Neuro Flashcards
Which cranial nerve is most prominent in eye movement? What muscles does it control?
CN3 - oculomotor
Superior rectus - supraduction
Medial rectus - adduction
Inferior rectus - infraduction
Inferior oblique - extorsion, elevation
Which cranial nerve is involved in intorsion/depression of the eye?
CN4 - trochlear
Superior oblique
Which cranial nerve is involved in the abduction of the eye?
CN 6 - abducens
Lateral rectus
What cranial nerve is part of the CNS?
CN 2 - optic
Which cranial nerves contribute to the parasympathetic nervous system?
CN 3 - oculomotor
CN 7 - facial
CN 9 - glossopharyngeal
CN 10 - vagus
Injury to what cranial nerve causes Bell’s Palsy?
CN 7 - facial
Tic douloureax results from what CN?
CN 5 - trigeminal
(trigeminal neuralgia)
What is the volume of CSF?
~150 mL
What is the specific gravity of CSF?
1.002 - 1.009
Where is CSF produced and at what rate/hr?
Ependymal cells of the choiroid plexus (in all four ventricles) at a rate of 30 mL/hr
What is CSF pressure?
5-15 mmHg
How does a decrease in CSF pH affect CBF?
CBF is increased (increased PaCO2 -> decreased cerebrovascular resistance)
At what PaCO2 does maximal vasodilation occur?
80-100 mmHg
At what PaCO2 does maximal vasoconstriction occur?
~25 mmHg
What is global CBF at a PaCO2 or 40 mmHg?
50 mL/100 g brain tissue/min
What is the change in CBF for a 1 mmHg increase in PaCO2?
increased by 1-2 mL/100 g brain tissue/min
Where in the brain is the blood brain barrier NOT located?
chemoreceptor trigger zone
hypothalamus
pineal gland
posterior pituitary gland
choroid plexus
What are SS of intracranial hypertension?
headache
N/V
papilledema (swelling of optic nerve)
pupil dilation and non-reactivity to light
focal neurologic deficit
seizures
coma
What is Cushing’s triad indicative of? What are the three components?
Intracranial hypertension
1. hypertension (increased ICP -> reduced CPP -> increased BP to preserve cerebral perfusion)
2. bradycardia (baroreceptor reflex activated by hypertension)
3. irregular respirations (compression of the medulla)
What is the most common site of transtentorial herniation?
The temporal uncus
oculomotor nerve crosses near here, fixed and dilated pupil results due to ischemia
What drugs reduce CSF production?
furosemide
acetazolamide
When should steroids not be used in a brain case?
TBI
functional pituitary adenoma
What are 4 ways to reduce intracranial hypertension?
Reduce cerebral spinal fluid
Reduce cerebral blood volume
Reduce cerebral edema
Reduce cerebral mass
Discuss blood supply and skull entry to the anterior circulation:
internal carotids enter the skull through the foramen lacerum
aorta -> common carotid -> internal carotid -> Circle of Willis -> cerebral hemispheres
Discuss blood supply and skull entry to the posterior circulation:
vertebral arteries enter the skull through the foramen magnum
aorta -> subclavian -> vertebral -> basilar -> posterior fossa structures and cervical spinal cord
List 6 risk factors for ischemic stroke:
- HTN (most important)
- smoking
- diabetes mellitus
- hyperlipidemia
- excessive alcohol intake
- elevated homocysteine level
When should a thrombolytic agent be initiated for an acute ischemic stroke?
within 4.5 hours of symptom onset (TPA)
When should large vessel occlusion embolectomy be performed?
within 6 hours of symptom onset
What are the three components of Triple H therapy? What is it used to treat?
hypertension
hypervolemia
hemodilution (Hct 27-32%)
cerebral vasospasm
Where does venous bleeding usually occur in a hemorrhagic stroke?
in the subdural space (between dura and arachnoid)
Where does arterial bleeding usually occur in a hemorrhagic stroke?
in the subarachnoid space (between arachnoid and pia)
How does nimodipine, a CCB, treat cerebral vasospasm?
It does not relieve the spasm, but rather increases collateral blood flow
Discuss motor response in the GCS:
NEF WiLl Obey
1- no response to pain
2 - extension to pain (decerebrate)
3 - flexion to pain (decorticate)
4 - withdraw from pain
5 - localize response to pain
6 - obeys commands
Discuss verbal response in the GCS:
1- no response
2 - incomprehensible sounds
3 - inappropriate words
4 - confused
5 - oriented
Discuss eye opening in the GCS:
1 - no eye opening
2 - eye opening to painful stimulus
3 - eye opening to speech
4 - spontaneous eye opening
Discuss pupil reaction in the GCS:
0 - both pupils dilate normally
-1 - only one pupil dilates normally
-2 - neither pupils dilate
Discuss grand mal seizures:
generalized tonic (rigidity) -clonic (jerking) activity
respiratory arrest -> hypoxia
acute treatment: propofol, diazepam, thiopental
surgical treatment: vagal nerve stimulator of foci resection
Discuss focal cortical seizures:
localized to a particular region
can be motor or sensory
usually no loss of consciousness
Discuss absence (petit mal) seizures:
temporary loss of awareness
remains awake
more common in kids
Discuss akinetic seizures:
temporary loss of consciousness and postural tone
can result in fall and head injury
more common in kids
Discuss status epilepticus:
seizure activity lasting > 30 minutes
OR
two grand mal seizures without regaining consciousness in between
respiratory arrest -> hypoxia
acute treatment: propofol, benzos, thiopental, phenobarbital, phenytoin, general anesthesia
What two types of seizures are more common in children?
akinetic
absence (petit mal)
The patient usually remains awake during what two types of seizures?
Focal cortical
Absence (petit mal)
What 3 medications are useful for locating seizure foci during cortical mapping?
alfentanil
etomidate
methohexital
Which anticonvulsants alter hepatic enzymes?
phenytoin - induction
carbamazepine - induction
valproic acid - inhibition
How are gabapentinoids excreted?
unchanged by the kidneys. caution in renal failure
Which anticonvulsants work by blocking voltage gated Na channels (membrane stabilization)?
phenytoin
carbamazepine
valproic acid
What is the mechanism of action of gabapentin?
inhibits the alpha 2 delta subunit of calcium channels in the CNS
What is the pathophys of Alzheimers:
increased Ach
What is the greatest risk factor of Parkinsons?
Old age
How is Parkinsons diagnosed?
Must have 2/4 cardinal signs:
- resting ‘pill-rolling’ tremor
- skeletal muscle rigidity
- postural instability = loss of balance with an altered gait
- bradykinesia = very slow movement and reflexes
What is Parkinsons treatment aimed at?
increasing dopamine or decreasing acetylcholine in the basal ganglia
How does levodopa and carbidopa treat Parkinsons?
levodopa is precursor of dopamine
DA cannot penetrate CNS
carbidopa is a decarboxylase inhibitor that prevents levodopa metabolism in the blood
this allows more to enter the CNS
What are SE of carbidopa and levodopa?
CV: increased inotropy, tachycardia, orthostatic hypotension
Other: dyskinesia, N/V
What other medications can be used to treat Parkinsons?
selegiline (MAO-B inhibitor -> decreased DA metabolism in CNS)
dopamine agonists
anticholinergics
catechol-o-methyltransferase inhibitors
amantadine
hormone replacement
Should levodopa be continued before surgery? Why or why not?
Yes, give morning of to prevent worsening symptoms like rigidity (impacts ventilation).
If longer surgery, can be given via OG tube.
What drugs are contraindicated in Parkinsons? What can they cause?
antidopaminergics like metoclopramide
butyrophenones like haloperidol and droperidol
phenothiazines like promethazine
can exacerbate extrapyramidal ss
What meds can be used to treat acute exacerbation of Parkinsonian symptoms?
anticholinergics
What procedure risk factors lead to increased occurrence of ischemic optic neuropathy?
prone positioning
Wilson frame
long duration of anesthesia
large blood loss
large ratio of colloid to crystalloid resuscitation
hypotension
What patient risk factors lead to increased occurrence of ischemic optic neuropathy?
male sex
obesity
diabetes
hypertension
smoking
old age
athersclerosis
Is ischemic optic neuropathy a nerve problem or a vessel problem?
a nerve problem
Is central retinal artery occlusion a nerve problem or a vessel problem?
a vessel problem
What are risk factors for central retinal artery occlusion?
horseshoe headrest (most common)
embolism
administering N2O after an intraocular gas bubble has been placed
What four classic signs and symptoms occur with Beck’s syndrome (anterior spinal artery syndrome)?
flaccid paralysis of lower extremities
bowel and bladder dysfunction
loss of pain and temp sensation
preserved touch and proprioception
List three spinal pathways that are supplied by the anterior spinal artery.
spinothalamic tract
corticospinal tract
autonomic motor fibers
List one spinal pathway that is supplied by the posterior spinal artery:
dorsal column
Which spinal cord tract transmits crude touch and pressure?
ventral spinothalamic tract
Which spinal cord tract transmits fine touch and proprioception?
dorsal column (cuneatus and gracilis)
Which spinal cord tracts transmit pain and temperature?
Tract of Lissauer
Lateral spinothalamic tract
Which spinal cord tract transmits limb motor function?
lateral corticospinal tract
Which spinal cord tract transmits posture motor function?
ventral corticospinal tract
What do Pacinian corpuscles transmit?
vibration
What do Meissner’s corpuscles transmit?
vibration
two point discriminative touch
What do Merkel’s discs transmit?
continuous touch
What do Ruffinis endings transmit?
prolonged touch and pressure
proprioception
What type of nerve fibers are first order neurons?
usually A-beta
some A-alpha
Where do first order neurons enter the spinal cord?
dorsal root ganglion
What information do first order neurons transmit and to where?
transmit sensory info from the dorsal column to the medulla
Where do first order neurons synapse?
ascend same side and synapse with second order neurons in the medulla
Where do second order neurons cross? Where do they ascend to?
cross to contralateral side in medulla
ascend to thalamus via medial lemniscus
Where do second order neurons synapse with third order neurons?
thalamic relay station - the ventrobasal complex
Where do third order neurons go?
pass through internal capsule and go toward somatosensory cortex in post central gyrus in parietal lobe
What is another name for the dorsal column?
medial lemniscal system
What type of fibers make up the first order neurons in the anterolateral system?
A-delta: “fast” pain, mechanoreceptors
C fibers: “slow” pain, polymodal nociceptors
At what laminae and where do pain neurons synapse with the second order neuron?
Rexed’s lamina 2 and 3 in the substantia gelatinosa
Where do second order neurons of the anterolateral system synapse with third order neurons?
reticular activating system and thalamus
Which sensory tract in the spinal cord transmits pressure?
Dorsal column
Which sensory tract in the spinal cord transmits temperature?
anterolateral system
Which sensory tract in the spinal cord contain slow conducting fibers?
anterolateral system
Which sensory tract in the spinal cord has 2-point discrimination?
dorsal column
Which sensory tract in the spinal cord contains rapid conducting fibers?
dorsal column
Which sensory tract in the spinal cord transmits vibration?
dorsal column
Which sensory tract in the spinal cord transmits proprioception?
dorsal column
Which sensory tract in the spinal cord transmits pain?
anterolateral system
Which sensory tract in the spinal cord transmits sexual sensations?
anterolateral system
Which sensory tract in the spinal cord consists of large myelinated fibers?
dorsal column
Which sensory tract in the spinal cord consists of small unmyelinated fibers?
anterolateral system
What is another name for the corticospinal tract? Why?
pyramidal tract
the pyramids are formed by the corticospinal neurons as they run through the medulla
other motor pathways outside of corticospinal tract are called “extrapyramidal tract” since the don’t pass through the pyramids
What is the path of motor neurons in the corticospinal tract?
exit - precentral gyrus frontal lobe
pass through - internal capsule
travel inferiorly - through pyramids of the medulla
Where do fibers that innervate the limbs crossover?
the fibers in the lateral corticospinal tract cross to the contralateral side in the medulla
then descend spinal cord
Where do fibers that innervate the axial muscles crossover?
the fibers in the ventral corticospinal tract remain ipsilateral as they descend and cross to the contralateral side when they reach the cervical or upper thoracic area
Where do fibers that innervate the axial muscles crossover?
the fibers in the ventral corticospinal tract remain ipsilateral as they descend and cross to the contralateral side when they reach the cervical or upper thoracic area
What are examples of upper motor neuron disease?
cerebral palsy
amyotrophic lateral sclerosis
In an upper motor neuron injury, what actions result?
contralateral spastic paralysis
hyperreflexia
Where do the upper motor neurons originate and end?
cerebral cortex
ventral horn of the spinal cord
Where do the lower motor neurons originate and end?
ventral horn of the spinal cord
neuromuscular junction
How does a lower motor neuron injury present?
ipsilateral flaccid paralysis
impaired reflexes
What three symptoms are associated with upper spinal cord injury?
hypotension
hypothermia
bradycardia
What type of anesthetic is best with chronic spinal cord injury?
general or spinal
What is the best treatment of hypertension in autonomic hyperreflexia?
remove the stimulus
deepens the anesthetic
use a rapid-acting vasodilator like Na nitroprusside
What is the best treatment of bradycardia in autonomic hyperreflexia?
atropine or glycopyrrolate
avoid positive chronotropes that cause vasoconstriction (would worsen htn)
What is amyotrophic lateral sclerosis?
progressive degeneration of motor neurons in the corticospinal tract
Where does ALS start and spread to?
weakness starts in hands and spreads to rest, affecting tongue, pharynx, larynx, and chest
What is the most common cause of death in ALS?
respiratory failure
What is the only drug that reduces mortality in ALS?
Riluzole - a NMDA receptor antagonist
How are the heart and ocular muscles affected in ALS?
They are not affected
Discuss neuromuscular blockers and ALS:
Avoid sux due to lethal hyperkalemia (lower motor neuron dysfunction -> proliferation of post junctional nicotinic receptors)
increased sensitivity to nondepolarizing neuromuscular blockers
consider postop mechanical ventilation if NMBs are given
What SS does upper motor neuron damage lead to?
spasticity
hyperreflexia
loss of coordination
What SS does lower motor neuron damage lead to?
muscle weakness
fasciculations
atrophy
