W10: Muscle Tone

Question 1

What is muscle tone?

Answer 1

The level of contraction that keeps our muscle on standby.

This standby state is responsible for keeping your body against gravity and to facilitate movements

**Normal muscle tone needs to be high enough to keep you against gravity but if its too high it won’t allow you to perform movement

Question 2

What is the scale for muscle tone?

Answer 2

Flaccidity
Hypotonia
Normal
Spasticity
Rigidity

Question 3

Why is hypertonus (spasticity/rigidity)?

Answer 3

Increased resistance to passive movement (the two most common impairments are spasticity and rigidity)

Question 4

What are some secondary changes that occur in hypertonus patients as a result of the increase in tone?

Answer 4

• Adaptive increases in muscle stiffness
• Changes in muscle length
• Structural reorganisation of connective tissue

Question 5

Define spasticity?

Answer 5

• A motor disorder characterised by a velocity dependent increase in muscle tone (often results in hyperexcitability –> reflexes become overactive. Faster movement = more resistance).

—> with exaggerated tendon jerk, resulting from hyperexcitability of the stretch reflex (note: usually a delayed phenomenon)

–> overactivity of the arc reflex leads to further spasticity

Question 6

Define rigidity?

Answer 6

Heightened resistance to passive stretch caused by hyperactivity in the upper motor neuron

(independent of stretch velocity –> y motor neurons?)

Question 7

What are the two types of rigidity?

Answer 7

Lead pipe rigidity is defined as a constant resistance to motion throughout the entire range of movement.

Cogwheel rigidity refers to resistance that stops and starts as the limb is moved through its range of motion.

Question 8

Clinical presentation of spasticity?

Answer 8

• Clasp-knife phenomenon (a velocity – dependent build-up of reflex resistance ie initial resistance when attempting passive movement, followed by a rapid decrease)
• Clonus (a sustained reflex response set in train by tendon percussion)
• Exaggerated tendon jerk (asymmetric reflex response generated by abrupt mechanical disturbance)
• Babinski response

Question 9

Clinical presentation of rigidity?

Answer 9

Constant increased resistance to passive movement of ANY speed
– Lead pipe
– Cogwheel

Question 10

Explain the tardieu scale?

Answer 10

1. Slow Stretch (V1): The muscle is stretched at a very slow speed. This is intended to measure the length of the muscle at rest, allowing the examiner to assess the range of motion without the influence of the stretch reflex.
2. Natural Speed Stretch (V2): The muscle is stretched at a speed similar to the natural speed of movement. This helps evaluate the muscle’s response to normal levels of stretch.
3. Fast Stretch (V3): The muscle is stretched as quickly as possible. This stretch is designed to elicit the stretch reflex and evaluate the degree of spasticity or resistance to passive movement.

Question 11

Treatment for hypertonus

Answer 11

• Pharmacological eg baclofen or botox
• Physical eg sensory, guided movement, exercise
• Biomechanical: orthosis or splints
• Surgical

Question 12

Secondary impairments of hypertonus?

Answer 12

Contractures ie muscle shortens, weakness & muscle atrophy

Question 13

Hypotonus:
Define flaccidity

Answer 13

Complete loss of muscle tone
Hypotonia: a reduction in the stiffness of a muscle to lengthening

Question 14

Common conditions of hypotonia

Answer 14

• Down syndrome
• Muscle disorders
• LMN injuries
• Cerebellar injuries

Question 15

How to assess hypotonia?

Answer 15

Observation & reflex testing

Question 16

Treatment of hypotonia?

Answer 16

• Strength training
• Co-ordination training
• Orthotic/assistive device prescription