What Facts Should I Know about Coma?

What Is the Medical Definition of Coma?

A coma is a deep state of unconsciousness in which individuals do not consciously respond to stimuli in their environment.

What Can Cause a Coma?

Coma can result from injury such as head trauma, or an underlying illness such as an infection or tumor, or toxins that enter the body.

What Happens When You Are in a Coma?

Patients in a coma are unable to think consciously and lack awareness of their surroundings, but they do retain basic life support functions, such as breathing and circulation. A person in a coma may look healthy and appear as if they are sleeping, but they are unable to respond to people and things around them. A patient in a coma may exhibit some movement such as eye opening or grimacing in response to the environment; however, the patient does not have control or awareness of these movements.

How Long Can You Be in a Coma before You Die?

A long-term coma is often referred to as a persistent vegetative state. This can last for years, depending on the medical circumstances and the cause.

What Are the Chances of Surviving a Coma?

In general, a coma is temporary, rarely lasting more than two to four weeks. After emerging from a coma, the prognosis is varied. Many people can recover fully, some require lifelong physical and occupational therapy, while others may recover only basic functions.

What Causes a Coma?

Head Trauma

  • Coma may result from significant traumatic injury to the head, such as from a car accident or fall.

Bleeding (Hemorrhage) into the brain or skull

Types of brain/skull hemorrhage include:

  • Intracerebral hemorrhage: bleeding within the brain tissue
  • Epidural hemorrhage: bleeding inside the skull, but outside the dura, (the covering of the brain)
  • Subdural hemorrhage: bleeding inside the skull, and inside the dura, but not in the brain tissue itself
  • Subarachnoid hemorrhage: bleeding in the space immediately adjacent to the brain tissue

Causes of brain/skull hemorrhage include:

Picture of the areas of the brain subject to injury
Picture of the areas of the brain subject to injury

Swelling of the brain (cerebral edema)

Causes of swelling of the brain

  • Infections
  • Chemical imbalances
  • Traumatic injuries
  • Problems with the flow of cerebrospinal fluid (CSF)

Lack of oxygen to the brain

The most common causes for lack of oxygen to the brain include:


  • External poisons are those that are ingested or inhaled
  • Internal poisons are by-products of the body's normal metabolism that for some reason cannot be excreted properly

Endocrine disorders

What Are the Symptoms of a Coma?

The main symptom of a coma is unconsciousness. A patient in a coma will have no conscious response to external stimuli and may appear to be in a deep sleep.

The patient in a coma may exhibit spontaneous body movements. Patients may shake or jerk abnormally, and the eyes may move. If the coma is severe, even basic body functions such as breathing may be affected.

When to Seek Medical Care for a Coma

Coma is a medical emergency. Call 9-1-1 and seek medical treatment immediately to avoid possible permanent damage to the patient.

What Is the Treatment for a Coma?

At the outset of a coma, it is important to diagnose and treat the underlying cause. Depending on the severity of the coma, the patient may require life-saving resuscitative measures. Once medically stable, treatments can be used to correct the underlying problem that is causing the coma.

For patients in a prolonged coma, or persistent vegetative state, the focus is on preventing infections, providing nutrition, and maintaining the patient's physical health. This includes proper nutrition and prevention of infections such as pneumonia (a common cause of death in those in a long-term coma) and bedsores. Sometimes, physical therapy is administered to prevent bone, joint, or muscle deformities.

What Is the Glasgow Coma Scale?

The Glasgow Coma Scale was developed to provide health-caregivers a simple way of measuring the depth of coma based upon observations of eye opening, speech, and movement. Patients in the deepest level of coma:

  • do not respond with any body movement to pain,
  • do not have any speech, and
  • do not open their eyes.

Those in lighter comas may offer some response, to the point they may even seem wake, yet meet the criteria of coma because they do not respond to their environment.

Glasgow Coma Scale
Eye Opening
To loud voice3
To pain2
Verbal Response
Confused, Disoriented4
Inappropriate words3
Incomprehensible words2
Motor Response
Obeys commands6
Localizes pain5
Withdraws from pain4
Abnormal flexion posturing3
Extensor posturing2

The scale is used as part of the initial evaluation of a patient, but does not assist in making the diagnosis as to the cause of coma. Since it "scores" the level of coma, the GCS can be used as a standard method for any health-caregiver to assess change in patient status.

What Is the Prognosis for a Coma?

In general, a coma is temporary, rarely lasting more than two to four weeks. After emerging from a coma, the prognosis is varied and typically depends upon the cause of the coma and the severity of the brain injury.

For those who do recover, recovery is usually gradual. Many patients can recover fully. Some require lifelong physical and occupational therapy, while others may recover only basic function.

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Severe Head Injury Symptoms

It is important to remember that a head injury can have different symptoms and signs, ranging from a patient experiencing no initial symptoms to coma.

A high index of suspicion that a head injury may exist is important, depending upon the mechanism of injury and the initial symptoms displayed by the patient. Being unconscious, even for a short period of time is not normal. Prolonged confusion, seizures, and multiple episodes of vomiting should be signs that prompt medical attention is needed.

Medically reviewed by Jon Glass, MD; American Board of Psychiatry and Neurology


National Institute of Neurological Disorders and Stroke; "Coma Information Page."; "Coma."

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