Coma is a word derived from the Greek word Koma which means deep sleep. Coma is a state of unresponsiveness in which the patient lies with his eyes closed and cannot be woken to respond appropriately to stimuli even with vigorous stimulation. The patient may grimace in response to painful stimuli and limbs may demonstrate stereotyped withdrawal responses, but the patient does not make localized responses or discrete defensive movements.

Coma is prolonged unconsciousness. An alteration in arousal represents an acute, life-threatening emergency condition, requiring immediate treatment for the preservation of life and brain function

Coma occurs due to the dysfunction Ascending Reticular Activating System which is the central brainstem structures on both sides from the caudal medulla to the rostral midbrain of both hemispheres. Various factors play an important role in the development of the coma such as metabolic, Ischemic hypoxic, Hypoglycaemic – Organ failure, Electrolyte disturbance, Toxic, structural causes, etc.

A coma is an acute, life-threatening situation hence the early diagnosis of the underlying cause should be quick to minimize further neurological damage. Coma requires early intervention that includes, Resuscitation with support of the cardiovascular and respiratory system, Correction of immediate metabolic upset, notably control of blood glucose and thiamine if indicated; control of seizures and body temperature; any specific treatments should be done when required

Coma: Causes

Various factors play an important role in the development of a coma. The important causes of coma include −

  • Trauma to the head causing brain injury is a common cause of coma. Trauma can lead to damage of the various brain parts and may present with internal hemorrhage causing loss of consciousness

  • Whenever there decrease in the blood supply to the brain, which leads the damage to brain cells such as in cases of stroke-causing coma

  • Hemorrhage, or bleeding in the brain due to various causes can cause damage and loss of consciousness

  • Hypoxia is a lack of oxygen to the brain, that occurs in cases of drowning, suffocation, and carbon monoxide poisoning and can cause coma

  • Certain infections, such as meningitis and encephalitis, can cause inflammation and damage to the brain, leading to coma

  • Overdosing on certain drugs, such as opioids, sedatives, and antidepressants, can cause respiratory depression and loss of consciousness

  • Tumors in the brain can cause coma by exerting pressure on the brain, leading to damage to the various brain parts

  • Certain metabolic disorders, such as liver failure, kidney failure, and diabetic ketoacidosis, alter the chemical balance of the body resulting in coma.

  • Patients with seizure disorder may go into a coma

  • Low blood sugar levels can lead to coma, particularly in people with diabetes.

Coma: Symptoms

A coma is a state of unconsciousness. The symptoms vary depending on the underlying cause. the common symptoms of coma include −

  • Loss of consciousness. The person is unresponsive to external stimuli, such as touch, sound, and light.

  • The person in a coma is unable to move voluntarily. They do not respond to commands to move their limbs or make any purposeful movements

  • The eyes of the patient are usually closed and no eye movements are present

  • Abnormal posture can be presented by the patient depending on the cause

  • The person's breathing may be irregular, shallow, or deep.

  • The person may exhibit abnormal reflexes, such as a lack of response to painful stimuli or exaggerated reflexes.

  • The person's vital signs, such as heart rate, blood pressure, and temperature, may be unstable or abnormal.

  • Seizures may occur in some cases of coma, particularly if the underlying cause is a seizure disorder or a brain injury.

Coma: Risk Factors

Various factors increase the risk of the development of coma. Some of the important risk factors of coma include −

  • Old age people are more at risk due to the increased risk of development of various abnormalities

  • People with chronic health conditions, such as diabetes, heart disease, and liver disease, are at a higher risk of developing a coma

  • People with substance abuse due to risk of increased poisoning or overdose

  • People who engage in high-risk activities, such as sports, extreme sports, or work in hazardous conditions, are at a higher risk of traumatic injuries that can lead to coma.

  • People with seizure disorders are at a higher risk of developing a coma

  • Patients taking medicines like sedatives, opioids, and antidepressants, can increase the risk

  • People with a history of stroke or tumors of the brain

Coma: Diagnosis

The diagnosis of coma is done by −

  • History − history of any chronic medical issues, drugs, any trauma should be asked

  • Clinical examination − Clinical examination should be done to look for any signs of trauma, infection, or other health conditions that may be causing the coma.

  • Neurological examination − Neurological examination should be done to assess the person's brain function, including tests of reflexes, muscle strength, and coordination.

  • Electroencephalogram (EEG) − An EEG helps to identify any abnormalities in brain function by recording the electrical activity of the brain

  • Imaging tests − Imaging tests, such as CT scans, MRI scans, and X-rays, are required to evaluate the brain, and to find the underlying cause. Brain damage and any brain abnormalities, such as bleeding, swelling, or tumors can be visualized by these tests.

  • Blood tests, urine culture, and serum electrolytes are used to check for metabolic imbalances, infections, or other health conditions causing the coma

  • Lumbar puncture − A lumbar puncture, or spinal tap, in which the removal of a sample of cerebrospinal fluid from the spinal cord is taken and tested. The test helps to identify infections, bleeding, or other abnormalities in the brain.

  • Evoked potentials − Evoked potentials are tests that measure the brain's response to visual, auditory, or other sensory stimuli. These tests can help evaluate the extent of brain damage and determine the potential for recovery.

Coma: Treatment

Treatment of the coma varies depending on the underlying cause. The essential measures include −

  • Maintaining the airway, breathing, and circulation should be done immediately if any of these is affected

  • The main aim of the treatment is to treat the underlying cause.

  • IV mannitol should be started if there is a rise in intracranial pressure.

  • Vitals should be managed.

  • If the cause of the coma is related to brain swelling or pressure, the patient may require surgery to relieve the pressure on the brain

  • If the infection is the cause, then intravenous antibiotics should be considered

  • Anti-epileptic drugs

Coma: Prevention

Some of the preventive measures that can reduce the risk of occurrence of coma include −

  • Avoiding head injuries

  • Managing chronic medical conditions such as diabetes, high blood pressure, and heart disease should be treated adequately by medications, and following a healthy diet, and getting regular exercise, can help reduce the risk of complications.

  • Avoiding substance abuse, alcohol, and smoking

  • Adequate treatment of infections and other medical conditions

  • Regular health check-ups help identify and manage any underlying medical conditions that may increase the risk of coma.


Coma is a state of the prolonged unconscious where the individual does not respond to any form of stimuli. Various factors affect brain function by decreasing its blood or oxygen supply and causing damage to the various parts of the brain leading to coma.

Coma is an acute life-threatening condition and hence should be treated at the earliest, the main treatment is to treat the underlying causes with supportive care.

Controlling chronic medical conditions, avoiding substance abuse, adequate treatment of various underlying causes and regular health checkups can help to reduce the coma to a certain extent.

Dr. Durgesh Kumar Sinha
Dr. Durgesh Kumar Sinha


Updated on: 17-Apr-2023


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