輕微腦損傷不是造成士兵創傷後壓力異常的主因


  January 30, 2008 — 新的研究認為,輕微的創傷性腦損傷(traumatic brain injury,TBI),所謂的腦震盪,或許不是從伊拉克戰場返國的美國士兵發生創傷後壓力異常(posttraumatic stress disorder,PTSD)與生理健康問題的主要原因。
  
  相反的,輕微TBI可能會造成嚴重的致命的創傷事件,而顯著增加PTSD和憂鬱的風險。
  
  主要研究者、Walter Reed 陸軍研究中心的Charles Hoge醫師向Medscape神經學&神經外科學表示,最令我們感到吃驚的發現是,我們本來預期腦震盪會造成生理健康問題和腦震盪後症候群,實際上卻是與PTSD和憂鬱有關。
  
  他指出,即使沒有輕微TBI病史,一般和腦震盪有關的這些症狀,如專注力差、易怒、健忘,頭暈和平衡問題,也與PTSD和憂鬱有關。
  
  這項研究登載於1月31日的新英格蘭醫學期刊(New England Journal of Medicine)。
  
  根據Hoge醫師所述,有關輕微TBI及其對士兵退伍後的不良健康影響的病理學很少,不過,他指出,這些服役期間的腦震盪事件可能會導致長期的健康問題。
  
  因此,研究者比較了輕微TBI的士兵的健康問題,輕微TBI的定義,是在服役期間發生造成意識喪失或者改變心智狀態的傷,和在返鄉後最初幾個月發生類似傷害的對照組比較。
  
  【傷害類型無關】
  研究者調查了來自兩個戰鬥旅的2525 名美國陸軍步兵,這些人都面臨高強度的戰鬥,在他們調派到伊拉克長達一年之後返家的3到 4個月進行調查。
  
  生理症狀,包括腦震盪後症候群,如記憶問題、平衡、專注力、耳鳴以及易怒等均加以評估;此外,也評估有無重度憂鬱和PTSD。
  
  整個研究組中,124人(4.9%)有發生喪失意識的傷害,260 (10.3%)人報告有發生其他心智狀態改變的傷害,總共有435 (17.2%)名士兵表示有其他傷害 。
  
  那些發生喪失意識的傷害者之中,43.9% 符合PTSD的規範,發生其他心智狀態改變的傷害者之中則是有27.3%符合,其他傷害者則有16.2%符合,無傷害者有9.1%符合。
  
  輕微TBI的士兵,特別是那些喪失意識者,和其他傷害的士兵相比,顯然更可能發生一般健康不佳、請病假、就醫、以及比較多的身體和腦震盪後症候群;不過,校正PTSD和憂鬱之後,輕微TBI不再與這些健康問題有關,除了頭痛之外。
  
  Hoge 醫師表示,當我們觀察有PTSD和沒有PTSD的人,根據傷害類型而言,對健康的影響並沒有差異,因此,並不是傷害本身與健康問題有關,而是PTSD和憂鬱有關。
  
  【極度壓力】
  根據Hoge醫師表示, PTSD和憂鬱之間的關聯、以及士兵發生生理健康問題的潛在機轉,可能是因為暴露在極度壓力下的生物處理過程。
  
  他表示,當自律神經系統積極活躍一段長時期,會出現長期壓力反應,對士兵的生理健康會有衝擊;腦損傷會影響到睡眠、會出現頭痛、疼痛、昏眩、平衡問題與其他症狀,事實上是因為過度活躍的自律神經系統。
  
  根據研究者表示,研究也指出,自我報告有輕微TBI病史而無意識喪失者,無法預測退伍後的生理健康問題;需要更清楚、更有效的定義。
  
  Hoge 醫師表示,我們對意識的測量相當不準確,士兵在戰場上暈眩和混亂的原因相當多,且根據此定義,我們無法確定這是否真正代表腦部功能的生理混亂。
  
  處理戰爭相關的混亂時,對醫師而言,重要的是醫師需聚焦在症狀減輕,以及預防二度腦震盪,確保士兵不會太早回到日常活動;Hoge 醫師表示,同樣重要的是,需教育病患有關的傷害和他們應預期的注意事項。
  
  【錯誤的結論】
  澳洲新南威爾斯大學的Richard A. Bryant博士在伴隨而來的編輯評論中表示,與TBI有關的健康問題比憂鬱和PTSD更不明顯,相當令我們驚訝。
  
  如果Hoge等人沒有評估PTSD和憂鬱,本研究的可能結論是,觀察發現許多士兵會因為輕微創傷性腦損傷而造成缺損,這個錯誤的結論通常發生在一些臨床設定上, 輕微創傷腦損傷之後所觀察的缺損,會造成錯誤的神經方面的判斷,而不是心理方面的痛苦。
  
  本研究由Military Operational Medicine Research Area Directorate,US Army Medical Research and Material Command贊助。

Mild Head Injury Not a Main Dr

By Caroline Cassels
Medscape Medical News

January 30, 2008 — New research suggests mild traumatic brain injury (TBI), also known as concussion, may not be the primary driver of posttraumatic stress disorder (PTSD) and physical health problems among US troops returning from the current war in Iraq.

Rather, it may be that mild TBI serves as a surrogate of an intense, life-threatening, traumatic event that significantly increases the risk for PTSD and depression.

"The most startling finding, that we were indeed surprised by, was the fact that the physical health symptoms and the postconcussive symptoms that we expected to be able to attribute to concussion actually turned out to be related to PTSD and depression," principal investigator Charles Hoge, MD, from Walter Reed Army Institute of Research, in Silver Springs, Maryland, told Medscape Neurology & Neurosurgery.

"Symptoms such as poor concentration, irritability, forgetfulness, dizziness, and balance problems, things that we typically associate with concussion — were correlated with PTSD and depression, and not with a history of mild TBI," he added.

The study is published in the January 31 issue of the New England Journal of Medicine.

According to Dr. Hoge, little is known about the epidemiology of mild TBI and its potential link to adverse health outcomes in soldiers following deployment. However, he added, there has been a lot of concern that these concussive events sustained during active duty may lead to long-term health problems.

As a result, the investigators compared health outcomes of soldiers who sustained mild TBI — defined as an injury with loss of consciousness or altered mental status — during deployment with their counterparts who experienced other types of injuries in the early months after returning home.

Injury Type Irrelevant

The investigators surveyed 2525 US Army infantry soldiers from 2 combat brigades, which saw high levels of combat, 3 to 4 months after their return from a yearlong deployment to Iraq.

Physical symptoms, including postconcussive symptoms such as memory problems, balance, concentration, ringing in the ears, and irritability were assessed. In addition, participants were evaluated for major depressive disorder and PTSD.

Of the total study group, 124 (4.9%) reported injuries with loss of consciousness and 260 (10.3%) reported injuries with altered mental status. A total of 435 (17.2%) soldiers reported other injuries.

Of those reporting loss of consciousness, 43.9% met criteria for PTSD, vs 27.3% of those reporting altered mental status, 16.2% with other injuries, and 9.1% with no injury.

Soldiers with mild TBI, particularly those who had loss of consciousness, were significantly more likely to report poor general health, missed workdays, medical visits, and a high number of somatic and postconcussive symptoms than soldiers with other injuries. However, after adjustment for PTSD and depression, mild TBI was no longer significantly associated with these physical health outcomes or symptoms, with the exception of headache.

"When we looked at those with PTSD and those without PTSD, there were no differences in the health concerns according to injury type. So it was not the injury that was correlated with the [health] symptoms but the presence of PTSD and depression," said Dr. Hoge.

Extreme Stress

According to Dr. Hoge, the underlying mechanisms responsible for the association between PTSD and depression and the onset of physical health problems in soldiers may be due to biologic processes associated with exposure to extreme stress.

"When the autonomic nervous system is revved up for a prolonged period — 24/7 for 12 months — there is a chronic stress reaction that has an impact on a soldier's physical health. Your sleep is affected, you might have headaches, pain, dizziness, balance problems, and other symptoms that might be attributed to brain injury when in fact it is due to a revved-up autonomic nervous system," he said.

According to the investigators, the study also suggests that a self-reported history of mild TBI without loss of consciousness lacks specificity in predicting postdeployment physical health problems and highlights the need for a clear, validated definition.

"We have measures for concussion that are very inaccurate. There are many reasons why a soldier may be dazed and confused on the battlefield, and with this definition, we can't be sure whether this truly represents a physiological disruption of brain function," said Dr. Hoge.

When managing war-related concussions, it is important for clinicians to focus on symptom alleviation and prevent a second concussion by ensuring the soldier does not return to active duty too early. Equally important, said Dr. Hoge is to educate patients about their injury and tell them what to expect.

Mistaken Conclusion

In an accompanying editorial, Richard A. Bryant, PhD, from the University of New South Wales, in Sydney, Australia, said the finding that health problems associated with TBI became nonsignificant after depression and PTSD were considered was "striking."

"If Hoge and colleagues had not assessed for PTSD and depression, the possible conclusion from this study would have been that mild traumatic brain injury is the causative agent for the impairment observed in many soldiers. This mistaken conclusion has often been made in clinical settings, and impairment observed in the aftermath of mild traumatic brain injury has been attributed incorrectly to neurologic insult, rather than psychological distress."

The study was supported by the Military Operational Medicine Research Area Directorate, US Army Medical Research and Material Command.

N Engl J Med. 2008;358:453-463.

    
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