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BIOE221
Session 10
Neurological Assessment –
PNS Motor, Sensory
Examination and Reflexes
Bioscience Department
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Session Objectives
o Review the major structures and functions of the nervous
system in order to be able to assess its motor, sensory
and integrative functions
o Identify the common symptoms relating to neurological
disorders
o Demonstrate examination of the neurological system by
assessing certain sensory and motor systems
o Recognise abnormal findings with these techniques
o Demonstrate examination of deep tendon reflexes
o Recognise abnormal findings with these reflexes
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Spinal Cord
Sensory & Motor Tracts
(Tortora & Derrickson, 2009, p.481)
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Spinal Nerves
o The 31 pairs of spinal nerves arise from the length of the spinal cord and supply the rest of the body
• 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal
o They are “mixed nerves”
• contain both sensory and motor fibres
o Sensory afferent fibres enter the cord through the posterior or dorsal roots
• See ‘dermatomes’
o Motor efferent fibres exit through the anterior or ventral roots
• The nerves exit the spinal cord in an orderly manner, each nerve innervating a particular segment of the body known as a myotome
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Dermatomes
o A dermatome is a circumscribed skin area that is
supplied mainly from one spinal cord segment through a
particular spinal nerve
o Dermatomes overlap
o Useful landmarks
• thumb, middle and little finger – dermatomes of C6,
C7, C8
• nipple – at level of T4
• umbilicus – at level of T10
• groin – at level of L1
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Common Myotomes
(Magee, 2008, p.155)
(Magee, 2008, p.549)
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Neurological Examination
o Last week
• Mental state
• Cranial nerves
• Motor system
o This week
• Sensory system
• Reflexes
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Neurological Sensory System
o Always compare sensation bilaterally
• If you observe a definite decrease – map it out to
determine the dermatome or myotome affected.
o Tests could include
• Sharp / dull – pain and crude touch
Sharp/Dull Test(Jarvis, 2016, p.652)
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Common Patterns of Sensory Loss
o Peripheral neuropathy
• Loss of sensation involves all sensory modalities. Loss is most severe distally (feet and hands); response improves as stimulus is moved proximally
• Causes: Metabolic disease, nutritional deficiency
o Individual nerves or roots
• Decrease or loss of all sensory modalities. Area of sensory loss corresponds to distribution of the involved nerve
• Cause: Trauma, vascular occlusion
o Spinal cord hemisection
• Loss of pain and temperature on contralateral side, starting one to two segments below the level of the lesion.
• Loss of vibration and position discrimination on the ipsilateral side, below the level of the lesion.
• Causes: Meningioma, neurofibroma, cervical spondylosis, MS.
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Common Patterns of Sensory Loss
o Thalamus
• Loss of all sensory modalities on the face, arm and leg on the
side contralateral to the lesion
• Cause: Vascular occlusion
o Cortex
• Since pain, vibration and crude touch are mediated by the
thalamus, there is little loss of this sensory function with a cortex
lesion.
• Loss of discrimination occurs on the contralateral side with loss
of recognition of shape, weight and finger finding.
• Cause: Cerebral cortex, parietal lobe lesion.
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Patterns of Sensory Loss
Peripheral neuropathy
Individual nerves or roots
Spinal Cord Hemisection
spinal cord transection
(Jarvis, 2016, p.686-687)
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Patterns of Sensory loss
Thalamus
Cortex
(Jarvis, 2016, p.686-687)
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Reflexes
o Reflexes• Involuntary basic defence mechanisms of nervous
system
• Permit quick reaction to potentially harmful situations
• Help body maintain balance & appropriate muscle tone
o Four types• Deep tendon (stretch) reflex
• Superficial
• Visceral (organic)
• Pathological (abnormal)
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Deep Tendon (Stretch) Reflex
o Measurement of DTR reveals
• intactness of reflex arc at specific spinal levels
• normal override on the reflex of higher cortical levels
o The deep tendon reflex (DTR) consists of:
• Tapping the tendon stretches the muscle spindles which activates the sensory afferent nerve
• The sensory afferent fibres carry the message from the receptor, through the dorsal (posterior) root, into the spinal cord
• They synapse in the cord with the motor neuron in the anterior horn
• Motor efferent fibres leave via the ventral (anterior) root and travel to the muscle, effecting a reflex response via the neuromuscular junction
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Rating Deep Tendon Reflexes
o The rating of reflexes is a subjective scale and must be considered in the context of the entire neurological examination of the client. Always compare bilaterally.
Rating Definition
4+ Very brisk, hyperactive with clonus,
indicative of disease (Hyper-reflexia)
3+ Brisker than average, may indicate
disease, probably normal
2+ Average, normal, NAD
1+ Diminished, low normal, or occurs only
with reinforcement (Hypo-reflexia)
0 No Response (areflexia)
(adapted from: Jarvis, 2016, p.655)
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Biceps Reflex (C5-C6)
(Jarvis, 2016, p.656)
• The biceps reflex is
performed indirectly by
striking your own thumb
which is placed over the
biceps tendon.
• Normal = Forearm flexion
• If it is difficult to illicit the
reflex use the upper limb
reinforcement technique.
• Patient looks away
and clenches teeth.
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Triceps Reflex (C7-C8)
(Jarvis, 2016, p.657)
• Be careful when positioning
the arm in people who have
shoulder/rotator cuff
injuries.
• Normal = forearm extension
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Patellar Reflex (L2-L4) Patellar reflex with
reinforcement
(Jarvis, 2012)
• For reinforcement technique have the
client grasp their own forearms and
gently pull
• Normal = lower leg extension
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Achilles Reflex (L5-S2)
(Jarvis, 2016, p.659)
• Passive dorsiflexion of the
foot, whilst the leg is relaxed
is required.
• Normal = plantar flexion
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Plantar Reflex (L4-S2)
(Jarvis, 2016, p.660)
Negative Babinski Positive Babinski
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Plantar Reflex (L4-S2)
o Normal response
• plantar flexion of all toes
• inversion & flexion of forefoot
o Abnormal
• dorsiflexion of big toe and fanning of all toes
– positive Babinski sign (UMN disease)
– Extend your neurological examination of the UMN’s
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Resources
Jarvis, C. (2016). Physical Examination & Health
Assessment (7th ed.). Sydney: Elsevier.
Tortora, G.J., & Derrickson, B. (2014). Principles of
Anatomy & Physiology (14th ed.). Hoboken, NJ: John
Wiley & Sons.
Magee, D. (2008). Orthopaedic Physical Assessment,
Missouri: Saunders Elsevier.
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