Patient education: Toxic-metabolic encephalopathy (The Basics)

What is toxic-metabolic encephalopathy? — "Encephalopathy" means a problem with how the brain is functioning. Toxic-metabolic encephalopathy, or "TME," is when this happens because of a chemical imbalance in the body or a buildup of toxins in the blood. Toxins can come from drugs, medicines, or other substances.

TME can be a sign that there is a serious illness, such as a problem with 1 or more organs. This must be treated right away. If the problem is not treated, it could lead to permanent organ damage or even death.

What causes TME? — TME happens when an organ is not working properly, or when too many toxins build up in the blood.

When the body is working normally, the organs work to keep the chemicals in the body balanced. When an organ is not working properly, it can lead to an imbalance. For example, TME might be caused by:

●Kidney or liver disease – The kidneys and liver work to filter and clean blood. If they are not working properly, waste products build up in the blood.

●Diabetes that isn't under control – If a person has diabetes that isn't under control, their blood sugar can build up to toxic levels.

●Problems with the lungs – With certain lung problems, like pneumonia, there can be too much carbon dioxide or not enough oxygen in the body.

TME can also be caused by toxins from outside of the body. These toxins might come from:

●Drinking alcohol or using other substances – For people who have a substance use disorder, stopping drinking or using certain substances ("withdrawal") can cause TME.

●Medicines that someone might use to treat other problems, such as seizures or depression

●Inhaling too much carbon monoxide – Carbon monoxide is a poisonous gas. It is released into the air when burning fuels like gasoline, wood, or charcoal.

●Being exposed to toxic chemicals

People might be more likely to get TME if they:

●Are older than 65

●Need to stay in the intensive care unit ("ICU") for another reason

●Have dementia

●Had a stroke or brain injury

What are the symptoms of TME? — Symptoms can include:

●Confusion or trouble thinking, paying attention, or understanding what is going on

●Memory problems

●Feeling sleepy or drowsy

●Acting jumpy or overreacting to small noises

●Feeling irritable

●Not being able to sleep, or sleeping during the day and being awake at night

●Hallucinations – This is seeing or hearing things that are not really there.

All of these symptoms together are sometimes referred to as "delirium." Delirium can be "hypoactive," which is when the person is sleepy and has trouble staying awake. Or it can be "hyperactive," which is when the person seems jumpy or irritable.

If the TME gets worse, other symptoms might include:

●Seizures

●Abnormal movement, like twitching or "jumping" of the arms and legs

●Coma

Is there a test for TME? — If a doctor thinks that someone has TME, they will ask about the person's symptoms and do an exam. For the exam, they will test the person's thinking, concentration, and memory. For example, they might have the person do simple number and word tests.

They will also do tests to look for the cause of their TME. These tests usually include:

●Blood tests

●Urine tests

●Chest X-ray

Some people might also need additional tests, such as:

●"Lumbar puncture," also known as a spinal tap – During this procedure, a doctor puts a thin needle in the lower back and removes a small amount of spinal fluid. This is the fluid that surrounds the brain and spinal cord. They will do lab tests on the sample.

●CT or MRI scan of the brain – These are imaging tests that create pictures of the brain.

●EEG – This test measures electrical activity in the brain and records brain wave patterns (figure 1).

How is TME treated? — TME is treated in the hospital. The most important part of treatment is finding out what is causing the TME and treating that problem.

If the doctor is not sure what is causing TME, they might start treatment by:

●Stopping medicines that could be causing the TME

●Giving thiamine, which is a form of vitamin B

●Using a "ventilator," which is a machine to help the person breathe

Sometimes, the problem that is causing the TME can't be fixed right away. And even after the problem is treated, it might take some time for all of the symptoms of TME to go away.

Some people with TME and hyperactive delirium might be at risk of hurting themselves or others. Doctors might give medicines called "sedatives" to keep them calm. The sedatives can make recovery from TME take longer, so doctors only give them when it is absolutely necessary.

In certain cases, the staff might also use restraints to keep the person from moving around a lot. But this is a last resort, and only done if the person is a danger to themselves or others.

If TME is treated early, it is possible to recover. Usually, the underlying health problem gets better before all of the symptoms of TME go away.

What will life be like? — A person who had TME might continue to have problems after getting better. This is more likely if their TME was severe, or if they had another brain problem like dementia or stroke before their TME.

A person who had TME might:

●Have problems with moving, speaking, or remembering things

●Feel depressed

Doctors and nurses will carefully monitor the person while they are recovering from TME. They can treat any symptoms if needed.

People who had TME might need to stay in a short-term rehabilitation program or skilled nursing facility while they recover. These places have nurses and other trained staff who can take care of the person.

More on this topic

Patient education: Delirium (confusion) (The Basics)
Patient education: Hepatic encephalopathy (The Basics)
Patient education: EEG (The Basics)

Patient education: Delirium (Beyond the Basics)