1 Veterans Affairs San Francisco Healthcare System , San Francisco, California.
2 University of California San Francisco , San Francisco, California.
J Neurotrauma. 2018 Jan 15;35(2):297-307. doi: 10.1089/neu.2017.5061. Epub 2017 Nov 20.
Mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) are highly comorbid conditions that often co-occur with chronic pain. We have shown that women with PTSD subsequent to intimate partner violence show attenuated brain response to repeated experimental pain that was related to symptoms of avoidance. The aim of this study was to extend our past findings to males with combat trauma and to examine brain response to experimental pain in men with and without PTSD who sustained mTBI during combat. Seventy male veterans performed an experimental pain paradigm during functional magnetic resonance imaging fMRI. Of the 70 total subjects, 46 self-reported a history of mTBI during combat (46 of 70). Of those with mTBI, 26 also met criteria for PTSD (26 of 46). As in our previous study, we examined change in brain activity to repeated heat pain with linear mixed-effects modeling for group by administration interaction effects. We observed a significant group by administration interaction to repeated heat pain within insular, frontal, and parietal cortices, such that the control group showed increased activation over time, whereas mTBI groups (mTBI-only, mTBI + PTSD) showed decreased activation within bilateral anterior insulas (AIs) between administrations. Importantly, change in the right AI response was inversely correlated with avoidance symptoms, but only in those with comorbid mTBI + PTSD. Further, in the comorbid group, greater AI attenuation was associated with decreased connectivity with anterior cingulate (ACC). The current study provides further evidence that repeated exposure to brief painful stimuli results in attenuation of insula activation over time in traumatized individuals. Further, in PTSD, AI shows greatest attenuation in those with the highest level of avoidance-a finding that was replicated across diverse samples. Thus, this mechanism may be a generalized mechanism of maladaptive response to experimental pain in those with significant trauma.
轻度创伤性脑损伤（mTBI）和创伤后应激障碍（PTSD）是高度共病的疾病，常与慢性疼痛同时发生。我们已经表明，经历亲密伴侣暴力后患有 PTSD 的女性对重复实验性疼痛的大脑反应减弱，这种反应与回避症状有关。本研究的目的是将我们过去的发现扩展到经历过战斗创伤的男性，并研究经历过战斗性 mTBI 且患有和不患有 PTSD 的男性对实验性疼痛的大脑反应。70 名男性退伍军人在功能磁共振成像（fMRI）期间进行了实验性疼痛范式。在 70 名总受试者中，有 46 名报告在战斗中经历过 mTBI（70 名中的 46 名）。在患有 mTBI 的人中，有 26 人也符合 PTSD 的标准（46 名中的 26 名）。与我们之前的研究一样，我们使用线性混合效应模型检查了重复热痛的大脑活动变化，以研究组间和给药间的相互作用效应。我们观察到在岛叶、额叶和顶叶皮层内存在显著的组间和给药间的相互作用，即对照组随着时间的推移表现出激活增加，而 mTBI 组（仅 mTBI、mTBI+PTSD）在两次给药之间表现出双侧前岛叶（AI）的激活减少。重要的是，右 AI 反应的变化与回避症状呈负相关，但仅在合并 mTBI+PTSD 的患者中。此外，在合并组中，AI 的衰减越大与前扣带（ACC）的连接减少有关。本研究进一步提供了证据表明，在创伤个体中，重复暴露于短暂的疼痛刺激会导致随着时间的推移岛叶激活的衰减。此外，在 PTSD 中，AI 在回避症状最高的患者中显示出最大的衰减——这一发现在不同的样本中得到了复制。因此，这种机制可能是那些经历过重大创伤的人对实验性疼痛产生适应性不良反应的一种普遍机制。
