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AS8.1-2 | Pain Physiology and Clinical Pain Assessment — SDL Guide (Part 3)
Self-Assessment: Consolidating Pain Physiology and Assessment Skills
To consolidate your understanding of pain physiology and clinical assessment, work through the following self-directed questions before proceeding to the formal micro-quiz. This self-assessment is designed to identify gaps in your knowledge and reinforce clinical reasoning.
First, trace the path of a nociceptive signal from a scalpel incision on the anterior abdominal wall to conscious pain perception: which receptor types are activated, which primary afferent fibres are recruited, where do they synapse in the spinal cord, which tract carries the signal superiorly, and which cortical regions encode the sensory and affective dimensions of the pain? Can you explain why ketamine attenuates post-operative pain by reference to a specific molecular event in the dorsal horn?
Second, consider a 75-year-old woman with moderate dementia who has had a hip replacement. She cannot reliably respond to verbal pain rating. Which assessment tool would you use, and what specific behaviours would you observe? After administering an opioid analgesic, at what time point would you reassess, and what constitutes an adequate analgesic response?
Third, a 30-year-old man reports 'pins-and-needles and burning' pain in his right hand that is worse at night and associated with hypersensitivity to light touch over the radial three digits. Classify this pain. What mechanism explains the nocturnal worsening? Which analgesic class is most likely to provide benefit?
Finally, reflect on the distinction between background pain (constant baseline pain present at rest) and breakthrough pain (transient exacerbation, spontaneous or incident-provoked, above the background level). Why does this distinction matter for analgesic prescribing? These questions map directly to the NMC 2024 competencies AS8.1 (anatomical and physiological principles of pain) and AS8.2 (eliciting and quantifying pain and tolerance).
CLINICAL PEARL
Neuropathic pain is often hidden inside what appears to be simple post-operative or cancer pain. When a patient's pain is poorly controlled despite adequate opioid titration, or when they describe electric-shock or burning qualities, suspect a neuropathic component. Apply the DN4 questionnaire (4 or more out of 10 points = probable neuropathic pain) or simply ask: 'Does the pain ever feel like electric shocks, burning, pins-and-needles, or hypersensitivity to touch?' If yes, an adjuvant is likely needed regardless of the opioid dose. Similarly, the observation that a patient grimaces or guards during dressing changes — a form of incident pain or movement-evoked pain — even while reporting acceptable background pain scores at rest is clinically significant and deserves separate management (short-acting opioid 30 minutes before the procedure, or procedural sedation if the pain is severe). The assessment scale score at rest tells you only part of the story.