Electrical Stimulation for muscle contraction - Lecture #6 (modalitites)

Question 1

Estem for pain modulation is

Answer 1

Transcutaneous Electrical Neural Stimulation (TENS)

Question 2

Estem for the purpose of activation of peripheral motor nerve (for muscular contraction)

Answer 2

Neuromuscular electrical stimulation (NMES)
* If were not getting any muscle contraction were not achieving our goal - there has to be a visible or palpable muscular contraction for this to be considered working

This can be used to faciliate strengthening (make muscle fire when it otherwise wouldnt) and prevent atrophy

Question 3

What nerve does NMES stimulate?

Answer 3

Peripheral motor nerve
* the nerve must be in good working order to the motor units in order for NMES to work

Question 4

Which kind of electrical stimuation would we use for deinnervated muscle tissue?

Answer 4

Electrical muscle stimulation (EMS)
* This essetially stimulates the sarcolima not the peripheral nerve

Question 5

What works by stimulating the peripheral motor nerve and not just the individual muscle fibers (sarcolima)

Answer 5

Neuromuscular electrical stimulation not electrical muscle stimulation

Question 6

Which has poor evidence to support the use: NMES TENS or EMS

Answer 6

EMS

Because muscles not attached to neurons (deinnervated) don’t have much left to live for so don’t do well with electrical stimulation

Question 7

With a stroke patient would we use NMES and EMS?

Answer 7

NMES

The problem w/ stroke pts is getting the impulse from the brain to the spinal cord. Theres nothing wrong w/ the peripheral nerves so we can activate them all day so they can recruit those motor units and cause muscle contraction

Question 8

Would we use EMS or NMES in an incomplete spinal cord injury?

Answer 8

Incomplete because some of those peripheral nerves are still intact

Question 9

What is functional electrical stimulation?

Answer 9

NMES or EMS for the purpose of facilitation of functional activity

EX: Knee extension w/ sit to stand, wrist extension to faciliate grip

Theres an anterior tib one that is used when walking. Essentailly they walk and when they hit terminal stance (beginning of going into DF) it triggers electrical stimulation to allow them to DF the foot while they go through swing phase

We just don’t want it to shock the muscles into concentrically contracting when they should be lengthening

Question 10

KNOW: The primary goal for NMES is muscle force (getting that actual muscle contraction)
* Our goal is to improve the voluntary contraction that occurs

Secondary goal: ROM / gait speed / prevention of contracture (because we now have more muscle force we should be able to work into this)

Question 11

What population should use NMES?

Answer 11

People w/ weak yet innervated muscles
* In early rehab stages, especially with poor voluntary contraction
* Its great in early phases of rehab its great because you don’t have to move a pts joint to get muscle contractoin
* works great early on because it allows us to recruit more motor units - however - it doesnt increase muscle size, so lateral on in rehab its not great because we stop getting stronger because we’ve recruited all the motor units but the muscles havent actually gotten bigger (therefore fore can no longer increase)
* Also, for NMES to work we have to get a similatr contraction of the m as they would in EX. However, this amount of current is really uncomfertable so strength training in a healthy population is better (because they can just train on their own) - EX is more comfertable on m tissue than NMES
* NMES combined w/ EX > EX alone

However, in the healthy, non-weak population there was no difference between estem and EX in strengthen gaints
* No added benefit to combining ES and EX

Question 12

KNOW: if were thinking about using NMES for strengthening we need to think about progressive overload (just like normal strengthening)
* We need to increase it over time to promote strength gains
* However, if we just want to stop atrophy from happening we can use the same amount everytime

Question 13

Which order are motor units recruited in skeletal muscle w/ strength training?

What about w/ NMES?

Answer 13

Smaller –> Larger motor units recruited

NMES = Random patterns of recruitment

Question 14

KNOW: Neural adaptations = increased motor units
* They increase the # of motor units recruited
* Increase the frequency that motor units are recruited
* Recruit more motor units at the same time

For NMES to induce strength gains, intensity must match traditional strengthening program

Question 15

Does NMES cause hypertrophy?

Answer 15

No cear evidence

It can only prevent atrophy - we cannot build up muscle mass w/ this

Question 16

With strength training or NMEs do a,, motor units have the same firing rate?

Answer 16

NMES

This can lead to a faster rate of fatigue
* with normal EX you can vary the frequency of contractions and which ones you recruit (big to small)
* With this you’re just sticking the electrodes on and they all fire at the same rate and big and small are stimulated (because everything under the pad is going to fire)

Question 17

NMES also leads to improved muscle extensibility (the ability to extend or be stretched)
* this is by activiating the muscle to go through its full ROM and then allowing it to relax
* Through this you can improve an agonist / antagonist tissue

Question 18

NMES can be used to reduce spasticity
* flexors are spasticitic so i put the pads on them to contract them a bunch to fagitue them out so they can relax
* Or you can put the muscles on the anatognist and cause the flexors to be stretched over and over

Question 19

Conditions indicated for NMES:

Post surgical: The idea so to get muscle contraction w/o moving the joint
* ACL repair
* Meniscus repair
* TKA
* etc

Critically Ill or Frial (so to keep that atrophy from happening)

Generally inactive (to prevent atrophy)
* Secondary to pain (w/ pain)

Neurological:
* Stroke (Cerebral vascular accident [CVA])
* Spinal cord injury
* Cerebral palsy
* Multiple sclerosis

Question 20

Precautions: for both

Pain of unknown origin

Active/open epiphysis

Titanium and most orthopedic implants are nonconductive to electricity and it is OK to place electrodes in this area

Adhesive allergy (for the actual pads)
* Consider changing to a gelled carbon electrode

Question 21

Contraindications:

Local application of e stim in area of:
* Pacemkaer (chgest gion L>R) -Cervical, lumbar, LE and distal UE have been shown to be OK, still clear w/ a cardioologist though

Pregnancy (lumbosacral, abdominal regions)

Carotid sinus (anterior neck)

Damaged skin

Lack of sensation

Malignant tumors

Eyes, internally, or reproductive organs

Poor cognition, inability to communicate - with tens this is a contraindication (because you need to know the strong comfortable senastion)
* However, not a contraindication w/ NMES / EMS because you can see when you get your desired affects (actual m contraction)
* howver it is a precuations for these because you need to do consistent skin checks to make sure you’re not burning them

Thrombosis/thrombophlebitits

Hemorrhage

Question 22

KNOW: You could def do Estem for a total knee pt joint because their implant is non electrically conductive (as long as it was made in the USA/europe)

Question 23

If nerve is severed than theres no point in NMES - could do EMS for the deinnervated muscle

Could pair this w/ ROM deficits and pair that w/ a functional activity

Dont forget skin inspection for thermal affects
* Only do this if they have lack of sensation (but I would air on the side of caution for this and do it anyways)

KNOW: if they have a patellar tendinopathy you wouldnt want to put estem on their quads and have them go through a long arc quad - that might irritate them
* so be careful that the activation of the muscles you turn on itsnt actually moving / negatively affecting the joint you’re trying to avoid

If they have activity partipation issues we can put the estem on and turn on when they really need to muscle to contract (think turning on for the DF part of ambualation then turning back off)

Question 24

With electrical stimulation (Tens or NMES / EMS doesnt matter which one) when we put the electrodes on does it recruit larger or smaller diameter nerves?
* what kind of nerves are motor nerves

Answer 24

Larger

Remember - this is talking about peripheral nerves not motor units (motor units are recruited randomly)
* NOTE: the biggest nerves are motor nerves

Even though the biggest nerves (recruited first) are motor nerves we get a sensory response before a motor response - this is also based on the location / placement of the electrodes. if they arent placed near those big motor nerves we can actually turn on those peripheral sensory nerves (even though their smaller) first.

Question 25

Parameteres for strengthening for MSK condition

We modify the burst frequency - normally the carrier frequency is preset - know the #’s for both

KNOW: A lower pulse frequency can reduce fatigue will probs want to increase time

Amplitude = maximal tolerable to achieve muscle contraction (so we need to see muscle contraction happening)
* maybe check and see if theres anything resisting current
* Maybe move electrodes closer to a peripheral nerve (because remember those big motor peripheral nerves are activated first if you’re near them - if you arent near them than you might be turning on nociceptive smaller nerves first)
* Ideally for strengthening >/ 50% of max voluntary contraction - but in the clinic you want it at maximally tolerated contraction

Ramp up / ramp down increasing will help not scare them but don’t go to long or you’ll fatigue their muscle

Duty cycle = work to rest cycle
* for strengthening from 1:3 to 1:5 (same for EX strengthening work rest cycle - 10 seconds of doing reps 30 seconds of not doing reps)
* Can increase the rest time to decrease fatigue or decrease the work time

Treatment time/duration: >/ 10 contraction or up to 1 hour per day
* 3-5x week
* 4-8 weeks

KNOW: if you have the estem activating concentric activation of the quads (knee extension) you would not want to work into flexion exercises (working against the estem into eccentric repetition)

Question 26

Things that can cause resistance to current in the body:

Answer 26

Hair
Callus
Lotion
Adipose

Question 27

Amplitude =

Answer 27

Intensity

Question 28

What is burst duration? (defintion / #’s)

Answer 28

How long each burst is

2-10 msec (normally preset)

Question 29

What is carrier frequency #

Answer 29

1000-2500hz

Question 30

Parameters for strengthening w/ neurlogical conditions:

you’re doing bursts of biphasic current

not a lot changed

pulse duration changed slightly (higher)

duration = 30 minutes longer

Sumarry = they can tolerate a little more current

Question 31

KNOW: for electrode placement we are normally going to be doing a bipolar arrangement
* meaning only 2 electrodes are required

Can use multiple channels (can stimualte 2 muscle groups at the same time)
* combined motiions for function (can do a co contraction to get a power grip)
* alternating activation - well we can have quad activation w/ 2 of these elctriodes then our other activation at a slightly different time for functional activties
* Essentially saying you could put two electrodes on the glutes and two on the quads and use it when someone stands up out of a chair (geared at functionally helping someone by getting that full m contraction)

Placed over target muscle belly
* arrged to recruit as many motor units as possible - can even use to target specific peripheral nerves (think putting it over radial nerve to get extension)
* Electrode size to match muscle size

Question 32

Going to feel like a muscle cramp
* I want a good contracion at a tolerable level

tell patients not to fight the estem (don’t contract against it)

communication is key - also don’t just leave the pt sitting there
* let the pt know what the goal is
* don’t freak out if something happens - just change some parameters around

Question 33

Question 34

case

Question 35

case