Coma and Vegetative State: Causes, Signs and Recovery

Author: Thomas C. Weiss
Published: 11 Dec 2013 - Updated: 13 Nov 2026
Publication Type: Informative

Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content

Synopsis

This information explains the difference between a coma, a state of unconsciousness in which a person cannot be woken and does not respond, and a vegetative state, in which a person has sleep and wake cycles and may open their eyes, move or make sounds, but shows no clear sign of awareness. It lists the main causes, including brain injury, stroke, lack of oxygen, tumors, seizures, drugs, alcohol and severe metabolic problems, and explains why the cause, the extent of brain damage, the person's age and the time spent unconscious shape the chances of recovery. It also describes the physical problems that develop during long periods of unconsciousness, such as pressure sores, infections and muscle wasting. The article is useful for families facing a loved one's prolonged unconsciousness and for caregivers and students wanting a clear overview.*

At a Glance

• 1 - Most people who come out of a coma do so within weeks.
• 2 - A coma rarely lasts more than two to four weeks without a change.
• 3 - People in a vegetative state may smile, cry or turn toward a sound as a reflex.
• 4 - Recovery after a coma caused by lack of oxygen is much less likely than after a traumatic brain injury.

Topic Definition

Vegetative State

A vegetative state, now also called unresponsive wakefulness syndrome, is a condition after severe brain injury in which a person has periods of eye opening and sleep-wake cycles but shows no consistent sign of awareness of themselves or their surroundings. Basic functions such as breathing, heart rate and reflexes continue because the brainstem still works. It is often called persistent when it lasts more than four weeks, and some people later move into a minimally conscious state or recover further.

Overview

Coma is a state in which a person's cortex, or higher brain areas, are damaged, resulting in loss of consciousness, an inability to be roused, and unresponsiveness to sound, pain, light, and touch. If the person's lower brain centers are damaged, a respirator might be needed for them to breathe. The damage may be reversible or irreversible. There are various causes of coma, including:

• Hypothermia
• A post-seizure state
• Trauma to the brain
• Masses or tumors in the brain
• Toxic effects of alcohol or drugs
• Stroke caused by clots or bleeding
• A lack of oxygen to the brain for prolonged periods

A person may also experience metabolic imbalances such as low or high blood sugar, high blood calcium, or kidney or liver failure abnormalities.

Persistent Vegetative State (PVS)

A vegetative state exists when a person can be awake yet is completely unaware. A person in a vegetative state can no longer think, reason, or relate meaningfully with their environment, recognize the presence of those they love, or feel emotions or discomfort. The higher levels of their brain no longer function. A vegetative state is called 'persistent' if it lasts longer than four weeks. As with a person who is in a coma, a person who is in a PVS is completely dependent on all care needs, cannot drink or eat, cannot speak, and is incontinent.

Unlike a person in a coma, a person in a PVS has sleep and wake cycles, or periods when they are awake and asleep. The person can sometimes sneeze, cough, and even smile or cry. The person might, at times, move their legs or arms. A person in a PVS may react automatically to touch, such as drawing a body part away, to sound - such as turning their head toward the sound, or light, such as blinking their eyelids. The person's eyes might move randomly.

If the person's gaze happens to momentarily stop in the direction of someone at the side of their bed, the person might misinterpret the gaze as the person in the PVS is looking at them. The behavior may be confusing and disconcerting to the onlooker, particularly a loved one, who might interpret the gaze as indicating that the person in a PVS is aware but unable to communicate with those around them. All of the behaviors described are automatic and do not require any functioning of the thinking portion of the person in a PVS brain.

Causes of a PVS

Coma has the potential to progress to a PVS. A person rarely remains in a coma for more than 2-4 weeks without recovering, dying, or progressing to a PVS. End-stage dementia may also progress to a PVS.

The rate of recovery is greatly dependent on the cause of the coma or PVS, whether the cause is reversible or not, the amount of damage to the person's brain, the region of the person's brain that is damaged, and the amount of time the person is in a coma or a PVS. When the cause of a coma is corrected before permanent brain damage happens, the coma usually reverses within days.

Unfortunately, when the death of large areas of a person's brain happens, the outcome is often grim. Dead brain tissue does not regenerate. Recovery from illnesses symptomatic of dead brain tissue, such as a stroke, usually is a result of other brain tissue being trained to assume the functions of the tissue that has been lost. If there is not enough brain tissue left to take over the functions of the lost brain tissue, the person will not recover.

The longer a person is in a coma, the larger and more diffuse the area of damage. The older the person, the less their chances are for experiencing a reversal of the coma and recovery of function. Since PVS is a late-stage outcome of causes of irreversible coma or the end stages of dementia, the outlook for a person's recovery is usually poor for a person in this condition.

Recovery from a Coma after Months or Years

People who recover from a coma after months or even years are scarce. Suppose a coma is caused by traumatic injury with bleeding in the person's brain, and the injury is limited. In that case, the person can recover - even when the coma has lasted for several months. The chances are greater in younger people. Yet even in a young person who has experienced brain trauma, if the coma lasts longer than six months, the person rarely recovers.

If someone experiences a prolonged coma, not due to trauma such as one due to a stroke, the chance of recovery is small. The rare person destined to recover will show some increase in responsiveness and functioning, no matter how gradual, within the first days to weeks of becoming unconscious. The lack of any improvement over some time is a signal they will not recover.

A person who experiences a prolonged coma due to irreversible damage to their brain caused by a prolonged period of oxygen deprivation has the least chance of recovering. If a coma from this condition, known as 'anoxic encephalopathy,' lasts longer than a week - recovery is rare. If the person does not die, they usually progress to a PVS.

Physical Impact of Prolonged Coma or PVS

The notion that an irreversible coma or PVS is a stable and non-progressive condition is inaccurate. While the brain lesion might not be changing or expanding, the changes happening to a person's body are progressive. The physical results of prolonged coma or PVS include the following:

• Risk of sepsis
• Muscle wasting
• Limb contractures
• Risk of pneumonia
• Skin breakdown/ulcers
• Risk of lung scarring or collapse
• Recurrent urinary tract infections

The longer a person is in a coma or PVS, the more profound and devastating the physical changes they experience. There are several characteristics of a vegetative state as well. These characteristics include:

• No purposeful movement
• Inability to follow instructions
• Inability to speak or communicate
• Might moan or make other sounds
• May react to a loud sound with a startle
• May smile or cry or make facial expressions
• Might briefly move eyes toward people or objects
• Sleep-wake cycle with periods of eye-opening/closing

At times, what is referred to as a 'secondary injury' can make being in a coma or vegetative state even direr. Secondary injuries may include pneumonia, infections, or bedsores. People emerging from a coma might also be threatened by a lack of appropriate nutrition, contractures, and deformities of their joints, bones, and muscles.

There are no exact numbers concerning how many people emerge from a coma or how many people will die while in a coma. Research has shown that most people emerge from deep comas within weeks after experiencing a brain injury. Each person, as well as the brain injury they experience, is unique. At times even doctors are surprised by a person's recovery. Instead of emphasizing complete recovery, treatment pursues improved function, prevention of further injury, and rehabilitation of people and their family members on physical and emotional levels.

Frequently Asked Questions

NOTE: Researched FAQs by Disabled World (DW)

What is the difference between a coma and brain death?

A person in a coma still has some brain activity and may recover. Brain death is the complete and permanent loss of all brain function, including the brainstem, and is legally recognized as death.

What is a minimally conscious state?

A minimally conscious state is a condition in which a person shows small but clear signs of awareness, such as following a simple command or tracking with their eyes, even if inconsistently.

Can people in a coma hear what is said to them?

Some studies suggest that parts of the brain may still respond to familiar voices, so families are often encouraged to talk to their loved one, although the person may not remember it.

How do doctors measure the depth of a coma?

Doctors often use the Glasgow Coma Scale, which scores eye opening, verbal response and movement. Lower scores mean a deeper level of unconsciousness.

What is a medically induced coma?

A medically induced coma is a controlled state of deep sedation that doctors use to protect the brain or body after severe injury or illness, and it can be reversed.

What care does a person in a long-term coma need?

Care includes feeding through a tube, regular turning to prevent pressure sores, help with breathing if needed, bladder and bowel care, physical therapy and infection prevention.

Can someone wake up from a vegetative state after years?

It is rare, but there are reported cases of people regaining some awareness after long periods, especially after traumatic brain injury rather than lack of oxygen.

Where can families find support when a loved one is in a coma?

Brain injury associations, hospital social workers, chaplains and family support groups can offer information, emotional support and help with care decisions.

Insights, Analysis, and Developments

Editorial Note: Few situations are harder for a family than sitting beside someone who cannot respond. Knowing the difference between a coma, a vegetative state and the minimally conscious state helps families understand what doctors are seeing and ask the right questions. Research using brain scans has shown that a minority of people who seem unaware may have some hidden awareness, which is why careful, repeated assessment by specialists matters. Good nursing care, prevention of pressure sores and infections, and support for family members remain essential whatever the outlook.*

Author Credentials: Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursuing Disability Studies. As a CNA Thomas has provided care for people with all forms of disabilities. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.

* Editorial additions by Ian C. Langtree.