title: Increased contact heat evoked potential stimulation latencies in responders to spinal cord stimulation for painful diabetic polyneuropathy.
abstract: OBJECTIVE
  To analyze sensory characteristics and small nerve fiber function in patients suffering from painful diabetic polyneuropathy (PDP) and compare outcomes in responders and nonresponders to SCS treatment.
  
  
  METHODS
  Fifteen patients with intractable PDP in the legs were recruited. If trial stimulation resulted in clinically relevant pain relief, a pulse generator was implanted and pain scores were measured after 12 months. Sensory characteristics (modified Inflammatory Neuropathy Cause and Treatment [md-INCAT] sum score) and small nerve fiber function (contact heat evoked potentials, CHEPs) were measured before implantation (D1), and CHEP measurement was repeated after two weeks of trial stimulation (D2). Outcomes in responders (N = 10) and nonresponders (N = 5) to SCS treatment were compared. Data were analyzed using nonparametric statistics.
  
  
  RESULTS
  At one year, clinically relevant pain relief was achieved in 10 out of 15 patients. The md-INCAT score did not differ between SCS responders and nonresponders (8.0 vs. 5.0; p = 0.59). No differences were found in CHEP outcomes at D1 vs. D2, except for dorsal forearm P2 latency, and the correlation between D1 and D2 CHEP outcomes was high. Volar N2 forearm latency (0.492 vs. 0.434; p < 0.01), dorsal forearm N2 latency (0.518 vs. 0.453; p = 0.04), and dorsal forearm P2 latency (0.660 vs. 0.589; p = 0.04) were increased in SCS responders as compared with SCS nonresponders.
  
  
  CONCLUSIONS
  From this small-scale clinical pilot study we conclude that forearm CHEP latencies are increased in PDP patients who respond to SCS therapy as compared with SCS nonresponders. Before the CHEP latency can be used as a predictor of SCS outcome in PDP patients, a large-scale study is needed.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Wouter A
authors.initials: WA
authors.lastname: Pluijms
authors.forename: Rachel
authors.initials: R
authors.lastname: Slangen
authors.forename: Maarten
authors.initials: M
authors.lastname: van Kleef
authors.forename: Elbert A
authors.initials: EA
authors.lastname: Joosten
authors.forename: Jos P H
authors.initials: JP
authors.lastname: Reulen
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003929:Diabetic Neuropathies / Q000628:therapy*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005121:Extremities / Q000503:physiopathology; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058748:Pain Perception; D011930:Reaction Time / Q000502:physiology*; D062187:Spinal Cord Stimulation / Q000379:methods*; D013997:Time Factors
keywords: Contact heat evoked potentials; diabetic neuropathies; electric stimulation therapy; painful diabetic polyneuropathy