Tone Abnormalities Flashcards
What is muscle tone?
Muscle tone is underlying tension in the muscle
that serves as a background for contraction
What are some challenges to assessing muscle tone?
‒ Must be assessed when there is no active
resistance to the muscle stretch
‒ Changes with movement, posture, intention, and
environment
What is hypotonicity?
abnormally low tone (Down syndrome, poliomyelitis)
What is flaccidity?
total absence of tone
What is hypertonicity?
abnormally high tone
What is rigidity?
velocity independent resistance to stretch
What is spasticity?
velocity dependent resistance to stretch
What is clonus?
rhythmic oscillations or beats of involuntary
contraction in response to quick stretch
What is not muscle tone?
‒ Voluntary muscle contraction
‒ Posture
What are fluctuating abnormal tones?
Disorders with abnormal involuntary movements or
dyskinesias
What are quantitative measures?
‒ Dynamometer or Myometer
‒ Isokinetic testing systems
‒ Electromyography (EMG)
‒ Pendulum test
What are qualitative measures?
‒ Clinical tone scale
‒ Muscle stretch reflex test
‒ Ashworth and Modified Ashworth Scale
What is the clinical tone scale?
Grade Description 0 No tone 1 Hypotonicity 2 Normal tone 3 Moderate hypertonicity 4 Severe hypertonicity
What is the muscle stretch reflex test?
Grade Description 0 No reflex 1+ Diminished reflex 2+ Normal reflex 3+ Brisker than average reflex 4+ Very brisk or hyperactive reflex
What is the modified ashworth scale?
Grade Description 0 No ↑in muscle tone 1 Slight ↑in muscle tone: catch and release or min. resistance at end ROM when moved in flexion/extension 1+ Slight ↑in muscle tone: catch followed by min. resistance throughout rest of ROM (< 1/2) 2 More marked ↑in muscle tone through most of ROM but affected part(s) move easy 3 Considerable ↑in muscle tone, passive movement difficult 4 Affected part(s) rigid in flexion or extension
What are some general considerations when measuring muscle tone?
‒ Note positions of limb, body, neck, and head relative
to each other and gravity
‒ Muscle tone is most accurately measured in mid ROM
of muscle’s length
‒ Standardize touch
‒ Consider muscle strength
‒ Document what position muscle tone was measured
What can asymmetrical and symmetrical tonic neck reflexes influence?
tone of the flexors and
extensors depending on
position of the head
When do ATNR and STNR reflexes occur?
during infancy and in
subjects with
neurological deficits
What is muscle composed of?
contractile elements (myofilaments), cellular elements, connective tissue covering fibers and muscle, and tendons attaching muscle to bone
What are the cellular elements of muscle?
• Neural stimulation causes a release of calcium
• Allows formation of cross-bridges binding actin and myosin
proteins
• Energy from ATP breaks the cross-bridges so new bonds can
be formed
• As new bonds are formed and broken it changes the length
of the contractile unit: sarcomeres
What are neural contributions of muscle tone and activation?
‒ Neural inputs come from periphery, spinal cord, brain centers
‒ The alpha motor neuron is the final common pathway that
directly stimulates muscle contraction
• Generation, summation, and conduction of an activating signal
What may friction between connective tissue be affected by?
pressure on tissues and by the viscosity of fluids in which
tissue reside
What is elasticity?
taut tissues contribute to resistance of muscle
to stretch and slack tissues contribute very little
What happens when a muscle is stimulated in the shortened position?
there is a delay before movement can occur or force can
be generated
How can physical agents change muscle tone and activation?
‒ Heat ↑availability of ATP to myofilaments
‒ Heat and cold can change elasticity or friction of tissues
‒ ES can change amount of muscle fiber neural stimulation
What are structure and function of nerves?
‒ Dendrites receive stimulus; axons conduct stimuli toward destination
‒ Signals are conducted across synapses to other neurons using
neurotransmitters (acetylcholine, norepinephrine or serotonin
What are action potentials?
Depolarization and repolarization initiated by Na/K pumps that quickly
alter the charge of a neuron, creating a wave of activity
What is transmission?
Myelin insulation increases speed of action potential transmission
(up to 80m/sec)
What are the sources of neural stimulation of muscle (sensory organs)?
peripheral inputs (muscle spindles, golgi tendon organs, cutaneous receptors), spinal inputs, and supraspinal inputs (sensorimotor cortical contributions, cerebellum, basal ganglia, limbic system, vestibular system, reticular-activating system)
What are peripheral inputs?
muscle spindles, golgi tendon organs, cutaneous receptors
What is a muscle spindle?
located in muscle and senses when muscle
is stretched
What are golgi tendon organs?
located in connective tissue between
muscle and tendon and senses maximal stretch (protective
mechanism)
What are cutaneous receptors?
located in skin and senses interaction
with external world (temperature, texture, pressure, pain
and stretch)
What are spinal inputs?
Located in the spinal cord and contribute to flexor or
extensor synergy patterns
What are supraspinal inputs?
(originate above the spinal cord) sensorimotor cortical contributions, cerebellum, basal ganglia, limbic system, vestibular system, and reticular-activating system
What are sensorimotor cortical contributions?
response to sensation,
idea, memory or external stimulus to move, act or respond
What is the cerebellum?
registers any discrepancies between signals from
motor cortex and peripheral inputs and corrects for movement
errors or unexpected obstacles during movement
What does the basal ganglia do?
modulates movement and tone (Parkinsonism)
What are other descending inputs?
vestibular system, reticular-activating system
What does the vestibular system do?
receives ongoing information about the head
position and movement
What does the reticular-activating system do?
receives information from multiple
sensory systems (vision, auditory, vestibular, somatosensory, motor
cortex, and cerebellum)
What does the limbic system do?
generates memories and attaches meaning to
changes in muscle tone or activation (activates SNS)
What is an UE flexion synergy pattern?
Scapular adduction Scapular elevation (variable) Shoulder external rotation Shoulder abduction Elbow flexion Forearm supination Wrist flexion Finger/thumb response (variable)
What is an UE extension synergy pattern?
Scapular abduction Shoulder internal rotation Shoulder adduction Elbow extension Forearm pronation Wrist extension Finger/thumb response (variable)
What is a LE flexion synergy pattern?
Hip abduction Hip flexion Hip external rotation Knee flexion Ankle dorsiflexion Toe extension(dorsiflexion)
What is a LE extension synergy pattern?
Hip adduction Hip extension Hip internal rotation Knee extension Ankle planter flexion Ankle inversion Toe flexion (planter flexion)
What does normal muscle tone depend on?
Depends on normal composition and functioning of
muscles, the peripheral and central nervous systems
What is required for normal muscle tone?
Multiple sources of neural input (both excitatory and
inhibitory) are required
What determines the amount of muscle tone or activation?
Sum of all the input determines the amount of muscle
tone or activation
What may result in abnormalities in muscle tone in activation?
Abnormalities in muscle tone and activation may result
when pathology or injury affect
– Muscles
– Alpha motor neurons
– Any other source of input to alpha motor neurons
What is low muscle tone (hypotonicity)?
insufficient
activation of the motor units to prepare for holding or
movement
What does hypotonicity cause?
poor posture, difficulty in movements, and pain
What causes alpha motor neuron damage or denervation?
poliomyelitis, demyelinating
diseases (MS), trauma to nerves, nerve compression
What is rehabilitation like after alpha motor neuron damage?
‒ Regrowth is generally slow and can occur only at a limited
distance
‒ Electrical stimulation (ES), hydrotherapy, and quick ice
have been used for rehabilitation of alpha motor neuron
damage
What causes insufficient excitation of alpha motor neurons?
• Prolonged immobilization with a cast for fracture healing
• Stroke, multiple sclerosis, or head injury also alters the
balance of excitatory and inhibitory inputs
What is some rehabilitation to increase tone?
‒ Physical agents are not often used after stroke, head injury,
or other supraspinal lesions
‒ ES, hydrotherapy, and quick ice may be used as an adjunct
to therapeutic exercises, orthotics, and functional training
of traditional rehabilitation
What is high muscle tone (hypertonicity)?
abnormally high
excitatory input to an intact alpha motor neuron
What are some associated effects to hypertonicity?
- Muscle spasms
- Contractures
- Abnormal postures leading to skin ulcers
- Difficulty with assisted dressing, transfers, hygiene
- May inhibit functioning
What is high muscle tone aggravated by?
pain, cold, or stress
What are spinal cord injuries?
Initial flaccidity is followed by spasticity
– Frequently, greater on one side
What is management for SCI?
Selective ROM exercises, prolonged stretch,
positioning or orthotics, medications, and surgery
What are cerebral lesions?
Stroke, Parkinson’s disease, multiple sclerosis
What is management for cerebral lesions?
Prolonged stretch or icing, inhibitory pressure or
casting, continuous passive motion, biofeedback, and
task training
What is spasticity?
Primary impairment or adaptive response? • Develops some time after injury • Recovery follows a predictable course • Voluntary motor output limited to movement in flexor or extensor patterns (synergies)
What is rigidity?
‒ Consequence of central nervous system pathology
• Parkinson’s, stroke, head injury, multiple sclerosis
‒ Posturing
• Decorticate posture
• Decerebrate posture
What is decorticate posture?
(above the brain stem) hypertonicity of neck and back extensors; hip extensors,
adductors, and internal rotators; knee extensors; ankle planter flexors
and invertors; wrist flexors; and finger flexors, elbow FLEXORS
What is decerebrate posture?
(below the brain stem) hypertonicity of neck and back extensors; hip extensors,
adductors, and internal rotators; knee extensors; ankle planter flexors
and invertors; wrist flexors; and finger flexors, elbow EXTENSORS
What is basal ganglia disease?
Parkinson’s disease
• Parkinson’s disease is a resting tremor that fluctuates
What is cerebral palsy?
‒ Involuntary writhing (wriging of wrists, etc.)
• Self-inflicted injuries are possible
what is management for cerebral palsy?
positioning, ROM
interventions, and neutral warmth
