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  1. 1. DM and HCP Early Detection of Heat and Cold Perception in Diabetic Neuropathy Issues and Reasons Dhananjay Kelkar Dhansai Laboratory, Mumbai
  2. 2. Anatomy of Heat, Cold and Pain Perception Small Fibers sub-serve warm cold and pain sensation The C fibers C Fibers Unmyelinated, without specialized Nerve endings, lying naked in tissues Distinct from A delta deep aches and pain
  3. 3. Symptoms 1 Diabetic foot ulcers has great impact on morbidity and mortality of life First symptoms to appear pain, hyperesthesia, hyperalgesia, allodynia - that is contact pain Abnormalities of C fibers supposedly responsible for early occurrence of symptoms
  4. 4. Symptoms 2 Other somatic sensations of pressure, touch, vibration, proprioception are likely as not, not affected at this stage Makes more sense to detect HC thresholds Early pain and heat hyperalgesia and later hypoalgesia>Further damage to C fibers Also impairs the warm thermal perceptions (Aron Vinik Exp Clin Endocrinol Diabetes- 109 (2001) (Suppl 2)
  5. 5. Time of Damage Other authors have also considered these to be the first fibers to be affected in diabetic neuropathy (Jamal et al, 1987, Dyck, 1988, Hanson et al, 1992, as quoted by Vinik vide above) Various symptoms occur when there is on going damage to the nerves initially
  6. 6. Time and Sequence of Damage Pain of A delta thinly myelinated is deep seated and gnawing, Pain of C fibers is described in most vivid terms like burning, bursting, walking on hot pebbles and sand etc Symptoms occur when structural damage has occurred - not without it
  7. 7. Some More Concerns Diabetes affects rhythmic vasomotion of small arterioles due to sympathetic damage early in disease, Loss of warm thermal threshold also occurs early with C fiber damage and correlates significantly to reduced vasomotion (Vinik ibid) Exact cause effect or association between vasomotion and C fiber damage as a time relationship is not established (ibid)
  8. 8. Pathological Evidence Skin biopsies in persons with Diabetes show uniform depletion of substance P, CGRP and the cytoplasmic proteins PGP 9.5 for small fiber specificity (Levy et al, 1992,Wallargren et al, 1995, Lauria et al, 1998,and others) Glabrous skin of the foot is far more affected by Diabetes than that of hand
  9. 9. Can we do something? Detect early? Of what use? Cost effective? Other benefits? Can we stop progression? Can we reverse abnormalities? Is detection easy?
  10. 10. Can we do something? - 2 Can we stop progression? Can we reverse abnormalities? Enough medical evidence to say yes to these questions if the detection is early enough Malady is failure of early detection
  11. 11. Can we do something?- 3 Detect early? Yes. Sensitive and simple instrument for detection, detects heat, cold, heat pain and cold pain thresholds, Used by many Further simplified on feedback after field study Reliable and reproducible thresholds Needs grasp of the working of the instrument
  12. 12. Can we do something? - 4 Cost effective? Needs time, about 15 to 20 minutes of technician, Used carefully no maintenance cost, after sales service, no consumables required etc;
  13. 13. Can we do something? - 5 Other benefits? Indicates simultaneous possibility of Autonomic dysfunction Acts as motivator for better glucose control
  14. 14. Tissue Damage Heat pain threshold range is 42 to 45 0 C Erythema takes place after an hour at 45 0 C Needs 10 second to a minute at 50 0 C And just One second at 55 0 C
  15. 15. A Little Physiology - 1 C fibers carry sensations slower, have a period of latency of about 500 milliseconds before the impulse gets initiated Consequently there is a further delay in reaching the sensation to the cortical areas as the velocities are slow, therefore There is a further delay for the registration of the sensation and response to it
  16. 16. A Little Physiology - 2 These factors dictate the working of he instrument These factors determine the rise of temperature in degrees as well as the time taken to change the level of temperature Applies also to the rate of fall of temperature in time
  17. 17. A Little Physiology - 3 A rate of one degree per second is generally recommended For heat and cold thresholds the rate of rise or fall of temperature seems best at 1 degree Celsius over 4 seconds This makes testing a little longer but gives precise thresholds, reduces the need for many readings, averaging etc
  18. 18. Needed Early detection Early detection of the early fibers that are affected HCP is an answer
  19. 19. Sensitometer-HCP Made in India
  20. 20. HCP Probe
  21. 21. A Little Physiology - 4 Concept of heat pain and cold pain should be understood; these thresholds are higher and lower than heat and cold respectively Cool pain is sensation of coolness with an additional component of un-comfort Heat pain is warmth plus pricking sensation It is the slight un-comfort and not, not the ability to bear
  22. 22. A Little Physiology - 5 The rate of rise or fall of temperature to detect Heat pain & Cool Pain also seems best at 1 degree Celsius over 4 seconds Two additional thresholds make testing a little longer but gives precise thresholds, Only cool and heat pain thresholds are enough for clinical practice
  23. 23. Operation of the instrument 1
  24. 24. Operation of the instrument 2
  25. 25. Normal range 32 to 34 o C is neutral zone Just bellow 32 o C & up to 30 o C is the Cool threshold range -age dependant 27 to 25 o C Cool pain 36 to 38 o C warm And 42 to 45 o C Heat pain zone Above ranges are true for clinical practice in an ambiant temperature of 27 to 37 o C
  26. 26. Other featchers It can be operated through PC Report can be generated through PC Data can be stored and retrieved for future use Data can be picked by hospital/clinic management system as well
  27. 27. Thank you for a patient hearing

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