Neuro Flashcards
What makes up the brainstem (top to bottom)?
midbrain, pons, medulla
Myelination is done by what type of cells?
Schwann cells in PNS
Oligodendrocytes in CNS
_______ is communication between brain and thoracic and abdominal viscera.
Vagus nerve (CN X)
Describe pathway of corticospinal tract.
R motor cortex -> cross at medullary pyramids -> anterior horn -> L side muscle
Symptoms of Lower motor neuron lesion
weakness/paralysis flaccidity diminished reflexes fasciculations (twitches) muscle atrophy
Symptoms of Upper motor neuron lesion
weakness/paralysis
spasticity
increased reflexes
Babinski’s sign
What is an abnormal Babinski?
stroke bottom of adult foot and big toe goes up
*normal during infancy
clonus
repetitive, rhythmic contraction of muscle when it is stretched (commonly ankle)
What are two sensory pathways and what signals do they transmit?
Posterior columns: proprioception, discrimination, vibration
Spinothalamic: pain and temp
Where does each sensory pathway decussate?
Posterior columns: medulla
Spinothalamic: immediately in spinal cord
Trace pathway of proprioception, vibration, and discrimination sensation from left side to body to brain.
L body -> posterior spinal cord -> posterior column -> cross at medulla -> medial lemniscus -> R thalamus
If pain/temp sensation loss on left side of body, then where is possible lesion?
right spinal cord or right thalamus
What pathology destroys an entire half of the spinal cord?
Brown-Sequard Syndrome
C6 dermatome
thumb
lateral arm
C7 dermatome
digits 2 and 3
C8 dermatome
digits 4 and 5
medial arm
Dermatome that runs back of calf to lateral foot
S1
Dermatome that runs down posterior arm and hand
C7
Dermatome that runs down shin to top of foot
L5
Which cranial nerves exit from each division of brainstem?
2-4 midbrain
5-8 pons
9-12 medulla
- Olfactory and vision pathway don’t go to brainstem
Effects of optic nerve lesion
blindness in one eye, other eye unaffected
Effects of left optic tract lesion
blindness in right hemisphere of each eye
Which cranial nerves innervate the extraocular muscles?
CN III, IV, VI
IV: superior oblique
VI: lateral rectus
III: all the rest (IO, SR, IR, MR)
Effects of complete CN III lesion
ipsilateral eye is “down and out”
dilated pupil
ptosis (drooping eyelid)
Cranial nerves involved in pupillary light reflex
oculomotor (CN III) - allows eyes to constrict with light
optic (CN II) - allows consensual response if CN III intact
Signs of Horner’s Syndrome
ptosis
miosis (constricted pupil)
anhidrosis (loss of sweating)
- loss of sympathetic pathway to face and eyes
_____ is only cranial nerve to project contralaterally.
CN VI
What are functions of cranial nerves that innervate the face (sensory and motor)?
CN V sensory: 3 branches - ophthalmic, maxillary, mandibular
CN VII motor: chewing muscles
- both involved in corneal reflex
Bell’s Palsy vs Cerebral stroke
Bell’s Palsy: CN VII lesion, paralysis of entire ipsilateral face
Stroke: UMN lesion, facial droop on contralateral side but forehead unaffected
Lesion affecting CN VIII that causes unilateral hearing deficit?
acoustic neuroma (or vestibular schwannoma)
What is the vestibulo-ocular reflex?
vision steady while head rotates side to side
“doll’s eye” test in coma patient to determine if brainstem intact
What nerve may be damaged if absent gag reflex?
CN IX (glossopharyngeal)
If when patient says “ahhh” uvula deviates to the left, then where is the lesion?
Right side of CN X (vagal)
How is CN XI tested?
test strength of shoulder shrug and head rotation (trapezius and SCM muscles)
How is CN XII tested?
“stick out your tongue”
tongue will deviate toward lesion side
Effects of cerebellar lesion
“Errors of rate, range, force, and direction”
IPSILATERAL ataxia, intention tremor, nystagmus, vertigo
Effects of basal ganglia lesion
CONTRALATERAL chorea, resting tremor, akinesia, rigidity
Pathophysiology of Parkinson’s
shortage of dopamine due to degeneration of substantia nigra (midbrain)
motor regions of cerebral cortex inhibited
Hallmark signs of Parkinson’s
bradykinesia
resting tremor
lead-pipe or cogwheel rigidity
shuffling, hunched-over gait
Main treatment of Parkinson’s
L-Dopa
Side effects of anti-Parkinson meds
Hallucinations, Schizophrenia (too much dopamine)
dementia vs delirium
delirium is an acute change in mental status
dementia is progressive decline in cognitive function
CT/MRI results of Parkinson’s
NORMAL; used to r/o other causes
Lewy Bodies may be seen on an autopsy of the brain in…
Parkinson’s disease
Dementia with Lewy bodies
Alzheimer’s disease
Risk factors of cerebral aneurysm
Smoking ETOH HTN Obesity PCOS Marfan syndrome
A ruptured cerebral aneurysm (
Berry aneurysm) is common cause of ___________.
subarachnoid hemorrhage
How to manage a cerebral aneurysm?
Known aneurysms monitored:
BP control
Cholesterol control
F/U imaging
Location of cerebral vs epidural vs subdural vs subarachnoid hemorrhages
cerebral - within parenchyma or ventricle
epidural - btwn dura and skull
subdural - btwn dura and arachnoid mater
subarachnoid - btwn arachnoid and pia mater
Which brain bleed most often caused by trauma?
epidural
Severe headache “The Worst Headache of my life!” lasting hours to day =
subarachnoid hemorrhage
Gold standard for inter-hemorrhage bleeding dx
Non-contrast head CT
How are subdural and epidural hemorrhages differentiated?
crescent shape bleed on CT = subdural
biconcave/rounded bleed = epidural
Inter-hemorrhage bleeding treatment
Reduce ICP (steroids, Mannitol) Control BP Pain killers Anti-seizure meds Surgery: Craniotomy, surgical clipping, endovascular coiling
Risk factors of stroke/TIA
Increasing age African American, American Indian, Hispanics HTN Smoking Diabetes Oral contraception ETOH Afib Heart valve issues Endocarditis
2 types of stroke? Which more common?
Ischemic (85%)
Hemorrhagic
define dysarthria
motor speech disorder due to neurological injury
define apraxia
altered voluntary movements
Signs of increased intracranial pressure?
Vomit w/o nausea Headache Papilledema Seizures Behavior changes Cushing's response (HTN, bradycardia)
“FAST” exam to identify location and severity of stroke
Face: facial droop
Arms: unilateral weakness
Speech: slurred
Time: seek immediate medical attention
What PE exam is used to assess stroke risk?
Look for bruit with U/S Doppler of carotids
How to treat ischemic stroke?
Aspirin immediately
tPA within 4.5 hours
Angioplasty and stents
How to treat hemorrhagic stroke?
Surgery: clipping, coiling, hemicraniectomy
Meds: Mannitol, corticosteroids
Contraindications to tPA use in strokes
Suspected intracranial bleed Recent surgery Recent head trauma Active bleeding Intracranial neoplasm HTN > 185/110
How is TIA different than full stroke?
- No brain tissue death
- Symptoms typically resolve in an hour
Define amaurosis fugax
temporary loss of vision (possible TIA or carotid stenosis)
DDX of altered mental status
High ICP Dehydration (or insulin overdose) Hypoglycemia Uremia Hyper/hypothermia Meningitis Stroke/TIA Concussion/brain injury Meds/Drugs
Work up of altered mental status
- Neuro exam: AAOx3, LOC, GCS
- Pulse ox
- Serum glucose
- CBC
- CMP (liver, kidney fxtn)
- Tox screen
- Head CT or MRI
Glasgow Coma Scale
Eye movement 1-4
Verbal response 1-5
Motor response 1-6
“less than 8 intubate”
13-15 = concussion
3 = dead
How to treat altered mental status from hypoglycemia?
IV Dextrose