减轻与管理疼痛的工具：来自 Dr. Sean Mackey 的见解
摘要
斯坦福大学疼痛医学部主任 Dr. Sean Mackey 从伤害性感受到大脑处理过程，系统阐释了疼痛的神经科学原理，并区分了疼痛体验中的感觉成分与情绪成分。本文探讨了心理状态、早期生活经历和个体差异如何塑造疼痛，同时提供了从非处方药、物理干预到正念练习和认知重构等实用工具。贯穿全文的核心主题是：理解”提示伤害的疼痛”与”仅令人不适的疼痛”之间的关键区别。
核心要点
- 疼痛是大脑事件，而非身体事件——来自外周nociceptors（伤害感受器）的信号本身并不是疼痛；只有当这些信号在大脑中汇聚时，疼痛才会产生。
- NSAIDs（布洛芬、萘普生、阿司匹林）在技术层面并非止痛药——它们是抗炎药和抗痛觉过敏药，作用于减少外周敏化，而非阻断原始疼痛信号本身。
- 揉搓、抖动或用流水冲洗受伤部位，能激活 A-beta 触觉纤维，在脊髓水平调节伤害性感受信号——这是一种免费且有效的neuromodulation（神经调控）方式。
- 疼痛抑制疼痛（条件性疼痛调节）：在一个部位施加痛觉刺激，可通过脑干下行通路抑制另一部位的疼痛。
- 疼痛与伤害的区别是疼痛管理中最具临床意义的概念之一——理解疼痛并不总等于组织损伤，可以从根本上改变患者的行为和治疗结果。
- 注意力分散和正念都有效，但二者调动不同的神经回路；mindfulness-based stress reduction（MBSR，正念减压）在焦虑、抑郁和疼痛方面具有强有力的循证依据。
- 灾难化思维是疼痛加重和治疗反应不佳的最强预测因素之一。
- 愤怒、焦虑和抑郁均会放大疼痛；“内隐愤怒”（压抑、郁积的愤怒）似乎比外显表达的愤怒危害更大。
- 运动通过增强疼痛处理回路中的抑制性张力，长期提高pain threshold（痛阈）。
- 抗炎饮食是管理慢性疼痛中一个被严重低估的工具。
详细笔记
什么是疼痛？
- 疼痛被定义为一种复杂的、主观的、感觉与情绪并存的体验，其功能是保护我们免受伤害。
- 疼痛影响约1亿美国人，每年在美国造成约5000亿美元的经济损失。
- Chronic pain（慢性疼痛）常被称为”隐形疾病”——可能没有可见的损伤，因此常遭到误解。
- 疼痛具有高度个体差异性——你的疼痛体验由大脑、情绪、记忆、信念和情境共同塑造。
伤害性感受与疼痛
- 皮肤、软组织和深层组织中的**Nociceptors（伤害感受器）**可检测热、冷、压力以及pH变化（如来自inflammation炎症的变化）。
- 信号通过两种纤维类型传导：
- A-delta 纤维：传导速度快；负责尖锐、即时的疼痛（如踩到图钉）。
- C 纤维：传导速度慢；负责钝痛和酸痛；汇聚到大脑情绪区域，传递不适感。
- 信号到达脊髓后经过调制，再上行传入大脑——疼痛只作为大脑层面的体验而存在。
- 过时的笛卡尔式”一对一”模型（刺激→疼痛）是不正确的；大脑的情绪、记忆、认知和预期都会塑造最终的疼痛体验。
大脑网络与疼痛
- 大脑中没有单一的”疼痛中枢”。
- 疼痛涉及一个分布式网络，包括岛叶皮层、扣带回皮层和杏仁核（以前称为”疼痛矩阵”）。
- 基于大脑的疼痛生物标志物是斯坦福大学的活跃研究领域。
非处方镇痛药物
| 药物 | 类型 | 关键说明 |
|---|---|---|
| 布洛芬 | NSAID（COX 抑制剂） | 半衰期短；每日最多服用3次；需随餐服用并补充水分 |
| 萘普生（Naprosyn） | NSAID | 每日两次；个体差异显著——对部分人群效果优于布洛芬 |
| 阿司匹林（81mg） | NSAID / 抗血小板药 | 每日小剂量用于心脏保护；325mg 剂量具有抗炎作用 |
| 对乙酰氨基酚（泰诺） | 中枢性作用 | 对胃部刺激小；每日最大剂量约4g；大量饮酒或有肝脏问题者应避免使用 |
| 塞来昔布 | COX-2 抑制剂（仅限处方） | 胃肠道刺激较少；需处方 |
- NSAIDs 是抗痛觉过敏药，而非真正的镇痛药——它们减少损伤后的敏化，但不阻断正常疼痛信号。
- NSAIDs 可能通过阻断炎症而延迟骨折和组织愈合——应以最低有效剂量使用。
- 咖啡因可通过前列腺素通路增强镇痛效果，对头痛/偏头痛有效；与 NSAIDs 合用时需随餐服用。
- 服用时机建议：布洛芬每日不超过3次；萘普生每日两次；均需随餐并补充水分服用。
- 有胃肠道、肾脏、心脏或出血问题的人群在使用 NSAIDs 前应咨询临床医生。
闸门控制理论与物理干预
- Gate control theory of pain（疼痛闸门控制理论）（Melzack & Wall，1960年代）：触觉纤维（A-beta）与脊髓伤害性感受纤维形成突触，并抑制疼痛信号的传递。
- 揉搓、抖动或用流水冲洗受伤区域可激活 A-beta 纤维→在脊髓水平调节疼痛信号→降低感知疼痛。
- 研究表明说脏话可降低疼痛感知（机制尚不明确）。
- TENS（经皮神经电刺激）：通过皮肤施加电振动的设备，激活 A-beta 纤维以实现脊髓水平的neuromodulation（神经调控）。
- 亲吻或安抚性触摸既能通过激活触觉纤维，又能通过积极的情绪意义来减轻疼痛。
条件性疼痛调节（CPM）
- 疼痛抑制疼痛：在远离主要疼痛部位施加痛觉刺激，可激活脑干下行抑制通路至脊髓，从而减轻主要疼痛。
- 最初由 Le Bars（约1978年）在啮齿动物模型中描述，称为弥漫性伤害抑制性控制（DNIC）。
- CPM 在某些慢性疼痛状况（如fibromyalgia纤维肌痛）中受到损害。
冷热疗法
- 传统指南：急性损伤后约前48小时使用冷敷；此后使用热敷。
- 冷敷可减少炎症化学物质（前列腺素、细胞因子、组胺）的释放，降低神经放电频率，减少伤害性感受信号频率。
- 热敷可促进血液循环、放松肌肉并促进愈合。
- 个体差异较大——使用对个人最有效的方式即可。
- 安全提示：不可将冰块直接长时间敷于皮肤（有冻伤风险）；冷敷至局部麻木感是一个合理的终止标准。
痛阈与个体差异
- Pain threshold（痛阈） = 刺激强度达到使感觉开始变得痛苦的水平。
- 影响因素包括：焦虑、既往创伤、早期生活经历、信念、预期、情绪状态、情境和社会线索。
- 男性与女性：平均而言，男性的热痛阈略高，但组内差异远大于组间差异——两组分布高度重叠。
- 社会情境的影响：研究表明，当由一位有吸引力的女性研究员施加刺激时，男性的痛阈会升高。
- 运动可能通过增强疼痛回路中的抑制性张力，长期提高痛阈。
- 认知训练（重构、正念）也可以改变痛阈。
疼痛的心理学方法
注意力分散
- 调动前额叶皮层和扣带回皮层网络。
- 策略包括：阅读、社交、散步、参与有吸引力的活动。
- 最大挑战：夜间，当无法进行分散注意力的活动时，慢性疼痛
English Original 英文原文
Tools to Reduce & Manage Pain: Insights from Dr. Sean Mackey
Summary
Dr. Sean Mackey, Chief of the Division of Pain Medicine at Stanford University, explains the neuroscience of pain from nociception through brain processing, distinguishing the sensory and emotional components of the pain experience. The conversation covers how pain is shaped by psychological state, early life experiences, and individual variability, while providing practical tools ranging from over-the-counter medications and physical interventions to mindfulness and cognitive reframing. A key theme throughout is understanding the critical difference between pain that signals harm versus pain that is merely uncomfortable.
Key Takeaways
- Pain is a brain event, not a body event — signals from nociceptors in the periphery are not pain themselves; pain only arises when those signals converge in the brain.
- NSAIDs (ibuprofen, naproxen, aspirin) are not technically painkillers — they are anti-inflammatory and anti-hyperalgesic drugs that reduce peripheral sensitization, not the raw pain signal itself.
- Rubbing, shaking, or running water over an injury works by activating A-beta touch fibers that modulate nociceptive signals at the spinal cord level — a free and effective form of neuromodulation.
- Pain inhibits pain (conditioned pain modulation): activating a painful stimulus at one site can inhibit pain at a separate site via brainstem descending pathways.
- The hurt vs. harm distinction is one of the most clinically important concepts in pain management — understanding that pain does not always equal tissue damage can dramatically change behavior and outcomes.
- Attentional distraction and mindfulness are both effective but engage different neural circuits; mindfulness-based stress reduction (MBSR) has strong evidence for anxiety, depression, and pain.
- Catastrophizing is among the strongest predictors of worsening pain and poor treatment response.
- Anger, anxiety, and depression all amplify pain; “anger in” (suppressed, simmering anger) appears worse than outwardly expressed anger.
- Exercise raises pain threshold over time by building inhibitory tone in pain-processing circuits.
- Anti-inflammatory nutrition is a critically underappreciated tool in managing chronic pain.
Detailed Notes
What Is Pain?
- Pain is defined as a complex, subjective, sensory and emotional experience that protects us from injury.
- It affects approximately 100 million Americans and costs ~$500 billion/year in the US.
- Chronic pain is often called the “invisible disease” — there may be no visible injury, making it frequently misunderstood.
- Pain is highly individual — your pain experience is shaped by your brain, emotions, memories, beliefs, and context.
Nociception vs. Pain
- Nociceptors in skin, soft tissue, and deep tissue detect heat, cold, pressure, and pH changes (e.g., from inflammation).
- Signals travel via two fiber types:
- A-delta fibers: fast-conducting; responsible for sharp, immediate pain (e.g., stepping on a tack).
- C fibers: slow-conducting; responsible for dull, aching pain; converge on emotional brain regions, conveying unpleasantness.
- Signals reach the spinal cord, are modulated, then ascend to the brain — pain only exists as a brain-level experience.
- The outdated Cartesian “one-to-one” model (stimulus → pain) is incorrect; the brain’s emotions, memories, cognitions, and expectations all shape the final pain experience.
Brain Networks and Pain
- There is no single “pain center” in the brain.
- Pain involves a distributed network including the insular cortex, cingulate cortex, and amygdala (formerly called the “pain matrix”).
- Brain-based biomarkers for pain are an active area of research at Stanford.
Over-the-Counter Pain Medications
| Medication | Type | Key Notes |
|---|---|---|
| Ibuprofen | NSAID (COX inhibitor) | Short half-life; take up to 3x/day; needs food and fluids |
| Naproxen (Naprosyn) | NSAID | Twice daily; individual variability — works better for some than ibuprofen |
| Aspirin (81mg) | NSAID / antiplatelet | Baby aspirin daily for heart health; 325mg becomes anti-inflammatory |
| Acetaminophen (Tylenol) | Centrally acting | Safe on stomach; max ~4g/day; avoid with heavy alcohol use or liver issues |
| Celecoxib | COX-2 inhibitor (Rx only) | Less GI irritation; prescription required |
- NSAIDs are anti-hyperalgesic, not true analgesics — they reduce sensitization after injury but do not block normal pain signals.
- NSAIDs may delay fracture and tissue healing by blocking inflammation — use at the lowest effective dose.
- Caffeine can potentiate the analgesic response and is effective for headaches/migraines via the prostaglandin pathway; take with food if combining with NSAIDs.
- Timing guidance: Take ibuprofen no more than 3x/day; naproxen twice daily; always with food and fluids.
- People with GI, kidney, heart, or bleeding issues should consult a clinician before using NSAIDs.
Gate Control Theory and Mechanical Interventions
- Gate control theory of pain (Melzack & Wall, 1960s): touch fibers (A-beta) synapse onto nociceptive fibers in the spinal cord and inhibit pain signal transmission.
- Rubbing, shaking, or running water over an injured area activates A-beta fibers → modulates pain signals at the spinal cord → reduces perceived pain.
- Swearing has been shown in studies to reduce pain perception (mechanism unclear).
- TENS (Transcutaneous Electrical Nerve Stimulation): devices that apply electrical buzzing to skin, activating A-beta fibers to achieve spinal cord-level neuromodulation.
- A kiss or comforting touch reduces pain both through touch fiber activation and positive emotional salience.
Conditioned Pain Modulation (CPM)
- Pain inhibits pain: applying a painful stimulus at a site distal to the primary pain activates brainstem descending inhibitory pathways to the spinal cord, reducing the primary pain.
- Originally described as Diffuse Noxious Inhibitory Control (DNIC) (Le Bars, ~1978) in rodent models.
- CPM is impaired in certain chronic pain conditions, such as fibromyalgia.
Heat and Cold Therapy
- Traditional guideline: Cold for the first ~48 hours after acute injury; heat thereafter.
- Cold reduces inflammatory chemical release (prostaglandins, cytokines, histamines), slows nerve firing rate, and reduces nociceptive signal frequency.
- Heat increases blood flow, relaxes muscles, and promotes healing.
- Individual variability is high — use whichever works best for the individual.
- Safety: Do not apply ice directly to skin for extended periods (frostbite risk); numbing the area to the point of anesthesia is a reasonable endpoint for cold application.
Pain Thresholds and Individual Variability
- Pain threshold = the stimulus intensity at which a sensation first becomes painful.
- Shaped by: anxiety, past trauma, early life experiences, beliefs, expectations, emotional state, context, and social cues.
- Men vs. women: On average, men have slightly higher heat pain thresholds, but within-group variability vastly exceeds between-group differences — the distributions heavily overlap.
- Social context matters: Studies show pain thresholds in men rose when an attractive female researcher administered the stimulus.
- Exercise raises pain thresholds over time, likely by increasing inhibitory tone in pain circuits.
- Cognitive training (reframing, mindfulness) can also change thresholds.
Psychological Approaches to Pain
Attentional Distraction
- Engages prefrontal cortex and cingulate cortex networks.
- Strategies: reading, socializing, walking, engaging activities.
- Biggest challenge: nighttime, when distraction is unavailable and chronic pain