
-Rigid in every direction
-Basal ganglion may be damaged, extrapyramidal
-Both flexion and extension is difficult (ex: Parkinson's disease)
What happens in pronator drift?
If UMN weakness, fingers flex, arm pronates, drifts downward. If patient has had a stroke, they will have fingers that flex and arm that slowly drops.
What is the grading system for strength?
5 - cannot overcome
4 - can overcome
3 - antigravity only
2 - not antigravity
1 - feel or see
0 - no movement
What tract has large fibers and what tract has small fibers?
Large fibers - Dorsal columns
Small fibers - Spinothalamic tract
Positive Romberg means. . .
What cranial nerves for the biceps reflex?
What can hyperreflexivity mean?
Brain lesion, spinal cord lesion!
Where do corticospinal tracts (descending) cross?
-Axons from motor cortex (UMN) descend on the same side of the brain until the level of the SPINOMEDULLARY JUNCTION
-This is where the fibers cross to the opposite side and continue to descend through the spinal cord until they reach the lower motor neuron on that side [crosses at lower medulla]
What are the two somatosensory ascending tracts?
1. Spinothalamic tract (pain and temperature)
2. Dorsal Column-Medial Lemniscus System (discriminatory touch and position sense)
When do the spinothalamic tracts cross?
Almost immediately after entering the spinal cord
When do the dorsal column-medial lemniscus tracts cross?
When they reach the level of the medulla
When does the spinothalamic and dorsal column-medial lemniscus tracts start to travel together to the thalamus (and then onto the sensory cortex)?
What CN has the longest path as it exits the brainstem?
What does the brain use all of its energy for?
-Membrane depolarization & repolarizatio
-NT release & uptake
-NT synthesis & metabolism
What is the function of astrocytic endsheaths?
They cover blood vessels.
-While neuron is firing, astrocyte is sensing what is going on (energy level used) and responding by sending signal to vessel to dilate or constrict to regulate the flow of blood and nutrients
When is the pentose phosphate pathway used?
In ketone breakdown
-Most active in newborn
-It requires vitamin B1 (thiamine) for its transketolase
-Alcoholics deficient in VB1 can get Wernicke-Korsakoff syndrome!
What does pos. and neg. CMR-G indicate?
+ = brain is using glucose (more glucose going in than out)
- = brain is producing glucose (more glucose going out than in)
What is the formula for CMR-G?
Glucose metabolism formula:
1 glucose + 6O2 = 6CO2 + 6H2O
Where is low glucose metabolism seen?
When eyes are stimulated, what increases?
Blood flow, glucose use and oxygen availability
What is the Glucose and Oxygen use in coma and epilepsy?
Low CMRG & Low CMRO2 in Coma
High CMRG & High CMRO2 seen in Epilepsy (neurons firing out of control)
Glucose and O2 in person who is drowning, AD and Strong anesthetic?
Drowning - CMRG same or higher, CMRO2 low
AD - Low CMRG & Low CMRO2
Strong anesthetic - Low CMRG & Low CMRO2
What is ischemia?
Local anemia due to lack of blood flow
What is infarction?
Severe ischemia leading to cell death or necrosis
What is a thrombus?
Clot that forms in place where it blocks blood flow
What is an embolus?
Clot that forms in one location and travels to the brain where it blocks blood flow.
What syndromes affect supratentorial structures?
Middle cerebral artery syndrome & Anterior Cerebral Artery syndrome
What syndromes affect posterior fossa structures?
Lateral Medullary syndrome (PICA), Medial medullary syndrome (anterior spinal artery) and Weber's syndrome (superior alternating hemiplegia - posterior cerebral artery affecting midbrain)
What does acetazolamide do?
Inhibits CA (carbonic anhydrase) - helps reduce CSF production
What does furosemide (Lasix) do?
It blocks the Na/K/2Cl pump & is often used to treat children with over production of CSF (& congestive heart failure!!) - helps reduce CSF production