Ultrasound and Biofeedback

diagnostic/real time ultrasound

views internal structures - ultrasound for babies

therapeutic ultrasound

heating tissue to decrease pain and increase healing

therapeutic ultrasound uses

• pain management

• trigger point management

• tendonitis/bursitis

• scars, adhesions

• sprain/strains

• absorption of medications

• wound healing

• fracture management

physical properties of US

• sound

• frequency

• intensity

• mode

• BNR

• treatment area

• refraction

• reflection

sound

• high frequency sound waves

• mechanical energy converted to thermal energy

• US > 20,000 Hz (human hearing limit) → not audible

ultrasound without gel

= useless

• need the gel to let the functions of it go into the tissue

how does it work

transducer head

• piezoelectric crystal

• high frequency, alternating electrical current

• crystal expands and contracts, producing sound waves

effective radiating area (ERA)

• area that radiates the US

• ERA < the sound head

• increase the ERA will heat tissue faster

treatment considerations of ERA

• size of treatment area

• movement of transducer head → should never be held in the same position because it can lead to burns

frequency

= waves/sec

• alternating compression-expansion cycles per second (MHz)

• depth of US penetration inversely related to frequency

• 1 MHz vs 3 MHz

1 MHz - frequency

• penetrates up to 3-5 cm

• deeper structures, i.e. joint capsules, muscle, fascia

3 MHz

• penetrates 1-3 cm

• superficial structures, i.e. superficial tendons, lateral epicondylitis, ankle tendons/ligaments, etc

Intensity (W/cm²)

• wave amplitude

• rate at which energy is delivered

• spatial average intensity (average over the ERA)

• no guidelines for therapeutic intensity

• 1.5 W/cm² = common setting

best practice for intensity

use the lowest intensity possible to achieve the desired therapeutic effect - most set at 1.5 W/cm²

mode

• duty cycle = 20%

• pulse duration/pulse period x 100%

beam nonuniformity ratio (BNR)

BNR = peak intensity/average intensity

usually preset, but good to understand

hot spots of BNR

• higher the BNR

• greater risk for burning and increasing discomfort

treatment implications

low BNR = more uniform

• less hot spots

• costs more $

keep it moving

• prevents burning

treatment area

• 2-4 x ERA to get significant heating

• treatment implications: treating large muscles or areas is ineffective

  • you can still do a big muscle like a calf, but you’d have to split it into sections which takes a lot of time

moving the sound head

• overlap by ½ the ERA

• remain perpendicular and in contact with skin

reflection

a lot of US is reflected, and not absorbed into skin

coupling agent/medium helps to transmit the waves into skin rather than being reflected

• aqueous gel

• underwater technique for wounds/irregular surfaces

  • 1 cm above skin

• gel bad

don’t use creams or ointments

refraction

if we don’t have a coupling medium, waves are refracted and don’t go into skin, vs if you do have a coupling medium, skin absorbs waves

sound head

• perpendicular to the skin, not at an angle

• absorption of US waves

• machine should not be turned on until it’s ready to go → prepped with gel and in position

treatment duration is dependent on:

• treatment area size

• treatment depth

• US settings (intensity, frequency, mode)

• specific condition treated

treatment duration: 1 MHz

1 MHz US (1.5 W/cm², 2 x ERA) → 11 min to warm up skeletal muscle 3.5° C

**deeper tissue

treatment duration: 3MHz

3 MHz US (1 W/cm², 2 x ERA) → 6 min to warm up superficial muscle 5.3° C

**superficial tissue

tissue cooling rate

• tissue cools rapidly after US treatment

• treatment implications: 4-5 minute window to stretch

  • skeletal muscle = 2 minute window

  • patellar tendon = 2-5 min window

  • achilles tenon = immediately or within 4 mins

variation and variability of US units

• no 2 machines are the same

• adjust treatment protocols based on unit and applicator

variation and variability of tissue response

• more heating in more dense tissue

• dense tissues

  • ligaments, tendons, bone

  • greater and faster rise in temp

• less dense tissue

  • muscle, blood, skin

treatment parameters of dense tissues

decrease duration or intensity, increase area, growth plates (would be bad to US growth plates because it could have an impact on their growth)

variation and variability of pt. response

responders: good

non-responders: doesn’t feel warming

over-responders: be cautious to not overheat

be cautious and try to slow increase in intensity, few sessions

thermal US

continuous US (100% duty cyce)

*always pick this!

non-thermal US

pulsed US (<100% duty cycle)

*don’t pick this

thermal effects of US

• tissue temperature elevation

  • ≤ 6 cm depending on frequency

  • increased tissue temp dependent upon: intensity, frequency, duration

  • results in increased blood flow, pain threshold, and elasticity

non-thermal effects of US: cavitation

• formation, growth, and pulsation of gas bubbles

• impacts cell membrane permeability

• controversial

*prob won’t see or use this

non-thermal effects of US: acoustical streaming

• forward movement of fluid

• by US waves

• relies on cavitation

• controversial

*prob won’t see or use this

Us documentation should include…

• duty cycle

• frequency

• intensity

• duration

• ERA

• treatment area

• coupling agent

• client position

• client response

• why is it being utilized

contraindications to US

• pregnancy - over low back or abdomen

• CA - over known/suspected malignancy

• over active epiphyseal bone growth

• TB infection

• hemorrhagic conditions

• impaired circulation

popular consensus of contraindications to US

• over eyes, reproductive organs, anterior neck

• application over pacemakers or any electronic device

• DVT or thrombophlebitis

• myositis ossificans (formation of bone inside muscle tissue after a traumatic injury)

precautions to therapeutic US

• over plastic or cemented implants

• over spinal cord or regenerating nerves

• impaired sensation, cognition, communication

• acute injury

• areas of infection

US for myofascial pain/trigger points

• strong evidence to treat pain: continuous US

• conflicting evidence for increased pain threshold

• unsubstantiated effect on cervical range of motion (ROM)

recommendations for pain tx: US for myofascial pain/trigger points

• 1 or 3 MHz, continous at 1.5 W/cm² for 10 min

• 4-5x/week for 2-3 weeks

US for back pain

• strong evidence for continuous US

• exercise and US significantly improved function, lumbar ROM, endurance

recommendations for pain tx: US for back pain

1 MHz, continuous at 1-2 W/cm² for 10 mins

3x/week for 4 weeks

US for shoulder pain

• thermal: insufficient evidence for nonspecific conditions

• non-thermal: no evidence for nonspecific shoulder pain and dysfunction

• best evidence: continuous US might be beneficial as adjunct to stretching and exercise

US for inflammatory conditions

lateral epicondylitis

• little and conflicting evidence with thermal or nonthermal

• manage pain and function

US for carpal tunnel syndrome: thermal

strong substantiated evidence that reduces pain and improves functional outcomes

• Continuous US, 1 or 3 MHz, at 0.5-1.5 W/cm² for 5-10 min

  5x/week for 4 weeks

US for carpal tunnel syndrome: pulsed US

minimal evidence, some positive studies

Pulsed (20%) US, 1 MHz, at 1 W/cm² for 15 min

5x/week for 3 weeks

US for calcific tendonitis

• thermal: moderate evidence for pain and dysfunction

• pulsed US: minimal evidence, but positive

• parameters widely varied

• trying to break up calcium deposits

recommendations for pain tx and increase functions: calcific tendonitis

Continuous US, 1 or 3 MHz, at 1-2 W/cm² for 10 min

3x/week for 4-8 weeks

US for bursitis

questionable and insufficient evidence → for pain, improved function, or ROM

US for arthritis

thermal: positive evidence for pain reduction, minimal evidence for increased ROM and/or functional improvement

pulsed: min, studies, no improvements in pain, ROM, or function when added to exercise

recommendations for pain tx and increase functions: arthritis

Continuous US, 1 MHz, at 1-2 W/cm² for 5-10 min

3x/week for 2-3 weeks

US for soft tissue healing: wound healing

continuous US: conflicting and insufficient evidence for wound healing

pulsed US: insufficient but positive

US for soft tissue healing: remodeling scar

insufficient evidence for US

US for soft tissue healing: tissue extensibility

• evidence from varied applications (knee, ankle, shoulder)

• conflicting outcomes

• not recommended but very poor studies

• insufficient power or too large tx areas

US for soft tissue healing: tissue swelling/ankle edema

insufficient evidence

other uses for therapeutic US: phonophoresis

• topical agent on skin or in US gel

• conflicting/insufficient evidence

• enhance absorption of topical agent - not likely

• thermal effect may enhance diffusion of topical agents into the skin

• not recommended for pain or inflammation

low-intensity pulsed US (LIPUS)

• pulsed

• med. frequency (1.5 MHz)

• low intensity (0.3 W/cm²)

• stationary application

• strong evidence and good justification

  • fresh and delayed bone fractures

  • stimulate osteogenesis

**only time you should really used pulsed US

strong substantiated evidence for continuous US

• pain for myofascial pain syndrome and trigger points

• pain and dysfunction with painful low back conditions

• pain and dysfunction of carpal tunnel syndrome

• pain associated with arthritis

moderate substantiated evidence for continuous US

• dysnfunction with nonspecific shoulder conditions

• calcific tendonitis

• bursitis

• wound debridement

pulsed US insufficient or conflicting evidence

• need better studies

• except for LIPUS for slow healing fractures

definition of biofeedback

• utilization of alternative sensory input to drive desired motor output

• teaching/learning technique reliant on immediate feedback

• decreasing ineffective movement/increasing desired outcome

goal of biofeedback: motor awareness

improves awareness of motor or kinesthetic performance or physiologic response using

• EMG → visual or auditory representation of mm activation

• PT can adjust sensitivity of reading

  • high sensitivity when goal is relaxation

    • treatment time = 10-15 mins

  • low sensitivity when goal is mm re-education

    • treatment time 5-10 min per mm groups

    • isometric contractions held 6-10 sec at 2/3 max intensity

goal of biofeedback: improved postural awareness

• visual awareness of midline with positive or negative reinforcement

• weight acceptance, weight shift

• different from visual cues alone (mirror)