Quantitative sensory testing

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The Quantitative Sensory Testing (QST) is a psycho-physical method for quantitative measurement of various sensory / sensitive and pain modalities that in the diagnosis of neuropathic pain (positive symptoms) and the diagnosis of sensory disturbances (sensory deficits, negative symptoms) can be used (Rolke, Baron, Maier et al. 2006).

development

The "German Research Association for Neuropathic Pain" (DFNS) headed by Rolf-Detlef Treede at the University of Mainz has examined modern stimulus instruments in standardized form for measurement in 180 normal people in order to generate a reference standard. Thirteen different sensitive and pain tests were combined into a test battery , although there are also alternative compositions.

Procedure of the DFNS protocol

The test requires the respondent to be alert and active. First of all, the warm and cold thresholds are tested using a thermode, then the warm-cold alternation and then the heat and cold pain . The epicritical sensitivity is then tested using glass fiber monofilaments (equivalent to von Frey hairs with a strength of 0.5 to 512 mN ) . This is followed by the examination by means of pin pricks , blunt needles which, due to their force (from 8 to 512 mN, corresponds to 0.8 to 51.2 g), produce acute pressure pain on a certain area of ​​skin. This is followed by testing for allodynia with sharp stimuli (pin pricks) and touching with a Q-tip, brush and cotton ball. Here, the patient must indicate the pain intensity felt by the irritation from 0–100. Then comes the wind-up test; First a single stimulus is rated 0–100 and then the sum of 10 single stimuli in a 60 Hz rhythm. The stimulation takes place by means of pin pricks. This is followed by the pressure measurement, for this purpose a pressure stimulator (algometer) is placed on the respective part of the body and pressed until the test person finds it uncomfortable. Finally, there is the usual pallesthesia (vibration measurement using a Rydel-Seiffer tuning fork ).

Selected DFNS stimulus instruments and how they work

  • The TSA 2001-II Thermal Sensory Analyzer (contact surface 9 cm², stimulation range 0 to 50 ° C; Medoc Ltd., Israel) device is used to generate defined heat and cold stimuli (comparable devices include: Thermotester Somedic, Sweden; contact surface 5 cm², and MSA Thermal Stimulator Somedic, Sweden, contact area 12.5 cm²). The examiner varies the stimulus temperature up to the perception of heat / cold or heat / cold / pain by the test person. The temperature stimuli stimulate intraepidermal free endings of the afferent Aδ (cold) and C nerve fibers, which function as polymodal receptors with a low threshold mechano-thermal-receptors for mechanical and thermal stimuli, or those with a high threshold mechano -thermal-receptors), which act as pain receptors (nociceptors).
  • The Rydel-Seiffer tuning fork is used to generate controlled vibrations. The tuning fork, which is set to vibrate (64 Hz), is placed with the end of its stem on a bone structure; the horizontal vibrations of the tines cause vertical 64 Hz impact movements of the handle, which are transmitted to the base. The oscillation amplitude / vibration amplitude, which decreases in the course of the oscillation process, can be determined semi-quantitatively on a scale from 0-8: 0-1 / 8 (= large amplitude, coarse vibration), to 7-8 / 8 (= smallest amplitude, finest vibration) ; the reading is carried out by the examiner after the test person has indicated the end of the vibration perception. Vibration perception is generated by mechanical stimulation of the mechanoreceptors of Meissner and Pacini bodies at the endings of the afferent Aß nerve fibers in the skin or skeleton.
  • To generate punctual mechanical pressure or contact, calibrated blunt glass fiber filaments with a contact area of ​​0.2 mm² and bending forces of 5 to 512 mN (Opti-hair 2, Marstock nerve test, Schriesheim) are pressed vertically onto the skin. The sensory modality of punctual pressure or touch perception is generated by stimulating the low-threshold mechano-receptors ( pressure receptors ) Merkel discs and Meissner bodies at the subepidermal endings of the afferent Aß nerve fibers.
  • Calibrated monofilaments (needle stimulators, pinprick stimulators) made of metal are used to generate punctual mechanical pressure pain effects (needle pressure pain), contact area 0.05 mm², stimulation forces 5 to 512 mN (Pinprick MRC Systems, Heidelberg). The sensory modality of punctual mechanical pressure pain is generated by stimulating the intraepidermal free endings of the afferent Aδ nerve fibers and C nerve fibers ( nociceptors , high-threshold mechano-receptors).
  • A so-called algometer (digital algometer from Somedic, Sweden), a kind of stamp with a contact area of ​​1 cm², is pressed onto the skin to generate deep pressure pain. The skin and underlying tissue are compressed and simultaneously nociceptors (high-threshold mechano-receptors) and pressure receptors (low-threshold mechano-receptors) are stimulated. A dull deep pressure pain develops that cannot be precisely localized.

DFNS reference values ​​(standard values)

The normal values ​​determined by the DFNS on the face, hand and foot differ significantly between the body regions, but not between the left and right halves of the body; they are also age and (to some extent) gender dependent. They are fairly constant when tested repeatedly for each person (intra-individual), but - like the number of sensory nerve fiber endings per square centimeter of skin - they differ considerably between individuals (inter-individual).

DFNS standard values ​​on the foot (selection). According to Rolke, Baron, Maier et al. 2006, p. 236
Sensory modality Stimulus instruments Unit of measure (measuring range) Measurement location Perception threshold, average (95% confidence interval)
vibration Rydel-Seiffer tuning fork 8th (1-8) Inner ankle approx 7.5 (5.5-7.9) / 8
warmth Thermal Sensory Analyzer ° C (0-50) Back of the foot approx. 37 (33-44) ° C
cold Thermal Sensory Analyzer ° C (0-50) Back of the foot approx. 29 (23-32) ° C
Temperature change Thermal Sensory Analyzer ° C (0-50) Back of the foot approx. 7 (2.5-22) ° C
Heat pain Thermal Sensory Analyzer ° C (0-50) Back of the foot approx. 45 (39-50) ° C
Cold pain Thermal Sensory Analyzer ° C (0-50) Back of the foot approx. 12 (2-28) ° C
Touch (pressure), selective Monofilaments Opti-hair2 mN (0.25-512) Back of the foot approx. 3 (0.25-25) mN
Pressure pain, punctiform Pin pricks MRC Systems mN (8-512) Back of the foot approx. 80 (15-430) mN
Deep pressure pain Somedic algometer kPa (1-2000) Sole of the foot, longitudinal arch approx. 400 (250-1100) kPa

reproducibility

Individual investigations under conditions and with the DFSN methodology (perception thresholds for warm and cold stimuli on the dorsum of the foot and for deep pressure pain on the longitudinal arch of the foot) were also carried out independently by other authors; their results agree quite well with the DFNS norm values.

Selected norms, generated outside of the DFNS protocol

Other authors examined other body regions or used other stimulation instruments. Liniger et al. examined the age-appropriate vibration perception threshold at the metatarsophalangeal joint of the big toe with the Rydel-Seiffer tuning fork (normal values ​​around 4-7.5 / 8). Other instruments for the controlled generation of vibrations are electrical devices, e.g. B. the biothesiometer (Biomedical Instruments, Newbury / Ohio USA) and the neurothesiometer (Horwell Scientific Laboratory Supplies, Nottingham UK) with a vibration frequency of 50 to 60 Hz and a stimulation range of 1 volt (minimum) to 50 volts (maximum vibration amplitude), as well as the Somedic Vibrameter (Somedic, Sweden) with a vibration frequency of 100 Hz and vibration amplitudes of 0.5 µm (finest vibration) to 500 µm (coarsest vibration). The vibration amplitude of the devices is varied by the examiner up to the perception by the test person. Kramer et al. examined the vibration perception threshold at the inner ankle with the Somedic Vibrameter (normal value around 2 µm); Peters et al. examined the tip of the big toe with the biothesiometer (normal value around 10 V).

Instruments for measuring the selective pressure or touch sensation are u. a. Semmes-Weinstein monofilaments made of plastic (including the 10 g monofilament, which is used to diagnose diabetic neuropathy). The normal (punctiform) pressure or contact perception threshold on the skin of the sole of the foot of the longitudinal arch is 4-5 mN. Pinprick stimulators for the generation of punctual pressure pain are also available made of optical glass fiber (pinprick stimulators, Marstock nerve test, Schriesheim; contact areas <0.1 mm²); Wienemann et al. at the plantar toe fold a normal pressure pain perception threshold of 128 mN.

evidence

The DFNS protocol is not generally applicable for diagnostic purposes; the entire test protocol is time-consuming, takes at least an hour, is prone to failure, and the various sensitive modalities show different inter-individual variances. The test can only be used as an additional diagnostic tool, as the evidence, particularly from prospective studies, has so far been limited. The test sensitivity is significantly lower than with a skin biopsy for counting the intraepidermal free nerve endings (IEFNE), which is methodologically complex and prone to failure. However, an indication can be given if the results of the conventional electrophysiological tests are normal, and especially if a lesion of small-caliber nerves is suspected (especially in small-fiber neuropathy ). Deviations from the (DFNS) normal values ​​can have disease values, e.g. B. in diabetic polyneuropathy (with atrophy of the endings of the sensitive A-ß-, A-delta- and C-fibers, beginning in the ends of the longest nerves of the body, i.e. in the feet) or leprosy (due to infestation of the Schwann cells with Mycobacterium leprae).

Decreased thresholds of perception (hypersensitivity)

Lower pinprick pressure pain thresholds on the foot and hand are accompanying symptoms in restless legs syndrome and in the hands in Parkinson's disease .

Increased thresholds of perception (decreased sensitivity, insensitivity)

Above-average increased stimulus perception thresholds are found in the arms and legs in chemotherapy-induced neuropathy, and in the leg in peripheral arterial occlusive disease . Raising the threshold for vibration sensitivity to 7 to 14 µm (Somedic Vibrameter) on the medial malleolus represents an advanced diabetic polyneuropathy; Increasing the perception threshold for vibration sensitivity to 30 to 50 V (Horwell Neurothesiometer) on the big toe means - compared to a lower increase - a significantly increased risk of painless diabetic foot ulcers. Perception thresholds for punctual pressure [Semmes-Weinstein filament over 75 g (corresponding to 750 mN)] or for punctual pressure pain [pinprick over 512 mN (corresponding to 51.2 g)] on the sole of the foot are found to be pathogenetic Basic condition - for painless foot ulcers in diabetes mellitus or leprosy .

The QST does not allow the level of the spinal nerve to be localized and it cannot differentiate between peripheral and central lesions of the nervous system. An etiological (cause) assignment is also not possible. The treatment guidelines for neuropathic pain list testing as a supplementary "can" recommendation.

Historical

The method of quantitative sensory testing goes back to the sensory physiologists Ernst Heinrich Weber (1795–1878) and Max von Frey (1852–1932). In 1896, von Frey first measured mechanical stimulus threshold values ​​in human skin using calibrated natural bristles or horse hair. The method of measuring vibration perception with a specially modified tuning fork was first presented in 1903 by Adam Rydel and Friedrich Wilhelm Seiffer .

literature

  • R. Rolke, R. Baron, C. Maier, TR.Tölle, RD.Treede, A.Beyer, A.Binder, N.Birnbaumer, F.Birklein, IC.Bötefür, S.Braune, H.Flor, V. Huge, R.Klug, GB. Landwehrmeyer, W.Magerl, C.Maihöfner, C.Rolko, C.Schaub, A.Scherens, T.Sprenger, M.Valet, B.Wasserka. Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): standardized protocol and reference values. Pain 2006; 123: 231-243 doi : 10.1016 / j.pain.2006.01.041
  • D. Heuss and Commission Guidelines of the German Society for Neurology: Diagnostics in Polyneuropathies. German Society for Neurology, accessed on June 16, 2020 .

Individual evidence

  1. ↑ M. Mücke, H. Cuhls, L. Radbruch, R. Baron, C. Maier, T. Tölle, R.-D. Treede, R. Rolke: Quantitative Testing . In: pain . tape 28 , no. 6 , 2014, p. 635-648 , doi : 10.1007 / s00482-014-1485-4 .
  2. ↑ H. Fruhstorfer, W.Gross, O.Selbmann: From Frey hairs: new material for a new design . In: European Journal of Pain . tape 5 , 2001, p. 341-342 , doi : 10.1053 / eujp.2001.0250 .
  3. ↑ AT.Alahmar: Quantitative sensory testing in type-1 diabetic patients with mild to severe diabetic neuropathy. In: Journal of Research in Medical and Dental Science. 2016, pp. 104-114 , accessed on May 23, 2020 .
  4. ↑ CT.Shun, YC.Chang, HP.Wu, SC.Hsieh, WM.Lin, YH.Lin, TY.Tai, ST.Hsieh: Skin denervation in type-2 diabetes: correlations with diabetic duration and functional impairments . In: Brain . tape 127 , 2004, pp. 1593-1605 , doi : 10.1093 / brain / awh180 .
  5. ↑ EA.Chantelau: Conventional deep pressure algometry is not suitable for clinical assessment of nociception in painless diabetic neuropathy. (pdf) In: Diabetic Foot & Ankle. 2016, pp. 1-6 , accessed on May 23, 2020 .
  6. ↑ C. Liniger, A. Albeanu, D. Bloise, JP Assal: The tuning fork revisited . In: Diabetic Medicine . tape 7 , 1990, pp. 859-864 .
  7. ↑ HH.Krämer, R.Rolke, M.Hecht, A. Bickel, F. Birklein: Follow-up of advanced diabetic neuropathy. Useful variables and possible pitfalls . In: Journal of Neurology . tape 252 , 2005, pp. 315-320 , doi : 10.1007 / s00415-005-0645-y .
  8. ↑ EJG.Peters, LA.Lavery: Effectiveness of the diabetic foot risk classification system if the International Working Group on foot the diabetic . In: Diabetes Care . tape 24 , no. 8 , 2001, p. 1442-1447 .
  9. ↑ NE.Wiggermann, RA.Werner, WM. Keyserling: The effect of prolonged standing on touch sensitivity of the foot: a pilot study . In: Journal of Physical Medicine and Rehabilitation . tape 4 , no. 2 , 2012, p. 190-200 , doi : 10.1016 / j.pmrj.2011.11.002 .
  10. ↑ T.Wienemann, EA.Chantelau: The diagnostic value of measuring pressure pain perception in patients with diabetes mellitus . (Erratum: Swiss Medical Weekly 2013; 143: w13798). In: Swiss Medical Weekly . 1423: w13682. 2012, doi : 10.4414 / swm.2012.13682 .
  11. ↑ K. Stiasny-Kolster, W. Magerl, WH.Oertel, JC.Möller, RD.Treede: Static mechanical hyperalgesia without dynamic tactile allodynia in patients with restless legs syndrome . In: Brain . tape 127 , 2004, pp. 773-782 .
  12. ↑ S. Hägele et al .: "Quantitative sensory testing in patients with idiopathic Parkinson's syndrome" Akt Neurol 2005; 32 - P76, doi : 10.1055 / s-2005-866653
  13. ↑ C.Miaskowski, J. Mastick, SM.Paul, K.Topp, B.Smoot, G. Abrams, LM.Chen, KM.Kober, YP.Conley, M.Chesney, K.Bolla, G. Mausisa, M .Mazor, M.Wong, M.Schumacher, JD.Levine: Chemotherapy-induced neuropathy in cancer survivors . In: J Pain Symptom Manage . tape 54 , 2017, p. 204-217 .
  14. ↑ PM.Lang, GM.Schober, R.Rolke, S.Wagner, R.Hilge, M.Offenbächer, RD.Treede, U. Hoffmann, D. Irnich: Sensory neuropathy and signs of central sensitization in patients with peripheral arterial disease . In: Pain . tape 124 , 2006, pp. 190-200 , doi : 10.1016 / j.pain.2006.04.011 .
  15. ↑ HH.Krämer, R.Rolke, M.Hecht, A. Bickel, F. Birklein: Follow-up of advanced diabetic neuropathy. Useful variables and possible pitfalls . In: Journal of Neurology . No. 252 , 2005, pp. 315-320 , doi : 10.1007 / s00415-005-0645-y .
  16. ↑ CA Abbott, L. Vileikyte, S. Williamson, AL. Carrington, AJM. Boulton: Multicenter study of the incidence of and predictive risk factors for diabetic neuropathic foot ulceration . In: Diabetes Care . tape 21 , no. 7 , 1998, pp. 1071-1075 .
  17. ↑ JA.Birke, DS. Sims: Plantar sensory threshold in the ulcerative foot . In: Leprosy Reviews . tape 57 , no. 3 , 1986, pp. 261-267 .
  18. ↑ EA. Chantelau: A novel diagnostic test for end-stage sensory failure associated with diabetic foot ulceration. Proof-of-principle study . In: Journal of Diabetes Science and Technology . 2020, p. 1-8 , doi : 10.1177 / 1932296819900256 .
  19. ↑ JJ.Holewski, R. Stess, PM.Graf, C.Grunfeld: Aesthesiometry: Quantification of cutaneous pressure sensation in diabetic peripheral neuropathy . In: Journal of Rehabilitation Research and Development . tape 25 , no. 2 , 1988, p. 1-10 .
  20. ↑ Tanja Schlereth et al .: Diagnosis and non-interventional therapy of neuropathic pain, S2k guidelines, 2019 . In: German Society for Neurology (Hrsg.): Guidelines for diagnosis and therapy in neurology . May 2019 ( dgn.org [accessed November 27, 2019]).