DPT Electrotherapy & Modalities 4 — Questions and Answers
Question 1: A therapist applies cryotherapy to an acute ankle sprain. Which physiological sequence correctly describes the local tissue response?
- Vasodilation → increased metabolism → reduced pain
- Vasoconstriction → reduced metabolism → decreased nerve conduction → analgesia (Correct answer)
- Vasodilation → increased collagen synthesis → edema reduction
- Vasoconstriction → increased nerve conduction → muscle relaxation
Correct answer: Vasoconstriction → reduced metabolism → decreased nerve conduction → analgesia
Cold causes vasoconstriction, reduces cellular metabolism and oxygen demand, and slows peripheral nerve conduction velocity, producing analgesia.
Question 2: The 'hunting response' during prolonged cold application refers to:
- Patient sensation of deep aching followed by anesthesia
- Cyclical vasoconstriction and vasodilation to prevent tissue freezing (Correct answer)
- Increased muscle spindle sensitivity causing reflex spasm
- Hunt's paradox of post-cryotherapy warmth perception
Correct answer: Cyclical vasoconstriction and vasodilation to prevent tissue freezing
The hunting (Lewis) response is a cyclical 5–10 minute alternation between vasoconstriction and vasodilation that occurs with prolonged cold exposure to prevent frostbite.
Question 3: A PT uses diathermy (shortwave) on a patient who has a copper IUD. This is:
- Safe if the IUD is below the treatment field
- Acceptable if pulsed mode is used instead of continuous
- Absolutely contraindicated due to metal implant heating risk (Correct answer)
- Permitted only if intensity is kept below 50 W
Correct answer: Absolutely contraindicated due to metal implant heating risk
Metal implants including copper IUDs are an absolute contraindication for shortwave diathermy because eddy currents can heat the metal to tissue-damaging temperatures.
Question 4: Which ultrasound coupling medium provides the best acoustic transmission?
- Air
- Ultrasound gel (Correct answer)
- Mineral oil
- Water in immersion technique
Correct answer: Ultrasound gel
Ultrasound gel has an acoustic impedance close to tissue, minimizing reflection at the transducer-skin interface and maximizing energy transmission.
Question 5: For phonophoresis to be effective, the drug must:
- Have a positive ionic charge to be repelled by the transducer
- Be in a coupling medium with suitable acoustic and drug permeability properties (Correct answer)
- Be applied via iontophoresis simultaneously with ultrasound
- Penetrate at least 5 cm to reach the target tissue
Correct answer: Be in a coupling medium with suitable acoustic and drug permeability properties
The carrier gel or medium must allow adequate ultrasound transmission and also facilitate transdermal drug delivery; purpose-formulated phonophoresis gels are preferred.
Question 6: Which outcome measure best assesses functional response to electrotherapy for chronic low back pain?
- Nerve conduction velocity pre/post treatment
- Visual Analog Scale (VAS) pain at rest only
- Oswestry Disability Index (ODI) before and after treatment course (Correct answer)
- Galvanic skin response during stimulation
Correct answer: Oswestry Disability Index (ODI) before and after treatment course
The ODI measures functional disability across daily activities and is validated for tracking meaningful change in chronic low back pain management.
Question 7: When using high-voltage pulsed current (HVPC) for wound healing, the cathode (negative pole) is typically placed over the wound during which phase?
- Inflammatory phase to reduce bacterial load
- Proliferative phase to attract fibroblasts and promote granulation (Correct answer)
- Remodeling phase to increase collagen cross-linking
- All phases equally; polarity does not matter
Correct answer: Proliferative phase to attract fibroblasts and promote granulation
During the proliferative phase, cathodal stimulation attracts positively charged fibroblasts and promotes granulation tissue formation through galvanotaxis.
DPT Electrotherapy & Modalities 4
A therapist applies cryotherapy to an acute ankle sprain.
Which physiological sequence correctly describes the local tissue response?