Role of CT Scan in Evaluating Craniocerebral Trauma

Introduction

Craniocerebral trauma or traumatic brain injury (TBI) is a medical condition that affects brain function that results from a blow or jolt to the head, sudden or violent hitting over the object, or the object piercing the head and entering the brain. The symptoms of craniocerebral trauma vary depending on the mild to severe damage. Mild TBI might have transient changes, while severe brain injury might cause prolonged symptoms such as loss of consciousness, sometimes resulting in coma or death. The severity of the traumatic brain injury is classified based on the duration of lack of consciousness, altered mental status, amnesia, and Glasgow coma scale (GCS) within the first 24 hours.

What Are the Causes of Craniocerebral Trauma?

The causes of craniocerebral trauma include:

• Falls - Falls from downstairs, ladder, bed, or other falls are the most common cause of traumatic brain injury in children and adults.

• Violence - Child abuse, domestic violence, gunshot wounds, explosive blast, and other assaults.

• Sports Injury - Common in young adults in sports such as baseball, football, soccer, hockey, or other extreme impact sports.

• Vehicle-Related Injury - Motorbike, car, or other vehicle collisions.

• Intentional self-harm.

What Are the Symptoms of Craniocerebral Trauma?

The symptoms of craniocerebral trauma depend on the severity of the brain injury. They include the following symptoms:

• Vomiting.

• Headache.

• Coma.

• Paralysis.

• Loss or decreased consciousness.

• Amnesia (memory loss).

• Vision changes such as dilated pupils, double vision, blurring, loss of eye movement, blindness, and sensitivity to light.

• Cerebrospinal fluid (CSF) leaks through the ears or nose.

• Difficulty in breathing and swallowing.

• Loss of bowel or bladder control.

• Slow pulse.

• Increased blood pressure.

• Facial weakness and drooping eyelids.

• Hearing problems (ringing in the ears).

• Speech problems such as slurred words and inability to understand and articulate words.

• Altered taste and smell.

How Is the Head Injury Classified?

Primary:

• Skull fractures.

• Scalp injuries.

• Extra axial hemorrhages - Subdural hematoma, epidural hematoma, subarachnoid hematoma, and intraventricular hemorrhage.

• Intra axial lesions - Cortical contusions and vascular lesions.

Secondary:

• Ischemia.

• Hypoxic damage.

• Cerebral edema.

• Brain herniations.

What Is the Glasgow Coma Scale?

Glasgow coma scale (GCS) was published in 1974 at the University of Glasgow that uses eye-opening, verbal, and motor responses to assess the patient's consciousness. Glasgow coma scale is scored from 3 to 15.

Eye Response:

• Spontaneous - 4.

• Open to verbal command - 3.

• Open to pain - 2.

• No eye-opening - 1.

Verbal Response:

• Oriented - 5.

• Confused - 4.

• Inappropriate words - 3.

• Incomprehensive sounds - 2.

• No verbal response - 1.

Motor Response:

• Obeys command - 6.

• Moves to localized pain - 5.

• Withdrawals from pain - 4.

• Flexes to pain - 3.

• Extends to pain - 2.

• No response - 1.

Brain injury is classified based on the GCS scoring. They are:

• Severe - GCS score 3 to 8.

• Moderate - GCS score 9 to 12.

• Minor - GCS score 13 to 15.

What Are the Indications of Computed Tomography (CT) in Craniocerebral Trauma?

The indications of computed tomography (CT) In craniocerebral trauma are:

• Patients with a high or moderate risk for craniocerebral injury should undergo nonenhanced computed tomography (NECT).

• Patients with mild TBI fail to reach a Glasgow coma scale (GCS) score of 15 within two hours.

• Patients suspected basal or open skull fracture.

• Alcohol or drug intoxication.

• Patients aged over 60 to 65 years.

• Vomiting.

• Amnesia.

• Seizure.

• Children aged less than two years old.

What Is the Role of CT in the Evaluation of Craniocerebral Trauma?

The role of CT in the evaluation of craniocerebral trauma is as follows:

• Epidural hematoma (EDH) appears as a biconvex or lens-shaped mass due to the reduced blood supply and does not cross the sutures. In the acute stage, EDH appears as a hyperattenuating or swirl sign indicating bleeding.

• Subacute hematoma appears as a homogenous hyperattenuating structure due to cessation of bleeding, and the chronic type appears as hypoattenuation due to the breakdown of clots formed.

• Acute subdural hematoma appears as a unilateral, hyperdense, crescent shape mass in computed tomography (CT) scan. It is found between the surface of the cerebral hemisphere and the inner table of the skull.

• Subdural hematoma appears concave towards the brain and is not restricted by suture lines, unlike epidural hematoma, which is convex towards the brain.

• Subarachnoid hemorrhage appears as high attenuation, dark, CSF-filled subarachnoid spaces around the brain. In acute hemorrhage, the sulci and subarachnoid cisterns appear white.

• Over the cerebral hemisphere, subarachnoid hemorrhage appears as low attenuation sulci with high attenuation subarachnoid blood.

• Intraventricular hemorrhage- Blood in the ventricles in intraventricular hemorrhage appears as hyperdense material often seen in occipital horns.

• Cerebral contusions appear as hyperattenuating structures in the temporal lobes and the frontal lobes near the floor of the anterior cranial fossa.

• Skull fracture appears as skull base or calvarial disruption on bone algorithm CT.

• Temporal bone fracture is better visualized in multidetector CT (MDCT) at a section thickness of one millimeter or lesser and appears as a lucent fracture line often involving the middle ear, facial nerve canal, and otic capsule.

• Intraparenchymal hematoma appears as a hypodense region inside the hyperdense intracerebral hemorrhage, which appears as a swirl sign. When the swirl sign is encapsulated, it is known as the black hole sign. The larger hematomas of more than 30 mL are more prone to expansion.

• Brain herniation - In foramen magnum herniation, the infratentorial brain displaced through the foramen magnum appears in a CT scan. Extracranial herniation appears as brain displacement through the brain deficit. In cingulate herniation, the supratentorial brain displacement below the anterior falx is visible in a computed tomography scan.

• In descending transtentorial herniation, the supratentorial brain displaces through the incisura, whereas in ascending transtentorial herniation, the infratentorial brain pushes through the incisura.

Conclusion

Computed tomography (CT) is the gold standard imaging tool used to accurately diagnose brain injury. CT shows high accuracy in detecting skull fractures, and intracranial lesions such as herniations, hemorrhage, and hydrocephalus which require surgical management. Based on Marshall and Rotterdam CT scores, CT scan findings can predict the early death of patients with traumatic brain injury. Marshall CT score published in 1992 is used to predict the outcome of traumatic brain injury, which classifies head trauma into six groups based on the parameters such as the presence of focal mass lesions and intracranial abnormalities. Rotterdam CT score uses the degree of basal cistern compression, midline shift, epidural hematomas, and subarachnoid blood for predicting the outcome.