NPTE-PT Therapeutic Modalities Application 3 — Questions and Answers
Question 1: A PT plans to use iontophoresis with dexamethasone to treat a patient with carpal tunnel syndrome. Dexamethasone is negatively charged; which electrode setup is correct?
- Place dexamethasone under the anode (positive electrode)
- Place dexamethasone under the cathode (negative electrode) (Correct answer)
- Polarity does not affect drug delivery direction
- Alternate polarity every 5 minutes
Correct answer: Place dexamethasone under the cathode (negative electrode)
Like charges repel; negatively charged dexamethasone is driven into tissue when placed under the cathode (negative electrode).
Question 2: Which ultrasound parameter should a PT DECREASE to minimize thermal effects while still promoting tissue healing in an acute inflammatory condition?
- Frequency
- Duty cycle (Correct answer)
- Transducer size
- Treatment area
Correct answer: Duty cycle
Reducing duty cycle (using pulsed mode) minimizes thermal accumulation while preserving non-thermal mechanical effects like acoustic streaming.
Question 3: A patient with a cardiac pacemaker presents for shoulder rehabilitation. Which modality is SAFE to apply to the ipsilateral shoulder?
- Shortwave diathermy
- Neuromuscular electrical stimulation (NMES)
- Therapeutic ultrasound (Correct answer)
- Transcutaneous electrical nerve stimulation (TENS)
Correct answer: Therapeutic ultrasound
Therapeutic ultrasound does not generate electrical current and does not interfere with pacemaker function when applied away from the chest.
Question 4: When treating a patient with spasticity using cryotherapy, which effect on the muscle spindle explains the temporary reduction in tone?
- Increased gamma motor neuron firing
- Decreased afferent (Ia) firing from muscle spindle due to cooling (Correct answer)
- Direct inhibition of alpha motor neurons at the spinal cord
- Increased Golgi tendon organ sensitivity
Correct answer: Decreased afferent (Ia) firing from muscle spindle due to cooling
Cooling slows the firing rate of muscle spindle afferents (Ia fibers), temporarily reducing the excitatory drive and decreasing spastic tone.
Question 5: Which type of electrical stimulation parameter is MOST appropriate for preventing disuse atrophy in a patient with an immobilized limb?
- High-volt pulsed current (HVPC) for edema control
- Neuromuscular electrical stimulation (NMES) with sufficient intensity to elicit a visible contraction (Correct answer)
- Conventional TENS at high frequency for pain relief
- Microcurrent (MENS) at subsensory levels
Correct answer: Neuromuscular electrical stimulation (NMES) with sufficient intensity to elicit a visible contraction
NMES at motor-level intensity produces muscle contractions that maintain muscle bulk and prevent disuse atrophy.
Question 6: A PT treating a patient with open wounds over the medial knee should avoid which modality directly over the wound?
- Pulsed shortwave diathermy
- Continuous ultrasound (Correct answer)
- Diathermy using inductive coil
- Infrared radiation
Correct answer: Continuous ultrasound
Continuous ultrasound over open wounds risks thermal injury to exposed tissue and is contraindicated; pulsed may be used cautiously per clinical guidelines.
Question 7: For a patient with chronic venous insufficiency and lower extremity edema, which physical agent modality is MOST appropriate to assist fluid mobilization?
- Moist heat pack applied to bilateral lower legs
- Intermittent pneumatic compression (IPC) (Correct answer)
- Ultrasound over the posterior calf
- Cryotherapy with compression wrap
Correct answer: Intermittent pneumatic compression (IPC)
Intermittent pneumatic compression mechanically mobilizes interstitial fluid proximally, reducing edema associated with chronic venous insufficiency.
NPTE-PT Therapeutic Modalities Application 3
A PT plans to use iontophoresis with dexamethasone to treat a patient with carpal tunnel syndrome.
Dexamethasone is negatively charged; which electrode setup is correct?