Presentation is loading. Please wait.

Presentation is loading. Please wait.

MUSCLE TONE AND SPASTICITY Irfan Motor Unit Basic unit of contraction in skeletal muscle Basic unit of contraction in skeletal muscle Composed of one.

Similar presentations


Presentation on theme: "MUSCLE TONE AND SPASTICITY Irfan Motor Unit Basic unit of contraction in skeletal muscle Basic unit of contraction in skeletal muscle Composed of one."— Presentation transcript:

1

2 MUSCLE TONE AND SPASTICITY Irfan

3 Motor Unit Basic unit of contraction in skeletal muscle Basic unit of contraction in skeletal muscle Composed of one or more muscle fibers and the motor neuron that controls them Composed of one or more muscle fibers and the motor neuron that controls them AP in motor neuron results in contraction AP in motor neuron results in contraction

4 Comparison of the function of muscle spindles and Golgi tendon organs. Golgi tendon organs are arranged in series with extrafusal muscle fibers because of their location at the junction of muscle and tendon.

5 The motor unit. (A) Diagram showing a motor neuron in the spinal cord and the course of its own axon to the muscle. (B) Each alpha motor neuron synapses with multiple muscle fibers. The motor neuron and the fibers it contacts defines the motor unit. Cross section through the muscle shows the distribution of muscle fibers (red dots) contacted by the motor unit.

6 A state of partial contraction that is characteristic of normal muscle, is maintained at least in part by a continuous bombardment of motor impulses originating reflexively, and serves to maintain body posture. Muscle tone refers to the amount of tension or resistance to passive movement in a muscle.

7 MUSCLE TONE

8 Negative feedback regulation of muscle tension by Golgi tendon organs

9 SPASTICITY Traditional concept Traditional concept Muscle hypertonia: velocity dependent resistance to stretch Muscle hypertonia: velocity dependent resistance to stretch Exaggerated reflexes (Ashworth‘s Scale) Exaggerated reflexes (Ashworth‘s Scale) New concept New concept Loss of longer latency reflexes (spinal) Loss of longer latency reflexes (spinal) Decrease of muscle activity during function Decrease of muscle activity during function Change in non-neural factors as a result of the decrease of supraspinal control Change in non-neural factors as a result of the decrease of supraspinal control Biomechanical changes in both passive and active muscles (Dietz 2003) Biomechanical changes in both passive and active muscles (Dietz 2003)

10 The increase of stretch reflexes is not the only reason for etablished spasticity. Factors which can lead to a mechanical resistant in movement are the reduced elasticity of the tendons and the biomechanical changes of musclefibres. Dietz 1992 Definitions of Spasticity

11 Neural Mechanisms Neural Mechanisms Weakness and decreased skills (Astereognosia) Weakness and decreased skills (Astereognosia) Changes in anticipatory contrast Changes in anticipatory contrast Cutane hyperreflexia Cutane hyperreflexia Hyperexitability of motorneurons Hyperexitability of motorneurons Muscle hypertonicity (hyporeflexia of tendon) Muscle hypertonicity (hyporeflexia of tendon) Non-neural Mechanisms Non-neural Mechanisms Biomechanical changes in muscles Biomechanical changes in muscles Tixotrophia (stiffness of myosin cross links) Tixotrophia (stiffness of myosin cross links)

12 Central Loss of Force Production Loss of central command to generate and sustain force Loss of central command to generate and sustain force No loss of contractile capacity: not the same as peripheral weakness, No loss of contractile capacity: not the same as peripheral weakness, Myopathy or general weakness Myopathy or general weakness Sahrmann 2002

13 Muscle Activation Deficits Delayed initiation and termination of muscle contraction Chae 2002 Delayed initiation and termination of muscle contraction Chae 2002 Altered sequence of muscle firing Altered sequence of muscle firing Dewald 2001 Excessive activation/cocontraction: too many muscles with inappropriate force Sarmann 1977 Excessive activation/cocontraction: too many muscles with inappropriate force Sarmann 1977

14 Sensory Deficits Deficits in awareness, processing and interpretation and kinesthetic memory Deficits in awareness, processing and interpretation and kinesthetic memory Fewer attempts at spontaneous movements Fewer attempts at spontaneous movements Altered sence of „weight“ of a limb Altered sence of „weight“ of a limb Altered sence of timing and speed Altered sence of timing and speed Difficulty replaying movements in their imagination and recognizing them in facilitation Difficulty replaying movements in their imagination and recognizing them in facilitation Contributes to development of pain Contributes to development of pain Ryerson, 2003

15 Spasticity Compensation Hypertonus Can develope to Fixation Stereotype Dynamic Biomechanical Changes Associated Reaction Established Spastic Pattern Without Specific Lesion Caused through a Lesion in CNS

16 Ryerson Composite Model for Intervention CNS Lesion Altered Sensation Pain Edema Central Loss of Force production Muscle Activation Deficit Trunk-Limb linkages Intralimb – Arm Movement linkages Intralimb – Leg Movement linkages Muscle shortening Muscle shifting Joint alignment Initiation Timing Cocontraction Sequencing Cessation Altered Postural ControlClinical Hypertonicity Loss of Refined Movement Generalized reflex release - spasticity Susan Ryerson 2003

17 Flaccidity Mal-alignment Length changes Neuralshock Diaschisis Plasticity Biomechanical changes Loss of pre-synaptic control Loss of recurrent inhibition Loss of reciprocal inhibition Novel connections (sp cord) Mass patterns Peripheral input gains control of SCC Inc Hyper-reflexia and AR`s Poor voluntary activity with poor specificity Hypertonia Loss of Golgi activity during voluntary movement NeuralNon-neural UMN LESION

18 CLINICAL IMPLICATIONS Non-neural components can be as significant in hypotonicity as hypertonicity Non-neural components can be as significant in hypotonicity as hypertonicity The non-neural effects can also add to the neural mechanism The non-neural effects can also add to the neural mechanism Limiation of range prevents movement and the static state further interferes with modulation of tonus Limiation of range prevents movement and the static state further interferes with modulation of tonus

19 Clinical Hypertonicity: Muscle Activation Deficits Clinical Significance: Clinical Significance: Do not treat the hypertonicity, treat the underlying cause Do not treat the hypertonicity, treat the underlying cause Central loss of force production is unique Central loss of force production is unique Basic trunk-limb (girdle) movement patterns Basic trunk-limb (girdle) movement patterns Spasticity is different from clinical hypertonicity Spasticity is different from clinical hypertonicity Intralimb movement sequences Intralimb movement sequences Muscle activation deficits result in disruption of voluntary Muscle activation deficits result in disruption of voluntary movement movement Prevent persistent posturing Prevent persistent posturing Ryerson, 2003

20 Process of plastic adaptation in the neuro-muscular systems Process of plastic adaptation in the neuro-muscular systems Primary Denervation Flaccid / Low tone Associated Reactions Recovery / New Etablishment Functional use Secondary Problems Bio-mechanical Changes of muscles Contractures Deformity

21 Anticipatory maintenance of body posture. At the onset of a tone, the subject pulls on a handle, contracting the biceps muscle. Contraction of the gastronemius muscle precedes that of the biceps to ensure postural stability.

22 Has Spasticity a definition? „Nowadays, the expression „spasticity“ is found so often in medical literature and is such an elementary neurological term that no one really expects a definition.“ Thilmann A.F Thilmann A.F. 1993

23 The importance of spasticity has changed: The importance of spasticity has changed: There is no relationship between spasticity and functional performance There is no relationship between spasticity and functional performance when Spasticity is defined as a stretch reflex when Spasticity is defined as a stretch reflex No consistant relationship between the amount of spasticiy and the performance for relearning skills and functions No consistant relationship between the amount of spasticiy and the performance for relearning skills and functions The different definitions are contradictory and are describing different clinical symptoms The different definitions are contradictory and are describing different clinical symptoms

24 Spasticity Spasticity Spastic movements disorders Dietz 2003 Spastic movements disorders Dietz 2003 Clinical hypertonicity Ryerson 2003 Clinical hypertonicity Ryerson 2003

25 Definitions of Spasticity Classic Definition: Classic Definition: Increased resistance of a limb to externally imposed passive joint movement Increased resistance of a limb to externally imposed passive joint movement Resistance increases with increasing amplitude and velocity Resistance increases with increasing amplitude and velocity Often accompanied by increased tendon jerks and clonus Often accompanied by increased tendon jerks and clonus Lance 1980

26 “Spasticity is a slowly developing movement disorder following a complete or partial loss of supraspinal control on the function of the spinal cord. Spasticity can be recognized through altered activity of the motor units as an answer to sensory or central command, which leads to abnormale cocontraction, masspatterns of movement and abnormale Postural control.“ Wiesendanger 1991 Definitions of Spasticity

27 “the loss of sarcomers leads very soon to changes of the mechanical properties in muscles and therefore to hypertonicity.” Volker Dietz

28 Definitions of Spasticity “Intrinsic mechanical stiffness of muscles can be responsible for spastic hypertonissity. This stiffness can come about through structural changes of the mechanical properties or through changes of the state in the muscle tissue itself.” Katz und Rymer 1989

29 It could be demonstrated that the tissue which surrounds the slow twitch muscle fibres are more sensitive to immobilisation as the ones which are surrounding the fast twitch fibres. Given et al 1995 Definitions of Spasticity

30 The neurological deficit Primary Impairments Primary Impairments Neurological weakness Neurological weakness Muscle activation deficit Muscle activation deficit Spasticity Spasticity Changes in tone Changes in tone Secondary Impairments Secondary Impairments Altered alignment Altered alignment Changes in muscle length and position Changes in muscle length and position edema edema pain pain Composite Impairments Composite Impairments Clinical hypertonicity (spastic movement disorder) Clinical hypertonicity (spastic movement disorder) Altered postural control Altered postural control Loss of selective movement Loss of selective movement

31 Sekian


Download ppt "MUSCLE TONE AND SPASTICITY Irfan Motor Unit Basic unit of contraction in skeletal muscle Basic unit of contraction in skeletal muscle Composed of one."

Similar presentations


Ads by Google