Neuro 1 Flashcards
What are the immediate upper and lower limb examination categories?
- Tone - testing the tone of major joints
- Power - testing the power of major muscle groups
- Reflexes - testing the deep tendon reflexes
- Sensation - testing sensation across the dermatomes
What are the steps before taking the exam?
- Ensuring you have the correct PPE
- Washing your hands
- Introducing yourself
- Confirming the patient’s name and date of birth
- Gaining consent from the patient
- Ensuring there is adequate exposure and positioning of the patient
What do you need to do throughout the examination?
throughout your examination you will need to provide clear instructions to the patient and respond to their verbal and non-verbal cues (for example looking out for pain or discomfort)
What does muscle tone refer to?
the amount of tension in a muscle
Why is there a constant tone at rest?
muscles are in a constant state of partial contraction
How can you test degrees of loss or increase of muscle tone?
by passively moving the joints and comparing the resistance to the movements by the muscles on both sides of the body.
What will be the result of a breach/disruption in the spinal segmental reflex arc and the simple spinal reflexes are not functioning?
Muscle will be without any tone
What happens when the muscle has no tone?
- it will be fully relaxed
- hypotonia
- Lower Motor Neuron (LMN) lesion
What are LMN of the spinal segmental neurons influenced by?
- nervous impulses received from:
1. cerebral cortex
2. midbrain
3. pons
4. medulla
What are these supra spinal neurons called?
Upper Motor Neurons (UMN)
What are the effects of upper motor neurons on lower motor nuerons?
inhibitory effect
What happens if the higher cerebral control is disrupted, as in an UMN lesion/problem?
- the inhibition is lost and the muscle tone is exaggerated 2. will experience hypertonia (sometimes spasticity)
What should you ask the patient about with tone?
- Always ask about any pain in the shoulder, elbow or wrist
- Ask the patient to relax “go floppy”, and test for tone at the relevant joints, remember to compare Left vs Right each time.
How do you note strength/power?
- numerical scale used - Medical Research Council (MRC) Muscle Power scale
- There is a 0 to 5 rating scale for muscle strength
What is a 0/5 score for power?
No movement
What is a 1/5 score for power?
Barest flicker of movement of the muscle, though not enough to move the structure to which it’s attached
What is a 2/5 score for power?
- Voluntary movement which is not sufficient to overcome the force of gravity
- E.g. the patient would be able to slide their hand across a table but not lift it from the surface
What is a 3/5 score for power?
- Voluntary movement capable of overcoming gravity, but not any applied resistance
- E.G the patient could raise their hand off a table, but not if any additional resistance were applied
What is a 4/5 score for power?
Voluntary movement capable of overcoming “some” resistance
What is a 5/5 score for power?
Normal strength
How can you indicate more subtle descriptions of power?
’+’ and ‘-‘ can be used indicate more subtle descriptions of power (e.g., 4+ or 4- , 3+ or 3-, etc.)
How would you grade a patient that can overcome “moderate but not full resistance”?
4+
What do you do as the examiner to test power?
-You (as examiner) will resist the movement by applying an opposing force and estimate the power of the contracting muscle/s
What do you do to the joint when testing for power?
- need to isolate and stabilize the joint to accurately measure the power
- for instance when testing ankle dorsiflexion you free hand will be stabilizing the leg at the malleoli
What is a reflex?
an involuntary response to a stimulus
What does the reflex depend on?
integrity of the reflex arc
What does a reflex pathway consist of usually?
- afferent (sensory) neurones conveying impulses from sensory receptors in the muscle spindle to the spinal cord (CNS)
- efferent (motor) neurones running from the anterior grey columns of the spinal cord (CNS) to the effector organ which is the limb muscle
What are the two types of reflex arc?
monosynaptic or multi synaptic
What. type of reflex arc are most myotatic reflex arcs?
monosynaptic
What happens when the tendon of a muscle is tapped with a tendon hammer?
causes stretching of the muscle spindles
Where does the stimulus travel to? What does this cause>
- travels to the spinal cord, which then stimulates the efferent motor neurons in the anterior grey columns (horns).
- results in involuntary contraction of the main muscle whose tendon was stretched by tapping
Can you always elict reflexes from completely normal individuals?
No may need to apply “reinforcement” to those individuals
What is an example of a reinforcement?
ask the patient either clench the teeth or squeeze an object in the contralateral (other) hand while you directly test the reflex on the limb to be tested
Is the range of briskness of reflexes variable?
range of briskness of reflexes is variable within and between individuals
What do you need to compare with reflexes?
ALWAYS be compared on both sides, left and right, as a difference comparatively may increase the relevance of the finding
What does the reflex arc in the spinal cord play an important role in?
maintaining muscle tone
Why is muscle tone important?
to maintain normal body posture
What is the law of reciprocal innervation on reflex skeletal muscle activity?
In the same limb the flexor and extensor muscles cannot contract simultaneously.
How does this law come into action?
The afferent nerves responsible for flexor reflex muscle action must have branches to synapse with the extensor motor neurons of the same limb to inhibit the extensor muscle contraction
What do you need to know when interpreting results of myotatic reflex tests?
- important to understand that higher centres of the brain influence the spinal segmental reflex arc which results in the modulation of the resultant motor activity
- In other words, abnormally exaggerated myotatic reflexes lead to a clinical picture of an upper motor neurone lesion
What will be the result if there is disorder in any of the components of the reflex arc (muscle spindles, afferent sensory neurones, efferent motor neurones and the effector organs - the muscle itself)?
complete absence (areflexia) of reflexes which is suggestive of a lower motor neurone lesion
What do you need to ensure to test for reflex?
that the relevant limb is completely relaxed, you will then attempt to elicit the reflex by tapping the relevant tendon with a tendon hammer
What is a dermatome?
An area of skin supplied by a single spinal nerve root of the spinal cord segment
What is a myotome?
A similarly innervated region of a skeletal muscle
On the skin what types of dermatomes overlap considerably?
the adjacent dermatomes (for example C4, C5, C6)
What does this overlap mean?
loss of a single spinal nerve root may not produce any detectable sensory loss in that dermatome
How would you detect a significant sensory loss?
at least three adjacent dermatomes should be affected
Where is there no overlap?
(for example C4 and T2 or C5 and T1) across the axial lines of the limb
What do peripheral nerves do?
carry nerve components from several spinal segments (or roots) to muscles and skin areas
What would damage to a peripheral nerve result in?
- may result in a wide ranging effects on more than one dermatomal area or myotomes
- may affect large areas of skin and several muscles.
How do you elicit light touch sensation on the upper limb dermatomal areas?
wisp of cotton wool
How do you carry out dermatome test?
- first demonstrate light touch with a wisp of cotton wool to your colleague by touching normal area of skin, just above the clavicle or over sternum
- Then ask your colleague to close the eyes while you examine individual dermatomal areas methodically, and find out whether they could feel the touch sensation as normal, dull or none at all
- Repeat the test on the opposite limb and compare
Where do you determine tone in upper limb?
- Shoulder
- Elbow
- Wrist
Where do you determine power in upper limb?
- Shoulder abduction and adduction
- Elbow flexion and extension
- Wrist flexion
Where do you determine reflex in upper limb?
- Biceps (C5, C6)
- Triceps (C7, C8)
- Suprinator (C6)
Where do you determine sensation in upper limb?
- Lateral aspect of the arm (C5)
- Lateral aspect of forearm (C6)
- Middle finger (C7)
- Little finger (C8)
- Medial aspect of forearm (T1)
- Axilla (T2)
Where do you determine tone in lower limb?
- Hip
- Knee
- Ankle
- Clonus
Where do you determine power in lower limb?
- Hip flexion and extension
- Knee flexion and extension
- Ankle dorsiflexion and plantarfelxion
How do you determine reflex in lower limb?
- Patellar (L2, L3. L4)
2. Achilles (S1, S2)
How do you determine sensation in lower limb?
- Lateral aspect of thigh (L2)
- Lower medial aspect of thigh (L3)
- Medial aspect of leg, medial foot and great toe (L4)
- Lateral side of leg, mid dorsum of foot and middle three toes (L5)
- Little toe, lateral foot and sole of foot (S1)
- Back of upper leg and thigh (S2)
