This document summarizes Dr. Kelkar's presentation on quantifying sensory neuropathy in diabetic patients. It discusses how 85% of diabetic foot problems are neuropathic due to loss of sensation. Clinical exams can detect neuropathy but are not always done and are subjective. Quantitative tests like monofilaments, biothesiometers and tuning forks can objectively measure light touch, vibration and temperature sensation loss. An Indian version of the biothesiometer has been developed and shows promising results correlating with international versions. Further developments of heat/cold tests and foot impression materials will improve diabetic foot care in India.

1. An update on sensory testing
Dr. Sanjeev Kelkar M.D.
1st
National Foot Group Meeting
Bangalore – 22nd
July 2001

2. Diabetic Sensory Neuropathy:1
• 85% of Diabetic Foot problem is neuropathic.
• It is the insensate foot that causes considerable morbidity.
• Repetitive, unnoticed trauma results in inflammation and
ulceration.

3. Diabetic Sensory Neuropathy:2
• Variety of trauma known.
• Diagnosis of sensory neuropathy often late when trauma
has already resulted in foot ulcer

4. Diabetic Sensory Neuropathy:3
• Late Diagnosis due to:
• Patient factors.
• No pain, no complaint
• Ulcer but no pain, no complaint
• Physician:
• No complaint, no examination 7% of patients were ever
examined in one of the Bangalore study in all years of
diabetes.

5. Diabetic Sensory Neuropathy:4
• Clinical examination (when done)
• Reveals evidence of neuropathy as
- Loss of reflexes
- Loss of pain, touch heat and cold sensation or
decrease
- Loss of proprioception
- Loss of vibration sense

6. Diabetic Sensory Neuropathy:5
• Clinically: Positive symptoms
• Dysesthesia
• Paresthesia
• Hyperesthesia
Examination:
Could still be insensate to touch, pain, temperature – The
painless – Painful foot.

7. Diabetic Sensory Neuropathy:6
Clinical Examination depends upon –
Clarity of communication by the physician.
Clarity of understanding of patient and clear response.
Difficult to quantify.

8. Diabetic Sensory Neuropathy:5
Quantifying the loss of function useful to correlate –
Degree of loss to the likelihood of developing morbidity
Important for early diagnosis of foot at risk develop
preventive strategies.

9. Diabetic Sensory Neuropathy:8
What sensations can vibration sense
Pain on analog scale – (suffers most on account subjective
variation of pain threshold, severity perception pressure:
force/area sense of pressure - quantifiable

10. Instruments for quantification:I
• Quantification needs instrumentation.
• Available or:
• Light touch + pressure
• SW monofilaments
• A nylon fiber, held again a foot and bent,
• Gives 10 gms of weight / pressure

11. Instruments for Quantification:2
• Simple, well tested method
• Identifies easily foot at risk if the patient cannot sense the
10 gm pressure.
• Correlates well with other tests.

13. Instruments for Quantification:3
• To test vibration sense
• Tuning fork – frequency of 128
• Diagnoses per sense or absence of vibration sense but does
not indicate quantifiable severity of loss.

14. Instruments for Quantification:2
• Graduated tuning fork:
• Weighted and graduated for 0 – 10
• The apex of the triangle rises from 0 – 10
• If vibrations are perceived beyond 6, vibration sense
considered normal.
• At best semi quantitative.

15. Instruments for Quantification:5
• Biothesiometer:
• Delivers vibrations in micron displacements increasing
with increasing voltage applied.
• Loss of vibration sense quantifiable well in terms of
voltage applied,
• V read off simply on the panel.

16. Instruments for Quantification:2
• Indian version available.
• Normal range on 300 normal, non diabetic Indian doctors
and nurses, across the country
• 4 to 9 volts
• Much higher thresholds in diabetics with neuropathy upto
48 volts, vibrations not perceived.

17. Instruments for Quantification:7
• Indian version tested in 75 patients by Dr. Vijay
Viswanathan against an English Biothesiometer.
• P value for inter instrumental interpersonal variation, on
first analysis – not significant
• Correlates well, needs more stringent analyses – under
way.

18. Instruments for Quantification:8
• Heat and cold perception thresholds
• Foreign instruments available but difficult to get Indian
version being developed by NNEF.

19. Correlations: 1
• “If any one sensation tested is abnormal, then the
possibility that there will be at least one more abnormal
sensation is high”.
Dyke - Thomas

20. Correlations: 2
• Abnormality detected on Monofilaments has equal
sensitivity and specificity with an abnormality detected on
biothesiometer.
• Quantifiable accuracy of course is greater with
biothesiometer.

21. Correlations: 3
• Biothesiometer voltage value on insensate vibration, of 25
volts, exposes the foot to risk of ulceration 43 times more
than a normal foot.
• Proportionate increase in risk is present with lower but
above normal voltage measurements.

22. Achievements
• Monofilaments in Indian version also available
• Biothesiometer available
• Heat and cold perception threshold under development.
• Materials tested for taking foot impressions for castes –
available graduated tuning fork developed, more
refinement under way.