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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
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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
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
Learning Objectives (cont’d) • 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
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
Overview (cont’d) Neurologic assessment evaluates: Mental status Cranial nerve function Motor system Coordination Sensory system Reflexes Meaningful neurologic assessment requires adequate stimulation
Functional Neuroanatomy Neurologic system Central nervous system Brain: cerebrum, brainstem, cerebellum Spinal cord Peripheral nervous system Cranial nerves Spinal nerves
Functional Neuroanatomy (cont’d) Functional division Sensory system (afferent) Motor system (efferent) Cerebrum Functions: movement, LOC, ability to speak and write, emotions, memory
Functional Neuroanatomy (cont’d) • Brainstem • Consists of midbrain, pons, medulla oblongata • Most cranial nerves originate in brainstem • Regulation of heart rate, blood pressure, and breathing
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)
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)
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)
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
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
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
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
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
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
Cranial Nerve Exam 12 cranial nerves = sensory and motor function Midbrain (CN III, IV) Pons (CN VIII) Medulla (CN IX to XII)
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)
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
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
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
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 gravisand botulism have abnormal deep tendon reflexes
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
Brainstem Reflexes Gag reflex (CN IX, X) Its absence may increase risk for aspiration Cough reflex (CN X)
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)