The Glasgow Coma Scale: Purpose and Application in Head Injury Assessment
The Glasgow Coma Scale (GCS) was developed as a standardized tool for reliable interobserver neurological evaluations of patients with head injuries, enabling clear communication between healthcare providers about a patient's neurological status and facilitating detection of neurological deterioration requiring intervention. 1
Components and Scoring
The GCS consists of three components that assess different aspects of neurological function 1:
- Eye Response (E): Scored 1-4, from no eye opening to spontaneous eye opening
- Motor Response (M): Scored 1-6, from no motor response to following commands
- Verbal Response (V): Scored 1-5, from no verbal response to oriented conversation
The total GCS score ranges from 3 to 15, with severity classifications 2:
- Mild TBI: 13-15
- Moderate TBI: 9-12
- Severe TBI: ≤8
Primary Clinical Applications
The GCS serves as a standardized method for assessing level of consciousness in patients with head injuries, particularly valuable when performed by less experienced providers 3
Serial GCS assessments are more valuable than single determinations for detecting neurological deterioration, with declining scores or persistently low scores indicating poorer prognosis 3, 1
The scale helps determine appropriate level of care and need for neurosurgical intervention, with scores ≤8 typically indicating need for airway protection and possible neurosurgical intervention 2
The GCS is a required component in TBI research and classification systems, used in more than 75 countries worldwide 3
Best Practices for Implementation
Always document individual component scores (E, M, V) separately before calculating the total score, as components often provide more prognostic information than the sum score alone 1, 2
Perform serial assessments to monitor trends rather than relying on single measurements, as this provides more valuable clinical information 3, 1
Use the GCS alongside other assessments like pupillary response for comprehensive neurological evaluation 1
Account for confounding factors that may affect GCS assessment, including sedation, intubation, facial trauma, and intoxication 1, 2
Important Limitations and Caveats
The GCS was not originally designed for mild TBI assessment but for evaluating comatose patients with head injury 3, 1
A single GCS determination is insufficient to diagnose mild TBI or determine the extent of parenchymal injury 3
Patients with identical sum scores but different component profiles may have different outcomes, highlighting the importance of reporting individual component scores 1
In the original multicenter studies validating the scale in the pre-CT era, approximately 13% of patients who became comatose had an initial GCS of 15, underscoring the importance of serial assessments 3
Common pitfalls include failing to assess each component separately, not accounting for confounding factors, and using a single GCS score rather than serial assessments 2
Historical Context and Evolution
The GCS was first described in 1974 by Graham Teasdale and Bryan Jennett and has since become one of the most commonly used clinical tools in medicine 3
Despite numerous attempts to modify or replace it, the GCS has remained the gold standard for assessing consciousness level in brain-injured patients due to its simplicity and practical usefulness 4
The scale has been incorporated into numerous clinical guidelines and scoring systems for evaluating impairment of consciousness in acute medical and trauma patients 3