How to read an abnormal ct scan: Case Studies of Traumatic Brain Injury Types

Why dread a bump on the head? June 2012

Lesson 3: How does a CT scan help diagnose TBI?

How to read an abnormal CT scan:

Case Studies of Traumatic Brain Injury Types

Every year, thousands of people in the US suffer from some type of traumatic brain injury (TBI) due to accidents such as motor vehicles accidents, sports accidents, and war injuries. A traumatic injury to the brain may cause handicaps in various aspects of a person’s life, and therefore it is very critical that TBI be identified and intervention be presented to the patients as quickly as possible. Regardless of the severity of the injury (mild, moderate or severe) an important step is to identify the extent of the injury.

As soon as a traumatic brain injury patient is brought to the hospital, the doctors typically have the patient get a head CT (computerized tomography) scan. CT has become a vital tool in the assessment of patients with serious head injury and has enabled much better quality in management of TBI. CT scans can show the bleeding, swelling, or pressure in the brain, fractures in the skull, as well as other structural abnormalities that may be caused by a traumatic injury. Looking at a CT scan, physicians can determine the best course of action and discuss about the functional difficulties that the patient may have after the accident as suggested by the locations of the injury in the brain. Here we will discuss four different types of brain injuries and their characteristics.

CASE #1

Injury Type: Epidural Hematoma
Incident Report: On April 27, 2010 a significant event occurred that altered Taylor’s cognitive abilities significantly. Taylor’s family was in a motor vehicle accident. When their car was hit by another car, Taylor hit the back of her head to her seat and she was catapulted from the back seat to the windshield. They were brought to the emergency room 20 minutes after the accident. Taylor was unconscious when she was brought to the hospital. Taylor was immediately given a CT scan.
CT Scan Results:

When the doctor looked at Taylor’s CT image, he saw the following signs of an epidural hematoma:

Wang 2011

There was a high density collection of blood (appears white on a CT) between the brain and the inner layer of the skull, biconvex, lens shaped. The build-up of blood was in the epidural space of the head, which is between the dura mater (the outer membrane of the brain) and the skull.

Action Taken & Outcome: Immediately after the CT scan, Taylor had an operation to remove the build-up of blood from the epidural space. She was in the intensive care unit for 4 days and in the acute care unit for 7 more days. The injury to the frontal lobe affected Taylor’s high-order cognitive skills such as planning, organizing of information, and executing complex tasks. Taylor is back at her school, but she is still receiving therapy to improve these skills and she is still working on sleeping problems, frustration, and being easily- tired.

CASE #2

Injury Type: Subdural Hematoma
Incident Report: Tom Huskins, age 12, was playing soccer for 3 years when he was kicked in the head in a soccer game 10 months ago. Upon being kicked in the head, Tom passed out and he was unconscious for about 15 minutes. When he was brought to the emergency room of the hospital, Tom was conscious and able to open his eyes in response to speech, and he was able to speak coherently but he was ‘disoriented’ about where he was. After some behavioral neurologic examinations, Tom was sent home but his parents were asked to watch him closely for any change in his mental state, or mood. According to Tom’s mom, the kick to the head changed him ‘overnight’. Tom woke up vomiting and he had difficulty in walking, and he could not stand any sound, light, or other stimuli. His parents brought Tom to the hospital and the doctors ordered a CT scan.
CT Scan Results: Tom’s CT scan showed the following markers which were indicative of a subdural hematoma.

There was build-up of blood in a space called “subdural space” which is between the dura mater and the brain. The injury looked crescent or sickle shaped. Spread more widely in the subdural space, with a crescentic appearance and a more irregular inner margin.

Action Taken & Outcome: Tom had an operation to remove blood and damaged tissue from his brain. He stayed in the hospital for 3 weeks. Tom continues to receive intensive physical therapy to improve his walking, gait and balance; speech therapy to work on reading, and other cognitive skills such as problem solving, and memory. Due to his young age and the extent of his injury, Tom is expected to have a good progress in improving these skills.
CASE #3

Injury Type: Diffuse Axonal Brain Injury
Incident Report: On July 14^th, 2011 when David was driving along the highway, he was hit by a mac truck when driving about 65 mph. The force of that hit sent him spinning, and hitting the truck a few more times until he landed on the opposite side of the highway. After impact he was found unconscious inside his car. David was air lifted to the hospital.
CT Scan Results: David got a head CT scan 3 hours after the accident, which did not reveal any structural abnormalities. 12 hours post-accident, David got another head CT, which was indicative of a diffuse axonal brain injury.
On David’s CT scan, DAI appeared as ball-shaped deformations of the damaged axons at white matter areas, corpus callosum and gray-white matter junctions.

Diffuse axonal injury (DAI) is associated with very severe trauma. During a traumatic injury, many forces are acting on the brain. These forces can cause twisting and shearing of the brain tissues. As in David’s case, the spinning and hitting caused twisting and shearing of his brain tissues. The neurons that make up our nervous system have delicate axons which are critical for transmission of signals throughout the brain and the body. With enough twisting of the tissues, these long, delicate axons of the neurons can tear or break. Injury to the axon prevents the normal electrical impulses from passing down the axon normally. In patients who suffer DAI, many areas of the brain can be injured simultaneously and axonal damage can often be found throughout the white matter. Typically, patients who have DAI lose consciousness immediately at the time of the trauma which can evolve into a coma that is often irreversible (Giannatempo et al., 2006). DAI is the most severe of all primary brain lesions. It is clinically more severe than the other injuries.

Action Taken & Outcome: Due to the nature of the injury, doctors do not usually operate on these type of head injuries, and David did not get an operation following the accident. As a result of this injury, David was in coma for 26 days. He is receiving intensive treatment to strengthen his physical and cognitive skills. David still suffers from loss of peripheral vision in both eyes, loss of depth perception in both eyes, migraine headaches, insomnia, short term memory loss, reading and math deficits, social withdrawal, depression, mood disorder and a number of other injuries and symptoms.
CASE #4

Injury Type: Open/Penetrating Head Injuries
Injury Description: David, Taylor, and Tom’s head injuries are classified as “closed head injuries”. Closed head injuries are clinically more common than open/ penetrating head injuries. Some severe cases of trauma may result in open head injuries that may be caused by knife or firearm wounds, fractures may be associated with a laceration (ripping or tearing) of the dura mater and a penetration of bone fragments, air or foreign objects into the cranial cavity.



CT Scan Results: This is a CT scan of a man with a gunshot wound to the right fronto-parietal region. It is observed on the CT scan that the bullet crossed the midline, ruptured the superior longitudinal sinus, which resulted in a large midline subdural hematoma.
A Note about All TBI Injury Types:

Traumatic brain injury usually leaves patients with an “invisible disability”. Despite looking physically healed and normal, these TBI survivors may have various cognitive challenges such as memory problems, understanding pragmatic and social cues, depression, mood changes, and difficulty in problem solving, planning and execution.

References:

Perron, Andrew. (2008). How to read a head CT scan. In J.G. Adams (Ed.), Emergency Medicine (753-763). Elsevier.

Giannatempo, G.M., Scarabino, T., Simeone, A., Casillo, A., and A. Maggialetti. (2006). In T. Scarabino, U. Salvolini, and J.R. Jinkins (Eds.), Emergency Neuroradiology (137-162). Springer.

Vinas, F.C., et al. (2011, June 2). Penetrating head trauma. Medscape. Retrieved from http://emedicine.medscape.com/