Novel Insights on the Management of Pain: Highlights From the ‘Science of Relief’ Meeting

Figures & data

Figure 1. Key types of pain.

CNS: Central nervous system; PNS: Peripheral nervous system.

Figure 2. Spinal mechanisms of action of tapentadol.

MOR: μ-opioid receptor; NA: Noradrenaline.

Figure 3. Potency of tapentadol in different models of pain.

(A) Acute nociceptive pain. (B) Inflammatory pain. (C) Neuropathic pain.

Data taken from [15].

AD: Allodynia; MOR: μ-opioid receptor; HA: Hyperalgesia; HS: Hypersensitivity; STZ: Streptozotocin.

Table 1. Tests applicable in clinical practice to identify peripheral and central sensitization.

Test	Nature	Action	Patients’ reaction if positive
Heat allodynia	Normally nonpainful heat stimuli evoke pain	Touch skin with object at 40°C (metal roller, glass of water)	Heat allodynia
Mechanical dynamic allodynia	Normally nonpainful light stroking stimuli on skin evoke pain	Stroking skin with painter’s brush, cotton swab or gauze	Sharp burning superficial pain in the primary affected zone, spreading into unaffected skin areas (secondary zone)
Mechanical punctate or pinprick hyperalgesia	Normally painful stimuli evoke increased pain	Manual pricking of the skin with a sterile pin or monofilament	Sharp superficial pain in the primary affected zone, spreading into unaffected skin areas (secondary zone)
Temporal summation	Repetitive application of identical single noxious stimuli is perceived as increasing pain sensation (wind-up-like pain)	Pricking the skin with sterile pin at <3 s intervals for 30 s	Sharp superficial pain of increasing intensity

Figure 4. Detecting central sensitization and neuropathic features in musculoskeletal pain syndromes.

Reproduced with permission from [22] © Springer Nature (2014).

NSAID: Nonsteroidal anti-inflammatory drug; OA: Osteoarthritis; PAG: Periaqueductal gray; SNRI: Serotonin-norepinephrine reuptake inhibitor.

Figure 5. Peripheral sensitization leads to and maintains central sensitization.

Figure 6. Key efficacy outcomes of the ELEVATE study.

^†Capsaicin 8% path was (noninferior) versus pregabalin (difference: 1.2%; odds ratio: 1.03; 95% CI: 0.71–1.50).

PNI: Posttraumatic/postsurgical nerve injury.

Reproduced with permission from [58], © Haanpää et al., licensed with CC BY-NC-ND 4.0.

Figure 7. Efficacy of capsaicin 8% patch and pregabalin on dynamic mechanical allodynia in the ELEVATE study.

Reproduced with permission from [58], © Haanpää et al., licensed with CC BY-NC-ND 4.0.

CI: Confidence interval; DMA: Dynamic mechanical allodynia; EoS: End of study; LS: Least squares.

Table 2. Recommendations of major guidelines for localized neuropathic pain.

Guidelines/guidance	Last update	First-line recommendation	Second-line recommendation
Neuropathic Pain Special Interest Group of the International Association for the Study of Pain	2015	• Tricyclic antidepressant • Gabapentin • Pregabalin • Topical lidocaine in frail and elderly patients	• Tramadol • Capsaicin • Topical lidocaine • Opioid analgesics (third line)
European Federation of Neurological Societies	2010	• Gabapentin • Pregabalin • Tricyclic antidepressants • Lidocaine-medicated plaster in PHN patients	• Capsaicin • Opioids
American Academy of Neurology	Reaffirmed 2018	• Gabapentin • Lidocaine plaster • Oxycodone or morphine • Pregabalin • Tricyclic antidepressants	• Aspirin in cream or ointment • Capsaicin (topical) • Methylprednisolone (Intrathecal)

PHN: Post-herpetic neuralgia.

Data taken from [65,67].

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