Grading Scale for Cerebral Concussions

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Barrow Quarterly - Volume 16, No. 1, 2000

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Grading Scale for Cerebral Concussions

Roberto Masferrer, MD†
Mauricio Masferrer, MD‡
Virginia Prendergast, NP†
Timothy R. Harrington, MD

†Masferrer Neurosurgical, Colorado Springs, Colorado
‡Mental Health Center of East Central Kansas, Emporia, Kansas
Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona


Traditionally, cerebral concussions have been defined as a transient loss of consciousness without neuroanatomical evidence of parenchymal injury. The concept, however, is no longer valid. When sustained in industrial accidents, motor vehicle collisions, and assaults, cerebral concussions can have forensic and medicolegal implications, and treating physicians must decide when is it safe for the injured patients to return to work or resume driving. Cerebral concussions also assume a significant role in sports, especially in high school and college. Medical personnel assigned to the sports arena must determine if athletes have been injured severely enough to preclude their continued participation in the event. Team doctors or coaches also must determine how soon injured athletes can participate in upcoming events. After a cerebral concussion, an athlete’s risk for a second injury increases, and second-impact syndromes can have devastating outcomes. A scientific consensus onhow to assess the severity of concussions has been lacking. In 1997 the American Academy of Neurology issued a practice parameter offering a grading scale to assess the severity of cerebral concussions sustained during athletic competitions. We concur with the need to grade these injuries, primarily to prevent the devastating sequelae associated with a second or repetitive injuries in sports. A grading scale could also be applied to concussions sustained in other circumstances and could be used for prognostic, medicolegal, and forensic determinations.

Key Words: cerebral concussion, closed head injury, head trauma, sport injuries, traumatic brain injury


In contemporary society cerebral concussions occur as a result of head trauma sustained in motor vehicle accidents, acts of violence, industrial accidents, falls, and sports. It is difficult to assess the incidence of cerebral concussions in the general population, but they are likely underreported. Each year 100,000 to 250,000 concussions may occur in sports alone.[4,16]

The classic definition of a cerebral concussion (commotio cerebri) implied a transient loss of consciousness but no underlying injury to the brain parenchyma. In contrast, the classic definition of a cerebral contusion (contusio cerebri) involved loss of consciousness with damage to the cerebral parenchyma. The hallmark of both injuries was loss of consciousness.[10] Based on these definitions, it was sometimes difficult to differentiate contusions from concussions or to determine the severity of injuries. Subjective and arbitrary values for the length of unconsciousness were used to determine whether a patient had suffered a concussion or a contusion. If consciousness was lost less than 10 minutes, it was considered a concussion; if the loss was longer, it was considered a contusion or a more serious intracranial injury.[1]

Computerized tomography (CT) and magnetic resonance (MR) imaging permit the degree of parenchymal damage to be quantified and graded, thereby improving the diagnosis of cerebral contusions. The degree of severity of a concussion, however, remains hard to assess based on imaging studies that are considered normal by definition. While a normal CT scan confirms the diagnosis, it provides no information about the severity of injury. The increased sensitivity of MR imaging, however, has revealed abnormal signal intensities in the brain parenchyma of some patients with cerebral concussions.[1,12,19,21] That the MR imaging studies of some patients with concussions are normal while others show abnormal signal intensities corroborates the concept that cerebral concussions have different levels of severity and supports the need for a universally accepted grading scale.

Historical Review

Loss of consciousness after head trauma has been known since Biblical times. In the classic story of David and Goliath, the Philistine giant lost consciousness after being struck in the head by a slingshot from the young shepherd. Whether Goliath suffered a concussion, a contusion, or a more serious brain injury is unclear as the young David did not allow the giant to recover from his posttraumatic slumber.

Millennia later in another epic saga (Historia Verdadera de la Conquista de la Nueva España), Bernal Diaz del Castillo described how Montezuma was struck in the temple by a rock. The Aztec leader immediately lost consciousness. He recovered transiently but became progressively ill and died within two days. This description probably represents the first report of an epidural hematoma in the New World. An Inca skull from the same period (housed at the Smithsonian Institute) has seven trephinations associated with skull fractures. Six of the trephinations show different stages of healing, indicating that preColumbian brain surgeons were successful and that repetitive head injuries were common among indigenous warring societies.

The first medical writings on head injuries date to the possible teachings of Imhotep, some 2,000 years before Christ. The Edwin Smith papyrus described 10 cases of head injury, one of which was a closed head injury with posttraumatic neurologic sequelae.[10,20]

The corpus Hippocraticum contains several references to both open and closed head injuries, including cerebral concussions, which were translated to Latin and then English as commotio cerebri. The following translation is from the book of Hippocratic aphorisms: "when commotion of the brain is caused by a blow, the victim loses his speech and cannot see or hear."[28]

In his work De Arte Medica, Cornelius Celsus noticed that a "cerebral hemorrhage" could occur without a skull fracture. Some 700 years later in Persia, Rhazes recognized that concussive states could occur without skull injury.[10] Nothing new was added to these concepts until the 16th century. When Bernal Diaz del Castillo was recording the death of Montezuma in Tenochtitlán, Ambroise Paré in France re-embraced the concept of commotio cerebri, which he referred to as "concussion," "commotion," or "shaking of the brain." In the 17th century, Jean Louis Petit's surgical teachings included a classification of skull fractures and intracranial hematomas. He described contre-coup injuries and gave two reasons for loss of consciousness: "concussions" or "the accumulation of blood inside the skull."[8]

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