During acute subdeltoid bursitis treatment, conventional TENS will modulate pain primarily through which mechanism?

The correct choice is gate control mechanisms. In the context of acute subdeltoid bursitis treatment using TENS (Transcutaneous Electrical Nerve Stimulation), the gate control theory of pain modulation is highly relevant. According to this theory, the stimulation of large-diameter A-beta sensory fibers can inhibit the transmission of pain signals carried by smaller A-delta and C fibers. This occurs at the spinal level, where the "gate" can either allow or block the passage of pain signals to the brain.

When TENS is applied, it delivers electrical impulses that activate these larger fibers, effectively "closing the gate" on pain transmission. As a result, the patient experiences a reduction in pain perception associated with the acute inflammatory condition of the subdeltoid bursa. This mechanism is particularly effective for acute pain relief during the early stages of tissue injury when inflammation and nociceptive signaling are heightened.

Stimulation of endorphins (the option related to natural pain relief mechanisms) is also a valid response to TENS; however, it generally involves longer-term analgesic effects and is more associated with lowered pain thresholds over time. Ascending and descending inhibition relate to more complex neural pathways that involve modulation both at the spinal level and central nervous system,