The High Yield Neurologic Examination John Engstrom, M.D. Sadly, - - PDF document

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The High Yield Neurologic Examination

John Engstrom, M.D. April 2019

Disclosures

Sadly, I have no conflicts to disclose “Exam of the genitalia reveals that he is circus sized.”

Medical Chart Quotes Medical Chart Quotes

“While in the ER, She was examined, X- rated and sent home.”

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Medical Chart Quotes

“Both breasts are equal and reactive to light and accommodation”

Overview – The Neurologic Examination

• Mental status-brief review
• Cranial nerves – common/urgent patterns
• Motor exam – common patterns
• Sensory exam – common patterns
• What is wrong with my walking?
• Demonstrate the 15 minute exam
• Other questions/demonstrations?

Screening Mental Status

• Orientation-time, place, person
• Attention-Digit span forward (nl > 6-7)
• Language-repetition, naming, comprehen
• Memory-Recall of 3 common objects at 5

minutes; if misses an answer give a prompt

• Abstractions-Similarities and differences

(e.g.-apple vs. orange; lake vs. river)

Screening for Visual Field Deficits

• Visual field screen if you suspect a brain problem
• Allows you to test function of broad areas of brain

– Lobes-occipital, temporal, parietal – Optic nerves, chiasm, optic tracts, and thalamus

• Clinical Importance

– “An anatomic sedimentation rate of the brain” – Detect abnormalities that require brain imaging – Localize the deficit (right vs. left brain)

3 Screening for Visual Field Deficits- Ambulatory, Cooperative Patient

• Imagine visual field cut in four equal pieces
• Move examiner finger in the center of each

quadrant with patient gaze fixed

• Test each eye by covering the opposite eye,

present stimulus in center of all 4 quadrants

• Describe the deficit in terms of the portion
• f the visual field affected

Assessment of Vision and Pupils

• Measure acuity with glasses on/contacts in
• Let the patient hold the vision card and read

the lines back to you

• Abnl pupils-indicate abnl CNs or brainstem

– Afferent-retina, optic nerve/tract, midbrain – Efferent-midbrain, third nerve, ciliary muscle – Pupils always react in cortical blindness

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Cranial Nerve Exam-Pupils

• Anatomic pathways-afferent CN II,

midbrain, efferent bilat parasymp in CN III

– Best tested in dim light – Estimate size before and after light stimulus – Assess baseline symmetry of shape and size – Assess direct and consensual response – No other part of the nervous system affected! – Nl less than or equal to one mm asymmetry

• Abnormalities may be in CN II or III

Common Pupillary Exam Patterns

• Context matters-Does the history or exam

suggest an active intracranial process?

• When genuinely abnl without explanation-

get a brain MRI

• Common False Positives

– Inadequacy of light stimulus (use bright light against a dim background) – Mydriatic drugs (unilateral if topical); child – Post surgical-cataracts, prosthetic eye

Outpatient Pupillary Exam Patterns

• Afferent pupillary defect

– Light stimulus in affected eye doesn’t reach brainstem due to diseased CN II – Both pupils dilated despite const light stimulus – Light in unaffected eye-both pupils react

Outpatient Pupillary Exam Patterns

• Efferent pupillary defect

– Accompanied by CN III palsy (eye down/out) – Light in affected eye-contralateral pupil constricts but ipsilateral pupil does not react – Light in unaffected eye-ipsilateral pupil constricts and contralateral pupil is unreactive – Consider urgent brain MRI or head CT

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What Cranial Nerves Have in Common

• Brainstem portion-many other brainstem

findings present (e.g.-MS, tumor)

• Subarachnoid space-CN and nerve roots

pass through the CSF after exit cord

– Often multiple CN involved – Example-infectious/carcinomatous meningitis,

• Skull base-inside/outside skull to target

tissue innervated (e.g.-motor/sensory)

Cranial Nerves III, IV, and VI

• Movements-eye out is VI, eye down and in

is IV, everything else is III

– Move finger in horizontal and vertical planes – Move finger in and down bilaterally-IVth

• Binocular diplopia

– Pt cover one eye; is only one image remaining? – Strongly consider ordering brain MRI to assess the brainstem, skull base, and orbit

CN VII-Examination

• Upper 1/3-furrowing brow, symmetry
• Middle 1/3-degree eye closure, symmetry

– Power testing-force eyelids open using thumbs-

• ne each at upper and lower orbit

– With effort, globe rotates upward-see sclera – Lack of effort, globe motionless-see iris + pupil

• Lower 1/3-excursion of smile, symmetry

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CN VII-Utility of Testing

• Lower 2/3 face-MRI of brain
• Entire face-Bell’s palsy

– LMN VII only finding – Acute onset; stabilize/improve over days-weeks

• Apparent Bell’s but CNS location (e.g.-MS,

brain tumor)

– Other neurol symptoms/signs – Coincident medical illness (e.g.-meningitis)

CN V, VIII, X

• CN V-test face with pin and light touch
• CN VIII-finger rub next to each ear;

audiogram if questionable

• CN X-uvula elevation in the midline

CN XII-Tongue

• Two muscles fused midline; separate CNs
• Bulk-smooth lateral contour, symmetry
• Power screen-tongue protrusion midline nl
• Grading power-tongue-in-cheek vs. resist
• Tongue fasciculations-all nl tongues twitch
• Dysarthria-slurred speech due to weakness

– Lips (labial dysarthria) – Tongue (lingual dysarthria) – Palate (nasal dysarthria)

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Motor Exam

• Bulk-place the contour of the muscle on a

perpendicular to your line of vision

• Tone-move limb passively across a joint

slowly and rapidly

• Power-grade 1-5 on the MRC scale
• Reflexes-grade 0-4
• Gaits-Demonstration at the end of talk

The Symptom of Weakness

• Patients mean a functional limitation of

motor activity

• Confused with:

– fatigue – depression (“neurasthenia”) – decreased sensation – decreased force moving a painful limb

The Weak Patient: Pertinent History

Temporal sequence Functional activities SOB Ambulation-independent vs. cane vs. walker

• vs. wheelchair

Stand up/reach overhead-proximal muscles Stand on toes; use pen/spoon-distal muscles Complete motor exam-not power alone

Examination Signs of True Weakness

• Reduced but constant resistance when

testing the power a muscle on clinical examination

• There are only two types of true weakness:

– Central: brain, brainstem, cord – Peripheral: anterior horn cell, root, plexus, nerve, neuromuscular junction, muscle

8 Weak Patient: History and Examination

NEUROLOGIC NON-NEUROLOGIC

UPPER MOTOR NEURON LOWER MOTOR NEURON BREAKAWAY FATIGUE POOR EFFORT OR ATTENTION PAIN

Breakaway Weakness is Not True Weakness

• DEFINITION: Variable resistance by the

patient during muscle power testing

• ASSOCIATED WITH PAIN: Cannot be sure

if some underlying weakness present

• UNASSOCIATED WITH PAIN: Poor effort
• r attention

Weak Patient: Central Weakness I

Power - ¯ distal > proximal in limbs ¯ extensors > flexors in arms ¯ dorsiflexors > plantar flexors in legs ¯ lower 2/3 of face (if from brain injury) Bulk - Normal Tone - spastic; Babinski sign(s) present Reflexes - ­

Weak Patient: Central Weakness II

Spasticity-velocity-dependent increase in tone to passive stretch of a limb that is greatest in the flexors of the arms and extensors of the legs

• Fast finger movts/foot taps -Rapid, repetitive

movements are slow in the fingers and feet; dominant side normally faster

• Pronator drift-hand pronation essential finding;

may also flex the fingers and drop the arm

9 Motor Exam-Grading Power

SCORE RESPONSE 5 Full power 4+/5- Minimal weakness 4 Mild weakness 4- Moderate weakness 3 Severely weak; able to move vs. gravity 2 Moves, but not against gravity 1 Flicker of contraction No muscle contraction

Motor Exam-The Challenge of Grading Power

• Most weakness is between 4 and 5
• Inter-examiner variability
• What do you do with the weight-lifter?
• Qualitative scale: mild, moderate, severe?
• Pattern of weakness usu more informative

than attempt to exactly quantify weakness

Motor Examination-Common Traps

• Focal atrophy from disuse
• Focal atrophy from pain w/ use-switch

sides-another form of disuse

• Apparent increased tone from patient

inability to relax during the exam-often labeled as paratonia

• Breakaway weakness

Grading Reflexes-Asymmetry Impt

SCORE RESPONSE 4 Clonus 3 Hyperactive 2 Normoactive 1 Hypoactive Trace Present with reinforcement only Absent

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The Weak Patient: Key Evaluation Features

Power Reflexes Sensation Anterior Horn Cells (Spinal cord) Patchy ¯ or normal normal Nerve Root (i.e. - Radiculopathy) ¯ or normal ¯* ¯ or normal Nerve-Axonal (i.e. – DSPN) ¯ distal ¯ distal ¯ distal Nerve - Demyelination (i.e. - GBS) ¯ diffuse ¯ diffuse ¯ patchy/ normal NMJ (i.e. -Myasthenia) ¯ proximal normal normal (+ bulbar) Muscle(i.e. - Polymyositis) ¯ proximal normal normal * - in distribution of affected root

Sensory Examination

• Light touch-tests primarily large diameter

nerve fibers and CNS sensory pathways

– Easy to test with finger or Q-tip – Can use over entire body – Can use VAS (0-10) for semi-quantitation – Change in quantity or quality of light touch?

• Pin sensation tests small diameter nerve

fibers and CNS pain pathways-sharp or dull

CNS Sensory Loss (2 Cs) and PNS Sensory Loss (2 Ps)

• Central-Circumferential limb/trunk distrib.

– Distribution belong to many nerves/nerve roots – Cord, brainstem, brain

• Peripheral-Patchy distribution over a limb

– In nerve or root distribution – Distribution belongs to single nerve/nerve root

• Exception: stocking-glove sensory loss of a

distal sensory polyneuropathy

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Gait Assessment-What is wrong with my walking?

• This is a visual engagement exercise-you

need to know what the gait looks like

• All material you need is reproduced in the

slides on your handout

Gait-Hemiparetic

• Affected leg is stiff from spasticity Leg

circumducts during walking

• Affected arm may be partially flexed in a

spastic posture

Gait-Parkinsonian

• Short small shuffling steps bilaterally
• En-bloc turning-multiple steps to turn

around instead of the normal two steps

• Reduced arm swing- “arms stiff like a

robot” when walking; unilateral or bilateral

• Retropulsion-tendency to fall backwards

when standing still and given a minor push

Gait-Alcoholic Cerebellar Degeneration

• Affects the truncal balance center in the

midline cerebellum

• Limb coordination-nl or minimally abnl
• Gait is wide-based
• Cannot tandem walk-no direction to falls
• Very severe-truncal bobbing when sits
• No leg sensory loss or weakness

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Gait-Steppage

• Due to foot drop of any cause
• To avoid tripping over the toes during the

foot drop, the patient compensates by lifting the proximal leg high in the air

• High risk of falls
• Socially embarrassing
• Correctable with ankle-foot orthosis (brace)

Gait-Sensory Ataxia

• Lack of sensation in the feet; Romberg sign
• Inability to tell position of feet in space

results in imbalance

– Visual compensation is gone in darkness (washing hair with eyes closed while standing) – Wide-based gait accompanied by sensory loss – Grab bars/shower chair; flashlight on key chain

• r flashlight app on smart phone

Gait that Shall not be Named

• Patient reports severe imbalance
• Despite imbalance, falls with injury rare
• Trunk pitches in many directions while

patient is walking

– Pt able to compensate for pitching – No falls

Demonstrate 15 Minute Exam

• Mental status-Orientation, attention,

language, abstractions, speech

• Cranial nerves II-XII
• Motor-Tone, tremor, power, coordination,

reflexes, gait

• Sensory-light touch/pin in face, hands, feet

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Conclusions

• A good screening neurologic exam can be

performed in 10-15 minutes

• Neurologic examination details will be

dictated by the history and initial neurologic examination findings

• The disease context and pattern of

neurologic findings is most helpful, not a single finding

Questions and Demonstrations

• What questions can I answer?
• What would you like to see me

demonstrate?