To increase the strength of a stimulation, which parameter should not be increased?

• A. Amplitude
• B. Phase duration
• C. Frequency
• D. Interpulse interval

Answer: (D)

Strength comes from delivering more charge over time by adjusting how pulses are delivered. The time between pulses, the interpulse interval, controls how often pulses arrive. Increasing this interval spaces pulses farther apart, reducing how many pulses occur per second (lowering the frequency) and lowering the total energy delivered in a given moment. So, to make stimulation stronger, you don’t want to increase the interpulse interval.

In contrast, increasing amplitude raises the charge per pulse, increasing phase duration lengthens each pulse and also raises charge per pulse, and increasing frequency raises the number of pulses per second. All of these can enhance overall stimulation, whereas lengthening the gap between pulses diminishes it.