Altered Consciousness (Altered Mental Status)

What altered consciousness means

Consciousness has two parts: arousal (being awake) and awareness (understanding yourself and your surroundings). Arousal depends on a network in the brainstem; awareness depends on the cerebral cortex. Altered consciousness happens when something affects the brainstem directly or affects large areas of both cerebral hemispheres.

Levels of consciousness

Paramedics use the quick AVPU scale: Alert, responds to Voice, responds to Pain, or Unresponsive. Doctors use the Glasgow Coma Scale (GCS), which scores eye opening (1 to 4), verbal response (1 to 5) and movement (1 to 6), for a total of 3 to 15. A score of 8 or less usually means the person cannot protect their own airway.

Causes of altered consciousness

Doctors often use the memory aid AEIOU TIPS to cover the causes.

Metabolic and toxic causes (most common)

• Low blood sugar in people taking insulin or sulfonylureas. It is quick to check and treat.
• Very high blood sugar in diabetic ketoacidosis or hyperosmolar state.
• Drugs and alcohol: alcohol intoxication, opioids, sedatives, and drug overdose of any kind.
• Medicine side effects, especially in older adults: sleeping pills, strong pain relievers, anticholinergics.
• Low oxygen or high carbon dioxide from lung disease, heart failure or carbon monoxide poisoning.
• Electrolyte problems: low sodium, high calcium.
• Organ failure: liver failure (hepatic encephalopathy) and kidney failure (uremia).
• Thyroid disease: severe hypothyroidism (myxedema).
• Vitamin B1 deficiency in Wernicke encephalopathy, linked to alcohol misuse.
• Temperature extremes: heat stroke and hypothermia.

Infections

• Sepsis, often from pneumonia or a urinary infection. In older adults, confusion may be the first and only sign.
• Meningitis and encephalitis: fever, headache, neck stiffness, light sensitivity, and sometimes a rash or seizures.

Brain causes

• Stroke, especially brainstem strokes or large strokes.
• Bleeding in or around the brain, including subarachnoid hemorrhage (a sudden "worst-ever" headache).
• Head injury, including bleeding that develops hours after the injury.
• Seizures: during a seizure or in the drowsy, confused period afterward (the post-ictal state).
• Brain tumors and abscesses, usually with gradual worsening.

Other causes

• Fainting from low blood pressure or heart rhythm problems: brief, with quick recovery.
• Shock from blood loss, severe infection or allergic reaction.
• Psychiatric conditions can mimic reduced responsiveness, but only after physical causes are excluded.

Delirium: the most common form

Delirium is an acute state of confusion that develops over hours to days and fluctuates through the day. The person may be agitated or quiet and withdrawn. It is very common in hospitalized older adults and people with dementia, and it is usually triggered by infection, dehydration, constipation, urinary retention, new medicines, pain or surgery. It is a sign of an underlying illness, not a disease of its own.

What to do if someone has reduced consciousness

1. Call 911 or your local emergency number.
2. Check breathing. If they are not breathing normally, start CPR.
3. If breathing, place them in the recovery position (on their side, head tilted back) to keep the airway clear.
4. If they have diabetes and can swallow safely, give a sugary drink. Never put food or drink in the mouth of a drowsy person who cannot swallow.
5. If an opioid overdose is possible, give naloxone if available.
6. Note what happened: when the change started, medicines, alcohol, injuries, seizures, and medical conditions. This helps doctors greatly.
7. Do not leave the person alone.

How doctors find the cause

Emergency teams check the airway, breathing and circulation, measure oxygen and blood sugar immediately, and assess GCS, pupils and limb movement. Common tests include:

• blood tests for sodium, calcium, kidney and liver function, blood count, ammonia, thyroid, blood gases and a toxicology screen
• blood alcohol and acetaminophen levels in possible overdose
• ECG
• CT scan of the head, then MRI if needed
• lumbar puncture if meningitis or encephalitis is suspected
• EEG to detect ongoing seizure activity that is not visible

Treatment

Treatment is directed at the cause: glucose for low blood sugar, naloxone for opioids, oxygen, antibiotics and antivirals for infection, clot-busting treatment or clot removal for stroke, surgery for bleeding, and seizure medicines. People with a low GCS may need a breathing tube and intensive care.

Frequently asked questions

What is the difference between altered consciousness and confusion?

Confusion is one form of altered consciousness. A confused person is awake but cannot think clearly or is disoriented. Altered consciousness also includes reduced alertness, such as excessive drowsiness, stupor and coma. Any new or sudden change in either needs urgent medical assessment.

What is the most common cause of altered mental status?

In emergency departments, the most common causes are infections such as sepsis, drug and alcohol effects, metabolic problems like low blood sugar or low sodium, and stroke. In older adults, infections and medicine side effects causing delirium are especially common.

What is a normal Glasgow Coma Scale score?

A fully alert, oriented person scores 15. Scores of 13 to 14 suggest mild impairment, 9 to 12 moderate, and 8 or less severe impairment, usually needing airway protection. The total matters less than changes over time, which doctors track closely.

Can low blood sugar cause unconsciousness?

Yes. The brain relies on glucose, and severe hypoglycemia can cause confusion, odd behavior, seizures and unconsciousness. It is most common in people using insulin or certain diabetes tablets. A finger-prick test confirms it, and glucose given by mouth, injection or IV usually reverses it quickly.