Brain Injuries¶

Concussion¶

This describes a condition caused by a severe blow to the head or a fall. The term is generally used to describe a temporary altered mental status without lasting physical effects. It is characterized by symptoms such as dizziness, loss of consciousness, slow breathing, and weakened pulse, vomiting, pallor and fall in body temperature. There may be visual disturbances and confusion. Concussion may also be accompanied by amnesia about events immediately before and after the head injury. Amnesia is described as being retrograde and anterograde. Retrograde amnesia describes loss of memory for events leading up to the injury. Anterograde amnesia describes loss of memory of events after the injury. There is a correlation between the duration of memory loss and the degree of severity of concussion.

Concussion severity and other types of head injuries are often rated using a diagnostic scale known as the Glasgow Coma Scale or GCS. The rating system uses three criteria to rate the severity of the head injury (eye opening, verbal response and motor response) with a score of 15 being the best possible score and 3 being the worst. Below is a reproduction of the scale.

Glasgow Coma Scale¶

Eye Opening (E)¶

Spontaneous: 4
To voice: 3
To pain: 2
None: 1

Verbal Response (V)¶

Orientated: 5
Confused: 4
Inappropriate words: 3
Incomprehensible words: 2
None: 1

Motor Response (M)¶

Obeys commands: 6
Localises pain: 5
Withdraw (pain): 4
Flexion (pain): 3
Extension (pain): 2
None: 1

GCS sum score = E+V+M best score =15; worst score =3

Severe brain injury = 1-8

Moderate brain injury = 9-12

Mild brain injury = 13-15

In most cases where concussion is the diagnosis, the effects resolve spontaneously; however, the recovery period can be variable. Headache is the most common complaint following concussion Other longer-term symptoms seen are fatigue, decreased concentration and anxiety. There also appears to be a relationship between the recovery period and the period of amnesia.

The majority of people who suffer a simple concussion do not require treatment at all. If they are seen at a hospital they may be discharged immediately after examination and evaluation or admitted for a brief period for observation, often 4 hours. Symptoms generally begin to improve after a short period of time and continue to improve until they resolve, generally within weeks.

In the case of persistent headaches, medication and reassurance may be given.

More severe cases of concussion are usually associated with other concomitant brain injuries such as contusion or hematoma. The prognoses in these cases will depend on the outcome of the associated brain injury.

Brain Contusion¶

Brain contusion is a bruising of the brain matter itself, or to be more specific, bruising of the grey matter comprising the neurons and small blood vessels. This is a more serious injury than a cerebral concussion. Brain contusion may range from mild to severe. The damage may range from hemorrhage to extensive disruption of the neural tissue.

There are three types of cerebral contusion lesions: coup, contrecoup and intermediate coup. A coup lesion is where the brain contusion occurs at the site of impact to the skull. A contrecoup lesion is when the contusion occurs opposite the site of the impact. When the contusion occurs at a site that is neither at nor opposite the impact site, it is referred to as an intermediate coup lesion.

Cerebral contusions most commonly involve the frontal and temporal lobes of the cerebral hemispheres. This is because in this area there are a number of bony ridges and protuberances at the base of the skull that the brain may come in contact with. Brain contusion is much more likely to occur when the brain contacts a bony prominence than a smooth surface.

Contusion results in specific types of damage. This includes edema (swelling of the brain due to accumulation of fluid), hemorrhage, infarction (obstruction of the blood vessels), ischemia (a lack of blood supply) and necrosis (tissue death).

The symptoms and residual effects of cerebral contusions depend on the location of the contusion. Contusion to the frontal lobes may cause personality changes; temporal lobe contusions may result in behavioral changes. Contusion to the parietotemporal region can cause language difficulties while injury to the parietal lobe may cause motor paralysis and sensory abnormalities. Contusions to the occipital lobes may cause visual damage and impairments.

The outcome of cerebral contusions can be highly variable. Recovery very much depends on the site and extent of the contusion, obviously smaller contusions have a better outcome and frontal lesions tend to recover with less dysfunction.

Brain Laceration¶

A cerebral laceration is tearing of the brain tissue. It is usually seen with penetrating injuries or is associated with skull fractures where a fracture fragment becomes depressed into the brain tissue. Laceration can also occur with blunt head injuries where acceleration or deceleration forces cause mass movement of the brain resulting in tearing or laceration of tissue.

Cerebral lacerations produce similar damage as contusions. A major difference however, is the frequently associated complication of cerebral hemorrhage along with its associated complications. Similar to contusions, the resolution from the laceration will depend on the site of the tear and the extent of the laceration. Neurological symptoms and dysfunction will vary depending on the area of the brain involved. Posttraumatic epilepsy is often associated with cerebral laceration due to the formation of scar tissue following the healing of the laceration.

Intracranial Hematoma¶

Intracranial hematoma results from trauma to the blood vessels and dural sinuses of the brain. Contusions, lacerations and fractures all might be the cause of intracranial hemorrhage with resultant hematoma.

Intracranial hematomas may be described as being extra-axial or outside the brain (developing within the spaces surrounding the exterior of the brain), or intra-axial where the hematoma develops within the brain matter itself. Intra-axial hematomas are also referred to as intracerebral hematomas.

Extra-axial hematomas are described according to their location in relation to the three meningeal layers surrounding the brain. The meninges comprise three layers, the pia mater (inner layer), arachnoid layer (middle layer) and the dura mater (outside layer). Because of the three layers, a virtual space exists between the brain, the layers and the skull. The pia mater covers the brain surface and hemorrhage may occur with hematoma formation between the brain surface and pia mater. Another space exists between the pia mater and the arachnoid that is known as the subarachnoid space (See Illustration). A space also exists between the arachnoid layer and the overlying dural membrane. A further space exists between the dura mater and the skull that is known as the epidural space. The major types of extra-axial hemorrhages and hematoma are therefore known as epidural hematoma, subdural hematoma and subarachnoid hematoma.

Intracerebral Hematoma¶

Hemorrhage in the cerebellar region of the brain is a major life threatening injury often leading to a fatal outcome due to cerebellar herniation. Symptoms of cerebellar hematoma may initially include severe headache, neck stiffness, drowsiness and inability to coordinate the muscles. Facial palsy and oculomotor abnormalities also develop. As the situation deteriorates coma sets in followed by death due to brain stem compression.

The clinical course and outcome of cerebellar hemorrhage is highly varied. Much depends on the size of the hematoma. Small hematomas may take a benign course and may not even require surgery, however hematomas of 3 cm or greater have poor outcomes. Coma is also an indicator of poor outcome as it is indicative of brain herniation.