Pain Oriented Sensory Testing

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The ANZCA have published guidelines on pain oriented sensory testing (POST)

Media:POST_ANZCA_Guidelines_2018.pdf

Below is a table comparing clinical vs QST methods that I have modified from several sources.

Summary of choice methods of assessing nerve function per sensation.
Fibres Sensation Finding Descriptor Clinical Relevance Testing Equipment and Instructions
Clinical QST Laboratory
Touch Dynamic mechanical allodynia Common to most NP. Central sensitisation. cotton wool or camel hairbrush - 2cm stroke over 1 second and repeat Von Frey filaments NCS, SEPs
Vibration Vibration detection threshold Infrequent but strongly suggestive of NP Tuning fork (128 Hz) Vibrameter† NCS, SEPs
Pinprick, sharp pain Punctate mechanical allodynia and hyperalgesia Common to most NP. Central sensitisation. Punctate mechanical allodynia - use a toothpick apply 2 stimuli per second (2 Hz) and repeat.

Punctate mechanical hyperalgesia - optionally tested with a neurotips needle.

Weighted needles LEPs, IENF
Touch Static or Pressure-evoked mechanical allodynia Common to most NP, also observed in inflammatory pain. Central sensitisation. Finger tip - apply pressure until blanching of nail bed for 1 second and repeat. Von Frey filaments
Cold Cold allodynia Infrequent but strongly suggestive of NP. Central sensitisation. Stainless steel 128 Hz tuning fork prongs applied to the skin for 1 second and repeat Thermode‡ None
Touch, Pain Temporal summation indicating hyperpathia Central sensitisation, test for "wind-up" Toothpick applied 2 stimuli per second (2Hz) for 30 seconds. Assess change in pre- and post- pain scores, and aftersensation.
C Warmth Warm allodynia Infrequent but strongly suggestive of NP. Peripheral sensitisation. Thermoroller or warmed C size battery at 45° applied for 1 second and repeat Thermode‡ LEPs, IENF
† or other device providing graded vibratory stimuli

‡ or other device providing graded thermal stimuli
NCS: nerve conduction studies, SEP: sensory evoked potentials, LEP: laser evoked potentials, IENF: intra-epidermal nerve fibre density. NP: neuropathic pain
Modified from various sources[1][2][3][4]

The function of the various sensory peripheral nerves are reproduced below.

Characteristics of sensory nerve fibres
Nerve fibre Myelinated axons Diameter (µm) Conduction velocity (m/s) Sensory information Usefulness of electroneuromyography Usefulness of QST
Yes   13-20   80-120 Proprioception, muscle spindle primary endings (Ia), golgi tendon organs (Ib) (and alpha motor neurons)   Yes (H reflex) No
Aβ   Yes   6-12   33-75 Discriminative mechanoreception (touch, vibration), proprioception, pain modulation (block nociceptive information, allodynia in sensitisation) Yes (sensory nerve conduction) Yes
Aγ   Yes   4-8   15-40 Touch, pressure (and gamma motor neurons) No
Thin 1-5 3-30 "rapid" pain, crude touch, pressure, temperature. AMH type I for rapid mechanical pain (high heat threshold >53C), AMH type II for rapid heat pain (lower heat threshold 43-47C). No Yes
C No 0.3-1.5 0.5-2.0 "slow" pain, touch, pressure temperature (and postganglionic autonomic). Polymodal. No Yes


See Also

References

  1. Cruccu & Truini. Tools for assessing neuropathic pain. PLoS medicine 2009. 6:e1000045. PMID: 19360134. DOI. Full Text.
  2. Zhu et al.. Concurrent validity of a low-cost and time-efficient clinical sensory test battery to evaluate somatosensory dysfunction. European journal of pain (London, England) 2019. 23:1826-1838. PMID: 31325385. DOI. Full Text.
  3. Backonja et al.. Value of quantitative sensory testing in neurological and pain disorders: NeuPSIG consensus. References 2013. 154:1807-1819. PMID: 23742795. DOI.
  4. Faculty of Pain Medicine. Pain Oriented Sensory Testing Guidelines. 2018.