Which current type is not typically used for stimulation of denervated muscle?

Which current type is not typically used for stimulation of denervated muscle?

• A. Direct current
• B. Alternating current
• C. Pulsed direct current
• D. Pulsed biphasic current

Answer: (B)

Stimulation of denervated muscle relies on directly exciting the muscle membrane because the nerve supply is gone. That requires a depolarizing stimulus with enough duration and a net charge in one direction to overcome the membrane’s resistance. Direct current, or monophasic/pulsed direct current with long pulse durations, provides a unidirectional flow that delivers net charge to the muscle membrane, making it capable of evoking contraction. Alternating current, on the other hand, continually reverses polarity and delivers little or no net charge over time, so it usually does not produce a sustained, functional contraction in denervated muscle. Pulsed biphasic current can be used in denervated muscle only if the pulse duration is long enough to directly excite the muscle membrane, but the typical approach emphasizes direct current or long-duration monophasic pulses.

Stimulation of denervated muscle relies on directly exciting the muscle membrane because the nerve supply is gone. That requires a depolarizing stimulus with enough duration and a net charge in one direction to overcome the membrane’s resistance. Direct current, or monophasic/pulsed direct current with long pulse durations, provides a unidirectional flow that delivers net charge to the muscle membrane, making it capable of evoking contraction.

Alternating current, on the other hand, continually reverses polarity and delivers little or no net charge over time, so it usually does not produce a sustained, functional contraction in denervated muscle. Pulsed biphasic current can be used in denervated muscle only if the pulse duration is long enough to directly excite the muscle membrane, but the typical approach emphasizes direct current or long-duration monophasic pulses.