A traumatic brain injury may cause a person to lose consciousness. A coma is a profound state of unconsciousness. External forces are not sufficient to rouse a person from a coma.

Different coma patients may display varying levels of consciousness. According to Brainline, the Glasgow Coma Scale is a tool that measures brain functions to determine what a person’s level of consciousness is.

What does the Glasgow Coma Scale measure?

According to the Centers for Disease Control and Prevention, the Glasgow Coma Scale measures three different functions: eye opening, motor function and verbal response. Different responses within each of these categories have numerical values from one to five assigned to them. The greater the patient’s level of consciousness, the greater the number of points he or she gains.

Upon assessing the patient, the person administering the test adds up the values. A higher GCS score indicates a mild head injury at worst, while a lower score indicates a severe head injury resulting in a profound coma.

What are the limitations of the GCS?

Only someone who has received proper training can test someone according to the GCS. The GCS cannot reliably assess head injury in children because they do not have consistent language skills. However, there is a modification called the Pediatric Glasgow Coma Scale that accounts for this discrepancy. There are factors unrelated to brain function that may alter consciousness level and affect GCS accuracy.

For all its limitations, the GCS is a useful tool for assessing the severity of a brain injury. One particular advantage is that it is possible to perform it in the field because it does not require special medical equipment.