Coma

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.

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 an injury such as head trauma, 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.

Picture of the areas of the brain subject to injury

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:

• High blood pressure (hypertension)
• Cerebral aneurysm: a weak spot in a blood vessel of the brain
• Arteriovenous malformation (AVM): an abnormal cluster of blood vessels
• Tumors

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 of lack of oxygen to the brain include:

• Heart arrhythmias
• Lung disease, including pneumonia, emphysema, or asthma.
• Anemia (low red blood cell count)
• Toxins

Poisons

• 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

• Myxedema coma (hypothyroidism)
• Diabetes
  • Hypoglycemia (low blood sugar)
  • Hyperglycemia (excessively high blood sugar)

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 their eyes may move.
• If the coma is severe, even basic body functions such as breathing may be affected.

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

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.

The Glasgow Coma Scale was developed to provide health caregivers with a simple way of measuring the depth of a coma based on 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.

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 the 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.

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 functions.