首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
医学
Neuroscientists now understand at least some of the physiology behind a wide range of unconscious states, from deep sleep to com
Neuroscientists now understand at least some of the physiology behind a wide range of unconscious states, from deep sleep to com
admin
2013-12-06
27
问题
Neuroscientists now understand at least some of the physiology behind a wide range of unconscious states, from deep sleep to coma, from partially conscious conditions to a persistent vegetative state, the condition diagnosed in Ms. Schiavo.
New research, by laboratories in New York and Europe, has allowed for much clearer distinctions to be made between the uncounted number of people who at some time become comatose, the 10,000 to 15,000 Americans who subsist in vegetative states and the estimated 100,000 or more who exist in states of partial consciousness.
This emerging picture should make it easier for doctors to judge which brain-damaged patients have some hope of recovering awareness, experts say, and already it is providing clues to the specific brain processes that sustain conscious awareness.
"Understanding what these processes are will give us a better sense of how to help the whole range of people living with brain injuries," said Dr. Nicholas Schiff, an assistant professor of neurology and neuroscience at New York-Presbyterian/ Weill Cornell hospital. "That is where this field is ultimately headed: toward a better understanding of what consciousness is."
The most familiar unconscious state is sleep, which in its deepest phases is characterized by little electrical activity in the brain and almost complete unresponsiveness. Coma, the most widely known state of impaired unconsciousness, is in fact a continuum. Doctors rate the extent to which a comatose person shows pain responses and reactions to verbal sounds on a scale from 3, for no response, to 13, for consistent responses.
As in sleep, people in comas may move or make sounds and typically have no memory of either. But they almost always emerge from this state in two to three weeks, doctors say, when the eyes open spontaneously. What follows is critical for the person’s recovery.
Those who are lucky, or who have less severe injuries, gradually awaken. "The first thing I remember was telling my ex-boyfriend, who was at the foot of the bed, to shut up," said Trisha Meili, who fell into a coma after being beaten and raped in 1990, and wrote about the experience in the book, I Am the Central Park Jogger.
In the days after this memory, Ms. Meili said, she slipped in and out of conscious awareness, "as if my body was taking care of the most important things first, and leaving my moment to moment awareness for last."
In fact, researchers say, this is precisely what happens. The primitive brain stem, which controls sleep-wake cycles as well as reflexes, asserts itself first, as the eyes open. Ideally, areas of the cerebral cortex, the seat of conscious thought, soon follow, like lights flicking on in the upper rooms of a darkened house.
But in some cases—Ms. Schiavo’s was one of them—the cortical areas fail to engage, and the patient’s prognosis becomes dire.
Neurologists were all but unanimous in diagnosing the condition of Ms. Schiavo, whose heart stopped temporarily in 1990, depriving her brain of oxygen. Brain cells and neural connections wither and die without oxygen, like marine life in a drained lake, leaving virtually nothing unharmed.
People with these kinds of injuries—Nancy Cruzan, whose case reached the Supreme Court in 1990 is an example—almost always remain unresponsive if they have not regained awareness in the first months after the injury.
In medical terms, they become persistently vegetative, a diagnosis first described in 1972 by Dr. Fred Plum of Cornell University and Dr. Bryan Jennett, a neurosurgeon at Glasgow University in Scotland. In a sense, the description of the diagnosis began the modern study of disorders of consciousness. "Before 1972 people talked about permanent comas, or irrecoverable comas, but we defined a different state altogether, with the eyes open, some reflex activity, but no sign of meaningful psychological responsiveness," Dr. Jennett, now a professor emeritus, said in an interview.
In an exhaustive review of the medical histories of more than 700 persistently vegetative patients, a team of doctors in 1994 reported that about 15 percent of those who suffered brain damage from oxygen deprivation, like Ms. Schiavo, recovered some awareness within three months. After that, however, very few recovered and none did so after two years.
About 52 percent of people with traumatic wounds to the head, often from car accidents, recovered some awareness in the first year after the injury, the study found; very few recovered after that. "It’s the difference between taking a blow to the brain, which affects a local area—and taking this global, whole-brain hit," said Dr. Joseph Fins, chief of the medical ethics division of New York-Presbyterian / Weill Cornell hospital.
Yet these statistics cannot explain the stories of remarkable recovery that surfaced during the debate over Ms. Schiavo’s fate. There was Terry Wallis, a mechanic in Arkansas who regained awareness in 2003, more than 18 years after he fell into unconsciousness from a car accident; Sarah Scantlin, a Kansas woman who, also a victim of a car accident, emerged from a similar state after 19 years; and several others, whose collective human spirit seemed to defy the experts, and trump science.
Researchers say these cases can be accounted for by recent studies that indicate the existence of yet another state of subdued responsiveness, one that represents a clear break from the vegetative.
The author mainly discusses neurologist’s understanding of______.
选项
A、brain-damaged patients who have some hope of recovering awareness
B、the whole range of people living with brain injuries
C、the physiology behind a wide range of unconsciousness
D、clues to the specific brain processes that sustain conscious awareness
答案
C
解析
本文主要阐述了各种类型的昏迷状态以及从神经学角度如何看待各种昏迷状态的生理学。文章第一段是全文的主题段落,说明了全文大意,因此选C。
转载请注明原文地址:https://kaotiyun.com/show/4SU3777K
本试题收录于:
医学博士外语题库考研分类
0
医学博士外语
考研
相关试题推荐
蛋白质吸收紫外光能力的大小,主要取决于
Convincingthepublictofollowhealthadvicecanbetoughandtime-consuming.Thismaybewhychangestohealthmessagesareof
ManyCanadiansenjoytheluxuryofalargeamountoflivingspace.Canadaisvast,andthehomesarelargeaccordingtothestan
A、TheAmericanpopulationincreasedby40percent.B、Somanyschoolchildrendiedofpoliointhenation.C、Apolioplagueswept
"BackintheVictorianera,sevenoutoftenulcersuffererswerewoman.Bythe1950s,thetrendhadreversed,nineoftenwere
Thehospitalshouldbeheldaccountableforthequalityofcareitdelivers.
Personalizedgeneticdiagnosisandtherapysayyou’reyoungandhealthy,andyougoinforaroutinephysical.Yourdoctortake
Backinthedarkages,circa1981,childrenallovertheworldweredyingofbacterialmeningitis.Hemophilusinfluenzatypeb(H
Alittleinformationisadangerousthing.Alotofinformation,ifit’sinaccurateorconfusingevenmoreso.Thisisaproblem
A、Latechildbearing.B、Widespreadfearandanxietyamongthemselves.C、Alcoholdrinking.D、Analarminglyhighnumberofbreastc
随机试题
真菌性阴道炎阴道分泌物外观呈
抗休克的最基本治疗措施是:
目前我国实行的工时制度主要有()。
小张去车站接一位陌生客人,他的预期会影响对这位客人的辨认。这种知觉的加工方式主要是()。(2008年)
Severalyearsintoacampaigntogetkidstoeatbetterandexercisemore,childobesityrateshaveappearedtostabilize,andm
下列给定程序中,函数fun的功能是:找出一个大于给定整数m且紧随m的素数,并作为函数值返回。请改正程序中的错误,使它能得出正确的结果。注意:部分源程序在文件MODI1.C中,不要改动main函数,不得增行或删行,也不得更改程序的结构!试题程序:#i
在某公司人力资源部就职的张晓鸣需要制作一份供新员工培训时使用的PowerPoint演示文稿。按照下列要求,并参考“完成效果.docx”文件中样例的效果,完成演示文稿的制作。在幻灯片2中插入考生文件夹下的图片“欢迎图片.jpg”,并应用“棱台形椭圆,黑色
Lookatthelistbelow.Itshowssomeofthestandsatatradefair.Forquestions6-10,decidewhichisthemostsuitablesta
A、Thescandals.B、Thesports.C、Thecrosswordpuzzles.D、Themainstories.C
Literatureisameansbywhichweknowourselves.Byitwemeet【M1】______futureselves,andrecognizepastselves;agai
最新回复
(
0
)