Effect of painless diabetic neuropathy on pressure pain hypersensitivity (hyperalgesia) after acute foot trauma

Abstract

Introduction and objectiveAcute injury transiently lowers local mechanical pain thresholds at a limb. To elucidate the impact of painless (diabetic) neuropathy on this post-traumatic hyperalgesia, pressure pain perception thresholds after a skeletal foot trauma were studied in consecutive persons without and with neuropathy (i.e. history of foot ulcer or Charcot arthropathy).Design and methodsA case–control study was done on 25 unselected clinical routine patients with acute unilateral foot trauma (cases: elective bone surgery; controls: sprain, toe fracture). Cases were 12 patients (11 diabetic subjects) with severe painless neuropathy and chronic foot pathology. Controls were 13 non-neuropathic persons. Over 1 week after the trauma, cutaneous pressure pain perception threshold (CPPPT) and deep pressure pain perception threshold (DPPPT) were measured repeatedly, adjacent to the injury and at the opposite foot (pinprick stimulators, Algometer II®).ResultsIn the control group, post-traumatic DPPPT (but not CPPPT) at the injured foot was reduced by about 15–25%. In the case group, pre- and post-operative CPPPT and DPPPT were supranormal. Although DPPPT fell post-operatively by about 15–20%, it remained always higher than the post-traumatic DPPPT in the control group: over musculus abductor hallucis 615 kPa (kilopascal) versus 422 kPa, and over metatarsophalangeal joint 518 kPa versus 375 kPa (medians; case vs. control group); CPPPT did not decrease post-operatively.ConclusionPhysiological nociception and post-traumatic hyperalgesia to pressure are diminished at the foot with severe painless (diabetic) neuropathy. A degree of post-traumatic hypersensitivity required to ‘pull away’ from any one, even innocuous, mechanical impact in order to avoid additional damage is, therefore, lacking.

Comparison of Postoperative Pain and Analgesia Requirement among Diabetic and Nondiabetic Patients undergoing Lower Limb Fracture Surgery – A Prospective Observational Study

“…In a study by Wienemann et al ., they concluded that physiological nociception and posttraumatic hyperalgesia to pressure is diminished at the foot with severe painless (diabetic) neuropathy. [ 16 ] This suggests that patients with painless diabetic neuropathy experience less posttraumatic/postsurgical pain in comparison to patients with painful diabetic neuropathy. This may be due to diabetic nerve damage leading to less pain.…”

Conventional deep pressure algometry is not suitable for clinical assessment of nociception in painless diabetic neuropathy

“…Lidocaine blockade of cutaneous nociceptors, increasing mechanical pain thresholds, but not tactile detection thresholds ( 32 ), changes the character of mechanically stimulated pain from sharp pricking pain to dull pressure discomfort ( 15 ). Interestingly, the mechanoreceptors stimulated by conventional algometer are subject to sensitisation from inflammation due to a single strong trauma ( 4 ), or chronic repetitive submaximal trauma ( 33 , 34 ), since DPPPT and mechanical detection threshold decrease in response to these conditions in healthy subjects.…”

“…The following structures were co-stimulated: glabrous skin and subdermal fat tissue, plantar fascia; medial plantar vein artery and nerve. Previous studies had reported that healthy subjects’ 1 cm 2 DPPPT averages around 20 to 50 N/cm 2 over abductor hallucis muscle ( 1 , 4 , 5 , 27 , 28 ).…”

A Novel Diagnostic Test for End-Stage Sensory Failure Associated With Diabetic Foot Ulceration: Proof-of-Principle Study

“…27 At the palmar side of the hand, the average pinprick-pain perception threshold is around 250 mN, and at the plantar side of the foot, it is around 120 mN. 28,29 Due to acquired individual psycho-physical irritability, 30 the pain response to pinprick stimulation varies little intraindividually, but considerably between people. Hence, in healthy human populations, the range of pinprick-pain perception thresholds is wide, reaching from <10 mN (1 g) to >1000 mN (100 g), with a bell-shaped logarithmic distribution, see Mücke et al 17…”