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Mayo Clinic Develops New Coma Measurement System

September 8, 2005
Mayo Clinic
Mayo Clinic neurologists have created the first new, reliable and easy-to-use clinical tool in 30 years for measuring coma depth, a proposed replacement for the Glasgow Coma Scale.

ROCHESTER, Minn. -- Mayo Clinic neurologists have created the firstnew, reliable and easy-to-use clinical tool in 30 years for measuringcoma depth, a proposed replacement for the Glasgow Coma Scale. The newscoring system, called the FOUR (Full Outline of UnResponsiveness)Score, will be described in the October issue of Annals of Neurology, to be published online Friday, Sept. 9.

When using the FOUR Score, evaluators assign a score of zero to fourin each of four categories, including eye, motor, brain stem andrespiratory function. A score of four represents normal functioning ineach category, while a score of zero indicates nonfunctioning.

A coma scoring system is used by physicians to initiallyassess a comatose patient to determine the severity of the braininjury, to monitor the patient's ongoing progress, and to determine thebest treatment during a coma. Scores also help physicians determinewhether a patient is likely to live, and if so, how disabled thepatient might be upon recovery.

Eelco Wijdicks, M.D., Mayo Clinic neurologist specializing intreating patients in intensive care and inventor of the FOUR Score,says a new scoring system is imperative due to limitations of thesystem used most commonly, the Glasgow Coma Scale.

"There are far too many drawbacks with the Glasgow Coma Scale;it's missing key and essential elements of a neurological exam ofcomatose patients," says Dr. Wijdicks. "Our new system is simple, yetmore comprehensive."

Dr. Wijdicks tested the FOUR Score prospectively at MayoClinic in 120 intensive care unit patients and compared scores byneurologists specializing in treatment of patients in intensive care,neuroscience nurses and neurology residents to scores using the GlasgowComa Score. He cites advantages of the FOUR Score found in this studyas follows:

  • Comatose patients remain fully testable even if a tube is inserted to enable breathing, which applies to almost half of all comatose patients
  • Brain stem reflexes, indicators of the entire brain's health emanating from the underside portion of the brain that controls breathing and consciousness, are tested, providing information for immediate intervention and prognosis
  • More precise measurements and higher agreement between evaluators than the Glasgow Coma Scale
  • Recognition of a locked-in syndrome
  • Attention to stages of brain herniation and breathing as indicators of coma depth
  • Scores have better correlation with outcomes, e.g., in the comatose patients with lower scores on the FOUR Score and the Glasgow Coma Scale, more patients with low FOUR Score ratings died

An accurate assessment of comatose patients is critical for thephysician's interaction with a patient's family, explains Dr. Wijdicks.

"A coma scoring system like the FOUR Score makes betterdoctors," he says. "It helps the doctor know what state the patient isin, and what the prognosis is to communicate better with the family. Ifwe only used the Glasgow Coma Scale, we would not be able to accuratelyexplain the patient's condition to the family -- we'd just be able togive a vague explanation. With the FOUR Score, in contrast, we can in afar more detailed way provide the family information on the patient'sstatus and what the outcome will be."

For example, according to Dr. Wijdicks, families need to know the answers to questions such as:

  • Is the patient in a locked-in state in which the patient is fully aware but cannot self-express and needs communication devices?
  • Does the patient need emergency surgery?
  • Should the patient be intubated to breathe properly?
  • Will the patient live or die? If the patient is near death, should a full brain death exam be performed?
  • Would the family want to prepare for organ donation?
  • Will the patient live and be independent, performing self-care normally or with a minor disability?
  • Will the patient live and be dependent, from needing part-time nursing assistance at home up to needing 24-hour care at a nursing home?

A person may become unconscious if the brain is injured through ablow to the head with an object, a motor vehicle accident, a fall orother trauma, or as a result of a disease. Someone who is totallyunconscious, unresponsive and cannot be aroused over a sustained timeis in a coma. This situation typically lasts only a few days or weeks.After this time, some people gradually awaken, while others enter avegetative state or die.

"Doctors should be crystal clear about the situation patientsare in," says Dr. Wijdicks. "Therefore, we've devised a system with thebare necessities of a neurological exam and made it so uncomplicatedand understandable that anyone on the medical team can use it -- anurse, an attending physician or a physician in training."


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Mayo Clinic. "Mayo Clinic Develops New Coma Measurement System." ScienceDaily. ScienceDaily, 8 September 2005. <>.
Mayo Clinic. (2005, September 8). Mayo Clinic Develops New Coma Measurement System. ScienceDaily. Retrieved November 30, 2023 from
Mayo Clinic. "Mayo Clinic Develops New Coma Measurement System." ScienceDaily. (accessed November 30, 2023).

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