Causes and Symptoms
Concussions can be caused by a variety of traumatic events: motor vehicle
accidents, penetrating injuries, sports injuries, strikes, and falls. Recent
studies indicate that the number of concussions from motor vehicle accidents and
falls have decreased, while penetrating injuries (gunshot
wounds) and sports-related injuries are on the increase.
Concussion is a common athletic injury that often goes unreported. Recent
information suggests that children heal more slowly than adults following head
trauma. Although concussions are the mildest traumatic brain injuries, they can
result in irreversible damage or death if a person suffers another head trauma
prior to recovering from the initial injury.
People who have experienced head trauma that disrupts brain activity and sometimes
causes brief unconsciousness, ranging from several seconds to minutes immediately
after an impact, are considered to have sustained a concussion. Direct, sudden,
powerful blows to the head or an impact to the body that jars the head cause the
brain to bounce inside the skull and suffer tissue bruising. Nerve fibers tear,
and chemical reactions are altered. The irregular interior surface of the skull
can damage fragile brain tissues. Direct mechanical trauma can injure cortical
tissue, while subdural hematomas can damage subcortical structures,
potentially leading to vasospasm and ischemia.
Concussions are described as mild, moderate, or severe, though there is a lack of
standardized definitions for each type of concussion. A mild concussion may or may
not involve a brief period of unconsciousness; the brain generally recovers
quickly and without long-term damage. However, approximately 15 percent of those
injured will continue to experience symptoms one year after the initial injury.
These symptoms may range from headaches to emotional or behavioral
problems. The US Centers for Disease Control and Prevention (CDC) and the National
Center for Injury Prevention and Control have developed recommendations for
standardized terminology, treatment, and prevention of mild traumatic brain
injuries. A severe concussion is considered an emergency and requires an extended
period of time for recovery.
Headache, dizziness, nausea, and disorientation immediately following the injury
are considered risk factors for long-term complications from the head injury. Each
person’s brain and injury are unique. Therefore, a wide variety of symptoms may
occur. Patients may experience blurred vision or suffer hearing problems. People
with concussions also report becoming uncoordinated and sensitive to light and
noises, and they may experience sensory changes in smell and taste. Patients may
become moody, cognitively impaired, unable to concentrate, or fatigued.
Researchers have determined that the major neuropsychological complications of
concussion may affect the brain’s memory, learning, and planning functions. Some
concussion patients taking tests, such as the Wechsler Abbreviated Scale of
Intelligence, have revealed decreased concentration, reaction, and processing
skills in performing intellectual tasks. Their strategies to solve problems are
impaired when compared to people who have not suffered concussions.
Medical professionals assess patients with a head injury by physical examination,
radiological tests, and a standardized scale that measures level of consciousness
called the Glasgow Coma Scale. Computed tomography (CT) and magnetic
resonance imaging (MRI) scans may also be used. The American Academy of Neurology
emphasizes the duration of loss of consciousness to determine the severity of
concussions. Evaluations also consider orientation and posttraumatic
amnesia. Medical professionals assess patients’ responses to
stimuli and memory of incidents before their injury, defining the concussion
according to the level of confusion, amnesia, and duration of loss of
consciousness. Physicians ask patients questions about who and where they are and
about the time and date. The duration of amnesia after the brain trauma helps
medical professionals to determine the extent of the injury and treatments that
would be most effective to heal the brain. The Colorado Medical Society developed
a popular system, assigning grades 1 (mild), 2 (moderate), and 3 (severe) to
concussions, to guide athletic personnel in examining players who suffer
concussions during games and deciding how long they must refrain from
participation in order to prevent additional damage.
Brain
damage and death can result from serial concussions.
Postconcussion complications may include second impact syndrome: If a patient
suffers another concussion before healing is complete following the first injury,
then the second concussion can be the catalyst for rapid cerebral swelling that
causes increased pressure within the structure of the brain. This pressure can
cause the brain to press on the brain stem and result in respiratory failure and
death. This condition is usually fatal.
More common is postconcussive syndrome (PCS), which consists of such cognitive and
physical symptoms as headache, anxiety, vertigo, nausea, and hallucinations. An
estimated 30 percent of professional American football players suffer from PCS.
Researchers have determined that people who experience several concussions, such
as athletes and soldiers, are more vulnerable to becoming clinically
depressed.
Treatment and Therapy
Patients who play sports should not be returned to play until symptoms of
concussion have resolved completely, both during rest and exercise. A slow return
to previous activities allows the brain to heal, resulting in fewer long-term
complications than for patients who resume activities more quickly. Although most
patients make a full recovery, some experience long-term concussion-related
conditions, such as memory loss and neurological
impairment.
Severe concussions with increased brain pressure require hospitalization, often in
a neurological intensive care unit. The patient’s head is maintained in a neutral
position. Immobilization should be continued until a full risk assessment
indicates it is safe to remove. The patient may have suffered internal bleeding in
the brain because of the injury, and blood clots can form there. Surgery may be
required to remove these clots. Patients with preexisting conditions such as
epilepsy and diabetes may develop complications related to those diseases and
require longer recovery times.
Physicians recommend wearing helmets to absorb shocks sustained during athletic activities involving the risk of head injury in order to prevent or minimize concussions. The American Academy of Neurology has demanded a ban on boxing because the sport involves knocking out opponents by inflicting concussions. Boxers often suffer permanent brain damage and are at a heightened risk for neurological diseases.
Perspective and Prospects
Concussions were first described in medical literature by Muslim physician Rhazes
(850–923). He differentiated between a head injury that caused neurological
symptoms from those injuries that resulted in lesions and structural damage. In
the nineteenth century, medical researchers developed hypotheses, often
controversial, regarding the physical and emotional influences of concussion
symptoms. Second impact syndrome was first defined in 1984.
The development of sports medicine increased the interest
in studying concussions. The understanding of the internal brain damage involved
in concussions did not significantly advance, however, until neuroimaging
technologies such as CT scanning and magnetic resonance imaging (MRI) were
developed in the late twentieth century. In the twenty-first century, medical
professionals utilize those techniques to view brain tissues and to observe the
physiological reactions to concussion-causing trauma. Positive emission tomography
(PET) has been developed to measure chemical changes in the brain. In the case of
concussion, the PET scan can be used to evaluate changes that signal areas of
injury in the brain. These technologies will likely yield more accurate diagnostic
exams for concussions.
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