COMA

The brain stem is the bridge between the brain and the spinal cord. It is responsible for a range of important functions, including the control of arousal levels. If there is a problem with the brain’s arousal system (the reticular activating system), or with its communications between other brain areas (such as the cerebral hemispheres), then the brain’s activity is impaired. Coma is a state of consciousness that is similar to deep sleep, except no amount of external stimuli (such as sounds or sensations) can prompt the brain to become awake and alert. A person in a coma can’t even respond to pain. A wide range of illnesses, conditions and events can cause coma. These causes share common characteristics: they either damage the reticular activating system or the cerebral hemispheres, or they suppress the functioning of the cerebral hemispheres.

Symptoms
The symptoms of coma include:

• The person looks like they’re asleep.
• No amount of sensory stimulation can wake them up.
• They may be breathing unusually.
• They may be holding their body in an unusual posture.
• Their pupils may be affected in a number of different ways - for example, one pupil is larger than the other or both pupils are constricted.

A wide range of causes
The various causes of coma can be broadly divided into three main categories, including:

• Intracranial - events occurring within the skull. This can include infection (such as meningitis), haemorrhage following a severe head injury, stroke, brain abscess, brain tumour, cerebral oedema (swelling of the brain) or the after-effects of an epileptic seizure.
• Extracranial - any external event that causes reduced oxygen or blood flow to the brain (cerebral hypoxia). This can include acute cardiac arrest (heart attack), alcohol poisoning, drug overdose (prescribed or illegal), carbon monoxide poisoning, liver or kidney failure, hypoglycaemia (low blood sugars), hyperglycaemia (high blood sugars), fever, electrocution and hypothermia (drop in body temperature).
• Psychiatric - mental disorders, including depression and catatonia, can cause a state of consciousness that appears very similar to coma.

Diagnosis methods
A coma is a medical emergency. A quick diagnosis can be life saving; for example, a person with diabetes may have dangerously lowered their blood sugar levels by accidentally injecting too much insulin. Immediate treatment is crucial in this type of life-threatening situation. Generally, medical personnel diagnose and treat coma patients in the following order:

• The airway, breathing, blood pressure and pulse of the person are checked.
• Their temperature is taken - for example, a high temperature may indicate fever and infection, while a low temperature suggests hypothermia.
• The body is examined for injuries - for example, the person may have sustained a serious head injury.
• The doctor checks for signs of brain damage - for example, complete limpness of the whole body or unusual breathing patterns.
• The pupils of the eyes can offer information on the cause of the coma - for example, unequal pupil sizes can indicate pressure in the brain, while pinpoint pupils could suggest narcotic overdose.
• A variety of blood tests can check a range of important factors including red and white blood cell counts, sugar levels, salt levels, alcohol levels, and blood levels of oxygen and carbon dioxide.
• Urine tests can show the presence of toxins and sugars.
• Scans of the brain, including CT and MRI, may be needed to help diagnose injuries to the brain.
• Suspected infections can be checked via lumbar puncture (a small amount of cerebrospinal fluid is drawn from the spine and tested in a laboratory).

Immediate intensive care
Proper diagnosis can sometimes take hours or even days. In the meantime, the person is given immediate intensive care. This would include:

• An intravenous line (IV or drip) to provide fluids and drugs.
• An oxygen mask.
• Urinary bladder catheterisation.
• Constant monitoring of their vital signs including pulse, breathing and blood pressure.
• Intravenous glucose.
• Pumping of the stomach, if it is thought the person ate or drank something poisonous.
• Administration of a narcotic antidote, if a drug overdose is suspected.
• A respirator, if the person is unable to breathe by themselves.

Treatment options
Treatment depends on the cause and severity, but may include:

• Intravenous administration of glucose in the case of hypoglycaemia.
• Intravenous administration of naloxone in the case of a heroin overdose.
• Surgery in the case of haemorrhage - for example, subdural haematoma (a blood clot between the brain and its covering).
• Antibiotics in the case of infections.

Recovery depends on the cause
The person’s prognosis depends on the cause and severity of the coma but, generally, anyone who falls into a comatose state is at risk of dying. In some cases, there may be a complete recovery with no loss of brain functioning, while in other cases, lifelong brain damage is the result. If the person’s brain was severely damaged or deprived of oxygen for a long time, they may be in a vegetative state. This means they can breathe, swallow and startle to stimuli such as loud noises, but have lost the higher brain functions that allow consciousness and personality. Brain death means the person has such severe brain damage that they are no longer able to breathe by themselves and need to be kept on a respirator. An electroencephalogram (EEG) typically shows no brain activity at all - the person has died, even though their heart continues to beat.

Where to get help

• Your doctor
• Emergency department of your nearest hospital
• Always call an ambulance in an emergency Tel. 000
• Neurologist

Things to remember

• Coma is a state of consciousness that is similar to deep sleep, except no amount of external stimuli (such as sounds or sensations) can prompt the brain to become awake and alert.
• A coma is a medical emergency.
• The wide range of causes includes head injury, stroke, cardiac arrest, hypoglycaemia, hyperglycaemia, hypothermia, drug overdose, and kidney or liver failure.

Brain death

Brain death is not the same as coma, because someone in a coma is unconscious but still alive. Brain death occurs when a critically ill patient dies sometime after being placed on life support. This situation can occur after, for example, a heart attack or stroke. The heart continues to beat while the ventilator delivers oxygen to the lungs (the heart can initiate its own beating without nerve impulses from the brain) but, despite the beating heart and warm skin, the person is dead. Since the brain has stopped working, the person won’t breathe if the ventilator is switched off.

Signs of brain death
Some of the signs of brain death include:

• The pupils don’t respond to light.
• The person shows no reaction to pain.
• The eyes don’t blink when the eye surface is touched (corneal reflex).
• The eyes don’t move when the head is moved (oculocephalic reflex).
• The eyes don’t move when ice water is poured into the ear (oculo-vestibular reflex).
• There is no gagging reflex when the back of the throat is touched.
• The person doesn’t breathe when the ventilator is switched off.
• An electroencephalogram test shows no brain activity at all.

Brain death is not the same as coma
Brain death differs from other states of unconsciousness in important ways. For example, coma is similar to deep sleep, except that no amount of external stimuli can prompt the brain to become awake and alert. However, the person is alive and recovery is possible. Brain death is often confused with a persistent vegetative state, but these conditions are not the same either. A persistent vegetative state means the person has lost higher brain functions, but their undamaged brain stem still allows essential functions like heart rate and respiration to continue. A person in a vegetative state is alive and may recover to some degree, given time. Brain death means the person has died.

Anguish for the family
Because life support machines maintain the person’s breathing and heart rate, they are warm to the touch. This gives the illusion that the person is still alive. Family members may hold a false hope that the person is just comatose and could wake up with time or treatment. It is important for the medical staff members to fully explain that brain death is final, and that the person is dead and has no chance of ever regaining consciousness again.

Organ donation is possible
In some cases, a person who is brain dead may be a candidate for organ donation. If the person was a registered organ donor, or if their family knew of their wish to be an organ donor, their death is declared but the ventilator is left on. Drugs that help preserve the internal organs are still given. The dead person then undergoes an operation to remove viable organs such as kidneys. After the operation is complete, the ventilator is switched off. Funeral arrangements can then be made by the family.

Where to get help

• Your doctor
• Neurologist
• Victorian Organ Donor Service - LifeGift Tel. (03) 9349 2278
• Australians Donate Tel. (08) 8351 5222

Things to remember

• Brain death occurs when a critically ill patient dies sometime after being placed on life support.
• In some cases, a person who is brain dead may be a candidate for organ donation.

Coma - vegetative state

Coma is a state of unconsciousness that is similar to deep sleep, except no amount of external stimuli (such as sounds or sensations) can prompt the brain to become awake and alert. A person in a coma can’t even respond to pain. In some cases, the person wakes up from their coma and, depending on the cause and severity of the coma, may or may not have permanent brain damage.

In other cases, the person descends into a vegetative state. If this lasts longer than a month or so, it is known as a persistent vegetative state. The brain has lost its higher functions (including consciousness, self-awareness and personality) but can still maintain involuntary functions such as breathing and swallowing, heart rate and blood pressure. Common causes of persistent vegetative state include severe head injury and oxygen deprivation. Comas usually only last a few weeks, but a vegetative state can continue for months or even years. The longer the person remains in this state, the bleaker their chances of making a recovery.
Signs of vegetative state
Some of the characteristics of a vegetative state include:

• The person looks like they’re asleep
• They can’t wake up, talk or respond to commands
• The eyes may open in response to stimuli
• The person is able to move their body
• Heart rate, blood pressure and respiration continue
• The person can randomly laugh, cry or pull faces.

The brain stem is undamaged
A person in a persistent vegetative state has damage to the cerebral hemispheres - the areas of the brain that govern sophisticated functions like consciousness, self-awareness and personality. However, the brain stem is intact, so the person retains motor reflexes, sleep-wake cycles and the activity of their autonomic nervous system. This includes the regulation of many functions essential to life such as heart rate, respiration and blood pressure.

Common complications
Common complications of a persistent vegetative state can include:

• Infections
• Pneumonia
• Bed (pressure) sores
• Contracture (muscles shorten and contort the body).

Ongoing medical care is vital
The person’s chances of recovery decrease as time goes by. There is often no way of knowing how long the vegetative state will last, so it is important to keep the person as healthy as possible in the hope they eventually recover. Medical care includes:

• Prevention and treatment of infection.
• Keeping the skin clean and regularly turning the patient to prevent bedsores and subsequent ulceration.
• Physical therapy to help keep the muscles supple.
• Good nutrition, delivered via an intravenous drip.

Prospects of recovery
The chances of recovery vary according to the location and severity of the brain damage. Generally, the longer the person remains in a vegetative state, the bleaker their chances. Recovery is usually a slow process, with the person first gaining some awareness of what’s going on around them and eventually being able to respond. However, only a small percentage of people who wake from a persistent vegetative state after six months or more are able to live independently. In most cases, they are permanently brain damaged and disabled.

Where to get help

• Your doctor
• Neurologist

Things to remember

• A person in a persistent vegetative state has damage to the areas of the brain responsible for consciousness, self-awareness and personality.
• The intact brain stem means the person retains motor reflexes, sleep-wake cycles and the activity of their autonomic nervous system.
• Common causes of persistent vegetative state include severe head injury and oxygen deprivation.
• The longer the person remains in a vegetative state, the bleaker their chances of recovery.

Hypoxia

Hypoxic injuries result when there is a substantial or complete lack of oxygen supplied to the brain, despite an adequate supply of blood flow. In severe cases of hypoxia, the person is often in comatose (in a state of unconsciousness) for periods ranging from hours to days, weeks, or months.

Following the emergence from coma, the person may remain confused and disoriented for a period of time, having no capacity to remember ongoing events. This may also last for hours, days, weeks or months.

In this state the person may be partially or fully awake, but can be confused, agitated and disoriented, absorbing little from the environment. The diminished oxygen supply to the brain may produce significant cognitive, physical and emotional impairments.

As a result, a hypoxic injury can have a profound impact, in terms of functional deficits, cost involved in treatment and the disruption it can have on people's lives and that of their families.

Diabetes and coma

A coma is a profound or deep state of unconsciousness. Coma can occur as a complication of an underlying illness, or as a result of injuries, such as head trauma. A persistent vegetative state (which is different from "brain-death") sometimes follows a coma.

Follow the links below to find information relating to coma.

Diabetes mellitus is a condition characterised by high blood glucose (sugar) levels. Uncontrolled diabetes may lead to coma or unconsciousness. The three types of coma associated with diabetes include ketoacidotic coma, hyperosmolar coma and hypoglycaemic coma.

Ketoacidotic coma
Ketoacidotic coma is more common in people with type 1 diabetes, which used to be called juvenile diabetes or insulin dependent diabetes mellitus (IDDM). This type of coma is triggered by the build-up of chemicals called ketones. Ketones are strongly acidic and cause the blood to become too acidic.

Ketones are by-products of fat breakdown; they can build up excessively when there is insufficient insulin in the body. When there is not enough insulin circulating, the body cannot use glucose for energy. Instead fat is broken down, which is then converted to ketones in the liver. Common causes of ketoacidosis include a missed dose of insulin or an acute infection.

Symptoms of ketoacidosis are:

• Extreme thirst
• Lethargy
• Frequent urination (due to high blood glucose levels)
• Nausea
• Vomiting
• Abdominal pain
• Progressive drowsiness
• Deep, rapid breathing
• A fruity or acetone smell on the breath may also be present.

Tests will reveal whether large amounts of ketones are present in the blood and urine.
Hyperosmolar coma
A hyperosmolar coma is caused by severe dehydration and very high blood glucose levels (hyperglycaemia).

Events that can lead to high blood glucose levels include:

• Forgotten diabetes medications or insulin
• An infection or illness, such as the flu or pneumonia
• Increased intake of sugary foods or fluids.

Those at most risk of this type of coma are people with type 2 diabetes who have an infection or acute illness and have reduced their intake of fluids or are taking diuretic medication or steroids.

The kidneys respond to high levels of blood glucose by doing their best to excrete it, along with a great deal of water. The person experiencing diabetic hyperosmolarity will be very thirsty but they can’t drink enough water to replace the lost fluids. They will become dehydrated and urgently need intravenous fluids. Without this kind of treatment, they may lapse into hyperosmolar coma.

Hyperosmolar coma develops slowly over several days, so if the high blood glucose levels are detected and treated early, coma can be prevented.

Hypoglycaemic coma
Hypoglycaemia, or low blood glucose levels (below 3.5mmol/L), may occur if a person on diabetes medication or insulin:

• Takes an extra or an increased dose
• Exercises strenuously without eating extra food or reducing their insulin intake
• Misses a meal or snack
• Drinks too much alcohol or drinks alcohol without eating food.

If the blood glucose level falls very low, the person may become unconscious (hypoglycaemic coma) and seizures may occur.

Symptoms of hypoglycaemia include:

• Trembling
• Palpitations
• Weakness
• Sweating
• Intense hunger
• Confusion, altered behaviour, drowsiness or coma – these may occur if the blood glucose level becomes very low.

Prolonged or frequent coma should be avoided and hypoglycaemia treated quickly.

First aid
First aid for someone who has lapsed into a diabetic coma includes:

• Dial triple zero (000) for an ambulance immediately.
• Don’t try to give them anything to eat or drink, as they may choke.
• Turn them onto their side to prevent obstruction to breathing.
• Follow any instructions given to you by the operator until the ambulance officers arrive.
• Don’t try to give them an insulin injection.

Diagnosis methods
A coma is a medical emergency. A quick diagnosis can save the person’s life. The cause of a diabetic coma is diagnosed using a number of tests, including:

• Medical history
• Physical examination
• Blood tests, including glucose and ketones
• Urine tests.

Treatment options
Treatment options for diabetes-related coma include:

• Ketoacidotic coma – intravenous fluids, insulin and administration of potassium and sodium.
• Hyperosmolar coma – plenty of intravenous fluids, insulin, potassium and sodium given as soon as possible.
• Hypoglycaemic coma – administration of the hormone glucagon to reverse the effects of insulin, or glucose given intravenously.

Where to get help

• Always call an ambulance in an emergency Tel. 000
• Emergency department of the nearest hospital
• Your doctor
• Diabetes specialist
• International Diabetes Institute Tel. (03) 9258 5000
• Diabetes Australia – Victoria Tel. 1300 136 588

Things to remember

• The three types of coma associated with diabetes include ketoacidotic coma, hyperosmolar coma and hypoglycaemic coma.
• Diabetic coma is a medical emergency and needs prompt medical treatment.
• Uncontrolled blood glucose levels may lead to hyper or hypoglycaemia.
• Low or persistently high blood glucose levels means your diabetes treatment needs to be adjusted. Speak to your doctor or health professional.
• Prevention is always the best strategy. If it is a while since you have had diabetes education, make an appointment with your diabetes educator for a review.

New Research About Stroke

Brain science has revealed that stroke and depression are closely linked. One large study (funded by the National Institutes of Health) found that people with depression are far more likely to suffer a stroke. In fact, high levels of depressive symptoms increased stroke risk by 73 percent, while moderate symptoms raised the risk by 25 percent.

Other studies show that at least two-thirds of stroke victims develop depression. People who have strokes in the left front part of the brain seem to be at increased risk, for reasons that are not yet clear. Post-stroke depression can severely interfere with recovery, and triples the risk of dying in the years immediately following a stroke.

Despite its prevalence, depression following stroke is not often recognized or properly treated. Believing that depression is a normal reaction to suffering a stroke could prevent people from seeking and getting help.

Good news: Antidepressants—especially those that act on the brain chemical serotonin—can greatly improve symptoms of post-stroke depression. Many experts believe that treating depression symptoms will speed stroke recovery, and studies are underway to determine which therapies are best.

Also, advances in our understanding of how the brain functions and repairs itself following injury have improved stroke recovery. A number of studies are investigating which rehabilitation strategies work best in which people. Beginning rehabilitation immediately seems to be critical to helping stroke victims recover lost function.

Treating and Preventing Stroke

Stroke is a medical emergency; if you notice any of the warning signs of stroke, you should get immediate medical attention. For some people with ischemic stroke, a "clot-busting" drug (called t-PA), can limit the secondary brain damage following a stroke—but only if it is administered within three hours of the stroke's onset.

Many strokes can be prevented. Primary risk factors that can be managed with lifestyle modifications include

• Smoking
• Excessive alcohol use
• Diabetes
• High blood pressure
• Obesity
• Inactivity

Some people may also inherit a vulnerability to stroke, which means you are at greater risk if you have a relative who has a stroke.