Neuro exam Ward Flashcards
What are the components of the neurologic exam?
- mental status: level of alertness, appropriateness of responses, orientation of time and place
- cranial nerves: pupillary light reflex, fascial sensation and strength, gag reflex
- motor system: muscle strength testing, gait, and coordination testing
- sensory: pinprick, light touch, vibratory, proprioception
- reflexes: deep tendon reflexes and plantar response (Babinski)
Describe abrupt or sudden onset/acute onset of neuro problem
Sudden onset of symptoms usually followd by gradual improvement is somewhat typical of cerebral hemorrhages, vascular diseases, and infections and head trauma
Describe progressive neuro problem
Certain neoplasms and degenerative diseases of nervous system may cause a more linear progression of neurological symptoms and deficits.
In some degenerative diseases, pt’s symptoms such as minor memory disturbances, increased irritability, or mild personality changes may be unremarkable initially, but quite significant and apparent many years later
Describe intermittent, relapsing episodes of neuro problem
Demyelinating diseases such as multiple sclerosis and certain vascular diseases often display a gradually deteriorating cycle of remission and symptoms
Describe the components of mental status exam
- level of alertness: consciousness of pt (awake, alert, drowsy, lethargic, comatose, etc)
- appropriateness of response: insight to question and situation and ability to respond concretely to this versus tangential or confused demeanor
- orientation: knows date, place, self, situation
Describe basic localization of cranial nerves
- Telencephalon: cerebral hemispheres (CN I)
- Diencephalon: rostral part of brainstem/paired structures on either side of 3rd ventricle (CN II)
- Mesencephalon: midbrain (CN III-IV)
- Metencephalon: pons (CN V)
- (Pontomedullary junction: CN VI-VIII))
- Myelencephalon: medulla (CN IX-XII)
Summarize the functions of the cranial nerves
- I: Olfactory: smell
- II: Optic: visual acuity, visual fields, optic fundi, afferent limb of pupillary light reflex
- III: Oculomotor: extraocular movements (supplies medial rectus, inferior rectus, and inferior oblique), supplies levator palpebrae muscle (lifts eyelid), and is efferent limb of pupillary light reflex
- IV: trochlear: supplies superior oblique m, extraocular movements
- V: trigeminal: facial sensation: ophthalmic (V1, forehead), maxillary (V2, cheek), mandibular (V3, jaw); jaw movements (motor portion of nerve); corneal reflex (afferent/sensor limb)
- VI: abducens: supplies lateral rectus muscle, extraocular movements
- VII: facial: facial movements of expression, taste to anterior 2/3 of tongue
- VIII: vestibulocochlear: hearing (cochlear division), balance by vestibular devision
- IX: glossopharyngeal: swallowing, rise of palate and gag reflex (along with CN X)
- X: Vagus: gag reflex (with CN IX) and swallowing, phonation
- XI: spinal accessory: innervates upper trapezius and sternocleidomastoid muscle (SCM) (shoulder shrug and neck movements, head turning to opposite side)
- XII: hypoglossal: innervates intrinsic tongue muscles
Describe testing of olfactory CN I
- use non-irritating, familiar odors (cinnamon, coffee, vanilla)
- have pt compress one nostril and sniff through other. Pt should be able to discern odors on each side
- loss of smell can occur with smoking, chronic sinus disease, head trauma, aging, Parkinson’s disease, cocaine use
- loss of sense of smell indicates ipsilateral lesion
Describe testing of Optic CN II
- test visual acuity with Snellen eye chart (pt stands 20 feet from chart)
- inspect fundi: locate optic disc, check for papilledema, pallor, or atrophy. Inspect retina for hemorrhages or exudates, spontaneous venous pulsations, hypertensive vascular changes, trace arteries and veins peripherally
- visual field test: pt in front of examiner. One eye covered during testing, patient to count fingers held up testing all 4 quadrants, also test blink response to lateral threat
- color vision (usually only done by ophthalmology)
- pupillary light reflex (tests CN II and III)
- lesions to optic nerve anterior to chiasm cause ipsilateral blindness
Describe testing of pupillary light reflex
- Tests CN II and III (afferent/sensory component CNII, efferent/motor component CNIII)
- shine light into eye and watch for pupillary constriction
- direct light reflex: stimulated pupil constricts
- consensual (indirect) reflex: opposite pupil constricts (along with stimulated pupil)
- light stimulus is given to one eye. CN II sends stimulus to brainstem/midbrain where it is transferred to CNIII to produce constriction in both eyes
What is opticokinetic nystagmus?
- normal physiologic response to fixating on a moving target
- asymmetric loss can be due to frontal or parietal lesion on side to which tape is moving
Describe testing of oculomotor CNIII
- check eyelid for ptosis (drooping of eyelid that does not clear upper margin of pupil)
- check pupil shape and symmetry
- reactivity to light (pupillary light reflex) and near reaction
- near reaction: reaction when gaze shifts from a far to a near object. As the object approaches, the pupils constrict with associated convergence of eyes (eyes move medially/nasally) and accommodation (thickening of lens by ciliary muscles). Helps to bring object into clear focus
Describe cardinal signs of gaze
- CNIII: adduction, downward gaze (aided by CNIV), elevation of eye
- CNIV: inward rotation, downward and lateral movement
- CNVI: lateral movement of eye
What are some findings with CN III lesions?
- ptosis (drooping of eyelid past upper margin of pupil) due to levator palpebrae weakness
- pupillary dilation or asymmetry: due to disruption of parasympathetic fibers. If severe, will see a fixed/dilated pupil
- position change of eye: “down and out” pupil due to weakness of extraocular muscles (MR, IO, IR, SR)
Describe compressive brainstem lesions related to CNIII
- hematomas: subdural or epidural
- large strokes, abscesses, tumors
- space occupying or expanding masses may cause brain to herniate through various dural openings in cranium. Initially, pupilloconstrictor fibers of CNIII causing dilation and fixation of pupil. Second effect is on somatic efferent fibers that supply extraocular muscles which then cause external strabismus (“down and out” of eye)
- aneurysms: areas of weakened arterial blood vessel walls causing dilation of arterial segment of internal carotid artery or posterior communicating artery generally within cavernous sinus causes similar findings as brainstem (uncal) herniation. Key difference is level of consciousness is preserved with aneurysms (prior to rupture) and is abnormal in herniation syndromes.
- diabetes mellitus: can cause extraocular muscle weakness but often spares puilloconstrictor fibers
Describe CN IV Lesions
- due to its long course around brainstem, CN IV is vulnerable to head trauma. Lesions result in:
- extorsion of eye (eye position drifts laterally)
- weakness of downward gaze (due to weakness of superior oblique muscle)
- vertical diplopia: increases when looking down
- head tilting: to opposite of lesion. Can be misdiagnosed as idiopathic torticollis
Describ CN VI lesions
- most common isolated CN palsy due to its long peripheral course. Seen often in pts with subarachnoid hemorrhage, late syphillis, and trauma. Lesions result in:
- convergent (medial) strabismus (esotropia): inability to abduct eye. Due to lateral rectus muscle weakness
- horizontal diplopia: maximal separation of images when looking toward paretic lateral rectus muscle
Describe testing of trigeminal CN V
- check facial sensation in forehead (VI), cheek (V2), and chin (V3) to pinprick, light touch, and hot/cold
- check motor function: check lateral jaw movements (lateral pterygoids), jaw clenchgin (temporal and masseter muscles)
- check corneal reflex (tests CN V and VII): lightly touch cotton wisp to cornea which should result in contraction of orbicularis oculi muscle (blink)
Describe trigeminal lesions
- decreased sensation of face and mucous membranes
- loss of corneal reflex
- weakness of muscles of mastication
- jaw deviation toward weak side (due to unopposed action of opposite lateral pterygoid muscle)
Describe corneal (blink) reflex
- protective reflex involving CN V (afferent limb) and CN VII (efferent limb)
- ask pt to look up and away from examiner
- take cotton wisp and approach opposite side of pt’s line of vision and touch cornea. Pt should blink in response.
- loss of blink reflex indicates lesion of CN V or VII. Can be seen in acoustic neuromas, brainstem (pontine) lesions, etc
Describe the functions of Facial CN VII
- Motor: facial expressions, eye and mouth closure
- sensory: taste for salty, sweet, and bitter substances to anterior 2/3 of tongue
- parasympathetic: secretion of saliva and tears
- general sensation: of external ear
Describe lesions of CN VII
- paralysis of muscles of facial expression (upper and lower portions of face) seen as a widened palpebral fissure and increased nasolabial fold (Bell’s Palsy)
- loss of corneal reflex (efferent limb)
- hyperacusis: increased sensitivity to sound
- crocodile tears syndrome: due to abberant regeneration of nerve after trauma. Pt sheds tears when chewing
Clinical note of Bell’s Palsy?
- peripheral facial paralysis
- can be caused by trauma or infection, but in most cases, is idiopathic (unknown)
Clinical note about bilateral facial palsies?
Can occur in Miller-Fisher variant of Guillain-Barre Syndrome
Clinical note of supranuclear (central) facial palsy?
- spares upper face and usually is associated with hemiplegia (weakness to one side of body)
- important in determining if weakness is central or peripheral in nature
Describe testing for hearing (cochlear division) of vestibulocochlear CN VIII
-check for hearing loss of hearing by whisper test or finger rub in each ear. If present, do Weber and Rinne tests
Describe Weber test
- performed on pts with unilateral hearing loss
- test for lateralization of sound
- place tuning fork (256 or 512 Hz) on vertex of skull or on forehead after striking fork between thumb and index finger
- ask pt where sound can be heard (one or both ears). In normal individuals, the sound is heard equally in both ears.
- In conductive hearing loss seen with occlusion of ear (cerumen impaction, perforation of eardrum, otosclerosis), the sound lateralizes to impaired ear
- in sensorineural hearing loss (nerve damage), the sound lateralizes to good (unaffected) ear
Describe Rinne test
- compares air to bone conduction (AC to BC)
- in normal individuals, air conduction is greater than bone conduction
- place vibrating tuning fork to mastoid bone
- when pt can no longer hear sound, quickly place tuning fork close to ear canal and ask if sound can be heard again (“U” of fork should face forward)
- In conductive hearing loss, bone conduction is heard as long or longer than it is through air. (BC>AC). Negative Rinne’s test
- In sensorineural hearing loss, air conduction is greater than bone conduction (AC>BC). Positive Rinne test. AC and BC are both diminished in sensorineural hearing loss which keeps ratios same as normal hearing person (AC>BC)
Vestibular division of CN VIII lesions result in:
- dysequilibrium (imbalance)
- nystagmus: rapid involuntary and rhythmic movement (or oscillation) of eye
Cochlear division of CN VIII lesions result in:
- destructive lesions lead to sensorineural hearing loss. Ex: acoustic neuroma
- irritative lesions can cause tinnitus (ringing in ears). Ex: medications (aspirin, some antibiotics, etc)
Describe functions of glossopharyngeal nerve CN IX
- motor: innervates stylopharyngeus muscle which elevates and widens pharynx on swallowing
- sensory: taste to posterior 1/3 of tongue, sensation to palate and pharynx, skin of external ear
- afferent limb of gag reflex
Describe testing for gag reflex
- tests CN IX (afferent/sensory) and X (efferent/motor)
- use a cotton tipped applicator to lightly touch posterior pharynx. This should elicit gag response.
- test each side individually
- Loss of gag reflex is generally an indicator of ipsilateral CNIX (perhaps CN X)