title: Pressure pain perception in the diabetic Charcot foot: facts and hypotheses.
abstract: BACKGROUND
  Reduced traumatic and posttraumatic (nociceptive) pain is a key feature of diabetic neuropathy. Underlying condition is a gradual degeneration of endings of pain nerves (A-delta fibers and C-fibers), which operate as receivers of noxious stimuli (nociceptors). Hence, the absence of A-delta fiber mediated sharp pain ("first" pain), and of C-fiber mediated dull pain ("second" pain). However, patients with diabetic neuropathy and acute Charcot foot often experience deep dull aching in the Charcot foot while walking on it.
  
  
  OBJECTIVE
  To create a unifying hypothesis on the kind of pain in an acute Charcot foot.
  
  
  RESULTS
  Absence of punctuate (pinprick) pain perception at the sole of a Charcot foot, as was shown recently, likely corresponds to vanished intraepidermal A-delta fiber endings. C-fiber nociceptors are reduced, according to histopathology studies. Both types of fibers contribute to posttraumatic hyperalgesia at the skin level, as studies show. Their deficiencies likely impact on posttraumatic hyperalgesia at the skin level and, probably, also at the skeletal level.
  
  
  CONCLUSIONS
  It is hypothesised that deep dull aching in an acute diabetic Charcot foot may represent faulty posttraumatic hyperalgesia involving cutaneous and skeletal tissues.
authors.affiliation: Diabetic Foot Clinic, Department of Endocrinology and Diabetes, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany.
authors.forename: Ernst A
authors.initials: EA
authors.lastname: Chantelau
authors.forename: Tobias
authors.initials: T
authors.lastname: Wienemann
keywords: Charcot neuroarthropathy; diabetic neuropathy; pain perception