Neuro Review part 1 Flashcards
What are the 2 “holes” in the skull?
transtentorial notch (small) and foramen magnum (large) through which the brain is attached to the spinal cord.
If brain swelling occurs, the brain has nowhere to expand but down towards the foramen magnum.
Cranial Nerves to know
I Olfactory - smell, often affected with a basilar skull fracture
II optic - sight, NOT pupil reaction
III oculomotor - pupillary function, flows out of midbrain (in brainstem) and transverse the transtentorial notch; therefore, with an increase in intracranial pressure, parasympathetic stimulation is blocked, sympathetic stimulation predominates = dilated pupils on the side of the injury
V trigeminal - corneal reflex, chewing
VIII vestibulocochlear - intactness of this cranial nerve is tested by doll’s eyes and cold caloric exams
IX glossopharyngeal - swallow, gag
X vagus - pharyngeal/laryngeal movement
all cranial nerves arise from the brain stem except cranial nerves I and II, which arise from the cerebrum above the brain stem
The basilar artery supplies blood to the ____
lower areas of the brain and the brain stem
2 vertebral arteries come together to form the basilar artery
The carotids supply blood to the ___
upper areas of the brain.
The left internal carotid is dominant for most people.
brain function based on anatomic location:
frontal lobe: personality, abstract thought, long-term memory
temporal lobe: hearing, sense of taste and smell, interpretations
occipital lobe: vision, visual recognition, reading comprehension
parietal love: object recognition by size, weight, shape; body part awareness
cerebellum: coordination, balance, gait
Circle of Willis
A circulatory anastomosis comprised of various arteries that supply blood to the brain. A well-developed Circle of Willis allows collateral blood flow to one area from another area in the event of an occlusion.
Less than 50% of the population has a well-developed Circle of WIllis.
The following arteries compose the Circle:
anterior cerebral artery (L and R)
anterior communicating artery
internal carotid artery (L and R)
posterior cerebral artery (L and R)
posterior communicating artery (L and R)
The basilar and middle cerebral arteries (MCA) are NOT part of the circle.
What is the first sign of a neurological problem?
a change in LOC (level of consciousness), except for an epidural hematoma which may cause pupillary changes first.
Reticular Activating System (RAS)
a network of neurons that connects the brain stem (lower RAS) to the cortex (upper RAS).
Upper RAS is responsible for awareness and lower RAS is responsible for sleep-wake cycle.
If the lower RAS is damaged, a coma occurs; if only the upper portion of the RAS is damaged, the patient loses awareness but still wakes up and goes to sleep.
Components of a Neuro exam
Mental status: LOC, speech/language, memory, attentions span/thought content/judgement, Personality
Motor function: strength/movement, pronator drift, flexion/distention, flaccid
Sensory function
Pupillary assessment: CN III
Reflexes: babinski, brain stem (Cough/Gag/Corneal), Doll’s eyes
What is Cushing’s triad?
a sign of herniation of the brain.
- Increase SBP (widening pulse pressure)
- Decrease Heart Rate
- Decrease Respiratory Rate
Glascow Coma Scale (GCS)
15 (Best) to 3 (Worst).
If the score is 8 or less, the outcome is poor.
What is homonymous hemianopsia?
loss of vision in half the field of each eye
State whether each change is on the same side or opposite to the pathology in the brain.
Eyes deviate:
Pupillary changes:
Visual changes:
Motor changes:
Babinski:
Eyes deviate toward the pathology.
Pupil changes are on the same side (ipsilateral)
Visual changes are opposite side of the pathology (contralateral).
Motor changes are opposite the side of pathology (contralateral).
Babinski is opposite side of the pathology (contralateral).
uncal herniation
Displacement of the the temporal lobe (uncus) against the brain stem and the third cranial nerve (oculomotor)
Lateral shift, NO initial change in LOC
Blown (dilated) pupil on the same side seen BEFORE change in LOC d/t compression of parasympathetic innervation to the affected side.
babinski on opposite side
Central Herniation
Swelling on both sides, downward displacement of hemispheres usually d/t diffuse edema (slow development). May be caused by cerebral edema secondary to encephalopathy or stroke.
Slight change in LOC and then could lead to coma and then death.
Pupils small initially and then blow.
bilateral babinski
What is encephalopathy?
nonspecific term for any diffuse disease of the brain that alters brain function or structure.
minor to major, can result in swelling, increased intracranial pressure (ICP)
Treatment:
1. identify etiology and treat
2. Keep patient safe.
3. avoid conditions that increase ICP
Right sided vs. Left sided stroke
Right sided: eyes deviate right, left muscle weakness, left homonymous hemianopsia, left babinski, EMOTIONAL lability
Left sided: eyes deviate left, right muscle weakness, right homonymous hemianopsia, right babinski, APHASIA
Treatment for Acute Ischemic stroke
- Rule out hypoglycemia (mimics a stroke)
- ABCs
- assess BP: do not treat unless SBP>220 or DBP>120. A sudden decrease will decrease perfusion
- IV, O2, cardiac monitoring
- baseline labs
- CT scan within 25 mins
Decide if thrombolytics are needed.
tPA inclusion and exclusion criteria:
Inclusion: onset s/s <4.5 hours, CT negative, No contraindications
Exclusion:
evidence of hemorrhage,
stroke or head trauma <3 months,
history of ICH,
major surgery in past 14 days,
active bleeding within 21 days,
MI within past 3 months,
seizure at stroke onset (history of seizure ok),
platelets < 100,
blood sugar <50,
INR >1.7 if on warfarin,
spontaneous clearing of symptoms or only minor symptoms,
persistent high BP (SBP>185, DBP>110)
Administration:
bolus (10%), IV infusion over 1 hour (remainder)
Post tPA
1. frequent neuro checks
2. BP management: SBP<180, DBP<105
3. Bleeding precautions
Pontine infarct stroke characteristics include: (think P)
- aPneustic breathing pattern
- Pinpoint Pupils
- Parasympathetic innervation (loses sympathetic nervous system innervation)
Subarachnoid Hemorrhage
caused by trauma, a rupture of an aneurysm, or a tumor; 5% of all strokes
usually aneurysmal is the middle cerebral artery (MCA) and is seen in those 50-70 yrs old
symptoms of a ruptured aneurysm:
1. sudden explosive headache
2. decreased LOC
3. nuchal rigidity, positive Kernig’s sign
Complications of a SAH:
hydrocephalus (villi which reabsorb CSF are blocked), rebleed, vasospasm
treatment of a vasospasm
- angioplasty (select cases)
- prevention includes:
CCB (nimodipine),
maintain cerebral perfusion pressure (60-70) with fluids, pressors, and inotropes (avoid hypotension!);
monitor and treat hyponatremia which may precede a vasospasm
brain tumors
s/s like a stroke, also seizures.
mortality remains high
usually includes steroid therapy (decadron) to prevent elevated ICP
Intracranial pressure (ICP) and Cerebral Perfusion Pressure (CPP)
normal is 0-10 mmHg
moderately high is 11-20 mmHg
increased >20 mmHg
CPP is more important than ICP alone.
CPP = MAP-ICP
normal 80-100 mmHg
minimum for perfusion is 50 mmHg
brain death < 30 mmHg
with elevated ICP, keep CPP around 70 mmHg (hypotension in the presence of elevated ICP can be devastating)
Strategies to lower ICP
- decrease volume: mannitol/furosemide/3% saline, position patient upright
- prevent dilation of cerebral vessels (ie prevent acidosis)
- ventriculostomy (reduce CSF)
- ABC’s to prevent secondary brain injury: Airway - control pH, Breathing - prevent hypoxia, Circulation - prevent hypotension
- prevent pain/agitation (propofol)
- avoid 0.45NS or D5W - why? these are hypotonic and would increase brain swelling
should hyperventilation be used to decrease ICP? No, will cause alkalosis resulting in vasoconstriction and will lower ICP and blood flow! Keep pH normal!
AVOID:
1. acidosis and alkalosis - these cause vasodilation and vasoconstriction.
2. hypotonic solutions - cause cerebral edema
3. hyperextension/flexion of the neck - prevents optimal jugular venous outflow
4. PEEP - increases thoracic pressure and prevents jugular venous flow
5. Low protein - decreases oncotic pressure
6. restraints or agitation
7. fever - leads to cerebral hypermetabolism
