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BIOE221

Session 10

Neurological Assessment –

PNS Motor, Sensory

Examination and Reflexes

Bioscience Department


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


Spinal Cord

Sensory & Motor Tracts

(Tortora & Derrickson, 2009, p.481)


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


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


Dermatomes

(Tortora & Derrickson, 2000)


Common Myotomes

(Magee, 2008, p.155)

(Magee, 2008, p.549)


Neurological Examination

o Last week

• Mental state

• Cranial nerves

• Motor system

o This week

• Sensory system

• Reflexes


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)


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.


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.


Patterns of Sensory Loss

Peripheral neuropathy

Individual nerves or roots

Spinal Cord Hemisection

spinal cord transection

(Jarvis, 2016, p.686-687)


Patterns of Sensory loss

Thalamus

Cortex

(Jarvis, 2016, p.686-687)


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)


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


Tendon Arc

(Jarvis, 2016, p.637)


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)


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.


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


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


Achilles Reflex (L5-S2)

(Jarvis, 2016, p.659)

• Passive dorsiflexion of the

foot, whilst the leg is relaxed

is required.

• Normal = plantar flexion


Plantar Reflex (L4-S2)

(Jarvis, 2016, p.660)

Negative Babinski Positive Babinski


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


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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bioe221 sn10 neurologicalpns · pdf fileprotection under the act. do not remove this notice....

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