Consciousness - decreased
Decreased consciousness is reduced alertness or awareness.
Stuporous; Mental status - decreased; Loss of alertness; Decreased consciousness; Alertness - decreased; Changes in consciousness; Obtundation; Coma; Unresponsiveness
A persistent coma is called vegetative state.
Many conditions can cause decreased consciousness, including:
- Alcohol intoxication
- Drug intoxication (particularly opiates, narcotics, sedatives, and anti-anxiety or seizure medications)
- Brain disorders
- Central nervous system diseases
- Lack of oxygen (hypoxia)
- Abnormal blood sugars (diabetic coma)
- Electrolyte or mineral imbalance
- Exposure to heavy metals or hydrocarbons
- Extreme fatigue or sleep deprivation
- Head trauma
- Heart failure
- Hypoglycemia (low blood sugar)
- Increased carbon dioxide levels (hypercarbia) often seen in emphysema
- Low blood pressure (hypotension)
- Metabolic disorders
- Thyroid or adrenal gland disorders
- Seizures such as those related to epilepsy
See the article on seizures for tips on how to care for a person who is having a seizure.
Persons with epilepsy or other seizure disorder should carry a Medic-Alert bracelet or pendant describing their condition. Such individuals should avoid situations that have previously triggered a seizure.
When to Contact a Medical Professional
See medical help if someone has unexplained, decreased consciousness. Call your local emergency number (such as 911) if normal consciousness does not return quickly.
What to Expect at Your Office Visit
Most often, a person with decreased consciousness will be evaluated in an emergency room setting.
The doctor will perform a physical examination. The exam will include a detailed look at the cardiovascular, respiratory, and nervous systems.
The health care team will ask questions about the person's medical history and symptoms, including
- When did the decreased consciousness occur?
- How long did it last?
- Has it ever happened before? If so, how many times?
- Did the person behave the same way on previous episodes?
- Does the person have known epilepsy or seizure disorder?
- Does the person have diabetes?
- Has the person been sleeping well?
- Has there been a recent head injury?
- What medications does the person take?
- Does the person habitually use alcohol or drugs?
- What other symptoms are present?
Tests that may be done include:
- Complete blood count or blood differential
- Electrolyte panel
- CT scan or MRI of the head
- ECG (electrocardiogram)
- EEG (electroencephalogram)
- Chest x-ray
- Toxicology panel
Treatment depends on the underlying cause of the decreased consciousness. How well a person does depends on the cause of the condition. The longer the person has a decreased or altered level of consciousness, the worse the outcome.
Blok BK, Newman TM. Syncope. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 52.
Huff JS. Altered mental status and coma. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 259.
Kirsch TD. Head injury. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 255.
Reviewed By: Jacob L. Heller, MD, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington, Clinic. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.