The importance of pulse frequency as a parameter in neurostimulation is well-known. Data published in Neuromodulation: Technology at the Neural Interface offer an analysis of the effects of pulse frequency alteration on stimulation thresholds, paraesthesia site coverage and patient sensation and satisfaction associated with spinal cord stimulation.
Measuring changes in perception threshold, therapeutic perception and discomfort threshold, researchers stimulated fifty patients at 26 pulse frequency rates between 40 and 1200Hz. Sustaining a pulse width of 300μsec, the researchers also observed the paraesthesia coverage of the painful area, as well as patient satisfaction and sensation.
The researchers found a statistically significant (p<0.05) inversely proportional relationship between pulse frequency and stimulation threshold, with the mean threshold decreasing for all three measures as the pulse frequency increased. “As pulse frequency increased from 40 to 1200Hz, the mean threshold decreases from 7.25 to 1.38 (perception threshold), 8.17 to 1.63 (therapeutic perception) and 9.2 to 1.85 (discomfort threshold)”, the authors noted. Differences became significant at 750Hz for perception threshold and therapeutic perception, and at 650Hz for discomfort threshold. Paraesthesia coverage was not observed to be significantly influenced by pulse frequency.
Unsurprisingly, the authors noted that pulse frequency significantly “affects patient sensation and satisfaction.”
Given the inverse relationship between pulse frequencies, stimulation thresholds and therapeutic perception, the authors recognise that pulse frequency is a “vital parameter” to the achievement of therapeutic success. According to these data, the quality of paraesthesia and patients’ individual sensory experience can be modified by pulse frequency.
Considering the implications of their research, the authors suggest that “higher pulse frequency may need to be set up at subthreshold amplitude to achieve positive response.”
The study was carried out by David Abejón (Hospital Universitario Quirón Madrid, Spain) and colleagues.