The human brain is one of the most complex systems on earth. It has the largest brain size of all vertebrates in relation to its body size and weighs about 1.5 kilograms with males having larger brains than females.

With its billions of neurons and nerve fibers, it has enough power to light a small bulb. The brain, as powerful and complicated as it may be, is also a very delicate organ and can go into a death-like sleep in a condition known as the coma.

Coma is a prolonged state of unconsciousness during which the individual is not aware of his or her surroundings. The person seems alive and looks like they are only sleeping but they cannot be wakened, neither can they respond to painful stimuli, light, and even sound.

Coma also occurs when a person scores below 8 on the Glasgow Coma Scale. The Glasgow Coma Scale (GCS) is a neurological scale that is used to measure and assess the level of consciousness of an individual.

The points of the scale range from 3 (which indicates deep unconsciousness) and 15 (Wakefulness). Coma differs significantly from brain death which is the loss of brain functions and inability to perform involuntary activity – such as breathing – needed to sustain life.

It also differs from Persistent Vegetative State in which the person is alive and retains some autonomic function. Coma, unlike the others, is usually induced by drugs, natural causes, or trauma to the brain.

A coma can occur gradually or rapidly depending on the cause and severity of the damage and it can last from several weeks to several years.

Causes of Coma

  • Traumatic brain injuries: Brain injuries caused by traffic collisions, sports injuries, or acts of violence that involve a blow to the head are common causes of comas.
  • Ischemic Stroke: A stroke occurs when there is a reduced or interrupted blood supply to the brain which may be caused by a burst blood vessel or blocked. A stroke can induce coma
  • Diabetes: In people living with diabetes have abnormal sugar levels. Hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) can cause a coma.
  • Hypoxia: This occurs when there is a lack of oxygen in the brain. Sodium and calcium outside the neurons (nerve cells) decreases, and intercellular calcium reduces, and this harms the communication between neurons. People who have been resuscitated after a heart attack or rescued from drowning may not awaken due to oxygen deficiency in the brain.
  • Brain Tumors: Tumors in the brain or brainstem can cause a coma.
  • Infections: Infections such as meningitis and encephalitis can cause the inflammation of the brain, spinal cord or the tissues surrounding the brain. Coma can be caused by severe infections in the brain that may result in brain injury.
  • Drugs and alcohol poisoning: Drug overdose and alchol poisoning can cause coma. Drugs weaken the synaptic functioning of the brain and could cause blood pressure and heart rate as well as abnormal breathing which can indirectly lead to a coma
  • Seizures: Continued seizures may lead to a coma.
  • Toxins: Exposure to cadmium, lead or carbon monoxide can cause brain damage and a coma.
  • Other Causes include: Malnutrition, blood loss, hypothermia, hyperthermia, and other biological disorders.

Signs and Symptoms of Coma

  • Inability to open eyes.
  • Lack of sleep-wake cycle.
  • Depressed brainstem reflexes, such as pupils not responding to light
  • Lack of responses in the limbs, except for reflex movements such as breathing
  • Lack of response to painful stimuli.
  • Irregular breathing


  • Physical tests: This seeks to check the person’s reflexes and see how they respond to painful stimuli. Pupil size can also be checked.
  • Blood tests: Blood tests would be taken to determine blood count, liver function, levels of electrolytes, glucose levels, signs of lead and carbon monoxide poisoning, and presence of illegal substances such as heroin and cocaine.
  • Spinal tap: A spinal tap or a lumbar puncture would be used to check for any infection of the central nervous system. The doctor inserts a needle into the comatose patient’s spinal cord, measures the pressure and extracts fluid that is sent to the laboratory for testing.
  • Imaging scans of the brain: CAT scan and MRI will be used to check for blockages or any damage to the brain. The electrical activity within the brain will be measured with an electroencephalography (EEG).

Glasgow Coma Scale

The GCS is used to assess the severity of brain damage after a head injury. It gives patients a score, based on verbal responses, response to stimuli, and how easily they can open their eyes.

  1. Eyes: Scores for eyes range from 1-4, 1 is when a person does not open their eyes, 2 on the scale is when they open their eyes in response to pain, 3 is when the eyes open response to voice and 4 is when they open them spontaneously.
  2. Verbal: Verbal scores range from 1-5, where 1 on the scale the person makes no sound, 2 is when they mumble but cannot be understood, 3 is when they speak inappropriate words, 4 means they speak but are confused, and 5 is normal communication.
  3. Motor reflexes: The scores range from 1-6, and 1-5 describe a person’s response to pain. A person who scores 1 does not make any movement, 2 on the scale is when they straighten a limb in response to painful stimuli, 3 occurs when they react in an unusual way to pain, 4 occurs when they move away from the source of pain, and 5 on the scale is when they can pinpoint the exact area of the pain. 6 means the person can respond and obey commands.

An overall score of 8 or less is indicative of a coma. If the score is from 9-12, it indicates that the person is conscious.


A coma is a severe medical condition that requires immediate attention. Medical professionals begin treatment by ensuring the immediate survival of the patient and securing breathing and blood circulation around the body.

Antibiotics and glucose may be administered on the person in case the coma is due to brain infection or diabetic shock.

Treatment depends on the underlying cause of the coma, for example, kidney failure, liver disease, diabetes, poisoning, and so on. In the case of brain swelling, surgery may be required.

Taking Care of a Coma Patient


A coma patient usually needs to be cared for in the intensive care unit (ICU) of a hospital. There, they can get extra care and attention from doctors, nurses, and other hospital staff.

They ensure the person gets nutrients, fluids, and any medicines needed to keep the body as healthy as possible.

These fluids are administered through a tiny plastic tube inserted in a vein or through a tube that brings fluids and nutrients into the stomach.

Some comatose people are unable to breathe into their lungs own and require a ventilator. Taking care of a comatose person is not easy, and it can get very frustrating for the friends and family of the patient.

They may feel scared and helpless, seeing their loved one in a continued unconscious state. Taking time to visit the hospital and talk to, read to, and even play music for the patient is vital because the person may be able to hear what is happening in their surroundings also if they cannot respond.

What happens after a Coma?

A coma usually lasts for a few weeks, after which the person may gradually begin to regain consciousness.

The patient may be groggy, agitated, or confused while waking up. Some people may make a full recovery and be completely unaffected by the coma while others may have disabilities.

Cases like that are usually caused by trauma to the brain. They will need medical assessment, physiotherapy, and support while rehabilitating, and some may require care for the rest of their lives.

The chances of someone recovering fully from a coma depends on their age, severity, and cause of their brain injury, and how long they have been in a coma. Predicting how long it will take for a person to recover or how long the coma will last is impossible.