title: Threshold Evolution as an Analysis of the Different Pulse Frequencies in Rechargeable Systems for Spinal Cord Stimulation.
abstract: BACKGROUND
  Pulse frequency (Fc) is one of the most important parameters in neurostimulation, with Pulse Amplitude (Pw) and Amplitude (I). Up to certain Fc, increasing the number of pulses will generate action potentials in neighboring neural structures and may facilitate deeper penetration of the electromagnetic fields. In addition, changes in frequency modify the patient's sensation with stimulation.
  
  
  METHODS
  Fifty patients previously implanted with rechargeable current control spinal cord stimulation. With pulse width fixed at 300 μsec, we stimulated at 26 different Fc values between 40 and 1200 Hz and determine the influence of these changes on different stimulation thresholds: perception threshold (Tp ), therapeutic perception (Tt), and discomfort threshold (Td). Simultaneously, paresthesia coverage of the painful area and patient's sensation and satisfaction related to the quality of stimulation were recorded.
  
  
  RESULTS
  Pulse Fc is inversely proportional to stimulation thresholds and this influence is statistically significant (p < 0.05). As Pulse Fc increased from 40 to 1200 Hz, the mean threshold decreases from 7.25 to 1.38 mA (Tp ), 8.17 to 1.63 (Tt ), and 9.20 to 1.85 (Td). Significant differences for Tp and Tt began at 750 Hz (Tp , Tt ) and at 650 Hz for Td. No significant influence was found regarding paresthesia coverage. As expected, Fc affects significantly patient's sensation and satisfaction.
  
  
  CONCLUSIONS
  Changes in Fc affect the quality of paresthesias. Within the evaluated parameters higher frequencies are inversely proportional to stimulation thresholds and Tt. It seems that Fc is a vital parameter to achieve therapeutic success.
  
  
  CONCLUSIONS
  Changes in Fc is a useful parameter to modulate the patient's sensory perception. Fc can be successfully used to adjust the quality of the paresthesias and to modify patient's subjective sensation. We showed that as the frequency increases, the patient's satisfaction with the perceived sensation decreases, suggesting that higher Fc may need to be set up at subthreshold amplitude to achieve positive response.
authors: Head of Pain Unit, Hospital Universitario Quirón Madrid, Madrid, Spain.
authors: David
authors: D
authors: Abejón
authors: Medtronic, Miami, FL, USA.
authors: Pablo
authors: P
authors: Rueda
authors: Director of Research Millennium Pain Center, IL, USA.|Biology Department, Illinois State University, Normal, IL, USA.|Wesleyan University, Bloomington, IL, USA.
authors: Ricardo
authors: R
authors: Vallejo
mesh_terms: D000704:Analysis of Variance; D001703:Biophysics; D016009:Chi-Square Distribution; D011211:Electric Power Supplies; D005260:Female; D006801:Humans; D008297:Male; D059408:Pain Management; D017288:Pain Threshold / Q000502:physiology*; D010292:Paresthesia / Q000628:therapy*; D017060:Patient Satisfaction; D012189:Retrospective Studies; D062187:Spinal Cord Stimulation / Q000295:instrumentation* / Q000379:methods*
keywords: High frequency electrical stimulation; low frequency electrical stimulation; neurostimulation; perception threshold; programming strategies; spinal cord stimulation