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 = kneejerk/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
•
•
Corneal
abdominal
•
Pupillary reflex to light and accommodation
•
•
Babinski
Extensor plantar reflex
2. Superficial
3. Visceral
4. Pathologic
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