Abnormal muscle tone and spasticty

what is muscle tone

internal state of muscle fiber tension within individual muscles and muscles group. It is the degree of tension or resistance during rest and in response to stretching.

what is normal muscle tone

normal state of balanced tension in the muscles

what are some influences in muscle tone

level of physical fitness, genetics, emotional state, postural demands

muscle tone continuum from absent to high tone

flaccid, hypotonic, normal, hypertonic

what are abnormal hypertonicity tones

spasticity, rigidity, dystonia

what is hypotonicity

abnormal decease muscle tension or tone

what is flaccidity

absent muscle tone

what may cause hypotonicity

UMN lesions temporarily or LMN long term

what is hypertonicity

abnormal increase in muscle tension / tone where there is increased resistance to PROM that is velocity dependent. Sometimes called spasticity.

what causes hypertonicity

UMN syndrome

what are examples of UMN lesions

brain and spinal cord lesions

what are examples of LMN lesions

anterior horn cell, peripheral nerve, SCI in distal thoracic / lumbar spine

how do UMN normally regulate LMNs

they produce disinhibition of spinal reflexes with hyperactive tonic stretch reflexes

what happens to UMN control of LMN when the UMN is damaged

there is no inhibition which results in hyper excitability of LMN and increased tone

supraspinal mediation of hypertonicity leads to

disinhibition of brain stem reflexes, decreased activity of inhibitory pathways in the brain and brainstem, failure of reciprocal inhibition. This results in over activity of excitatory pathways in the brain and brainstem.

what does a LMN lesion lead to

decreased tone due to loss of innervation to the skeletal muscles, which is a loss of connection.

are pathological reflexes present with UMN or LMN lesions

UMN lesions

what does atrophy look like for UMN lesion

diffuse

what does atrophy look like for LMN lesion

denervation of muscle groups with fascinations

what does strength look like with UMN lesions

decreased strength in a regional distribution

what does strength look like with LMN lesions

decreased in the distribution of the root, plexus, or peripheral nerve

UMN lesion signs are present when there is damage to

cortical spinal pathway which includes the motor cortex, descending pyramidal tracts, brainstem, descending vestibular tracts and dorsal reticulospinal tracts

what are features of UMN syndromes

spasticity, spasms / co-contraction, extensor plantar response (babinski), clonus, exaggerated DTRs, mass movement, stereotyped movement, associated reactions

what is spasticity

velocity dependent resistance to passive stretch

what is the initial high resistance with spasticity

spastic catch

what is the inhibition and limb relaxation with spasticity

release

with spasticity, the larger and quicker the stretch means

the stronger the resistance of the spastic muscle

what is a risk when there is immobilization in a shortened position

contracture

how do plastic rearrangments occur

spinal reactivity and supra spinal command

what is rigidity

velocity independent resistance constantly due to PROM

rigidity is commonly due to

basal ganglia lesions / extrapyramidal syndromes commonly seen in parkinsons patients

what are the two types of rigidity

cogwheel rigidity and lead pipe rigidity

rigidify leads to uncontrolled

tensing and inability of the muscles to relax normally

what is cogwheel rigidity

resistance that occurs over a tremor

what is lead pipe rigidity

resistance throughout the movement

decerebrate rigidity

extensor response in the trunk and limbs when the brainstem lesion occurs below the red nucleus in the brainstem

decorticate rigidity

UEs in flexion and LEs in extension when there is a brainstem lesion that occurs above the red nucleus which leads to decreased inhibition of rubrospinal tract

what is dystonia

involuntary muscle contractions that are commonly twisting, writhing repertitive movements and increased tone

why does dystonia occur

idiopathic, genetic, or aquired brain injury to the basal ganglia

postural dystonia

sustained abnormal / rigid postures that may be minutes to hours or permanent

focal dystonia

involuntary contractions of only one body part such as wry neck

what is segmental dystonia

two or more adjacent areas of spasticity

ataxia is due to

cerebellar / spinocerebellar lesions or degeneration

ataxia is

impaired timing, poor co-contraction, inconsistent movements and difficult with stabilizing postures (without muscle weakness)

when does ataxia occur

during voluntary movements where there is balance, coordination, and or gait disturbances

athetosis is due to

basal ganglia or cerebellar lesions

athetosis is

slow involuntary non-purposeful movements that are writhing. They are not sustained, patterned, or repetitive. Propensity to affect UEs

why do we evaluate muscle tone

it contributes to abnormal motor control of volitional movement, alters posture, restricts ADLs, contributes to contractures, effects hygiene, contributes to skin breakdown, leads to painful alignment

examination of abnormal muscle tone involved what 6 things

observation of positioning, measurement of spasticity, deep tendon reflexes, clonus, developmental reflexes, impact of postural demands

what positions can we observe tone in

hypotonic or hypertonic

how do we assess spasticity

PROM slowly then quick PROM via the modified ashworth scale or tradieu scale

what type of measure is the modified ashworth scale

body structure and function

what is the purpose of the modified ashworth scale

to measure spasticity (not tone!)

what population do you complete the modified ashworth scale with

patients with CNS lesions

is the modified ashworth scale a good measure

the reliability is inconsistent but it is the best we have

0 on modified ashworth

no increase in muscle tone

1 on modified ashworth

slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when affected parts is moved in flexion or extension

1+ modified ashworth

slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of the ROM

2 modified ashworth

more marked increase in muscle tone through most of the ROM (more than half), but affected parts easily moved

3 modified ashworth

considerable increase in muscle tone, passive movement is difficult and present throughout most of the ROM

4 modified ashworth

affected parts stiff in flexion or extension with velocity

what scale is used for research with spasticity

tardiue scale

what is the purpose of the tardieu scale

assess muscle response to stretch at various given velocities

measures in tardieu scale

quality and angle of muscle reaction, 3 speeds, quality of muscle reaction, joint angle (early or late)

0 deep tendon reflex score

absent, no response

1+ deep tendon reflex score

slight / decreased or diminished response

2+ deep tendon reflex score

normal

3+ deep tendon reflex score

brisk, exaggerated

4+ deep tendon reflex score

very brisk, clonus

clonus

alternate involuntary muscular contraction and relaxation in rapid succession. it is a continuous rhythmic reflex tremor initiated by the spinal cord below an area of spinal cord injury set in motion by reflex testing.

when is clonus abnormal

with greater than 3/4 beats

what do you need to document with sustained clonus

fatiguing or non fatiguing

when should you assess developmental reflexes

if there is brainstem involvement

what should you document about developmental reflexes

absent, tone change, visible movement of extremities, exaggerated full movements, obligatory and sustained

why do you need to test developmental reflexes if there is brainstem involvement

there can be decreased inhibition of these primitive / developmental reflexes

STNR

cervical flexion results in arm flexion and leg extension. Cervical extension results in arm extension and leg flexion.

ATNR

cervical rotation results in UE ipsilateral extension and contralateral flexion

TLR

supine positioning with cervical extension results in whole body extension. Prone positioning with cervical flexion results in whole body flexion.

positive support

both feet on the ground results in leg extension

flexor withdrawl

painful stimulus on the bottom on the foot results in ipsilateral knee flexion withdrawl

crossed extension

painful stimulus on the bottom of the foot results in the contralateral LE extension for support

startle reflex

scarring leads to whole body reflex

grasp reflex

something in the palm leads to grasping

Impact of postural demands you need to look at tone and document

change in position, observation, and document the quality

what does increased postural demand due to tone

it increases tone

what can impact tone

environmental factors such as tonic reflexes, effort and movement, stress and anxiety, meds, general health, environmental temperatures, CNS arousal or alertness, urinary bladder status, fever / infection, metabolic or electrolyte imbalances

various treatment for tone

botox, baclofen, phenol injections, surgical intervention, deep brain stimulation, stretching, weight bearing, strength