The High Yield Neurologic Examination • Mental Status-Brief Review • Cranial Nerves – Common/Urgent Patterns John Engstrom, M.D
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Overview – The Neurologic Examination The High Yield Neurologic Examination • Mental status-brief review • Cranial nerves – common/urgent patterns John Engstrom, M.D. • Motor exam – common/urgent patterns April 2017 • Sensory exam – common/urgent patterns • Selective demonstrations Q1: Which statement regarding the Screening Mental Status mental status exam is false? 1) Attention span (immediate recall) is not • Orientation-time, place, person abnormal in patients with dementia • Attention-Digit span forward (nl > 6-7) 2) Language testing is a screen for aphasia • Language-repetition, naming, comprehension 3) If recent memory testing is abnormal, then • Memory-Recall of 3 common objects at 5 attention is probably also abnormal minutes; if misses an answer give a prompt 4) Abstractions are often abnormal in the setting of dementia • Abstractions-Similarities and differences (e.g.-apple vs. orange; lake vs. river) 5) Attention span is often abnormal in late dementia 1 Assessment of Vision Screening for Visual Field Deficits • Measure acuity with glasses on/contacts in • Allows you to test function of broad areas of brain • Establishing a visual field cut establishes a – Lobes-occipital, temporal, parietal – Optic nerves, chiasm, thalamus structural lesion (eye vs. brain) • Clinical Importance • The pupils always react in cortical blindness – “An anatomic sedimentation rate of the brain” – Afferent-retina, optic nerve/tract, brainstem – Detect abnormalities that require brain imaging – Efferent-midbrain, third nerve, ciliary muscle – Localize the deficit (right vs. left brain) 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 of the visual field affected 2 Q2: What causes sustained dilation Cranial Nerve Exam-Pupils of a pupil in response to a light? • Anatomic pathways-afferent CN II, 1) Afferent pupillary defect midbrain, efferent bilat parasymp in CN III 2) Hippus – Best tested dim light; Est size before/after light 3) Efferent pupillary defect – Assess baseline symmetry of shape and size 4) Stroke affecting the parietal lobe – Assess direct and consensual response 5) Stroke affecting the occipital lobe – No other part of the nervous system affected! • Abnormalities may be in CN II or III Common Pupillary Exam Patterns • Common False Positives – Mydriatic drugs (unilateral if topical); child – Inadequacy of light stimulus (use bright light against a dim background) – Post surgical-cataracts, prosthetic eye • Afferent pupil defect-Light stimulus doesn’t reach brainstem due to diseased CN II – Pupil dilates despite constant light stimulus – Examples-multiple sclerosis, meningioma 3 Urgent Outpatient Pupillary Exam Pattern • Exclude false positives • History/exam suggest intracranial process? • Efferent pupil dilated unilaterally (6-9 mm) – Accompanied by CN III palsy (eye down/out) – Greater than 1 mm asymmetry – Compression of CN III by temporal lobe brain tissue displaced from a mass – Consider urgent brain MRI or head CT What Cranial Nerves Have in Common Cranial Nerves III, IV, and VI • Brainstem portion-many other brainstem • Movements-eye out is VI, eye down and in findings present (e.g.-MS, tumor) is IV, everything else is III • Subarachnoid space-CN and nerve roots – Move finger in horizontal and vertical planes pass through the CSF after exit cord – Move finger in and down bilaterally-IVth – Often multiple CN involved • Monocular diplopia – Example-infectious/carcinomatous meningitis, – Pt cover one eye; is only one image remaining? • Skull base-inside/outside skull to target – Strongly consider ordering brain MRI to cover tissue innervated (e.g.-motor/sensory) brainstem, skull base, and orbit 4 Cranial Nerve VII-Muscles of Q3: What facial movement is normal in Facial Expression upper motor neuron weakness? • Upper 1/3-Furrowing the eyebrows 1) Smile • Middle 1/3-Eye closure-can test power by 2) Eye closure forcing eyes open against resistance 3) Eyebrow furrowing • Lower 1/3-Smile 4) Lower 2/3 of face • All three affected-Lower motor neuron 5) Upper 2/3 of face facial paresis (e.g.-Bell’s palsy) • Lower 2/3 affected-upper motor neuron (brain or upper brainstem) CN VII-Utility of Testing CN VII-Examination • Lower 2/3 face-MRI of brain • Upper 1/3-furrowing brow, symmetry • Entire face-Bell’s palsy • Middle 1/3-degree eye closure, symmetry – LMN VII only finding – Power testing-force eyelids open using thumbs- one each at upper and lower orbit – Acute onset; stabilize/improve over days-weeks – With effort, globe rotates upward-see sclera • Apparent Bell’s but CNS location (e.g.-MS, – Lack of effort, globe motionless-see iris + pupil brain tumor) • Lower 1/3-excursion of smile, symmetry – Other neurol symptoms/signs – Coincident medical illness (e.g.-meningitis) 5 CN V, VIII, X, XI • CN V-test three divisions of face with pin or light touch • CN VIII-finger rub next to each ear; audiogram if questionable • CN X-uvula elevation in the midline • CN XI-symmetry/power of shoulder shrug CN XII-Tongue Motor Exam • Two muscles fused midline; separate CNs • Bulk-smooth lateral contour, symmetry • Bulk-place the contour of the muscle on a • Power screen-tongue protrusion midline nl perpendicular to your line of vision • Grading power-hold tongue-in-cheek vs. • Tone-move limb passively across a joint resistance slowly and rapidly • Dysarthria-slurred speech due to weakness • Power-grade 1-5 on the MRC scale – Lips (labial dysarthria) • Reflexes-grade 0-4 – Tongue (lingual dysarthria) • Gaits-Demonstration at the end of talk – Palate (nasal dysarthria) 6 The Weak Patient: The Symptom of Weakness Pertinent History Temporal sequence • Patients mean a functional limitation of Functional activities motor activity SOB • Confused with: – fatigue Ambulation-independent vs. cane vs. walker – depression (“neurasthenia”) vs. wheelchair – decreased sensation Stand up/reach overhead-proximal muscles – decreased force moving a painful limb Stand on toes; use pen/spoon-distal muscles Complete motor exam-not power alone Breakaway Weakness is Not Examination Signs of True Weakness True Weakness • Reduced but constant resistance when • DEFINITION: Variable resistance by the testing the power a muscle on clinical patient during muscle power testing examination • ASSOCIATED WITH PAIN: Cannot • There are only two types of true weakness: determine if underlying weakness present – Central: brain, brainstem, cord • UNASSOCIATED WITH PAIN: Poor effort – Peripheral: anterior horn cell, root, plexus, or attention nerve, neuromuscular junction, muscle 7 Weak Patient: History and Examination Q4: Which statement is FALSE re/ clinical utility of distinguishing UMN from LMN weakness on exam? 1) Informs decision to obtain imaging NEUROLOGIC NON-NEUROLOGIC 2) Informs the decision of what part of the nervous system to image UPPER MOTOR LOWER MOTOR FATIGUE BREAKAWAY NEURON NEURON 3) Determines need for neuromuscular referral POOR EFFORT 4) Helps determine differential diagnosis PAIN 5) None of the above statements is false Weak Patient: Central Weakness I Weak Patient: Central Weakness II Power - distal > proximal in limbs Spasticity-velocity-dependent increase in tone extensors > flexors in arms to passive stretch of a limb that is greatest in the dorsiflexors > plantar flexors in legs flexors of the arms and extensors of the legs lower 2/3 of face (if from brain injury) -Rapid, repetitive movements are slow in the Bulk - Normal fingers and feet; dominant side normally faster Tone - spastic; Babinski sign(s) present -Pronator drift-pronation the essential finding; may also flex the fingers and drop the arm Reflexes - 8 Motor Exam-Grading Power Motor Exam-The Challenge of SCORE RESPONSE Grading Power 5 Full power • Most weakness is between 4 and 5 4+/5- Minimal weakness • Inter-examiner variability 4 Mild weakness • What do you do with the weight-lifter? 4- Moderate weakness • Qualitative scale: mild, moderate, severe? 3 Severely weak; able to move vs. gravity • Pattern weakness usually more informative 2 Moves, but not against gravity than attempt to exactly quantify weakness 1 Flicker of contraction 0 No muscle contraction Motor Examination-Common Traps Motor Exam-Grading Reflexes • Focal atrophy from disuse or pain with use SCORE RESPONSE • Tongue fasciculations-all tongues twitch 4 Clonus • Apparent increased tone from patient 3 Hyperactive inability to relax during the exam 2 Normoactive • Nocturnal headaches can be caused by CO2 1 Hypoactive retention during sleep in NM resp failure Trace Present with reinforcement only 0Absent 9 Q5: Which answer is an inadequate Weak Patient-Lower Motor explanation for an absent DTR? Neuron Weakness 1) Inadequate stretch on tendon being struck • All features of true weakness on exam 2) Contracture of the tendon • Patterns of weakness and other findings 3) Vinca alkaloid use (e.g.-vincristine) determine the differential diagnosis 4) Muscle weakness – Distal polyneuropathy-weakness first in distal 5) Absence of muscle tissue attached to the legs with sensory loss and absent ankle reflexes tendon being struck – Myopathy-proximal weakness in arms and legs without sensory loss or reflex changes – Global new areflexia-always needs explanation CNS Sensory Loss (2 Cs) and PNS Sensory Loss (2 Ps) Sensory Examination • Central-Circumferential