Coma

Coma

Overview

Coma is a state of prolonged loss of consciousness. It can have a variety of causes, including traumatic head injury, stroke, brain tumor, or drug or alcohol intoxication. A coma may even be caused by an underlying illness, such as diabetes or an infection.

Coma is a medical emergency. Quick action is needed to preserve life and brain function. Healthcare professionals typically order a series of blood tests and a brain scan to try to learn what's causing the coma so that proper treatment can begin.

A coma doesn't usually last longer than several weeks. People who are unconscious for a longer time might transition to a lasting vegetative state, known as a persistent vegetative state, or brain death.

Symptoms

The symptoms of a coma commonly include:

Closed eyes.

Depressed brainstem reflexes, such as pupils not responding to light.

No responses of limbs except for reflex movements.

No response to painful stimuli except for reflex movements.

Irregular breathing.

There are three main symptoms of a coma:

Unconsciousness. This is like a very deep sleep, and it’s impossible to wake you up.

Lack of eye response. This means your eyes stay closed, and someone holding your eye open doesn’t cause you to react. Your eyes might have some reflex movements, such as reacting to light, blinking, or turning when your head is moved, but these reflexes might not happen as expected if your coma is very deep.

Lack of motor (movement) response. This means you don’t consciously move. You may still have some reflex responses, but not if your coma is very deep. The type of reflexes you show can also indicate how deep your coma is.

While the above symptoms usually happen with a coma, there can also be some variation. Some people may have different movement responses.

The Glasgow Coma Scale

The Glasgow Coma Scale (GCS) is the most widely used scale for grading how severe a coma is. The GCS has three main categories, and each category gets a score. A score of 15 is the highest possible, and it means you’re awake and aware of your surroundings. You can also understand and respond to questions and follow commands.

Generally, having a score of 8 or less means you’re in a coma. The lower the score, the deeper the coma is. A score of 3 is the lowest possible. The GCS measures three categories:

Eye response (1 - 4).

Motor response (1 - 6).

Verbal response (1 - 5).

Causes

Many types of problems can cause a coma. Some examples are:

Traumatic brain injuries. These are often caused by traffic collisions or acts of violence.

Stroke. Reduced or stopped blood supply to the brain, known as a stroke, can result from blocked arteries or a burst blood vessel.

Tumors. Tumors in the brain or brainstem can cause a coma.

Diabetes. Blood sugar levels that become too high or too low can cause a coma.

Lack of oxygen. People who have been rescued from drowning or revived after a heart attack might not awaken due to lack of oxygen to the brain.

Infections. Infections such as encephalitis and meningitis cause swelling of the brain, spinal cord or the tissues that surround the brain. Severe cases of these infections can result in brain damage or a coma.

Seizures. Ongoing seizures can lead to a coma.

Toxins. Exposure to toxins, such as carbon monoxide or lead, can cause brain damage and a coma.

Drugs and alcohol. Overdosing on drugs or alcohol can result in a coma.

Risk factors

Risk factors for coma include:

Serious head injury.

Stroke.

Bleeding in and around the brain, known as an intracranial bleed.

Brain tumor.

Diabetes with blood sugar that's very high or very low.

Health conditions, such as hypothyroidism or very low sodium in the blood.

Very low blood pressure from serious heart failure.

Epilepsy, including having seizures that last more than five minutes or that happen one after another without the person regaining consciousness.

Serious infection, such as sepsis, encephalitis or meningitis.

Near drowning, which decreases oxygen to the brain.

Excessive use of alcohol or use of illegal drugs.

Exposure to carbon monoxide, lead or other toxins.

The risk of coma goes up with age. This is especially true if older adults:

Have a brain disease or another condition such as diabetes, high blood pressure or kidney disease.

Take several medicines, which can lead to drug interactions or accidental overdose.

Complications

Although many people gradually recover from a coma, others enter a persistent vegetative state or die. Some people who recover from a coma end up with major or minor disabilities.

During a coma, bedsores, urinary tract infections, blood clots in the legs and other problems may develop.

Diagnosis

Because people in comas can't express themselves, healthcare professionals must rely on physical clues and information provided by family members and friends. Be prepared to provide information about the affected person, including:

Events leading up to the coma such as vomiting or headaches.

Details about how the affected person lost consciousness, including whether it occurred quickly or over time.

Noticeable symptoms before losing consciousness.

Medical history, including other conditions the person may have had in the past. This includes whether the person has had a stroke or ministroke.

Recent changes in the person's health or behavior.

The person's drug use, including prescription and nonprescription medicines, unapproved medicines, and illicit drugs.

Physical exam

The exam is likely to include:

Checking the affected person's movements and reflexes, response to painful stimuli, and pupil size.

Observing breathing patterns to help diagnose the cause of the coma.

Checking the skin for signs of bruises due to trauma.

Speaking loudly or pressing on the angle of the jaw or nail bed while watching for signs of arousal, such as vocal noises, eyes opening or movement.

Testing reflexive eye movements to help determine the cause of the coma and the location of brain damage.

Squirting cold or warm water into the affected person's ear canals and watching eye reactions.

Laboratory tests

Blood samples typically are taken to check for:

Complete blood count.

Electrolytes and sugar. Sugar is also called glucose.

Thyroid, kidney and liver functions.

Carbon monoxide poisoning.

Drug or alcohol overdose.

A spinal tap, also known as a lumbar puncture, can check for signs of infections in the nervous system. During a spinal tap, a healthcare professional inserts a needle into the spinal canal and collects a small amount of fluid for analysis.

Brain scans

Imaging tests help pinpoint areas of brain injury. Tests might include:

CT scan. This uses a series of X-rays to create a detailed image of the brain. A CT scan can show bleeding in the brain, tumors, strokes and other conditions. This test is often used to diagnose and determine the cause of a coma.

MRI. This uses powerful radio waves and a magnetic field to create a detailed view of the brain. An MRI scan can detect bleeding in the brain, brain tissue damaged by an ischemic stroke and other conditions. MRI scans are particularly useful for examining the brainstem and deep brain structures.

Electroencephalogram (EEG). This measures the electrical activity inside the brain through small metal discs called electrodes attached to the scalp. A low electrical current travels through the electrodes, which record the brain's electrical impulses. This test can determine if seizures might be the cause of a coma.

Treatment

A coma is a medical emergency. Healthcare professionals typically first check the affected person's airway and help maintain breathing and circulation. A person in a coma might need breathing assistance, medicines through a vein and other supportive care.

Treatment depends on the cause of the coma. A procedure or medicines to relieve pressure on the brain due to brain swelling might be needed. Emergency responders might give glucose or antibiotics through a vein in the arm. These may be given even before blood test results return in cases of very low blood sugar or an infection affecting the brain.

If the coma is the result of a medicine or an illegal drug overdose, healthcare professionals typically give medicines to treat the condition. If the coma is due to seizures, medicines can control seizures. Other treatments might focus on medicines or therapies to address an underlying disease, such as diabetes or liver disease.

Sometimes the cause of a coma can be completely reversed, and the affected person regains function. Recovery usually occurs gradually. A person with severe brain damage might have permanent disabilities or never regain consciousness.

Type of Doctor Department :  Neurology