The term coma is defined as the inability to follow commands, speak, or open the eyes in response to a painful stimulus¹.

Quantification

A clinically commonly used scale for quantifying coma is the Glasgow Coma Scale (GCS), although no exact GCS score can be defined for coma. More than 90% of patients with a GCS ≤ 8 fulfill the criteria for the definition of coma, whereas no patient with a GCS ≥ 9 fulfills the criteria for coma². Therefore, a GCS ≤ 8 is a commonly accepted definition of coma in relation to the GCS score³.

Cause

Coma is the result of one or more of the following causes⁴:

Dysfunction of the upper brainstem or mesencephalon.
Bilateral dysfunction of the diencephalon
Diffuse lesion in both cerebral hemispheres (cortical or subcortical)

Differential Diagnoses

Differential diagnoses of coma include⁵:

Locked-in syndrome
Catatonia
Neuromuscular diseases such as myasthenia gravis or Guillain-Barré syndrome

References

Handbook of Neurosurgery. Greenberg M, ed. 9th Edition. New York: Thieme; 2019 ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩

Coma

Quantification

Cause

Differential Diagnoses

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