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The word coma comes from the Greek word ‘Koma,’ which means deep sleep. Coma is a state of unconsciousness that can last from a few weeks to years. In this state, the person may not be able to do any voluntary activities such as limb movement, talking, eating, etc. The affected person lies on a bed for a prolonged duration and is kept alive by means of artificial life support. The majority of the cases of coma respond well to treatment and recover within a few weeks or months. However, in some cases, a patient may remain in a state of coma for several years.  


There are multiple causes of coma. One of the most common causes is traumatic head injury. It may occur as a result of a road traffic accident, violent attack, etc. Your brain can lose its functional ability after a traumatic head injury. Another important cause is stroke which occurs due to reduced or obstructed blood supply to the brain. Tumors of brain tissue can also lead to a comatose state.


Infections such as meningitis or encephalitis can damage the tissues of your brain and spinal cord. Untreated infections can lead to severe complications, which include coma. Limited or reduced supply of oxygen is another cause. If a person is drowning, caught in a house fire, or resuscitated from a heart attack, it is possible that they may go into a state of coma due to shortage of oxygen. Other causes of coma include ill-maintained diabetes, seizures, lead poisoning, carbon monoxide poisoning, alcohol toxicity, and drug overdose.

Risk Factors And Epidemiology

Risk factors of coma are linked with its causes. A direct injury to the head or a traffic accident can lead to coma due to tissue damage and blood loss. Diabetes is a major risk factor because too high or too low blood sugar can affect the functioning of your brain. People with a history of stroke, seizures, or brain infections should remain cautious as a recurrent attack can be risky for their brain. People over the age of 60 and those with weakened immune systems are also at risk of brain damage due to infections or systemic diseases. 

Signs And Symptoms

Patients who are in a coma can go through different states of consciousness. One of these states is called a persistent vegetative state. In this state, the patient is unable to do any voluntary activity, but their reflexes are active. They may develop irregular breathing during this state. If the person regains some awareness and they are able to follow some commands such as blinking or moving their fingers, it is called a minimally conscious state. If the person does not respond to any stimulus and even their reflexes don’t work, it is called the state of brain death. 


The diagnosis process is carried out to identify the cause of coma. The first step is history which is obtained by a family member, friend, or attendant. This is followed by a physical examination in which the state of consciousness is checked. This can be determined by checking the reflexes directly or using a Glasgow coma scale (GCS). Other lab tests can be done for further confirmation of the diagnosis. These include blood tests, urinalysis, blood sugar levels, serum electrolytes, LFTs, TFTs, CT scans, MRIs, or electroencephalography (EEG). If alcohol, toxins, or drugs are considered a possible cause, blood tests are done specifically to determine their levels. 

Differential Diagnosis

Coma is an outcome of a traumatic injury or a medical condition. A person with temporary consciousness loss will not be declared comatose unless tested professionally for possible causes. The causes of coma need to be differentiated based on history, symptoms, physical examination, and diagnostic tests. 


If a person goes into a coma, it is a state of medical emergency. The first step is to secure the airway passage and regular breathing rate. This can be done by an airbag or ventilator. After maintaining the patient’s vital signs, the next step is to treat the underlying cause. If the person has suffered from a traumatic head injury, intravenous fluids and antibiotics will be delivered to restore circulation and reduce the risk of infections.


In cases of raised intracranial pressure or brain tissue swelling, medicines or procedures will relieve that pressure. Appropriate treatment measures will be followed to lessen symptoms in cases of infections, systemic diseases, poisoning, alcohol, or drug overdose. In some cases, it may take weeks or months to recover from a comatose state. During this period, the patient is kept alive by artificial breathing, nutritional supplements, and necessary medicines. Medicines are prescribed for certain causes, such as antibiotics for infections or diabetic medications for maintaining blood sugar levels.


The prognosis of a comatose patient depends on the cause and its severity. The presence of other systemic diseases such as diabetes, hypertension, etc., can also influence their prognosis.


It is hard to prevent coma since it can occur suddenly without a preexisting cause. However, patients with diabetes, brain diseases, or a history of stroke should follow the necessary measures to maintain their health. Diet, hydration level, and exercise are important to stay in good health. Alcohol or drug overdose should be avoided, and if you experience any neurological symptoms, contact medical help immediately. 

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on April 29th, 2023.