traumatic brain injury ( tbi ) caused by motor vehicle accidents , firearms , and falls are recorded as a leading cause of death and lifelong disability among young adults.[14 ] the glasgow coma scale ( gcs ) has been extensively studied for its ability to predict outcomes in tbi patients .
representative tbis that could induce unconsciousness include intracranial hematoma , cerebral contusion and axonal injury .
patients with severe major injuries in two or more different sites , who require surgical intervention to stabilize vital signs may often experience cardiac arrest in the prehospital arena and thus display poor prognosis .
this institute , which is a 15-year - old level 1 urban trauma center in japan , has no record of any patients with blunt injury who were alive on arrival and required life - saving surgical operations for two different sites of injury , one of which was the head .
however , patients have been encountered who showed diffuse axonal injury ( dai ) and required insertion of a sensor into the intracranial space to control intracranial pressure , and also underwent a major operation for injuries at other sites .
no reports to date appear to have indicated characteristics of extracranial injuries in patients with dai .
the present study therefore retrospectively investigated the characteristics of extracranial injuries in patients with dai .
the study was conducted by reviewing medical records from january 2003 to december 2007 . in this study ,
dai was defined as present in a patient who showed no focal lesions and prolonged unconsciousness lasting 24 h. accordingly , to identify dai , the study included patients meeting the following criteria : 1 ) head injury without cerebral contusion > 1 cm on computed tomography ( ct ) , subdural hematoma , or epidural hematoma ; 2 ) gcs on arrival < 15 ; and 3 ) magnetic resonance imaging ( mri ) including t2 * -weighted imaging performed during hospitalization .
the study excluded patients meeting the following criteria : 1 ) age > 60 years or 2 ) death due to head injury .
subjects were divided into two groups : severe tbi group ( patients with gcs 8 ) and moderate tbi group ( patients with gcs > 8) . in this study ,
the term tbi was used in place of dai because some unconscious patients with tbi did not show any traumatic lesions on mri .
the following variables were analyzed between the severe tbi group : sex , age , mechanism of injury , incidence of skull fracture , gcs on arrival , systolic blood pressure , shock index ( i.e. , heart rate / systolic blood pressure ) , status of light reflex , abbreviated injury scale ( ais ) of the extracranial regions ( face , thorax , abdomen , extremities and external structures ) , sum of extracranial ais scores , value of arterial base excess ( base excess is defined as the amount of strong acid that must be added to each liter of fully oxygenated blood to return the ph to 7.40 at a temperature of 37c and a pco2 of 40 mmhg ) as measured by blood gas analysis on arrival ; presence of traumatic microbleeds detected by t2 * -weighted imaging , duration of hospitalization , and glasgow outcome score at 3 months after admission .
the ais is an anatomical scoring system in which injuries are ranked on a scale of 16 ( 1 , minor ; 2 , moderate ; 3 , serious ; 4 , severe ; 5 , critical ; 6 , unsurvivable injury ) . t2
* -weighted imaging was performed in the axial plane using the following parameters : repetition time , 900 ms ; echo time , 30 ms ; excitations , 2 ; flip angle , 200 ; matrix , 256  192 ; section thickness , 5 mm with a 2.5-mm gap , and imaging time , 2 min 56 s. all foci > 1 mm in diameter showing signal hypointensity on t2 * -weighted imaging were defined as traumatic microbleeds .
statistical analyses were performed using the unpaired student 's t - test and the  test .
a total of 469 patients with head injury were admitted during the investigation period . of these ,
138 patients > 60 years old , 53 patients with cerebral herniation , and 100 patients with intracranial mass lesions due to cerebral contusion and/or intracranial hematoma were excluded . of the remaining 178 patients , 113 were alert on arrival and were excluded .
thirty - five of the remaining 65 patients showed persistent disturbance of consciousness for 24 h after admission and underwent mri , and were thus defined as subjects in this study ( the severe tbi group , n=19 ; the moderate tbi group , n=16 ) .
no significant differences were apparent between the two groups with regard to sex , age , mechanism of injury or incidence of skull fracture [ table 1 ] .
subject background data shock index was significantly higher in the severe tbi group than in the moderate tbi group , while base excess on arrival was lower in the severe tbi group than in the moderate tbi group [ table 2 ] .
physiological data and ais on arrival ais of the face , thorax , extremities and external structures showed no significant differences between the two groups , but ais of the abdomen and the sum of extracranial ais scores were higher in the severe tbi group than in the moderate tbi group [ table 3 ] .
four patients in the severe tbi group showed abdominal injury requiring surgery ( diaphragmatic rupture , n=2 ; splenic rupture , n=1 ; bladder rupture , n=1 ) , but the moderate tbi group included no such cases ( p=0.1 ) .
in addition , the severe tbi group included four patients with pelvic fractures , whereas the moderate tbi group had no such cases ( p=0.1 ) .
ais for extracranial injury on arrival the number of traumatic microbleeds detected by mri was higher in the severe tbi group than in the moderate tbi group [ table 4 ] .
duration of hospitalization was longer and outcomes were worse in the severe tbi group than in the moderate tbi group [ table 5 ] .
none of the remaining 434 patients with blunt trauma who were excluded from the study and were alive on arrival required life - saving surgery for two different sites of injury , one of which was the head .
only one of the patients excluded from the study showed dai and acute subdural hematoma requiring surgery , and underwent delayed repair for diaphragmatic rupture .
this study demonstrated that patients with severe tbi were more likely to have abdominal injury than patients with moderate tbi , representing the first investigation to report such a relationship .
the combination of head and abdominal injuries is usually rare , maybe because the abdomen is relatively far from the head compared to other regions , and is protected by the bony thorax and pelvis . as a result
, the abdomen and head might rarely receive the same high - energy impact at the same time .
dai forms when axons undergo rapid stretching as a result of angular acceleration , damaging the axonal cytoskeleton and resulting in a loss of elasticity and impairment of axoplasmic transport.[1215 ] subsequent swelling of the axon occurs with discrete bulb formations or elongated varicosities that accumulate transported proteins .
these swollen axons may become disconnected and contribute to additional neuropathological changes in brain tissue , resulting in the formation of dai .
dai occurs more frequently with force applied in the coronal plane , rather than in the sagittal or axial planes.[1518 ] the severity of dai depends on the energy of the impact .
two cases in the severe tbi group showed diaphragmatic rupture , induced when the body quickly decelerated while the organs continued to move downward or forward at a much higher velocity , tearing vessels and tissues from the normal points of attachment .
rapid changes in acceleration or deceleration to the head and abdomen , such as moving rapidly and then suddenly hitting the ground in a traffic accident or fall , could be associated with a rare combination of injuries to the head and abdomen .
shock index was higher in the severe tbi group than in the moderate tbi group in the current series , while base excess on arrival was lower in the severe tbi group than in the moderate tbi group .
in addition , no correlation has been observed between base excess and severity of head injury .
hemorrhaging from extracranial injuries in a patient with severe tbi tends to result in hemorrhagic shock following a reduction in base excess due to hypoperfusion of tissues , as severe tbi is obviously associated with more severe extracranial injuries than moderate tbi .
such hypotension could induce a second brain insult to the head injury , so hypotension may affect the outcomes in severe tbi .
the association seen between the number of traumatic microbleeds detected on mri and outcomes has also been reported in several previous studies .
tbi itself does not necessarily represent a medical emergency requiring treatment ; immediate concerns are amnesia ( a mild form of dai ) and damage to the brainstem ( a severe form of dai ) .
both these possibilities may be excluded in the present case , as we selected surviving patients with prolonged unconsciousness .
clinically , patients with amnesia could still complain of pain induced by any concomitant organ injury , so there is little chance of overlooking hidden injuries . in contrast , severe brainstem injuries can easily prove lethal by causing malfunctions in respiration and circulation .
patients with such injuries tend to present in a deeply comatose state , and thus may be more likely to have abdominal injuries in comparison with patients with severe tbi , as more severe unconsciousness was associated with a greater risk of the presence of abdominal injury according to the present results .
patients with severe tbi were more likely to have abdominal injuries when compared with patients showing moderate tbi .
hidden organ injuries could be missed because unconscious patients are unable to complain about injuries . from this retrospective study
, it appears that physicians should be aware of the possibility of such co - morbidities when treating severe dai .
patients with severe tbi are more likely to have abdominal injury than patients with moderate tbi .
physicians should thus be aware of the possibility of such complications when treating severe tbi .
 background : characteristics of extracranial injury in patients with diffuse axonal injury ( dai ) have not been clarified.materials and methods : this retrospective study reviewed medical records from january 2003 to december 2007 . 
 subjects comprised 35 patients meeting the following criteria : 1 ) head injury without mass lesion ; 2 ) glasgow coma scale ( gcs ) on arrival < 15 ; and 3 ) magnetic resonance imaging ( mri ) examination including t2 * -weighted imaging . 
 subjects were divided into two groups : severe traumatic brain injury ( tbi ) group ( patients with gcs 8 , n=19 ) and moderate tbi group ( patients with gcs > 8 , n=16).results : shock index ( heart rate / systolic blood pressure ) was significantly higher in the severe tbi group than in the moderate tbi group , while base excess on arrival was significantly lower in the severe tbi group than in the moderate tbi group . the abbreviated injury scale ( ais ) for the face , thorax , extremities and external structures showed no significant differences between the severe tbi group , but ais for the abdomen and the sum of extracranial ais was greater in the severe tbi group than in the moderate tbi group . 
 duration of hospitalization was longer and outcomes were worse in the severe tbi group than in the moderate tbi group.conclusion:because patients with severe tbi are more likely to have abdominal injury than patients with moderate tbi , physicians should be aware of the potential for such complications when treating severe tbi . 
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
CONCLUSION