Incontro Nazionale Neurofisiologia:
Nuove Strategie
“Controversie sulla diagnosi e terapia del dolore
neuropatico”
Palermo, 29-30 novembre 2012
Il QST fornisce elementi utili
nella diagnosi di DN?
Si  David Yarnitsky
No  Valeria Tugnoli
Discussant
Marcello Romano, Stefano Tamburin,
Premesse
Romano
Palermo, 29-30 novembre 2012
Quantitative Sensory Testing
1. Psychophysical tests: cooperation of the patient is
needed
2. Method to assess and quantify the function of
sensory systems
3. Quantify sensory changes – positive and negative
(vs. EMG and Evoked Potential )
4. Stimuli (mechanical, thermal, painful) of controlled
intensity  measure of thresholds
5. Evaluation of the entire sensory system
receptor  cortex
6. Follow up after therapy and surgery
QST
Sensory stimuli:
Thermal (hot / cold)
vibrators
Mechanical (touch, pressure)
electrical
Painful stimuli:
- Thermal (cold pain / heat
pain), mechanical
(pinprick, pressure pain
sensibility), electric
P. Hansson et al. Pain, 2007
Threshold calculation
Method of limits
Stimulus intensity increasing /
decreasing,
As soon as the patient feel the
sensation, he/she presses a button
Method of levels
Stimulus intensity is predetermined
The patient is asked after stimulus
administration: the answer
determines the level of the next
stimulus ( o )
Thermal QST
Computerized system based on the principle of Peltier
(the temperature of the thermode varies as a function of the
intensity and direction of the current)
The subject is instructed to report when it senses a
change in temperature (cold or hot) or pain (cold or hot),
then responses are recorded and the detection and pain
thermal thresholds are calculated
“Small fibre” neuropathies –
many not detected by conventional nerve conduction and
EMG studies, particularly at early stages
•
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Diabetic
Alcohol-related
Uraemic
Nutritional deficiency
Amyloidosis
Inflammatory
Toxic (including chemotherapy-induced)
HSAN Type IV, V, HMSNs
Erythromelalgia
HIV
© Imperial College London
Negative signs
Thermal thresholds: cold (CDT), warm (WDT)
Thermo-algesic thresholds: cold pain (CPT), hot pain (HPT)
Negative symptoms: hypo/anesthesia, hypo/analgesia)
Normal
Hypoestesia for all modalities
Positive signs
Allodynia: pain evoked by mechanical innocuous stimuli
Thermal hyperalgesia: Excessive pain response to thermal stimuli
Aftersensation: persistence of pain after the end of stimulation
Thermal hyperalgesia
37.4
34.5
27.3
12.3