This document discusses muscle tone, including its physiology, characteristics of normal and abnormal tone, and approaches to managing tone issues. Muscle tone refers to a continuous low-level contraction that keeps muscles firm and ready to respond. It is important for posture, balance, and movement. Abnormal tone can include hypotonia (low tone) or hypertonia (high tone), and has various causes. Managing tone issues depends on whether it is low or high, and may involve positioning, stretching, splinting or other techniques. The Modified Ashworth Scale is used to assess levels of high muscle tone.
2. What is Muscle Tone?
• “Continuous state of mild contraction, or a state or preparedness in the
muscle” (Pendleton, 2012, p. 468)
• “Muscle tone does not produce active movements, but it keeps the muscles
firm, healthy, and ready to respond to stimulation” (Marieb & Hoehn, 2010,
p. 296)
3. Physiology of Muscle Tone
• Signals received at
neuromuscular junction
result in continuous
muscle contraction
Muscles and muscle tissue, 2013
4. Characteristics of Normal Tone
• High enough to resist gravity, yet low enough to allow movement
• Slight, involuntary, resistance to passive movement
• Ability to maintain position of limb if placed passively, and then released
• Ease of ability to shift between stability ↔ mobility
• Ability to use muscles in groups or selectively with normal timing and
coordination
5. Why is Muscle Tone Important?
• Across the lifespan, normal muscle
tone allows us to engage in
meaningful occupations by:
• Keeping muscles ready for action
• Maintaining posture
• Maintaining balance
• Laying framework for quick, reflexive
movements
6. Causes of Abnormal Tone
• Children
• Down Syndrome
• Cerebral Palsy
• Muscular dystrophy
• Adults
• CVA
• TBI
• Brain tumor
• SCI
• MS
• Myasthenia gravis
• The onset and course of abnormal tone is dependent upon the cause
7. Hypotonia
• Abnormally low tone
• Likely to occur in the acute stages of CVA, contralateral to brain lesion
• Diminished deep tendon reflexes
• Flaccidity: complete absence of deep tendon reflexes
8. Hypertonia
• Abnormally high tone
• Likely to occur following the acute stages of CVA
• May occur in synergistic movement patterns: Co-contraction of flexors and extensors
• Flexor synergy often seen in UEs
• Extensor synergy often seen in LEs
• Rigidity: simultaneous high tone of agonist and antagonist
• Lead pipe
• Cogwheel
• Decorticate
• Decerebrate
10. Spasticity
• Spasticity is a subset of hypertonia
• Overactive reflexes
• Involuntary movements
• Feel a “catch” with passive movement
• May lead to contractures if unmanaged
• Clonus: Repetitive contractions in antagonist
muscles in response to rapid stretch
• Can be associated with moderate-severe
spasticity
• Finger flexors and ankle plantar flexors
• Medical management
• Botox injections
• Baclofen pump
11. Managing Tone: General
• Aims of early positioning and mobility
• Provide support
• Inhibit abnormal tone
• Promote symmetry
• Provide normal sensory input
• Relieve pain and provide comfort
• Develop and reinforce basic elements of movement
• Principles to remember
• Normal movement cannot be superimposed on abnormal tone
• Proximal stability facilitates distal mobility
12. Managing Hypotonia
• Check for subluxation at glenohumeral joint before ROM
• Position patient in supported sit
• Facilitate tone
• Quick stretches in attempt to elicit clonus
• Cold temperatures
13. Managing Hypertonia
• Deep, slow stretches
• Deep pressure on muscle belly
• Warm temperatures
• Splinting and serial casting to encourage functional position of extremities
14. Assessing High Tone: Modified Ashworth Scale
Grade Description
0 No increase in muscle tone
1 Slight increase in muscle tone, catch when limb is moved
1+ Slight increase in muscle tone
2 More marked increase in muscle tone through >50% of the ROM, but affected
easily moved through passive range
3 Considerable increase in muscle tone, passive movement difficult
4 Affected limb rigid in flexion or extension
15. References
Bohman, I. M. (2003). Handling skills using in the management of adult hemiplegia (2nd ed.). Albuquerque: Clinician’s
View.
Marieb, E. N., & Hoehn, K. (2010). Muscles and muscle tissue. Human anatomy and physiology (8th ed) (pp. 275-319). San
Francisco: Pearson Education, Inc.
Muscles and Muscle tissue (2013). Overview of Muscle Tissue. Retrieved from
http://classes.midlandstech.edu/carterp/Courses/bio210/chap09/lecture1.html.
Pendleton, H. M. H., & Schultz-Krohn, W. (2012). Evaluation of motor control. Pedretti's occupational therapy: Practice skills
for physical dysfunction (7th ed.) (pp. 468-473). St. Louis: Mosby/Elsevier.
Hinweis der Redaktion
-These are just a few of the causes of abnormal tone
-Decorticate is more common, and often indicates more positive outcomes
-Decerebrate is not as common, and often indicates less positive outcomes
Modified Ashworth Scale – measures deep tendon reflexes; used to quantify the degree of hypertonicity
Place the patient in a supine position. If testing a muscle that primarily flexes a joint, place the joint in a maximally flexed position and move to a position of maximal extension over one second (count "one thousand one”) If testing a muscle that primarily extends a joint, place the joint in a maximally extended position and move to a position of maximal flexion over one second (count "one thousand one”)
0 – No increase in tone
1 – slight increase in tone, catch and release or minimal resistance at end of ROM when affected limb is moved into flexion or extension
1+ - slight increase in tone, catch, followed by minimal resistance throughout the remainder (<half of the ROM)
2 – more marked increase in muscle tone through most of ROM, but affected limb easily moved
3 – considerable increase in muscle tone, passive movement difficult
4 – affected part rigid in flexion or extension
