Altered mental status diagnostic criteria

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Pratik Bahekar, MBBS [2]


Altered mental status can be accessed by various scales. However, identifing underling conditions causing altered mental status is crucial in the management of the patient.

Diagnostic Criteria

Assessing LOC involves determining an individual's response to external stimuli.[1] Speed and accuracy of responses to questions and reactions to stimuli such as touch and pain are noted. Reflexes, such as the cough and gag reflexes, are also means of judging LOC. Once the level of consciousness is determined, clinicians seek clues for the cause of any alteration. Usually the first tests in the ER are pulse oximetry to determine if there is hypoxia, serum glucose levels to rule out hypoglycemia. A urine drug screen may be sent. A CT head is very important to obtain to rule out bleed. In case, meningitis is suspected, a lumbar puncture must be performed. A serum TSH is an important test to order. In select groups consider vitamin B12 levels. Checking serum ammonia is not advised.

Glasgow Coma Scale

The most commonly used tool for measuring LOC objectively is the Glasgow Coma Scale (GCS). It has come into almost universal use for assessing people with brain injury,[2] or an altered level of consciousness. Verbal, motor, and eye-opening responses to stimuli are measured, scored, and added into a final score on a scale of 3–15, with a lower score being a more decreased level of consciousness.

Confusion Assessment Method for the ICU (CAM-ICU)

Many studies have shown that mental status examination is less efficetive to access mental status changes. CAM-ICU is a very good tool to access delirium.

Patient is accessed on following 4 features,

  1. Onset of symptoms, is acute(change from baseline) or fluctuating as calibrated by Richmond Agitation Sedation Scale or Glasgow Coma Scale.
  2. Inability to focus as measured by Attention Screening Examination.
  3. Thinking is not organized
  4. Altered level of consciousness if Vigilant, Lethargic, Stupor, Coma.

If feature 1 and 2 are present along with 3 or 4 then patient is assessed to have delirium by CAM-ICU scale.[3]


The AVPU scale is another means of measuring LOC: people are assessed to determine whether they are alert, responsive to verbal stimuli, responsive to painful stimuli, or unresponsive. To determine responsiveness to voice, a caregiver speaks to, or, failing that, yells at the person. Responsiveness to pain is determined with a mild painful stimulus such as a pinch; moaning or withdrawal from the stimulus is considered a response to pain. The ACDU scale, like AVPU, is easier to use than the GCS and produces similarly accurate results.[4] Using ACDU, a patient is assessed for alertness, confusion, drowsiness, and unresponsiveness.[4]

The Grady Coma Scale classes people on a scale of I to V along a scale of confusion, stupor, deep stupor, abnormal posturing, and coma.


  1. von Koch CS, Hoff JT (2005). "Diagnosis and management of depressed states of consciousness". In Doherty GM. Current Surgical Diagnosis and Treatment. McGraw-Hill Medical. p. 863. ISBN 0-07-142315-X. Retrieved 2008-07-04.
  2. Porth C (2007). Essentials of Pahtophysiology: Concepts of Altered Health States. Hagerstown, MD: Lippincott Williams & Wilkins. p. 835. ISBN 0-7817-7087-4. Retrieved 2008-07-03.
  3. "" (PDF). External link in |title= (help)
  4. 4.0 4.1 Posner JB, Saper CB, Schiff ND, Plum F (2007). Plum and Posner's Diagnosis of Stupor and Coma. Oxford University Press, USA. p. 41. ISBN 0-19-532131-6.