Disorders of consciousness (synonyms: Drowsiness; Unconsciousness; Clouding of consciousness; Coma; Coma cardiale; Coma cerebrale; Coma hypercapnicum; Coma prolonge; Irritable syndrome of the mesodiencephalon; Coma; Coma-like disorder; Comatose state; Precoma; Drowsiness; Somnolence; Sopor; Stupor; Cerebral coma; ICD-10 R40.-: Somnolence, Sopor and Coma) refer to changes in ordinary everyday or normal consciousness.
One can distinguish quantitative from qualitative disorders of consciousness.
Three forms of quantitative disorder of consciousness are distinguished:
- Somnolence (ICD-10 R40.0) – refers to drowsiness with abnormal sleepiness; it characterizes the mildest form of reduction in consciousness. In some texts, drowsiness with slowed thinking/acting is seen as a separate disorder of consciousness.
- Sopor (precoma; ICD-10 R40.1) – refers to severe clouding of consciousness.
- Coma (ICD-10 R40.2) – denotes severe profound unconsciousness characterized by the absence of response to responding.
Coma of unknown etiology (CUE) is when there is a decrease in vigilance (deep somnolence, sopor or coma) that is not primarily due to trauma or cardiac cause.A decrease in vigilance (from Latin vigilantia = “alertness”, synonym: quantitative disorder of consciousness) is characterized by decreased alertness.
In quantitative disorders of consciousness, one can distinguish a decreased level of consciousness (somnolence, sopor, coma) from an increased level of consciousness (brightness of consciousness).
Qualitative disorders of consciousness include delusions, hallucinations, narrowing of consciousness. Normal mental processes are disturbed.
The disorder of consciousness is a symptom that can have many different physical (bodily) or psychological causes.
Disorders of consciousness can be a symptom of many diseases (see under “Differential diagnoses”).
The prevalence (disease frequency) of quantitative disturbance of consciousness is 5% to 9% in emergency department patients; up to 2% of all patients are comatose on arrival, with preserved cardiovascular function.
Course and prognosis: Course and prognosis depend on the underlying condition.Coma is associated with a high average mortality, higher than for polytrauma, myocardial infarction (heart attack), or apoplexy (stroke) (25-50% in various studies.In medicine, polytrauma refers to multiple injuries to different body regions sustained simultaneously, with at least one injury or the combination of multiple injuries being life-threatening (definition: Harald Tscherne).
Note: More than 30% of patients have multiple conditions explaining the loss of consciousness.
