Measures of Traumatic Brain Injury SeverityPaul Carufel, MA, CBIS and Jerry Wright, MS, CBISTRehabilitation Research Center, Santa Clara Valley Medical CenterSan Jose, CA
Glasgow Coma Scale (GCS):
Loss of Consciousness (LOC):
Statement of the problem: Descriptions and labels of severity of injury are often not terribly informative and sometimes are misleading. Clinical issue: There are a variety of approaches to describing traumatic brain injury (TBI) severity. The most commonly used reported measure, the Glasgow Coma Scale (GCS) does not provide much information for long term prognosis by itself.
Best practice approach: Four common methods used to determine severity of TBI will be presented with detailed descriptions and 'compare and contrast' observations. These include: the GCS, duration of post-traumatic amnesia (PTA), duration of loss of consciousness (LOC) and use of neuroimaging findings (CT, MRI). The utility, advantages, and disadvantages of each will be described. Further research needed will also be addressed.
- The GCS is a scale for measuring level of consciousness in which scoring is determined by three factors: amount of eye opening, verbal responsiveness, and motor responsiveness.
- It is used by trained staff at the site of an injury like a car crash or sports injury, for example, and in the emergency department and intensive care.
- Scores range from 3 to 15, with lower scores representing more serious injuries.
- There are often serial scores taken. One recommendation is to take the best score within the first 24 hours after injury. This is not universally accepted.
- Factors like drug use, alcohol intoxication, shock, or low blood oxygen can alter a patient’s level of consciousness. If an individual is intubated, a verbal score may not be possible. These factors could lead to an inaccurate score on the GCS.
- GCS scores are not very predictive of later functional outcome.
- Loss of consciousness is the complete or near-complete lack of responsiveness to environmental stimuli. An individual in a coma.
- There is not a standardized approach to measuring LOC. Some propose that GCS Total Scores of 3-8 reflect LOC states. Others propose emergence from LOC is reflected by a GCS Motor Score of 6.
- This is not a good self-report variable, but one that patients are often asked.
- LOC has been found to be predictive of some outcomes but not others (notably neuropsychological outcomes).
- Neuroimaging findings are often reported from Magnetic resonance imaging (MRI) and computed tomography (CT) findings. Presence of findings may reflect more severe injuries.
- Radiologic brain imaging is the most useful means of visualizing and categorizing the location, nature, and degree of damage to the central nervous system sustained by patients with traumatic brain injury (TBI).
- The Traumatic Brain Injury Model Systems bases abnormal findings on review of all scans taken over the first week post injury.
- Neuroimaging findings have been found to be very predictive of short term outcomes, but less useful for outcomes beyond one year.
- Describe the components of each measure.
- List weaknesses or limitations of each measure.
- Match measures with the most appropriate time frame post-injury.
Post-traumatic Amnesia (PTA):
- Post-traumatic amnesia (PTA) is a state of confusion that occurs immediately following a traumatic brain injury (TBI) in which the injured person is disoriented and unable to remember events that occur after the injury.
- PTA may be difficult to assess. There are several measures designed for serial testing of emergence from PTA, incluting the Galveston Orientation and Amnesia Test (GOAT), the Westmead PTA Scale and the O-LOG. Sometimes general orientation questions are used. There is lack of consistency in the field.
- Accurate measurement relies on serial testing, which is more challenging.
- PTA has been found to be one of the better predictors of later outcome.
Brain Injury Severity:
Acute injury severity is determined at the time of the injury, but this does not always accurately reflect later functional outcome.
- One issue with most of these measures is a lack of universal definition or method of collection.
- The Common Data Elements initiative is an attempt to clarify terms and instruments.
- Injury severity terms such as “Mild” do not necessarily reflect the seriousness of the brain injury and may be misleading.