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  • Updated 07.12.2023
  • Released 05.16.2020
  • Expires For CME 07.12.2026

Coma due to supratentorial and cerebellar lesions



Coma is characterized by the absence of arousal (wakefulness, vigilance) and awareness of self and environment, lasting for more than 1 hour. Comatose patients have closed eyes, do not communicate, and do not arouse to verbal, tactile, or noxious stimuli (12). The terminology and etiologies of coma have not changed historically since the seminal work by Plum and Posner. Workup starts with imaging to delineate anatomic from physiologic causes, which drives the ensuing investigation and treatment.

Key points

• First action is to discriminate between structural and physiologic with noncontrast CT head.

• Information regarding etiology must be taken from alternative sources such as family, medication lists, or the environment, as the patient cannot give any history.

• Vital signs and laboratory values offer some clinical clues.

• Airway, breathing, and circulation are the first tenets of care.

• Etiology strongly influences outcomes.

Historical note and terminology

Plum and Posner first discussed the idea of coma when they stated, “the ancient Greeks knew that normal consciousness depends on the intact brain and that impaired consciousness signifies brain failure.” The word “coma” means “deep sleep or trance.” The patient is described as lying with eyes closed, not being able to be aroused to respond appropriately to stimuli even with vigorous stimulation. They acknowledge that the patient may grimace to painful stimuli and may demonstrate stereotyped withdrawal responses but does not make localizing movements (12). In 2008 Koehler and Wijdicks published a history of the historical events that led to the landmark publication of Stupor and Coma in which teachable and recognizable clinical signs were first reported, marking a paradigm shift in the treatment of coma (08). In 1974, the Glasgow Coma Scale was introduced for evaluating consciousness in traumatic brain injury and is still the most widely used scale (17). In 2001, the Richmond Agitation-Sedation Scale attempted to quantify consciousness and agitation in the intensive care population with a 10-point scale where coma was defined as RASS-5: no response to voice or physical stimulation (15).

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