Glasgow Coma Scale - an overview (2023)

The Glasgow Coma Scale (GCS) is universally utilized as an initial assessment tool.

From: Handbook of Clinical Neurology, 2015

Head and Face

David J. Magee PhD, BPT, CM, in Orthopedic Physical Assessment, 2021

Glasgow Coma Scale

The Glasgow Coma Scale (seeTable 2.5) is a scoring scale of eye opening and motor and verbal responses that can be administered to individuals to objectively measure the level of consciousness and severity of the head injury. The responses are scored between 1 and 5 with a combined total score of 3 to 15, with 15 being normal. An initial score of less than 5 is associated with an 80% chance of being in a lasting vegetative state or death. An initial score of greater than 11 is associated with 90% chance of recovery. Concussions are usually rated between 13 and 15. Its primary use in evaluating individuals for concussion is to rule out more severe brain injury and to help determine which individuals need immediate emergent medical attention.133

The first test relates to eye opening. Eye opening may occur spontaneously, in response to speech or pain, or there may be no response at all. Each of these responses is given a numeric value: spontaneous eye opening—4; response to speech—3; response to pain—2; and no response—1. Spontaneous opening of the eyes indicates functioning of the ascending reticular activating system. This finding does not necessarily mean that the patient is aware of the surroundings or of what is happening, but it does imply that the patient is in a state of arousal. A patient who opens his or her eyes in response to the examiner’s voice is probably responding to the stimulus of sound, not necessarily to the command to open the eyes. If unsure, the examiner may use different sound-making objects (e.g., bell, horn) to elicit an appropriate response.

The second test involves motor response; the patient is given a grade of 6 if there is a response to a verbal command. Otherwise, the patient is graded on a 5-point scale depending on the motor response to a painful stimulus (seeTable 2.5). When scoring motor responses, it is the ease with which the motor responses are elicited that constitutes the criterion for the best response. Commands given to the patient should be simple, such as, “Move your arm.” The patient should not be asked to squeeze the examiner’s hand, nor should the examiner place something in the patient’s hand and then ask the patient to grasp it. This action may cause agrasp reflex, not a response to a command.185

If the patient does not give a motor response to a verbal command, then the examiner should attempt to elicit a motor response to a painful stimulus. It is the type and quality of the patient’s reaction to the painful stimulus that constitute the scoring criteria. The stimulus should not be applied to the face, because painful stimulus in the facial area may cause the eyes to close tightly as a protective reaction. The painful stimulus may consist of applying a knuckle to the sternum, squeezing the trapezius muscle, or squeezing the soft tissue between the thumb and index finger (Fig. 2.47). If the patient moves a limb when the painful stimulus is applied to more than one point or tries to remove the examiner’s hand that is applying the painful stimulus, the patient is localizing and a value of 5 is given. If the patient withdraws from the painful stimulus rapidly, a normalwithdrawal reflex is being shown and a value of 4 is given.

Traumatic Brain Injury, Part I

Scott A. Goldberg, ... Andrew Jagoda, in Handbook of Clinical Neurology, 2015

The Glasgow Coma Scale

The Glasgow Coma Scale (GCS) was developed in 1974 as a measure of the depth of impaired consciousness from a TBI. It was intended to provide an easy to use tool to facilitate communication between care providers and was intended for serial use to monitor a patient's neurologic function over time (Teasdale and Jennett, 1974). It has since been adapted for widespread use based on its relative simplicity and association with prognosis and has been further modified for use in the pediatric population (Holmes et al., 2005). The GCS consists of three dimensions: motor responsiveness, verbal performance, and eye opening (Table 23.1).

Table 23.1. The Glasgow Coma Scale

Motor responseNoneExtensorFlexorLocalizesCommandSpontaneous
Verbal responseNoneUnintelligibleInappropriateConfusionSpontaneous
Eye openingNoneTo painTo commandSpontaneous

(Adapted from Teasdale and Jennett, 1974.)

Low GCS has been shown to correlate with poor outcomes, with mortality rates as high as 76% for patients with a post-resuscitative GCS of 3 (Baxt and Moody, 1987; Marshall et al., 1991). As the GCS was developed as a serial exam, a single field GCS is of limited utility (Winkler et al., 1984). A decreasing GCS is more predictive of poorer outcome than an initially low GCS (Marshall et al., 1991; Servadei et al., 1998), while a GCS trending up is predictive of improved outcomes (Winkler et al., 1984). In children as well, an improving GCS increases rates of survival (White et al., 2001). Patients with an initially high GCS that remains high have the best outcomes and some authors have suggested that in isolated head trauma, patients with a serial GCS of 14 or 15 may not need transport to a designated trauma center (Horowitz and Earle, 2001; Ellis et al., 2007).

However, the GCS has several limitations. Most importantly, it requires an interactive patient. The GCS is best determined by the prehospital provider only after correction of other sources of blunted neurologic response, including opiate overdose, hypoglycemia, hypoxemia, or hypoperfusion. Further, it must be performed prior to sedation or paralysis. If the patient has evidence of airway compromise, a cursory GCS evaluation should be performed in tandem with preparation for airway maneuvers requiring sedatives or paralytics. It also must be stressed that the GCS is intended for serial examinations and outcomes cannot be adequately determined until a trend in GCS has been established.

(Video) Glasgow Coma Scale made easy

A further limitation of the GCS is its questionable interrater reliability, especially when performed by prehospital providers (Green, 2011). Recently, a simplified scoring system has been developed and validated in the prehospital setting (Thompson et al., 2011). The simplified motor score (SMS) is a three-point scoring system (Table 23.2) and has been found to predict outcomes in TBI with similar accuracy to the GCS (Thompson et al., 2011). In the future, the SMS may well replace the GCS in prehospital and hospital assessments of patients with TBI. In the meantime, if the GCS is to be used in the field, it is recommended that providers receive ongoing training and access to standardized scorecards in order to maximize interrater reliability (Lane et al., 2002).

Table 23.2. The Simplified Motor Score

PointsPatient response
0Withdraws to pain (or worse)
1Localizes pain
2Obeys commands

(Adapted from Thompson et al., 2011.)

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Head Trauma

Ron M. Walls MD, in Rosen's Emergency Medicine: Concepts and Clinical Practice, 2018

Glasgow Coma Scale

The GCS is a 15-point scale used in an attempt to quantify the patient's LOC and is an objective method of following the patient's neurologic status (Table 34.2). It was originally developed during a time when CT scanning was not available to communicate changes in neurologic status in comatose patients with TBI (Fig. 34.6). The score assigns points based on the patients best eye opening (spontaneous opening = 4 to no response = 1), motor response (obeys commands = 6 to no response = 1), and verbal response (oriented = 5 to no response = 1). Due to its ease of use, it has been adopted in the routine assessment of all trauma patients, including those with MTBI who are not comatose.5 However, the GCS score can reflect impairment from conditions other than brain injury, such as distracting injuries, intoxication from drugs and alcohol, hypoxemia, and sedative medications. Furthermore, patients can deteriorate from an expanding intracranial hematoma after what appears clinically to be a mild brain injury. Although TBI is often categorized into mild, moderate, and severe based on the GCS score, it really represents a spectrum of injury.

Neurosensory Diagnostic Techniques for Mild Traumatic Brain Injury

Joo Hyun Park MD, PhD, Ja-Won Koo MD, PhD, in Neurosensory Disorders in Mild Traumatic Brain Injury, 2019

Glasgow Coma Scale

The GCS is commonly used to provide an initial assessment score for patients with TBI and has been widely accepted in the fields of neurosurgery, emergency medicine, and acute trauma as a marker of the severity of head injury in adults17–20; GCS scores range from 3 to 15 (Table 17.1). These scores are often not included in mTBI studies because the very nature of a mild injury would result in a GCS score of at least 14 or 15, which is frequently normal. Nonetheless, the GCS is widely accepted as one of the best predictors of outcome following more moderate to severe injuries and, as such, is appropriate for the identification of more severe injuries.21 Some authors have reported the efficacy of the GCS-Extended (GCS-E; Table 17.1), which includes duration of PTA along with the traditional GCS, for the prediction of symptoms in mTBI patients.17 The use of the GCS-E in mTBI patients has shown that longer lengths of amnesia following injury are associated with greater incidences of dizziness, depression, and cognitive impairments during the first weeks after the injury.17 Thus, it is important to assess PTA multiple times beginning with an initial assessment and then at documented intervals throughout the stages of recovery.

Table 17.1. Glasgow Coma Scale and Extended Version

(Video) Advanced Critical Care Nursing: Glasgow Coma Scale Overview

Eye Response (E)Verbal Response (V)Motor Response (M)Duration of Amnesia (A)
No eye openingNo verbal responseNo motor response31–90 days1
Eye opening in response to painEyes opening spontaneouslyExtension (decerebrate response) on painful stimuli8–30 days2
Eye opening to speechInappropriate wordsAbnormal flexion (decorticate response) on painful stimuli1–7 days3
Eyes opening spontaneouslyConfusedWithdrawal from pain3–24h4
OrientedLocalizes to pain30min to 3h5
Obeys commands<30min6
Glasgow Coma Score (E+V+M)of 15
Glasgow Coma-Extended score (E+V+M+A)of 22

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Pediatric Emergencies and Resuscitation

Robert M. Kliegman MD, in Nelson Textbook of Pediatrics, 2020

Glasgow Coma Scale.

Although it has not been systematically validated as a prognostic scoring system for infants and young children as it has in adults, GCS is frequently used in the assessment of pediatric patients with an altered level of consciousness. The GCS is the most widely used method of evaluating a child's neurologic function and has 3 components. Individual scores for eye opening, verbal response, and motor response are added together, with a maximum of 15 points (Table 81.3). Patients with a GCS score ≤8 require aggressive management, generally including stabilization of the airway and breathing with endotracheal intubation and mechanical ventilation, respectively, and if indicated, placement of an intracranial pressure monitoring device. TheFull Outline of Unresponsiveness (FOUR) score is another useful assessment and monitoring tool (seeTable 85.1).

Coma Scales

T.E. Gofton, G.B. Young, in Encyclopedia of the Neurological Sciences (Second Edition), 2014

Glasgow Coma Scale

The Glasgow Coma Scale (GCS) (Table 1) is almost universally used in emergency rooms and intensive care units (ICUs), and is by far the most common coma scale cited in the neurosurgical literature. However, it has not been used consistently in different hospitals, and the later versions of the GCS have not been adequately tested for reliability. The GCS was designed for the initial assessment of patients with head injury. Problems with the use of the GCS arise when patients are intubated and cannot respond verbally or if the eyes are swollen shut, preventing ocular assessment. A theoretical disadvantage is the three-dimensional assessment: The total score is obtained by adding the values for three motor activities – eye opening, best motor response, and best verbal response. These are assumed to be independent variables but they are not. Because they covary, their addition may not be valid. Furthermore, to achieve a score of 6–12, there are more than 10 simple combinations of variables, each with very different clinical profiles. It seems unlikely that all patients with specific scores ranging from 6 to 10 will be equivalent in disease severity. Additionally, there is little difference in outcome over several different score values (e.g., between 10 and 15). The GCS is often insufficiently sensitive for the detection of changes in the level of consciousness in patients following head injury or with masses and risk of herniation when they are in lighter stages of impaired consciousness. Furthermore, in the application of the GCS to patients who have been in the ICU for an extended period of time, eye opening does not equal conscious awareness because patients with persistent vegetative state (VS) may show this and patients with seizures show spontaneous eye opening.

Table 1. Glasgow Coma Scale

Best motor responseObeys6
Withdraws (flexion)4
Abnormal flexion3
Extensor response2
Verbal responseOriented5
Confused conversation4
Inappropriate words3
Incomprehensible sounds2
Eye openingSpontaneous4
To speech3
To pain2

However, the GCS has been the standard scoring assessment throughout the world for 20 years. It seems unlikely that it will be easily replaced, even by potentially superior scoring systems. The Innsbruck and the Edinburgh-2 Coma Scales have some of the same problems as the GCS but the Reaction Level Scale (RLS 85) has a number of advantages over the others.

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(Video) Glasgow Coma Scale (GCS) | NCLEX


Sports Neurology

David W. Wright, Jeffrey J. Bazarian, in Handbook of Clinical Neurology, 2018

The level of alertness

The most recognized scale for alertness is the GCS (Jennett and Bond, 1975) (Table 9.3). The GCS scores range from 3 to 15, with 3 the most severe (unresponsive even to noxious stimulation) and 15 meaning completely awake and alert. Mild TBI is considered a GCS of 13–15, although most clinicians consider 14–15 more accurate for the mTBI category, since patients with GCS of 13 at 30 minutes postinjury have outcomes more like patients with moderate TBI (GCS 9–12) (Stein, 2001). The upper end of the GCS is a poor discriminator for mild TBI, and only serves to separate those with more severe intracranial injury. Patients who remain altered or have a waxing and waning level of consciousness in the ED should undergo a more extensive evaluation, including CT imaging and observation/admission until they are fully alert.

Table 9.3. Glasgow Coma Scale

ResponseScaleScore (points)
Eye-opening responseEyes open spontaneously
Eyes open to verbal command, speech, or shout
Eyes open to pain (not applied to face)
No eye opening
Verbal responseOriented
Confused conversation, but able to answer questions
Inappropriate responses, words discernible
Incomprehensible sounds or speech
No verbal response
Motor responseObeys commands for movement
Purposeful movement to painful stimulus
Withdraws from pain
Abnormal flexion, decorticate posture
Extensor response, decerebrate posture
No motor response

Mild brain injury = 13–15 points; moderate brain injury = 9–12 points; severe brain injury = 3–8 points.

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Coma, Persistent Vegetative States, and Diminished Consciousness

A. Demertzi, ... M. Boly, in Encyclopedia of Consciousness, 2009

Behavioral Evaluation

In 1974, Teasdale and Jennett's Glasgow coma scale (GCS) was published in ‘The Lancet.’ This standardized bedside tool to quantify consciousness became a medical classic, thanks mainly to its short and simple administration. The GCS measures eye, verbal, and motor responsiveness. There may be some concern as to what extent eye-opening is sufficient evidence for assessing brainstem function. Additionally, the verbal responses are impossible to be measured in cases of intubation and tracheotomy. Most importantly, the GCS is not sensitive enough to detect transition from the VS toward the MCS.

To differentiate VS patients from MCS patients, the most appropriate scale is the coma recovery scale-revised (CRS-R). The CRS-R has a similar structure to the GCS, containing, in addition to motor, eye, and verbal subscales, also auditory, arousal, and communication subscales. Despite its longer administration (i.e., c. 20min) as compared to the GCS and the full outline of unresponsiveness (FOUR), it is the most sensitive in differentiating VS patients from MCS patients. This is because it assesses every behavior according to the diagnostic criteria of the VS and the MCS, such as, the presence of visual pursuit and visual fixation. Importantly, the way we assess these behavioral signs need to be standardized and uniform, permitting between-centers comparisons. For example, for the assessment of visual pursuit, some scales use an object or finger (FOUR), some use a mirror, a person, an object, and a picture (Western Neuro-Sensory Stimulation Profile), some use an object and a person (Wessex Head Injury Matrix; Sensory Modalities Assessment and Rehabilitation Technique), and some a moving person (Coma/Near Coma Scale). We have shown that the use of a mirror is more sensitive in detecting eye tracking and, hence, identify MCS patients. These findings stress that self-referential stimuli have attention-grabbing properties and are important in the assessment of DOC.

Despite their pros and cons, each scale contributes differently in establishing the diagnosis and prognosis of DOC. The administration and interpretation of findings should be decided and discussed in terms of the person who uses the scale, the place where it is administered (e.g., intensive care vs. chronic rehabilitation settings), and the reasons for administration (e.g., clinical routine vs. research purposes).

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Traumatic Brain Injury, Part II

Louise M. Crowe, ... Vicki Anderson, in Handbook of Clinical Neurology, 2015

Injury severity

Using traditional severity measures such as the Glasgow Coma Scale (GCS) (Teasdale and Jennett, 1974), post-traumatic amnesia, and duration of unconsciousness, a dose-response relationship has been clearly demonstrated between injury severity and post-TBI impairment, with increasing TBI severity associated with reduced cognitive abilities and behavior and social problems. Logically, this relationship makes sense, with a TBI of increased severity resulting in more damage to the brain and a longer recovery time, impacting skill acquisition. Some functional domains seem to be particularly vulnerable to TBI though, with difficulties in attention, language, and behavior reported even after mild TBI (Yeates et al., 1997; Anderson et al., 2001, 2006; Dennis and Barnes, 2001; McKinlay et al., 2002; Crowe et al., 2013).

In young children, defining TBI severity accurately can be difficult, as the GCS relies on verbal responses and these skills are not developed in early childhood; therefore the GCS is modified to account for this. Further, the immature language skills in young children make post-traumatic amnesia, another commonly used measure of TBI severity, difficult to ascertain.

Brain pathology identified on neuroimaging may also provide insights into recovery. Recently studies have moved from conventional imaging to looking at quantifying structural changes and examining brain volumes. For example, recent research using novel structural imaging techniques from our group showed that the number of lesions on susceptibility-weighted imaging was a significant predictor of IQ outcomes (Beauchamp et al., 2013). Similarly, white matter loss in the corpus callosum was correlated with full scale IQ and parental ratings of social integration (Gale and Prigatano, 2010). Research utilizing diffusion imaging studies has reported associations between brain pathology and neurobehavioral outcomes (Wozniak et al., 2007; Ewing-Cobbs et al., 2008; Levin et al., 2008; Babikian et al., 2009). For example, reduced white matter integrity in the frontal region and corpus callosum has been associated with reduced processing speed and cognitive and motor outcomes after TBI in children (Ewing-Cobbs et al., 2008; Levin et al., 2008). Reduced white matter integrity in the frontal and supracallosal regions of the brain has also been correlated with executive function outcomes (Wozniak et al., 2007).

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Traumatic Brain Injury, Part I

Mark Faul, Victor Coronado, in Handbook of Clinical Neurology, 2015

Severity measures

The most common severity assessment for TBI is the Glasgow Coma Scale score (GCS) (Teasdale and Jennett, 1974; Shah and Kelly, 2003). This score is commonly used in prehospital settings and in EDs and is the total of three combined scores: Glasgow Motor, Glasgow Verbal, and Glasgow Eye movement. Each component of the score identifies the patient's crude functional status. It has also been shown to be a useful system in determining TBI severity (Evans, 2006). Early severity classification of TBI is based partly on the use of the GCS, where 80% of all head injuries are mild TBI (GCS score between 13 and 15) (Kraus and Norjah, 1988), 10% are classified as moderate TBI (GCS score between 9 and 12), and the remaining 10% are classified as severe, scoring 8 or less on GCS (Saatman et al., 2008). Although GCS is more frequently calculated in the ED, GCS data collected at the injury scene also helps guide the transport of the patient to the appropriate healthcare facility (Sasser et al., 2012). However, differences in injury scene GCS and ED GCS can lead to inaccurate predictions of TBI severity 15% of the time (Andriessen et al., 2011). Substance use and intubation, as well as facial swelling, can interfere with an accurate GCS assessment.

Other severity measures of TBI have been studied but were deemed unreliable when applied to TBI. Examples of TBI severity measures include LOC and post-trauma amnesia (PTA), which are commonly collected on state surveillance datasets (Marr and Coronado, 2004) and trauma registries. The LOC has been shown to be an unreliable predictor of a TBI diagnosis, with studies showing the presence of LOC and a TBI diagnosis occurs at different frequencies, such as 32%, (Walker et al., 2007), 36% (Boswell et al., 2002), and 50% (Dutton et al., 2011). Another severity measure is PTA which is measured using units of time of the amnesia after the injury. Such information is collected from the patient immediately after the trauma event. Immediate PTA has also been an unreliable predictor of a diagnosis of TBI because not every patient has PTA. However, when present, the duration of PTA is a good indicator of the extent of cognitive and functional deficits after TBI (Khan et al., 2003) and it is considered to be a good predictor of outcome (Alexander, 1995; Bowen et al., 1999; Nakase-Richardson et al., 2011). Nonetheless, the validity of self-reported data and the ability of a TBI patient to recognize their cognitive, behavioral, and emotional symptoms have been called into question for people sustaining a TBI (Sbordone et al., 2000) as up to 25% of patients change their self-evaluation of symptoms over a 3 month time period (Gronwall and Wrightson, 1980). Thus, as a measure, PTA, which involves cognition, has limited usefulness during the diagnosis of TBI.

Because most TBIs are classified as mild, some researchers have attempted to develop further categorizations of mild TBI. An early example to further categories of mild TBI was made by Esselman and Uomoto (1995), who developed a classification of mild TBI injury into grades I–IV. Their classification of mild TBI into graded categories based on severity made use of many symptoms (amnesia, loss of consciousness, confusion, anatomic lesions, abbreviated injury scoring, and the duration of symptoms). Approximately 41 different classification scales of gradations of mild TBI severity have been developed (Anderson et al., 2006). Overall, these progressive efforts have not been integrated into medical practice because there is no consensus among experts on the best grading system for mild TBI (Cobb and Battin, 2004).

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What 4 classifications are used in the Glasgow Coma Scale? ›

Injury Epidemiology

Generally, comas are classified as: severe, with GCS ≤8, moderate, GCS 9–12, and minor, GCS ≥13. Forty years after its development, the GCS has become an integral part of clinical practice and research worldwide.

What is a good Glasgow Coma Scale score? ›

The GCS is scored between 3 and 15, 3 being the worst and 15 the best.

Why is GCS important? ›

Assessment of level of consciousness using the Glasgow Coma Scale (GCS) is a tool requiring knowledge that is important in detecting early deterioration in a patient's level of consciousness. Critical thinking used with the skill and knowledge in assessing the GCS is the foundation of all nursing practice.

What factors affect GCS? ›

Interfering Factors
  • Pre-existing factors. Language or cultural differences. Intellectual or neurological deficit. ...
  • Effects of current treatment. Physical e.g. intubation or tracheostomy. Pharmacological e.g. sedation or paralysis.
  • Effects of other injuries or lesions. Orbital/Cranial fracture. Dysphasia or Hemiplegia.

Is GCS only used for trauma? ›

The Glasgow Coma Scale (GCS) is used to objectively describe the extent of impaired consciousness in all types of acute medical and trauma patients.


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