Physical Agents utilized in Physical Medicine and Rehabilitation

1. Physical Agents utilized in Physical Medicine and Rehabilitation C. Scott Bickel, PT, PhD Department of Physical Therapy School of Allied Health Professions LSU – Health Sciences Center May 13, 2005

2. APTA’s position statement (1995): “Without documentation which justifies the necessity of the exclusive use of physical agents/modalities, the use of physical agents/modalities in the absence of other skilled therapeutic or education intervention, should not be considered physical therapy.” Modalities

3. Physical Agents • Heat • Cold • Water • Pressure • Sound • Electrical Current

4. General Indications • Purported Uses • Modulate pain • Reduce or eliminate inflammation • Increase rate of healing • Modify muscle tone • Increase connective tissue extensibility

5. Commonly used modalities • Temperature modalities • Cryotherapy - ice • Heat • Superficial – hot packs • Deep - Ultrasound • phonophoresis • Electrical stimulation • TENS • Iontophoresis • NMES

6. Less commonly used modalities • EMG Biofeedback • Spinal Traction • Short-wave diathermy • Infrared

7. Cryotherapy • Historical perspective • Ancient Greeks and Romans • Late 1880’s, cold compresses after surgery • Early 1960’s, cold therapy widely recognized by healthcare as a result of studies by Grant (1964) and Hayden (1964). • Military studies.

8. Cryotherapy • Why Ice? • Mild cooling often used in an effort to control: • Inflammation • Pain control • Reduce spasticity • RICE • Ice probably more effective than cold packs.

9. Cryotherapy

10. Ice • Vasoconstriction • Immediate vasoconstriction • 10-15 minutes • Vasodilation? • Slows the acute inflammatory response • Reduced tissue temperature • Slows rate of chemical reactions • Immediate application • Reduces pain

11. Contraindications Cold hypersensitivity Raynaud’s disease Regenerating peripheral nerves PVD Precautions Over superficial main branches of nerve Peroneal nerve Open wounds Poor sensation Ice

12. Ice evidence • Temperature will drop from skin to ~2-7 cm deep. (MacAuley et al 2001) • 10 minutes is sufficient. • Several studies – immediate application of ice after ankle sprain = quicker return to sport

13. Superficial Heat • Often used for: • pain control • increase tissue extensibility • Done prior to or in conjunction with other treatments.

14. Heat

15. Superficial Heat • Vasodilation (Bickford and Duff 1953 and others) • Increased blood flow • Primarily a local effect • Increase tissue extensibility (Lentell et al 1992) • Cannot stretch a cold muscle • Can heat a muscle with exercise • Increase metabolic processes • Pain control • Primarily a local effect

16. Superficial Heat • Hot packs • Paraffin wax • Hydrotherapy • Timeframe = ~20 minutes • Contraindications • Acute injury • Patients with impaired sensation • Heat near malignant tissue • In area of thrombophlebitis

17. Ice or Heat • Ice – acutely (<24-48 hours), then can move to heat if desired. • Symptomatic relief. • Heat Vs. Cold • If assists in pain relief they can be utilized at home.

18. Ultrasound • Therapeutic Ultrasound sends high frequency sound waves through tissue and has a thermal effect. • Deep heat • 2-5 cm • 1 MHz - 5cm / 3 MHz - 2cm • Ultrasound head is small, so can only heat a fairly small area (2x size of soundhead)

19. Ultrasound • Typical applications of Ultrasound • Pain control (Munting 1978) • Increase tissue extensibility (Knight 2001) • accelerate healing • Wounds (Dyson 1978), bone fractures (Duarte 1983) • Phonophoresis • Application of ultrasound in conjunction with a topical drug preparation for enhanced delivery • (ex. hydrocortisone). • Enhanced delivery (McNeill et al Pharm Res 1992)

20. Questions?

21. Electrical Stimulation • Common uses: • Pain control (TENS, interferential) • Iontophoresis (Direct Current) • Muscle stimulation (NMES) • Tissue healing (wound care)

22. Electrical Stimulation • Main parameters to be familiar with • Frequency • Muscle – force/frequency relationship • Pulse Duration • Strength Duration curve

23. Force Frequency Relationship 50-60 Hz – force levels off

24. Strength / Duration Levels of stimulation

25. TENS • Transcutaneous Electrical Nerve Stimulation • Used for Pain control • 2 theories of how TENS may control pain • Gate control theory – high frequency TENS • Opiate-mediated control – low frequency TENS

26. TENS • Gate-control theory of pain modulation • Ex. Bump your head, you rub it. From Kandel, Schwartz, and Jessell Principles of Neural Science

27. TENS • Opiate-mediated control • Endorphins • E-stim may promote endorphin release. • Cats • Non-human primates

28. TENS evidence • Which answer do you want? • Deyo et al. A controlled trial of TENS and Exercise for Chronic LBP. New Eng J. Med. 1990. • 4 groups • TENS ▪ sham TENS • TENS + exercise ▪ sham TENS + exercise • Exercise groups did better than TENS • TENS added no additional benefits

29. TENS evidence • Chabal et al. Long-term TENS Use: Impact on Medication Utilization and PT costs. Clin. J. of Pain. 1998 • 376 patients • TENS vs. no TENS • TENS group had 55% and 69% reduction in costs for medications and PT, respectively.

30. Iontophoresis • Iontophoresis – use of direct current to enhance transcutaneous administration of ionizable substances. • Most commonly used: • Dexamethasone – anti-inflammatory agent • Conditions: • Epicondylitis, tendonitis, etc…

31. Iontophoresis evidence • Nirschl RP et al. Iontophoretic admistration of dexamethasone sodium phosphate for acute epicondylitis. AJSM, 2003 • Randomized, double-blind, placebo-controlled trial. • 199 patients with acute epicondylitis • Ionto 40 mA-minutes of treatment 3/wk x 2 wks • Short-term f/u – ionto significantly improved • By 1 month – no diff b/t groups

32. Muscle Stimulation (NMES) • Specific Uses: • Facilitation of muscle contractions • NMES for restricted joint motion and contractures • NMES to control spasticity • Functional electrical stimulation

33. Muscle re-education and facilitation • Goal – re-establish “normal” voluntary motor control. • Typically patient tries to perform the contraction or desired movement along with the stimulation. • Data – may or may not be better than voluntary exercise alone.

34. NMES for restricted joint motion and contractures • PROM • Some evidence suggests E-stim may help: • Knee flexion contractures • Wrist/finger flexion contractures after CVA • Typical protocol: • 30 mins, 3 times/day, 7 days/week, 4 weeks. • “maximum comfortable extensor contraction”

35. NMES to control spasticity • How is spasticity reliably measured? • For example (Peterson and Klemar, 1988) • Spastic plantar flexors. • Stimulated the tibialis anterior • 2-3 seconds on/10 seconds off for 30 minutes • Reduced spasticity for up to 6-14 hours. • Reciprocal inhibition – activate the antagonist and this may produce an inhibition to the spastic muscle and therefore reduce spasticity.

36. Functional Electrical Stimulation (FES) • FES – the use of e-stim to produce limb movements important for ADL can be considered FES. • Example: prevent shoulder subluxation during movements or to produce dorsiflexion during gait.

37. Functional Electrical Stimulation (FES) • Can e-stim be used to make people walk? • Complete SCI? • Parastep. • May not get very far due to fatigue. • Patients may find it easier to get around in the wheelchair.

38. Parastep

39. Muscle fatigue with NMES Tibialis anterior Vs. Quadriceps femoris Bickel et al, 2003

40. Functional Electrical Stimulation (FES) • In SCI patients, e-stim has been shown to: • Evoke training responses like: • Increase VO2 • Increase muscle mass • Improve muscle endurance • Muscle Plasticity • Give the appropriate stimulus, can evoke changes!

41. Muscle Hypertrophy after SCI? • Is it possible to evoke muscle hypertrophy after complete SCI? • Studies have reported modest hypertrophy (0-20%). Cycling exercise has been reported to increase muscle area by 12%. • Is this the appropriate exercise? • Is 12% enough?

42. Acute SCI (< 1 yr), n=3 4 sets of 10 2 days per week for 8 weeks Total contractions = 640 Dudley et al. 1999

43. Chronic SCI • 6 males, Complete SCI (ASIA A) • Levels of injury = C5-T9 • Duration of injury = 12 ± 7 yrs (5-21 y) • Age = 34.8 ± 4.8 yrs. (28-41 y) • Body mass = 82.0 ± 23.3 kg (59.8-111.8 kg)

44. Chronic SCI Training 24 weeks of training, 2 days per week Electrical stimulation (ES) was used to activate primarily the QF muscle group (30 Hz trains of 450 µsec biphasic pulses) ES amplitude was increased to evoke 4 sets of 10 dynamic knee extensions Ankle weights were used as progressive loading over training protocol All training was performed at subjects’ homes An investigator provided instruction by telephone Region of interest

45. Results After 6 months of training: Right QF muscle CSA increased from 34 ± 10cm2 to 58 ± 14cm2(p = 0.004) Left QF muscle CSA increased from 36 ± 11cm2 to 62 ± 17. cm2, (p = 0.002) This equated to ~70% increase in QF muscle size in both thighs Before After A single slice (MRI) of the right thigh from 1 subject, before and after training.

46. QF muscle size of the left leg at 0, 3, and 6 months of electrically stimulated RT (n = 6). * ‡ *p=0.002, 6 Mo. vs. PRE ‡ p=0.002, 6 Mo. vs. 3 Mo.

47. Muscle Hypertrophy/SCI • 6 months of training – QF muscle nearly the size of AB controls • Health benefit: • Improved glucose tolerance in subjects with impaired OGTT • Improved exercise capacity?

48. Fatigue Resistance • Electrical stimulation of SCI muscle has been shown to: • Increase type IIa fibers • Increase capillary density • Increase enzymes of energy supply • Increase fatigue resistance • Same principles can be applied to other conditions.

49. Electrical Stimulation after ACL • Snyder-Mackler et al. Strength of the QF muscle and Functional Recovery after ACL reconstruction. JBJS. 1995. • RCT of Electrical Stimulation vs volitional ex. • 110 patients seen first 6 weeks post-op. • ES group - 70% recovery of QF function • Volitional group – 56% recovery of QF function • Key to study – stimulation was done at high intensities

50. Summary • Modalities are used fairly frequently. Most used for pain control to treat the symptoms, rarely will be a long-term solution. • Electrical stimulation has shown promise in the treatment of muscle after injuries (SCI, ACL, etc…)