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Brain Death: Causes, Symptoms, Diagnosis, Difference between Brain beath, Coma and the Persistent Vegetative State : Medicine

Jul 07, 2023

Brain Death: Causes, Symptoms, Diagnosis, Difference between Brain beath, Coma and the Persistent Vegetative State : Medicine

Brain death is a medical condition defined as the irreversible and complete loss of all brain functions, including those of the brainstem. In brain death, there is no possibility of recovery or return to normal brain activity.

It is important to differentiate brain death from a coma or a persistent vegetative state, as brain death represents the permanent and irreversible cessation of all brain activities.

Read this blog further for a quick overview of this important topic Brain Death: Causes, Symptoms, Diagnosis, Difference between Brain beath, Coma and the Persistent Vegetative State for MEDICINE to ace your NEET PG exam preparation.

Causes Of Brain Death

There are various causes of brain death, which can be categorized into two main types

Traumatic and non-traumatic causes. Here are some of the causes of brain death;

  • Traumatic Brain Injury: Severe head injuries resulting from accidents, falls or physical assault can lead to brain death. This can occur due to direct damage to the brain tissue, bleeding, or swelling disrupting the brain's normal functioning.
  • Stroke: An ischemic stroke or hemorrhagic stroke can cause brain death. Ischemic stroke occurs when a blood clot blocks a blood vessel supplying the brain, while a hemorrhagic stroke involves bleeding in the brain due to a ruptured blood vessel. When the blood supply is compromised, brain cells can die, leading to brain death.
  • Hypoxia: Hypoxia refers to a reduced oxygen supply. Prolonged can cause severe brain damage and ultimately result in brain death. This can happen due to suffocation, drowning, cardiac arrest, severe respiratory failure, or complications during the surgery.
  • Brain Tumors: Certain types of brain tumors particularly those that are malignant or located in critical areas of the brain, can cause brain death. Tumors can exert pressure on vital brain structures, disrupt blood supply or cause uncontrolled brain swelling, leading to irreversible brain damage.
  • Infections: Severe infections of the brain such as meningitis or encephalitis, can cause inflammation and damage to the brain tissue. If left untreated or uncontrolled, these infections can progress and result in brain death.
  • Metabolic Disorders: Some rare genetic or acquired metabolic disorders can lead to brain death. These conditions disrupt the normal metabolic processes of the brain, leading to the accumulation of toxic substances or energy depletion, which can cause irreversible damage.
  • Drug Overdose: Overdosing on certain drugs particularly those that depress the central nervous system such as opioids or sedatives, can cause respiratory depression and subsequent brain damage If oxygen supply is compromised for an extended period.

Symptoms Of Brain Death

 Few symptoms of brain death include:

  • Light has no effect on children's pupils.
  • The person does not react to pain.
  • The corneal reflex prevents the eyes from blinking when the eye surface is touched.
  • Oculocephalic reflex- The inability of the eyes to follow head motion.
  • The oculo-vestibular reflex prevents the eyes from moving when cold water is put into the ear.
  • There is no gagging reaction on touching the throat.
  • The patient does not breathe when the ventilator is turned off.
  • There is absolutely no brain activity visible on an electroencephalogram.

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Diagnosis Of Brain Death

Usually, a clinician with special training in brain death evaluation makes the diagnosis of brain death in an intensive care unit. Diagnoses of brain death require the presence of three conditions: persistent coma, the absence of brainstem reflexes, and the inability to breathe on one's own. When a patient doesn't open their eyes, respond verbally, or move an arm after being subjected to painful stimulation, they are said to be in a coma. 

Testing several reflexes, such as pupil reactivity to light and coughing or gagging with throat suctioning, is used to determine the function of the brainstem. The last stage is an apnea test, which involves momentarily taking a patient off artificial breathing and watching for spontaneous breaths if a coma and the lack of brainstem reflexes are confirmed.

The patient meets the requirements for brain death if there is no sign of respiration after 10 minutes and the blood carbon dioxide level rises by 20 millimeters of mercury or higher.

 The confirmation of brain death requires additional radiographic testing, such as radionuclide investigations, transcranial Doppler ultrasonography, or cerebral angiography, in patients who cannot undergo an apnea test due to extremely low blood pressure or low oxygen levels.

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Is Brain Death Similar To Coma And Persistent Vegetative State?

Significant distinctions exist between brain death and other unconscious states. For instance, coma is identical to deep sleep, with the exception that no amount of external stimulation can cause the brain to become awake and alert. But while the person is still alive, a recovery is still feasible. 

A persistent vegetative state and brain death are not the same thing, despite the fact that they are frequently misunderstood. In a persistent vegetative state, higher brain functions are lost, but vital processes like breathing and heartbeat can still work since the brain stem is still intact whereas in brain death even the vital processes are absent. When given enough time, a person in a vegetative state may make some progress toward recovery. The person has passed away if their brain has stopped functioning.

Can A Brain Dead Person Donate The Organs?

Even if they are brain-dead, some people may be eligible to donate their organs. The ventilator is left on even after a person is certified dead if they were a registered organ donor or if their family was aware of their desire to be an organ donor. Still being provided are medications that assist protect internal organs. The remaining organs, including the kidneys, are removed during an operation on the deceased person. The ventilator is shut off when the procedure is finished. Following that, the family can arrange the funeral.

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