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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.
| Fibres | Sensation | Finding Descriptor | Clinical Relevance | Testing Equipment and Instructions | ||
|---|---|---|---|---|---|---|
| Clinical | QST | Laboratory | ||||
| Aβ | 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 |
| Aβ | Vibration | Vibration detection threshold | Infrequent but strongly suggestive of NP | Tuning fork (128 Hz) | Vibrameter† | NCS, SEPs |
| Aδ | 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 |
| Aδ | 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 | |
| Aδ | 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 |
| Aδ | 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 | ||||||
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 |
|---|---|---|---|---|---|---|
| Aα | 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 | |
| Aδ | 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
- ↑ Cruccu & Truini. Tools for assessing neuropathic pain. PLoS medicine 2009. 6:e1000045. PMID: 19360134. DOI. Full Text.
- ↑ 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.
- ↑ Backonja et al.. Value of quantitative sensory testing in neurological and pain disorders: NeuPSIG consensus. Pain 2013. 154:1807-1819. PMID: 23742795. DOI.
- ↑ Faculty of Pain Medicine. Pain Oriented Sensory Testing Guidelines. 2018.
