chapter 6 neurologic assessment
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Chapter 6 Neurologic Assessment. Learning Objectives. After reading this chapter you will be able to: Define key terms related to neurologic assessment Describe functional anatomy of the nervous system Explain the cortical function of different lobes of the brain - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 6Neurologic Assessment
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Learning Objectives
After reading this chapter you will be able to: Define key terms related to neurologic
assessment Describe functional anatomy of the
nervous system Explain the cortical function of different
lobes of the brain Describe common techniques used to
assess the mental status
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Learning Objectives (cont’d)
Describe functions of the brainstem, the cerebellum, and 12 pairs of cranial nerves
Identify the parameters necessary to obtain a Glasgow Coma Scale and be able to interpret the results
Describe common techniques to assess the cranial nerves, the sensory system, the motor system, coordination, and gait
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Describe the importance of assessing sedation and delirium in the ICU
Describe techniques used to assess deep, superficial, and brainstem reflexes
Explain the relationship between vital signs and neurologic status
Identify the importance of ICP monitoring and the value of assessing cerebral perfusion pressure
Learning Objectives (cont’d)
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Overview
Injuries of the nervous system May affect respiratory system May affect patient cooperation with respiratory
procedures History may indicate nature of dysfunction Exam localizes and quantifies severity of
dysfunction Initial interaction with patient is first step in
neurologic assessment
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Overview (cont’d)
Neurologic assessment evaluates: Mental status Cranial nerve function Motor system Coordination Sensory system Reflexes
Meaningful neurologic assessment requires adequate stimulation
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Functional Neuroanatomy
Neurologic system Central nervous system
• Brain: cerebrum, brainstem, cerebellum• Spinal cord
Peripheral nervous system• Cranial nerves• Spinal nerves
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Functional Neuroanatomy (cont’d)
Functional division Sensory system (afferent) Motor system (efferent)
Cerebrum Functions: movement, LOC, ability to speak
and write, emotions, memory
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Brainstem Consists of midbrain, pons, medulla oblongata Most cranial nerves originate in brainstem Regulation of heart rate, blood pressure, and
breathing
Functional Neuroanatomy (cont’d)
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Cerebellum Posterior part of the brain Responsible for equilibrium, muscle tone, and
coordination Cerebellar lesions cause:
• Loss of coordination (ataxia)• Tremors• Disturbances in gait and balance
Functional Neuroanatomy (cont’d)
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Spinal cord From base of the brain down to L1 (45 cm) Connects brain to the body for motor and
sensory function 31 spinal nerves
• C1-C8, T1-T12, L1-L5, S1-S5, one coccygeal• Posterior (dorsal) roots = sensory• Anterior (ventral) roots = motor
Functional Neuroanatomy (cont’d)
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Spinal cord Herniated vertebral disk is the most common
spinal nerve root pathology Involvement of multiple nerve roots
• Guillain-Barré Phrenic nerves arise from spinal roots C3 to
C5• Damage can result in diaphragmatic paralysis
Functional Neuroanatomy (cont’d)
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Mental Status and LOC
LOC and mentation: most important parts of the neurologic exam
Changes due to CNS dysfunction Initial goal of exam is to determine
patient’s awareness Starts with patient encounter
Compromise of LOC may be due to: Generalized dysfunction (e.g., overdose) Abnormality in specific area
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Glasgow Coma Scale (GCS)
Most widely used instrument to quantify neurologic impairment
Test Motor response Verbal response
• Poorly suited for patients with impaired verbal response (e.g., aphasia, hearing loss, tracheal intubation)
Eye opening
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Glasgow Coma Scale (cont’d)
Scale goes from 3 (deep coma) to 15 (fully awake)
GCS of 12-15 = non-ICU observation GCS of 9-12 = significant insult GCS <9 = severe coma = requires
endotracheal intubation
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Mini-Mental State Examination
MMSE or Folstein test 30-point questionnaire to assess cognition Samples various functions
• Arithmetic, memory, orientation Score interpretation
• >27/30 = normal• 20-26 = mild dementia• 10-19 = moderate dementia• <10 = severe dementia
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Sedation and Delirium in the ICU
Delirium occurs in 60% to 80% of mechanically ventilated patients
Associated with: Longer hospital stay Higher mortality Poor long-term cognitive function
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Sedation and Delirium in the ICU (cont’d)
Richmond Agitation Sedation Scale (RASS) Titrate sedation
Confusion Assessment Method for the ICU (CAM-ICU) Evaluates delirium
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Cranial Nerve Exam
12 cranial nerves = sensory and motor function Midbrain (CN III, IV) Pons (CN VIII) Medulla (CN IX to XII)
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Cranial Nerve Exam (cont’d)
Ipsilateral findings except on CN V Acoustic problem (CN VII, VIII) Pupillary response (CN II, III) Corneal reflex (CN V, VII) Gag reflex (CN IX, X)
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Sensory Exam
Somatosensory pathways Spinothalamic (ST) = pain, temperature Dorsal column-medial lemniscus (DCML) =
vibration, position sense (proprioception) Evaluates ability to perceive sensations
with eyes closed Assessment of light touch, pinprick, and
temperature
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Motor Exam
Patient’s ability to move on command Motor strength and range of motion Scale from 0 (no movement) to +5 (full
range of motion and full strength) If unconscious = response to pain
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Motor Exam (cont’d)
Upper motor neuron (UMN) Babinski’s sign, hyperreflexia, clasp-knife Decorticate and decerebrate posture
Lower motor neuron (LMN) Loss of strength, tone and reflexes, muscle
waste and fasciculations
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Deep Tendon Reflexes
Evaluate spinal nerves Triceps, biceps, brachioradialis, patellar,
Achilles tendon Westphal’s sign = absence of patellar reflex
Scale from 0 (no reflex), +2 (normal), +5 (hyperreflexia)
Myasthenia gravis and botulism have abnormal deep tendon reflexes
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Superficial Reflexes
Plantar reflex Tested when suspected L4-L5 or S1-S2
injury Babinski’s sign
Dorsiflexion of the great toe with fanning of remaining toes
Normal in children 12 to 18 months of age
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Brainstem Reflexes
Gag reflex (CN IX, X) Its absence may increase risk for aspiration
Cough reflex (CN X)
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Brainstem Reflexes (cont’d)
Pupillary reflex (CN II, III) PERRLA
• Pupils equal round reactive to light and accommodation
Anisocoria Myosis = pontine hemorrhage, narcotics Mydriasis = brain injury, anticholinergics Mid-position fixed pupils = severe cerebral
damage Corneal reflex (CN V, VII)
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Coordination, Balance, and Gait
Assessment of cerebellar function Patient should be able to follow commands
during exam Dysmetria = under- and overshooting of goal-
directed movements Romberg test = balance
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Vital Signs and Neurologic System
Brainstem = breathing Lesions from cerebrum to cervical cord
cause changes of breathing patterns Cheyne-Stokes respiration
Intracranial cause, hypoxemia, cardiac failure
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Vital Signs and Neurologic System (cont’d)
Ataxic breathing: marker of brainstem dysfunction
Increased ICP = Cushing’s triad Hypertension, widening pulse pressure,
bradycardia, bradypnea
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Intracranial Pressure Monitoring
Indications Monitor patients at risk for life-threatening
intracranial hypertension Monitor evidence of infection Assess effects of therapy for reducing ICP
Although hyperventilation decreases ICP, cerebral perfusion pressure (CPP) is the most critical element to monitor