Strength Duration Curve in Electrical Stimulation

Which of the following best describes the strength duration curve?

Short pulse durations require lower amplitude to reach the threshold than long pulse durations.

What is the expected response for sensory nerves when amplitude increases with a constant duration?

The only E.Stim unit capable of delivering enough charge to reach the threshold of the muscle membrane is _____ because it has a long duration.

Match the specific waveform with its characteristic:

Which pulse duration represents the longest duration?

In biphasic waveforms, polarity effects occur only if the waveform is balanced.

What happens to the motor response as more motor units are recruited?

Pulses with long durations require _____ amplitude to reach the threshold of the same nerve.

Which type of current is characterized by a waveform where the current consistently flows in one direction?

Strength Duration Curve

The Strength Duration Curve demonstrates the relationship between the amplitude (strength) and duration of an electrical pulse.
The area of a pulse (strength x duration) represents the charge delivered.
Short pulses require higher amplitude (strength) to reach threshold.
Long pulses require lower amplitude (strength) to reach threshold.
Charge remains constant regardless of pulse duration and amplitude.
Example: Short and strong pulse (landscape orientation) vs. long and weak pulse (portrait orientation) deliver the same charge.

Nerve Activation with Electrical Stimulation (E.Stim)

Nerve activation sequence with increasing E.Stim: sensory, motor, pain.
Sensory nerves have a lower threshold for activation than pain nerves.

E.Stim Response with Increasing Amplitude

Constant Duration and Increasing Amplitude:
Sensory: tingling, buzzing
Motor: weak contraction that strengthens as more motor units are recruited
Pain

Muscle Membrane Threshold

Muscle membrane has a higher threshold than nerve membranes.
Only Direct Current (DC) can effectively stimulate muscle tissue due to its long duration.

Waveforms of Therapeutic Current

Monophasic: Current flows in one direction; either anode (positive) to cathode (negative) or vice versa. Produces a polarity effect. Represented by pulses above or below the 0 line.
Biphasic: Current flow changes direction; represented by pulses above and below the 0 line. Produces a polarity effect only if unbalanced.
Polarity refers to the direction of electron flow.

This quiz explores the Strength Duration Curve and its implications in electrical stimulation, specifically in nerve activation. It covers the relationship between pulse strength and duration, and how different nerve types respond to increasing electrical stimulation. Test your understanding of these essential concepts in the context of E.Stim.