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Running head: TRAUMATIC BRAIN INJURY 1

Diagnosing and Managing Traumatic Brain Injuries

November 15th

, 2011

TRAUMATIC BRAIN INJURY 2

Abstract

Traumatic brain injuries are a serious and common occurrence in the United States. They are

one of the leading causes of death and can cause numerous long term effects on patients.

Imaging is one of the best ways to diagnose and manage a brain injury. There are five different

types of traumatic brain injuries and they are diagnosed using magnetic resonance imaging and

computed tomography. It is important for patients to receive quick and accurate images in order

to have the best possible outcome.


Diagnosing and Managing Traumatic Brain Injuries

Traumatic brain injury (TBI) is one of the leading causes of mortality and morbidity in

the world. “It is estimated that 10 million people sustain TBI each year worldwide, and the

Centers for Disease Control and Prevention in the USA estimates that 1.7 million people suffer

TBI annually” (Kim & Gean, 2011, p.39). The use of imaging is critical in the diagnosis and

management of these injuries. Computed tomography (CT) and magnetic resonance imaging

(MRI) are the most common imaging modalities used to diagnose and manage TBI.

Categories of Brain Injuries

The two different categories of injury when discussing TBI are primary and secondary.

The primary injuries, such as epidural hematoma, subdural hematoma, subarachnoid

hemorrhage, cortical contusion and traumatic axonal injury, are caused by the direct result of the

impact. The secondary injuries, such as cerebral swelling, herniation, and ischemia, can develop

minutes to days after the primary injury. “This classification highlights that TBI is not a one-

time event but rather a continuous and progressive injury that necessitates optimal medical and

surgical management to maximize patient recovery and prevent successive injury” (Kim & Gean,

2011, p.39).

Primary Injuries

Epidural Hematoma

An epidural hematoma (EDH) commonly occurs at the coup site, which is the site of

impact, and is usually accompanied with an overlying skull fracture. EDH is caused by an

"Injury to a meningeal artery/vein, diploic vein, or dural venous sinus result(ing) in a classically

lentiform-shaped collection of blood that strips the dura away from the inner table of the skull"

(Kim & Gean, 2011, p.40). The most common occurrence of EDHs are found in the temporal or


temporoparietal regions and are usually due to an injury of the middle meningeal artery, the

transverse/sigmoid sinus, or the sphenoparietal sinus. In rare occasions EDHs can occur in the

frontal region of the brain, opposite of the trauma site. These are called contrecoup EDHs and

only nine cases have been reported in literature.

EDHs are more common in males than females, with the ratio being 4:1. The peak

incidence is within a mean age of 20-30 years, and is rare in patients older than 50 years. It is

very uncommon for a delayed EDH to occur, “with a reported incidence of approximately 3%”

(Takeuchi, Takasato, Masaoka, & Otani, 2010, p.152).

Imaging epidural hematomas

When imaging EDHs,

the preferred modality is CT.

The hematoma in the images

typically appear to be

lentiform or biconvex in

shape. (See Fig. 1) EDHs do

not cross cranial sutures, but

are able to cross the midline.

This is one way to distinguish an

EDH from the various other

hematomas (Kim & Gean, 2011).

Subdural Hematoma

A subdural hematoma (SDH) usually occurs at the contrecoup site, even though it can

occur at the coup site. SDH’s are caused by an "Injury to superficial bridging veins results in

Fig. 1 A. Epidural hematoma beneath a skull fracture. B.

Arrow pointing to the skull fracture.

Note. Kim, J.J. & Gean, A.D. (2011). Imaging for the diagnosis and

management of traumatic brain injury. Neurotherapeutics, 8(1), 39-53.

Retrieved on November 4, 2011, from doi:10.1007/s13311-010-0003-

3


bleeding between the meningeal layer of the dura and arachnoid, and blood may continue to

accumulate in this space" (Kim & Gean, 2011, p.41). Some of the common places for SDHs to

occur are over the cerebral convexities, along the tentorium cerebelli, and along the flax cerebri.

According to Cantu and Gean (2010) "an acute SDH is the most common cause of death due to

head injury in sports" (p.1561). SDHs are believed to be

caused by the acceleration/deceleration forces that

accompany these injuries.

Imaging subdural hematomas

A SDH will appear crescent in shape and can be

extremely subtle, so window settings and adjustments are

crucial in diagnosing. SDH's are able to cross cranial suture

lines, but do not cross the midline, which is the opposite of

an EDH. It is common for an SDH to cause a

shift in the midline. (See Fig. 2) "The volume of

the extra-axial collection is proportional to the

extent of mass effect and midline shift" (Cantu &

Gean, 2010, p.1562).

Subarachnoid Hemorrhage

A Subarachnoid hemorrhage (SAH) occurs in nearly half of patients that suffer a large

head injury and can commonly be associated with other types of hemorrhages. "SAH may result

from direct laceration of the small cortical vessels traversing the subarachnoid space,

redistribution of intraventricular hemorrhage exiting the fourth ventricular outflow foramen, or

direct extension from cortical contusion/hematoma" (Kim & Gean, 2011, p.43). The blood that

Fig.2 A CT image of a SDH on the left

side. The image shows a midline shift

that is common in a SDH.

Cantu, R.C. & Gean, A.D. (2010). Second-impact

syndrome and a small subdural hematoma: an

uncommon catastrophic result of repetitive head

injury with a characteristic imaging appearance.

Journal of Neurotrauma, 27(9), 1557-1564.

Retrieved November 4, 2011, from

doi:10.1089/neu.2010.1334


fills the subarachnoid space causes a rise in intracranial pressure and displaces the cerebrospinal

fluid. According to Sehba, Pluta, and Zhang (2010), this moment of increased pressure is

usually described by patients as "the worst headache of my life" (p.28) .

Imaging subarachnoid hemorrahages

An SAH is observed on CT images as linear

areas of high attenuation. (See Fig. 3) They can be

found in the cerebral sulci, Sylvian fissures, or basilar

cisterns. Some patients with TBIs may only have a

small SAH as the only abnormal finding on a CT scan,

so it is crucial to identify them accurately. Patients that

have an accompanying SAH with other TBI's have a

significantly worse outcome and are less likely to

achieve a good recovery in comparison with the

TBI's that are not accompanied with SAH (Kim &

Gean, 2011).

Cerebral Contusion

A cerebral contusion (CC) can be caused by either direct trauma or

acceleration/deceleration injury. CCs usually occur at the contrecoup site and are caused when a

moving head collides with a stationary object. Although CC's can occur at the coup site beneath

a skull fracture, they are more common and severe in contrecoup injuries. CC's are commonly

referred to as a bruise in the brain that are caused by the rough and irregular surfaces of the skull.

These impacts with the skull cause hemorrhagic contusions (Kim & Gean, 2011).

Fig. 3 A CT image of a SAH. The arrow

head shows the linear areas.

Note. Kim, J.J. & Gean, A.D. (2011). Imaging for

the diagnosis and management of traumatic brain

injury. Neurotherapeutics, 8(1), 39-53. Retrieved

on November 4, 2011, from doi:10.1007/s13311-

010-0003-3


Imaging cortical contusions

A CC can be imaged

using CT or MRI, but MRI is

more sensitive in detecting

small hemorrhagic contusions.

CC's appear as "small, focal

areas of pepechial hemorrhage

peripherally located in the

brain" (Kim & Gean, 2011, p.43).

They can be very subtle on the

initial CT scan, but about half of

contusions will evolve and grow

larger over time. (See Fig. 4) Due

to the evolving of CC's it is crucial that serial CT imaging and close monitoring of patients is

done.

Traumatic Axonal Injury

A Traumatic axonal injury (TAI) is typically caused by extreme

acceleration/deceleration or by child abuse, such as shaking baby syndrome. TAI involves the

loss of neural function in the areas of the brain where white and grey matter meet, which is

usually away from the area of direct trauma with the skull. The white matter in the brain is

denser than the gray matter, "due to the different inertial characteristics based on these densities,

as the brain rotates during acceleration-deceleration events, lower density tissues move more

rapidly than those of greater density. This velocity difference causes sheering of neuronal

Fig. 4 A. The initial CT scan of a patient, the short

arrow is pointing to a small CC. B. A CT scan of the

same patient 6 hours later, the short arrows pointing to a

much larger CC.

Note. Kim, J.J. & Gean, A.D. (2011). Imaging for the diagnosis and

management of traumatic brain injury. Neurotherapeutics, 8(1), 39-

53. Retrieved on November 4, 2011, from doi:10.1007/s13311-010-

0003-3


axons" (Shipley, 2011, para. 4). This process is usually bilateral, covers a large area and is near

the cerebral cortex, corpus callosum, or brain stem (Kim & Gean, 2011).

Imaging traumatic axonal injuries

The most diagnostic imaging modality for TAI is

MRI, due to CT being insensitive to white matter lesions.

Most CT scans show up normal with TAI injuries because

they are nonhemorrhagic (Marquez de la Plata et al., 2011).

TAI usually shows up on the MRI as multifocal areas of

abnormal signal in the white matter. (See Fig. 5) Many

studies have indicated that MRI can predict the

length of coma in TAI patients. "The volume of

white-matter lesions has been correlated to the

degree of injury, as measured by MRI"

(Wasserman, 2011, para. 5).

Secondary Injuries

Cerebral Swelling

The cause of cerebral swelling can be either cerebral edema or cerebral hyperemia.

Cerebral hyperemia is due to "Dysautoregulation with vascular engorgement and increased

cerebral blood volume" (Kim & Gean, 2011, p.46). This was believed to be the main mechanism

that caused cerebral swelling. Some of the recent studies have suggested that the main causes of

cerebral swelling are due to edema, which is "due to the failure of cell membrane pumps,

resulting in intracellular water leakage" (Kim & Gean, 2011, p.46). Images of cerebral swelling

Fig. 5 An MRI of a patient with a TAI,

the arrows are pointing to the abnormal

signal in the white matter.

Note. Kim, J.J. & Gean, A.D. (2011). Imaging for

the diagnosis and management of traumatic brain

injury. Neurotherapeutics, 8(1), 39-53. Retrieved

on November 4, 2011, from doi:10.1007/s13311-

010-0003-3


due to hyperemia appear as the loss of sulci, with gray and white matter differentiation intact.

(See Fig. 6) Images of cerebral edema with

appear as the loss of gray and white matter.

Cerebral Herniation

Cerebral herniation is due to part of

the brain being compressed by a hematoma.

This causes part of the brain to move from

one compartment of the cranium to

another. Subfalcial herniation, uncal

herniation, and cerebellar tonsillar

herniation are the three major types of

herniation that can occur separately or in

combination (Agamanolis, n.d.). Patients that suffer from herniation "typically undergo

decompressive craniectomy with mass lesion evacuation" (Kim & Gean, 2011, p.47).

Cerebral Ischemia and Infarction

Cerebral ischemia and infarction are not very common in

TBI patients, but occasionally they are present on CT scans.

Ischemia is usually due to a blood vessel being compressed by a

cerebral herniation. (See Fig. 7) Infarctions are common in the

anterior or posterior cerebral artery following a subfalcine or uncal

Fig. 6 A and B are CT images of a patient with

cerebral swelling. Both images show

differentiation in gray and white matter, with loss

of sulci.

Note. Kim, J.J. & Gean, A.D. (2011). Imaging for the

diagnosis and management of traumatic brain injury.

Neurotherapeutics, 8(1), 39-53. Retrieved on November 4,

2011, from doi:10.1007/s13311-010-0003-3

Fig. 7 A CT image that has bilateral multifocal ischemic lesions.

Cantu, R.C. & Gean, A.D. (2010). Second-impact syndrome and a small subdural hematoma: an

uncommon catastrophic result of repetitive head injury with a characteristic imaging appearance. Journal of

Neurotrauma, 27(9), 1557-1564. Retrieved November 4, 2011, from doi:10.1089/neu.2010.1334


herniation (Kim & Gean, 2011). MRI and CT are able to provide a vast amount of information

and assessment of the size, location, and severity of cerebral ischemia and infarctions (Leiva-

Salinas, Wintermark, & Kidwell, 2011).

Imaging traumatic brain injuries

Imaging plays an important role in diagnosing and managing TBI’s. It is critical that the

right images are taken and the best modality is used to properly diagnose an injury. According to

Kim and Gean (2011):

For diagnosis of TBI in the acute setting, noncontrast CT is the modality of choice

as it quickly and accurately identifies intracranial hemorrhage that warrants neurosurgical

evacuation. CT readily identifies both extra-axial hemorrhage (epidural, subdural, and

subarachnoid/intraventricular hemorrhage) and intra axial hemorrhage (cortical

contusion, intraparenchymal hematoma, and TAI or shear injury). While CT is the

mainstay of TBI imaging in the acute setting, magnetic resonance imaging (MRI) has

better diagnostic sensitivity for certain types of injuries that are not necessarily

hemorrhagic (p.40).

Both CT and MRI are used in the prognosis and management of TBI and advancements

are continually made to increase the quality of the images.

Conclusion

In conclusion, CT and MRI are crucial in diagnosing and managing TBI. The images that CT

and MRI provide are important in identifying the acute primary injuries when making a

diagnosis and identifying secondary injuries to guide the management process. Due to the large

number of individuals that suffer from TBI, it is imperative that high quality images are

produced to provide the best possible treatment for patients.


References

Agamanolis, D.P., (n.d.) Traumatic brain injury and increased intracranial pressure.

Neuropathology Web site. Retrieved from http://neuropathology-web.org/chapter4/

chapter4cHerniations.html#herniations

Cantu, R.C. & Gean, A.D. (2010). Second-impact syndrome and a small subdural hematoma: An

uncommon catastrophic result of repetitive head injury with a characteristic imaging

appearance. Journal of Neurotrauma, 27(9), 1557-1564. doi:10.1089/neu.2010.1334

Kim, J.J. & Gean, A.D. (2011). Imaging for the diagnosis and management of traumatic brain

injury. Neurotherapeutics, 8(1), 39-53. doi:10.1007/s13311-010-0003-3

Leiva-Salinas, C., Wintermark, M., & Kidwell, C.S. (2011). Neuroimaging of cerebral ischemia

and infarction. Neurotheraputics, 8(1), 19-27. Retrieved from

http://www.springerlink.com/content/k0125231757l8v13/fulltext.pdf

Marquez de la Plata, C.D., Garces, J., Kojori, E.S., Grinnan, J., Krishnan, K., Pidikiti, R.,

…Diaz-Arrastia, R. (2011). Deficits in functional connectivity of hippocampal and

frontal lobe circuits after traumatic axonal injury. Archives of Neurology, 68(1), 74-84.

doi:10.1001/archneurol.2010.342

Sehba, F.A., Pluta, R.M., & Zhang, J.H. (2011). Metamorphosis of subarachnoid hemorrhage

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Shipley, C. (2010). Traumatic brain injury and diffuse axonal injury. Trial Image Inc. Web site.

Retrieved from http://trialimagestore.com/article_traumatic_brain_injury.html

Takeuchi, S., Takasato, Y., Masaoka, H., & Otani, N. (2010). Contrecoup epidural hematoma.

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http://emedicine.medscape.com/article/339912-overview#a21

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