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Neurology System

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					Neurology System
     Reflexes
Reflex Arch

• Spinal nerves have sensory (Afferent) &
  motor (Efferent) portions
• Control DTRs & superficial reflexes
• Simple reflex arch needs a sensory &
  motor neuron
• Ex. Of normal reflex arch = knee-
  jerk/patellar reflex
Reflex Arch

• Reflexes= basic defense mechanisms of
 the nervous system
  – Involuntary
  – Unconscious
  – Allow quick reaction to painful/damaging
    situations
  – Maintain balance
  – Appropriate muscle tone
Four Types of Reflexes
1. Deep tendon
  •   Patellar or knee jerk
2. Superficial
  •   Corneal
  •   abdominal
3. Visceral
  •   Pupillary reflex to light and accommodation
4. Pathologic
  •   Babinski
  •   Extensor plantar reflex
Deep Tendon Response
• Briskly tap the tendon of a partially stretched
    muscle
•   For the reflex to fire, all components of the
    reflex arch must be intact
    –   Sensory nerve fibers
    –   Spinal cord synapse
    –   Motor nerve fibers
    –   Neuromuscular junction
    –   Muscle fibers
Deep Tendon Response

• Tapping the tendon activates special
 sensory fibers in the partially stretched
 muscle, triggering a sensory impulse that
 travels to the spinal cord via peripheral
 nerve
• the stimulated sensory fiber synapses
 directly with the anterior horn cell
 innervating the same muscle.
Deep Tendon Response

• When the impulse crosses the
 neuromuscular junction, the muscle
 suddenly contracts, completing the reflex
 arch.
Deep Tendon Response

• Each deep tendon reflex involves specific
  spinal segments
• Abnormal reflex help locate an a
  pathologic lesion
The Plantar Response

• Normally flexion of toes
• Dorsiflexion of the big toe & fanning of
 the other toes = Babinski Response
  – Indicative of CNS lesion in corticospinal tract
  – Babinski may also be seen in unconscious
    states due to drug or alcohol intoxication or
    postictal period
Grading Reflex Response

• Compare Right and Left Sides
• Graded on a 4 point scale
  – 4+ very brisk,hyperactive with clonus
  – 3+ brisker than average
  – 2+ average, normal
  – 1+ diminished, low normal
  – 0 No response
4 point scale

• Subjective
• No standard exists
• Wide range of normal
• Advise to assess DTRs only as part of the
 complete neurologic exam
Abnormal Findings

• Clonus
  – Short jerking contractions of the same muscle
• Hyperreflexia
  – Exaggerated reflex
  – Monosynaptic reflex arch from higher cortical
    levels
  – Brain attack
• Hyporeflexia
  – Absence of reflex
  – Lower motor neuron problem
  – Spinal cord injury
Reinforcement
• Reflex response fails
  – Vary position
  – Increase the strength
• Reinforcement Technique
  – Relaxes muscles
  – Enhances response
  – Isometric exercise in muscle group away from
    the one being tested
sample multiple choice

• During a neurologic examination, the
 tendon reflex fails to appear. Before
 striking the tendon again, the examiner
 might use the technique of:
A. Two-point discrimination
B. Reinforcement
C. vibration
D. graphesthesia
Complete Neurologic Exam
• Mental Status
• Cranial Nerves II - XII
• Motor System – muscle size, strength, tone,
    gait, and balance, RAMs
•   Sensory System – superficial pain, light touch
    and vibration, position sense, stereognosis,
    graphesthesia, 2 point discrimination
•   Reflexes – DTRs, biceps, triceps, brachioradialis,
    patellar, Achilles
    – Superficial – abdomonal , Plantar
Neurologic Screening Exam
• Mental Status
• Cranial Nerves
  – II Optic
  – III, IV, VI Extraocular muscles
  – V Trigeminal
  – VII Facial Mobility
• Motor Function- gait & balance, Knee
 flexion (hop or shallow knee bend)
Screening
• Sensory function – superficial pain & light
 touch (arms & legs)
  – Vibration – arms & legs
• Reflexes
  – Biceps
  – Triceps
  – Patellar
  – Achilles
Neurologic Recheck
• In house patients with head trauma or
  neurologic deficit due to systemic disease
  process must be monitored closely for change in
  status or signs of  ICP. Use this shortened form
  of the neurologic exam:
    LOC
    Motor function
    Pupillary Response
    Vital Signs
LOC
• A change in the level of consciousness is the
    single most imp. Factor in this exam. It is the
    earliest sign. Check arousal, awareness,
    orientation – person, place & time.
•       A person is fully alert when his eyes open at
    your approach or spontaneously, orientated x3,
    follows verbal commands appropriately. If not
    fully alert increase the amt. Of stimulus used as
    follows: name called, light touch on arm,
    vigorous shake of shoulder, pain (Nail bed,
    sternal rub)
Motor Function

• Check voluntary movement with
  commands (raise right arm, squeeze
  fingers)
• If spontaneous movement occurs in
  reaction to noxious stimuli = Localizing,
  documented as a purposeful movement
Pupillary Response

• Size, shape, and symmetry of both pupils
• In a brain injured person – a sudden,
 unilateral, dilated and nonreactive pupil is
 ominous. When  ICP pushes the brain
 stem down (uncal herniation) it put
 pressure on Cranial nerve III (runs parallel
 to brain stem) causing pupil dilatation
Vital Signs

• TPR & B/P prn
• Note pulse & B/P are notoriously
 unreliable parameters of CNS deficit.
 Changes are late consequences of  ICP
  – Cushing Reflex = sudden  B/P with widening
    pulse pressure ; pulse  slow & bounding
Glascow Coma Scale
• Objective tool that defines LOC by
 assigning it a numeric value. Scale divided
 into 3 areas;
  – Eye opening
  – Verbal response
  – Motor response
• Alert, normal person scores 15
• Score of 7 or < reflects coma