Muscle Tone and Manual Muscle Testing

1. Muscle Tone and Manual Muscle Testing PHT 1261C Tests and Measurements Dr. Kane

2. Definitions • Tone • Factors affecting tone • Postural Tone • Hypertonia • Hypotonia • Dystonia • Spasticity – velocity dependent • Clasp knife response • UMN syndrome • Clonus • Babinski Sign • Rigidity • Lead pipe • Cogwheel

3. Definitions - continued • Hypotonia – flaccidity • LMN syndrome • Spinal Shock/Cerebral Shock • Dystonia • Focal vs. segmental vs. posturing • Decorticate Rigidity • Decerebrate Rigidity • Opisthotonus

4. Variations in Tone • Volitional Effort and movement • Stress and anxiety • Position and interaction of tonic reflexes • Medications • General Health • Environmental temperatures • State of CNS arousal or alertness • Urinary bladder status • Fever/infection • Metabolic or Electrolyte imbalances

5. Examination of Tone • Initial Observation of resting posture & palpation • Common posturing – see Table 8.1 page 235 • Palpation – consistency, firmness & turgor • Passive Motion Testing • Responsiveness of muscles to stretch • Vary speed for spasticity and clonus • Grading Scale • 0 = no response (flaccidity) • 1+ = decreased response (hypotonia) • 2+ = Normal response • 3+ = exaggerated response (mild to moderate hypertonia) • 4+ = sustained response (severe hypertonia) • Active Motion Testing/Special Tests • Pendulum test • Myotonometer

6. Spastic Hypertonia – Modified Ashworth Scale • Gold standard subjective 5 point ordinal scale • Interrater & intrarater reliability is good • Problems: • Inability to detect small changes • Limited to extremity testing only • Grades • 0 = no increase in muscle tone • 1 = slight increase in muscle tone; catch & release • 1+ = slight increase in tome with catch & minimal resistance through rest of range • 2 = marked increase in tone through most of ROM • 3 – considerable increase in tone; passive motion difficult • 4 = affected parts rigid in flexion or extension

7. Deep Tendon Reflexes • Table 8.3 page 237 O’Sullivan • Grading Scale • 0 = no response • 1+ = present but depressed, low normal • 2+ = Average, normal • 3+ = Increased, brisker than average; possibly but not necessarily normal • 4+ = very brisk, hyperactive with clonus; abnormal • Increased with UMN lesions; decreased with LMN • Reinforcement maneuvers

8. Manual Muscle Testing • Palmer Chapter 2 • Not applicable for strength testing in patients who lack voluntary or active control of muscular tension (e.g. CNS disorders) • Not appropriate for spasticity • May get inaccurate results due to gravity and activation of stretch reflex • Reliability – ½ grade intertester is acceptable • Follow proper procedures • Give clear instructions • Demonstrate and explain • Improved with dynamometry

9. Manual Muscle Testing - continued • Validity • Palpate muscle • Proper stabilization • Prevent substitution muscles or patterns • Not functional

10. MMT Uses • 1. Establish a basis for muscle re-ed and exercise; • Develop plan of care • Show progress • Shows effectiveness of treatment • Additional information before muscle transfer surgery • 2. Determines how functional a patient can be. • 3. Determines a pt.'s needs for supportive apparatus – orthoses, splints, assistive devices • 4. Helps determine a diagnosis. • 5. Determines pt.'s prognosis

11. Factors that Contribute to Effectiveness of Muscle Contraction • Length of muscle when activated • Active insufficiency • Type of contraction • Eccentric > Isometric > Concentrically • Muscle Fiber Types • Type I slow twitch – fatigue resistant • Type II fast twitch – fatigue rapidly • Must consider speed of contraction & resistance applied • Type II – require less resistance to reach “normal” grade • Speed of contraction • Increased speed = increased tension ECCENTRIC • Increased speed = decreased tension CONCENTRIC

12. Anatomical Factors that affect Muscle Contraction • Number of motor units per muscle • Functional excursion • Cross sectional Area • Line of pull of muscle fibers • Number of joints crossed • Sensory receptors • Attachments to bone & relationship to joint axis • Age of pt. • Sex of pt.

13. Evaluating Skeletal Muscle Strength • Anatomical, physiological, & biomechanical knowledge of skeletal muscle positions and stabilization • Elimination of substitution motions • Skill in palpation & application of resistance • Careful direction for each movement that is easily understood by the patient • Adherence to a standard method of grading muscle strength • Experience testing many individuals with normal muscle strength & varying degrees of weakness

14. Factors to Consider in MMT • Weight of limb or distal segment with minimal effect of gravity (GM) • Weight of limb plus the effects of gravity (AG) • Weight of limb plus gravity plus manual resistance

15. Factors Affecting Grading of MMT • Amount of manual resistance applied (opposite torque exerted by muscle) • Ability of muscle to move through complete ROM • Evidence of presence or absence of muscle contraction by palpation & observation • Gravity and manual resistance • GM – muscle contracts parallel to gravitational force • AG – muscle contract against the downward gravitational force • Grades are dependent on: age, sex, body build, occupation, etc.

16. Factors affecting MMT Results • Fatigue • Joint ROM limitations • Range grade/strength grade (-20 degrees/4 (good) • Pain • Subjectivity • Positions –AG/GM • Range • Palpation • Resistance –break or make method • Stabilization • Provides support • Prevents substitution motions • Substitution • Recording measurements

17. Procedure For Specific MMT • Position in AG position & stabilize – see page 31 • Expose body part & drape appropriately • Explain the test and demonstrate to patient • Determine available ROM • PROM or AROM; test range; possibly goniometry • Align body part to direction of muscle fibers • Stabilize proximal segment • Have patient move distal segment through test ROM or hold at end range of motion • Observe and palpate muscle belly • Apply resistance – end range or through range • Record grade & date & initial; document in SOAP