Neurologic
Assessment
Chapter 6
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
Components of a Neurological Assessment
• 1. Interviewing the patient
• 2. Determining level of consciousness
• 3. Pupillary Assessment
• 4. Cranial Nerve Testing
• 5. Vital Signs
• 6. Motor Function
• 7. Sensory Function
Interviewing your patient
• Purpose: gather information, either from the
family or patient. It also established a
baseline sensorium
• READ THE PATIENTS CHART FIRST, KNOW
PAST HX
• Identify the following when assessing neuro
status:
• Headache
• Difficulty with speech
• Inability to read or write
• Altered level of consciousness or memory
• Confusion or change in thinking
Consciousness
Reticular Activating System (RAS)
• Network of neurons and fibers in the brain stem which
receive input from the sensory pathways and project to
the entire cerebral cortex
• Arousal is dependent on adequate functioning of RAS
• Arousal is a function of the brain stem, it does not have
anything to do with the thinking parts of the brain
(basically it allows for physical reaction)
• If a patient opens their eyes when called upon, they have
an intact RAS for example but does not tell you if they
are cognitive, awake or aware
Consciousness
Cortex
• Modulates incoming information via connections to the
RAS
• Requires functioning RAS
• Awareness means that the cerebral cortex is working and
that the patient can interact with and interpret his
environment
• We evaluate awareness in many ways but tend to focus
on four areas of cortical functioning:
• Orientation
• Attention span
• Language
• Memory
Level of Consciousness
• Consciousness is defined as the state of being
aware of physical events or mental concepts.
Conscious patients are awake and responsive to
their surroundings
• The level of consciousness has been described as
the degree of arousal and awareness.
• A manifestation of altered consciousness implies
an underlying brain dysfunction.
• Its onset may be sudden, for example following
an acute head injury, or it may occur more
gradually, such as in hypoglycemia.
Causes of Altered Level of Consciousness
• Profound hypoxemia
• Hypercapnia
• Cerebral
hypoperfusion
• Stroke
• Convulsions
• Hypoglycemia
• Recent administration
of sedatives or
analgesic drugs; drug
overdose
• Tumors
• High Ammonia levels
from liver failure
• Renal failure
• Encephalopathy
(hepatic, anoxic,
metabolic)
• Brain lesions, swelling
• subarachnoid
hemorrhage
• alcohol intoxication
• Severe shock
• Infection
ALOC
• The clinician must determine the cause of
the ALOC and suggest appropriate exams
such as:
• CT of the brain (to rule out bleeding,
swelling…)
• ABG to assess Co2, Pao2
• Blood Glucose levels with an Accucheck
• Pupil dilation to assess drugs
• Physical exams to determine significance
Assessment of LOC
• Observe patients response to verbal or motor stimuli
• No response to voice or light touch, then attempt painful
stimuli such as:
• Sternal rub
• Supraorbital pressure
• Pinching upper arms
Localizing is when a patient does a purposeful gesture,
such as picks up tubing, pulls at linen
Localizing is purposeful and intentional movement
intended to eliminate a noxious stimulus, whereas
withdrawal is a smaller movement used to get away
from noxious stimulus.
Assessment of Awareness
• The Glascow Coma Scale (GCS) helps us to
decrease the subjectivity of our responses
• GCS is a neurological scale that aims to give a
reliable, objective way of recording the
conscious state of a person for initial as well as
subsequent assessment.
• A patient is assessed against the criteria of the
scale, and the resulting points give a patient
score between
• 3 (indicating deep unconsciousness) and 15
(most awake/alert)
Functional Neuroanatomy
• Central nervous system
• Brain: cerebrum, brainstem,
cerebellum
• Spinal cord
• Peripheral nervous system
• Cranial nerves
• Spinal nerves
Functional Neuroanatomy
• Functional division
• Sensory system (afferent)
• Motor system (efferent)
Cerebrum
• Largest part of the brain.
• Lesions lead to abnormalities in movement,
LOC, ability to speak and write, emotions
and memory
Functional Neuroanatomy
• 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)
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
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
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
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
Mental Status and LOC
• Compromise of LOC may be due to:
• Generalized dysfunction (e.g.,
overdose)
• Abnormality in specific area
Assessing Consciousness
• LOC – wakefulness and alertness
• Content of consciousness –
awareness and thinking.
Delirium
• Alternating levels of consciousness and
deficits in attention and organized thinking.
• Occurs in 60 to 80% of ventilated patients
• Caused by hypoxia, electrolyte or acid/base
imbalance, sleep deprivation, sedation,
strange surroundings, medication side
effects.
Glasgow Coma Scale
• 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
GCS
• Scores less than 9 indicate severe
coma and typically require
endotracheal intubation.
Cranial Nerve Exam
• 12 cranial nerves are connected to the
brain, most coming from the brainstem.
• Evaluated by using a combination of
sensory and motor tests.
• Important reflexes such as gag reflex are
controlled by cranial nerves
Cranial Nerve Assessment
• See Wilkins text – page 113
Sensory Examination
• Evaluates ability to perceive sensations
with eyes closed
• Assessment of light touch, pinprick, and
temperature
Motor Examination
• 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
Deep Tendon Reflexes
• Evaluate spinal nerves
• Scored on a scale from 0 (no reflex), +2
(normal), +5 (hyperreflexia)
• Myasthenia gravis and 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
Pupil Response
Brainstem Reflexes
• Gag reflex (CN IX, X)
• Its absence may increase risk for
aspiration
• Cough reflex (CN X)
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
Vital Signs and Neurologic System (cont’d)
• Ataxic breathing: marker of brainstem
dysfunction
• Increased ICP = Cushing’s triad
• Hypertension, widening pulse
pressure, bradycardia, bradypnea
Ancillary Testing
• Imaging – CT scan/MRI
• Angiography
• EEG
• Lumbar Puncture – Infections/GB
Intracranial Pressure Monitoring
• Indications:
• Monitor patients at risk for life-threatening
intracranial hypertension
• Monitor evidence of infection
• Assess effects of therapy for reducing ICP
• Cerebral perfusion pressure (CPP) is the
most critical element to monitor. MAP - ICP
Declaration of Brain Death
• Irreversible condition when all perceptible
brain activity has stopped.
• Caused by: stroke, brain injury, cardiac
arrest
• Two steps:
• Clinical examination
• Confirmatory test
Declaration of Brain Death
• Documentation of the absence of
reversible conditions
• Hypothermia
• Sedation or NMB
• Major metabolic disturbances
• Shock
Apnea Test
• Apnea test
• Start with normal PaC02 and Pa02
• Monitor for 8-10 minutes. PaC02 increase
to 60 mmHg or 20 mmHg above baseline
with apnea is a positive test.
• Absences of spontaneous breathing after
increase in PacC02