Exam 1 Lecture 2 Pathophysiology of Tone part 2: Tone to end Flashcards
What is tone?
•Muscle tone is the resting level of tension in a muscle in response to passive stretch
- –Allows a muscle to make an optimal response to voluntary/reflexive commands
- –Reflects balance of excitatory and inhibitory influences
How does damage to the CNS effect tone?
•Damage to central nervous system often results in an alteration in regulation of muscle tone
Hypotonia
What is it
Infants
Other symptoms
PT managment
–Decrease in resistance to passive limb manipulation
–Flaccid
- •Infants have a floppy quality or “rag doll” appearance
- –Arms and legs hang by sides
- –Little or no head control
- •Other symptoms include
- –Difficulty with mobility, posture, breathing and speech, lethargy, ligament and joint laxity, and poor reflexes
- •PT Management
- –Developmental positions, strengthening, sensory stimulation, positioning and bracing, weight bearing
Hypotonia vs muscle weakness
Hypotonia is Not the same as muscle weakness
- –True muscle tone is the ability of a muscle to respond to a stretch
- •Low tone results in a slow ability to initiate a muscle contraction and an inability to maintain the contraction
- –True muscle weakness is characterized by the force exerted by a muscle is less than expected
Hypotonia: causs
•Many causes though the underlying cause is often difficult to determine
- –Trauma, environmental factors, or by genetic, muscle, or central nervous system disorders
- •Down syndrome, muscular dystrophy, cerebral palsy etc
Hypotonia: development as an adult
Development as an adult may be associated with
- –Cerebellar degeneration (such as multiple sclerosis, Friedreich’s ataxia, or multiple system atrophy)
- •Neurons that control muscle coordination and balance, deteriorate and die
Is hypotonia or hypertonia more common?
Hypertonia is more common
Hypertonia
More common than hypotonia
–Increase in resistance to passive limb manipulation
–Damage to UMN and or descending pathways making afferent pathways more responsive
–Can be spastic (spacticity) or rigid (rigidity)
Pathological spread of reflexes
- Sign of hyperactivity
- Contraction of muscles that have different actions while eliciting a reflex
- Contraction of thigh adductors while testing patellar reflex
What is spacticity?
Velocity dependent increase in resistance to a passive stretch
- –Classified as a symptom of UMN syndromes
- Can include
- –Spastic paresis—spasticity combined with muscle weakness, often in someone with an incomplete SCI
- –Spastic paralysis—absence of voluntary muscle control in someone with spasticity
- Can result in secondary impairments in muscles and other tissues
- Stiffness, contracture of muscle, tendon, joint
- Spastic muscles seem to undergo intrinsic structural changes which explains why more tension is usually developed with spasticity over time when stretched relative to non spastic muscles
- Stiffness, contracture of muscle, tendon, joint
What is spastic paresis?
Spastic paresis—spasticity combined with muscle weakness, often in someone with an incomplete SCI
What is spastic paralysis?
Spastic paralysis—absence of voluntary muscle control in someone with spasticity
What are two things that clinicians recognize the same spasticity in?
–Clinicians also recognize that the same spasticity is triggered by the light touch or hair tug or a hitting a bump in a wheelchair
(I’m not sure what “also” is referring to here)
Clonus
hyperactive stretch reflex
Characteristics of spasticity following cerebral lesions
–Damage to corticobulbar fibers
–Decrease excitation of descending inhibitory pathways
–Extensors of LE & flexors of UE
–Easier to pharmacologically control
Characteristics of spasticity following spinal cord lesions
–Damage to all descending activity
–Flexor & extensor involvement
–More resistant to pharmacologic control
Must use different techniques than what we would use if it was a brain injury (for example, to break clonus)
Synergy Patterns of Extremities: Flexion
–Upper extremity
- •Scapular retraction/elevation or hyperextension, shoulder abduction, external rotation, elbow flexion, forearm supination, wrist and finger flexion
- Looks like primitive reflex
–Lower extremity
- •Hip flexion, abduction, and external rotation, knee flexion, ankle dorsiflexion, inversion, and toe dorsiflexion