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51 Cards in this Set
- Front
- Back
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When is it important to test CN I?
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In cases of head trauma, mental status change, and seizure disorder.
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How should you test CN I and what is the most common cause of unilateral anosmia?
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You should test it with aromatic compounds rather than irritating ones so spices/coffee instead of ammonia, alcohol. Most common cause of unilateral anosmia is nasal obstruction (stuffy nose from having a cold!)
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What might you be afraid of with head trauma and potential CN I involvement?
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Be mindful of a fracture in the cribriform region which can produce leakage of CSF. You can test for it with filter paper or by testing it for glucose since CSF has near blood concentrations of it.
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What is myopia and hyperopia?
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Myopia is nearsightedness and hyperopia is farsightedness. Neuro causes of vision affect BOTH, whereas refractive problems typically affect one or the other.
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How would you distinguish a visual acuity loss due to refractory problems to one due to neuro problems?
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Make the patient look through a pinhole. This should improve vision! If it does not then you should think it is a neurologic problem.
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How is CN II tested?
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By various methods including: "confrontation", tangent screen, red color, automated perimetry is often used
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What causes patchy monocular loss?
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retina or optic nerve damage
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What causes bitemporal loss?
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Damage to the optic chiasm
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What causes homonomous loss?
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Damage posterior to the optic chiasm (structures such as the optic tract, lateral geniculate, optic radiations, occipital lobe)
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What causes homonomous superior quadrantanopia?
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Damage to the temporal lobe
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What causes homonomous inferior quadrantanopia?
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Damage to the parietal lobe.
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What is Marcus-Gunn pupil and what causes it?
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It is an eye with optic nerve damage such that the pupils will not constrict so much. On exam light shifted from the good eye to the bad eye will produce pupil dilation.
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How would you distinguish optic neuritis from papilledema?
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Both show loss of normal margins with dilation of veins and swelling of the optic nerve head on fundoscopic exam, however, in optic neuritis the patient would have severe vision loss.
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Under what conditions does papilledema occur?
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Longstanding high blood pressure or severe pressure elevations.
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What sign upon physical exam would be a precursor to papilledema?
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loss of spontaneous venous pulsations. It is an early and very subtle sign of increased intracranial pressure.
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What extraocular muscles control up gaze?
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Superior rectus and inferior oblique
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What extraocular muscles control down gaze?
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Inferior rectus and superior oblique
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What is displopia the hallmark of?
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dysconjugate gaze of recent onset
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What can help you localize vision weakness to one or two muscles when someone has diplopia?
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Knowing the position in which the images are most widely separated.
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When someone has diplopia what can help you determine whether to look for problems with horizontal movers or vertical movers?
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Knowing whether the images are horizontally or vertically displaced
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What are two examples of what can cause eye muscle weakness without damage to a cranial nerve?
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myopathies, muscle damage
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How does the red glass eye test help you determine weakness?
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Shine a pen light into the eye with a red glass lens in front and without. The image from an eye that doesn't move enough will appear to be further off to the direction that the weak muscle normally moves. By covering one eye with a red glass, then the other, you can determine which eye is abnormal.
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What is a symptom that you would be able to notice on a patient when you first walk into the room that may help you determine if they had a weak extraocular muscle?
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They may have his/her head turned or tilted to compensate and eliminate the diplopia due to the induction of the vestibular system.
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What is heterophoria?
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the drifting of an eye when its fixation on a target is broken
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What is heterotropia?
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Strabismus. The two eyes don't look in the same direction. There is exo-, eso-, hyper-, and hypo-.
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What must be in tact for smooth tracking to occur?
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The integrity of the ipsilateral visual cortex is necessary for smooth tracking.
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What is Parenaud's syndrome and what causes it?
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Parenaud's syndrome is an inability to look upward voluntarily. It is caused by rostral midbrain lesions... in particular with this syndrome it is due to masses pressing on the dorsum of the midbrain.
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What is the differential diagnosis for failure of upgaze?
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Masses pushing on the dorsum of the midbrain (parinaud), dementing illnesses, certain extrapyramidal degenerative disorders (progressive supranuclear palsy)
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What are the symptoms of Horner's syndrome?
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Ptosis, miosis, anhydrosis
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What can cause Horner's syndrome?
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Damage to any part of the sympathetic pathway: cervical chain, carotid plexus, upper thoracic roots, lower brachial plexus, cervical spinal cord.
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What is Adie's or Holmes-Adie's pupil?
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It is an idiopathic, not progressive condition where the pupil has a slow reaction to light change. Accommodation is usually better preserved. The damage is to the parasympathetics therefore the damaged eye is the one that is tonically a bit dilated. Often deep tendon reflexes especially the achilles tendon reflex are decreased or absent. One possible etiology or viral or bacterial infection.
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You have a patient who has lost the sensory limb of the corneal reflex, what kind of lesion do you suspect?
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Either a lesion of the trigeminal nerve or lesion of the lateral brain stem usually due to stroke or a mass pressing on it. (spinal nucleus)
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What are causes of peripheral facial nerve palsy and what are other symptoms that may be seen?
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Peripheral facial palsy may be idiopathic (Bell’s palsy) or may be due to diseases like zoster or Lyme or may occur with lesions lateral to the brain stem. Peripheral facial nerve palsy can also have symptoms of hyperacusis, loss of anterior taste and dry eye depending on how much of the facial nerve is involved.
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What is one of the symptoms that is preserved with facial nerve palsy?
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Patients are still able to wrinkle their foreheads because the weakness is only of the lower face. (central lesions to CN VII)
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How is hearing tested?
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Hearing is tested with fingers, a tuning fork or audiometry. If a patient has lost hearing in one ear a vibrating tuning fork should be placed on their head. If they hear it better in the bad ear, then their problem is getting the airway into the inner ear... not a problem with the nerve! Good news.
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What is the Weber test?
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It is placing a tuning fork on a person's head to see if they can hear better in the good or bad ear. This can help determine nerve vs. conduction issues.
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What is the Rinne's test?
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Place a vibrating tuning fork on the mastoid. When you can't hear it anymore place it in front of the ear. Normally you can hear it again when this is done. If you can't hear it again, it means that air conduction is blocked.
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What is the oculocephalic reflex?
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It is the fact that the eyes normally move equally and oppositely to head movements and vestibular function can be checked by looking at effects on eye motions.
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What is nystagmus?
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It is spontaneous movements of the eyes produced by the illusion of motion with rapid, saccadic corrections. Nystagmus is named by the fast component even though it is not the functional component. Slow component is the tonic component and the fast component is the checking component.
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What is vertigo?
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The illusion of movement in the absence of it.
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What is vertigo a sign of?
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It indicates that the vestibular system is functioning abnormally
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What does peripheral vertigo result in and what other symptom may be present?
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Peripheral vertigo usually results in unidirectional nystagmus that is proportional to the degree of symptoms and which may be associated with hearing change.
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What does central vertigo result in?
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It results in multidirectional nystagmus without much actual vertigo. This is due to damage in the cerebellar or vestibular region.
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How do you test the vestibular component of CN VIII?
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You can only test each vestibular apparatus independently by stimulating one at a time. This is done by caloric testing which sets up convection currents in the ear tested.
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How does caloric testing work?
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Convection currents tell the brain that you are moving. The eyes move slowly in the opposite direction. If you are conscious, your visual cortex with recognize that your eyes are drifting off target and will fire a rapid saccade to reacquire the target. The amount of nystagmus produced by caloric testing can be quantified as an index of health of the inner ear and vestibular nerve.
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What is benign positional vertigo?
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It is a common condition. BPV is caused by loose otoliths that cause vertigo in certain positions lasting for less than a minute when the otoliths strike receptors.
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What does CN IX innervate?
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It provides sensory innervation of the middle ear, the pharynx, and posterior 1/3 of the tongue (taste and feeling). Also provides motor innervation of the stylopharyngeus muscle.
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How can you test CN IX?
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The only meaningful way to test CN IX is with the gag reflex. (sensory limb of the gag reflex). In order to do this you need to touch each side of the pharynx or the posterior 1/3 of the tongue independently without touching soft palage or fauces.
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How do you test CN X?
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open mouth, tongue depressor, have patient say "Aah". The palate should elevate in the midline. If it is not symmetrical and the uvula deviates to one side as the motion takes place then the side of the palate that is lower and the side the uvula points away from is the weak side.
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How do you test cranial nerve XI?
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Shrug shoulders... push down... tests trapezius. Prevent movement of head to the side... tests SCMs.
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How do you test CN XII?
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Have the patient protrude his/her tongue, wiggle it, push it against inside of cheek... can't push it against the strong side.
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