DPT Electrotherapy & Modalities 3

Question 1

Which pulse characteristic of TENS is most responsible for determining comfortable sensory versus motor recruitment?

Accepted Answer

Pulse duration (µs)

Answer

Pulse duration (width) determines which fiber types are recruited; longer durations recruit larger motor fibers, while shorter durations preferentially stimulate sensory Aβ fibers.

Question 2

A patient reports increased pain 24 hours after ultrasound treatment to the Achilles tendon. The most likely cause is:

Accepted Answer

Excessive thermal effects from continuous mode at high intensity

Answer

Continuous ultrasound at high intensity over a superficial tendon can generate excessive heat, causing delayed inflammatory pain flare-up.

Question 3

Acupuncture-like TENS (AL-TENS) is characterized by:

Accepted Answer

Low frequency (1–10 Hz), high intensity producing visible muscle twitching

Answer

AL-TENS uses low frequencies (1–10 Hz) and high intensity sufficient to elicit rhythmic muscle twitching, theorized to release endorphins via motor fiber stimulation.

Question 4

For a patient with lymphedema, which electrophysical agent should be AVOIDED?

Accepted Answer

Thermal ultrasound over the affected limb

Answer

Thermal ultrasound increases local blood flow and capillary permeability, potentially worsening edema formation in lymphedematous tissue.

Question 5

The inverse square law applies to which modality and explains why treatment distance is critical?

Accepted Answer

Infrared radiation

Answer

Infrared radiation intensity is inversely proportional to the square of the distance from the source, so doubling distance reduces intensity by 75%.

(DPT) Board Certified Doctor of Physical Therapy Practice Test

(DPT) Board Certified Doctor of Physical Therapy Practice Test

DPT Electrotherapy & Modalities 3