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What are Sodium Overlap Syndromes?

Sodium is a mineral that your body needs to survive. It is found in table salt and many foods. A sodium channel is like a door in the cells in your body. This door is usually closed, but can be opened if it receives a small electric current or if a certain kind of molecule touches it. When the door is open, it lets sodium ions come into the cell.

Sodium channels are important for cells that can be excited, which means that they can move or change under certain conditions. Muscle cells and the neurons in your nervous system are examples of excitable cells.

Sodium overlap syndromes, also called channelopathies [chan-uhl-OP-uh-thees], are conditions in which the sodium channels in your child’s cells don’t work the right way. This usually happens because of a problem in your child’s DNA, which leads to the sodium channels being built in the wrong way. Other times, it can happen because of an autoimmune disorder that damages the cell lining, which contains the sodium channels.

Sodium overlap syndromes most often affect the nerve cells and muscle cells, especially those in the heart which are sensitive to electric currents. Some syndromes that scientists know or suspect to be caused by sodium channel problems include:

  • Febrile epilepsy [FEH-bruhl EP-uh-lep-see]
  • Dravet syndrome
  • Epilepsy [EP-uh-lep-see]
  • Long QT syndrome
  • Brugada syndrome
  • Ventricular [ven-TRIK-yoo-ler] fibrillation
  • Irritable bowel syndrome
  • Erythromelalgia [eh-RITH-roh-mehl-AL-juh]
  • Fibromyalgia [fahy-broh-mahy-AL-juh]


There are many different sodium overlap syndromes, and your child’s symptoms will vary depending on which specific condition they have. The two most common types of symptoms are related to the nervous system and the heart.

Nervous System Symptoms

Children with sodium overlap syndromes can have symptoms that are related to problems in the nervous system, such as:

  • Pain
  • Seizures
  • Trouble controlling their muscles
  • Problems with their digestion

Heart Symptoms

The heart uses electric currents and sodium channels to know when to beat. If there is a problem with these channels, your child might have problems with their heart such as:

  • Arrhythmia [uh-RITH-mee-uh](irregular heartbeat)
  • Bradycardia [brad-i-KAHR-dee-uh] (slow heartbeat)
  • Tachycardia [tak-i-KAHR-dee-uh] (fast heartbeat)
  • Heart failure

Sometimes, these problems might not show up in your child, but when they do cause symptoms these are the most common:

  • Extreme tiredness (Fatigue)
  • Trouble breathing
  • Fluttering or pounding in the chest
  • Swelling in the lower part of the body
  • Dizziness or lightheadedness

Heart symptoms can sometimes get worse when your child is exercising, tired, or working hard.

When to See a Doctor

You should talk to a doctor if your child has any of the symptoms above. Sometimes, sodium overlap syndromes don’t have any symptoms, and many of the symptoms that do show up can also be caused by other conditions. Your child’s doctor can do tests that will rule out or diagnose these other problems, helping make sure that your child gets care for the right condition.


The most common causes for sodium overlap syndromes are genetic problems and damage to the ion channels from other diseases.

Genetic Causes

Your child’s genes contain their DNA, which is the code that tells every cell in their body how to work and how to be built. This code can have errors, called mutations. Usually, mutations are harmless, but sometimes they can change the way that certain parts of the cell work or are formed. Researchers have found certain genes that cause problems with the way the cell builds sodium channels. If your child has a mutation in these genes, they might have a sodium overlap syndrome.

Acquired Syndromes

Many syndromes are genetic, which means they are present in your child from the time they are born, but some can happen as a result of other diseases. Autoimmune disorders are conditions where the body attacks itself. Common examples of autoimmune disorders are rheumatoid arthritis [ROO-muh-toyd ar-THRY-tis] and multiple sclerosis [skluhr-OH-sis]. Researchers think that some autoimmune diseases might attack the sodium channels in the cells, which can make them stop working.

Diagnosis and Tests

If your doctor thinks that your child has a sodium overlap syndrome, they will start with a physical exam and might ask you questions about your child’s medical history, as well as any family history. Some factors that you might want to think about or write down before doctor appointment include:

  • Your child’s symptoms
  • How long they’ve had symptoms
  • If anything makes the symptoms better or worse
  • If any close family members (parents, siblings, grandparents, aunts or uncles) have had a sodium overlap syndrome or similar symptoms in the past

Usually, these conditions can’t be diagnosed with just a physical exam and will require more testing, starting with a genetic test to look for problems in your child’s genes that might cause a sodium overlap syndrome.

Heart Symptoms

If your child has symptoms in their heart or cardiovascular system, diagnostic tests might include:

  • Electrocardiogram [ih-LEK-trow-KAR-dee-oh-GRAM] (EKG), which is a non-invasive test that records your child’s heartbeat.
  • Electrophysiology [ih-LEK-trow-FIZ-ee-OL-oh-gee] study, which will help your doctor figure out how easy it is for your child to fall into an abnormal heart rhythm.
  • Exercise stress test, which is where an EKG is done while your child is walking or running on a treadmill to help the heart beat more.
  • A non-exercise stress test, which is where an EKG is performed right after a child is given medicine to help the heart beat faster, like they are playing hard.

Nervous System Symptoms

Doctors can do tests on your child’s nervous system to see how well it is working and to look for problems. Some common tests for these problems include:

  • Nerve Conduction Study, or NCS. This test uses electrodes to pass small electric currents through your child’s nerves to see how well they send and receive signals. It is often done with an EMG, described below.
  • Electromyography [ee-LECK-tro-my-AH-graf-ee], or EMG. An EMG is similar to an NCS but tests how well your child’s muscles respond to electrical currents. This test might be a little uncomfortable, but usually doesn’t cause pain, and can help diagnose many problems with the muscles.


The treatment for your child’s sodium overlap syndrome will depend on the specific condition that they have. Since there is no cure for these disorders, your child’s treatment plan will probably focus on helping with the symptoms they are dealing with. Some examples of treatments include:

  • Medicine. Many medicines can help with the heart problems and the neurological symptoms that sodium overlap syndromes cause. For instance, if your child has epilepsy, antiepileptic [AN-tee-ep-uh-LEP-tik] medicine might help. Other medicines can help with a fast heartbeat or high blood pressure.
  • Physical Therapy. Sodium overlap syndromes can make it hard for your child to move or control their muscles. Physical therapy can teach your child exercises and stretches that will help them keep control of their muscles for longer, and can also make them stronger.
  • Implantable cardioverter-defibrillator [KAR-dee-OH-ver-TUHR dee-FIB-rill-AY-tohr], or ICD. If your child’s sodium overlap syndrome causes an arrhythmia, an ICD can help. This device is implanted near your child’s heart and can give an electric shock in case their heart stops.
  • Pacemaker. If your child has an arrhythmia, where the heart doesn’t beat regularly like it should, a pacemaker can help. This device is installed in your child and gives a very small electric shock to the heart to keep it beating like normal.

Because there are many kinds of sodium overlap syndrome, each might require different treatment. You should talk to your child’s doctor and medical team about what treatment options are available, as well as the risks and benefits of each


Sodium overlap syndromes are usually caused by genetic or autoimmune disorders. Neither of these problems can be prevented, so the best thing you can do is take your child to the doctor if they show signs of these conditions. Early diagnosis can help your child get care sooner, and can make some treatments easier or more effective for your child.
Sodium overlap syndromes are a group of conditions that cause problems in the sodium channels, which are found in nerve cells, muscle cells, and the cells of the heart. Sodium channels help these cells move and send signals in response to electric currents, so problems with the channels cause symptoms that affect movement, heartbeat, and the nervous system.