Pediatric Myoclonus

What is pediatric myoclonus?

Pediatric myoclonus causes children to have sudden, quick muscle movements that they can’t control (involuntary). The movements can be small or large, and they can happen once in a while or many times a day.

Myoclonus isn’t a disease itself but may be a sign of another neurological condition, such as epilepsy. Neurological conditions affect the brain, spinal cord and nerves. Some forms of myoclonus are harmless, and others may be related to more serious conditions. A doctor’s evaluation can show the cause of myoclonus and whether your child needs treatment.

What are the different types of pediatric myoclonus?

Doctors usually group myoclonus into two broad types.

Benign (physiologic) myoclonus

These muscle twitches are common and harmless, such as hiccups or sleep starts that happen as a child falls asleep (sleep myoclonus). A rare type is benign myoclonus of early infancy, which looks like brief, jerking movements. Benign myoclonus usually goes away on its own, so children usually don’t need treatment.

Secondary (symptomatic) myoclonus

These movements are symptoms of another condition, such as epilepsy, a metabolic disorder or a genetic syndrome. A rare, epilepsy-related type is myoclonic epilepsy in infancy. A metabolic disorder is a condition that disrupts the body's ability to process nutrients. Genetic syndromes are conditions caused by a problem with a person’s genes. Secondary myoclonus may need testing and treatment by a neurologist. These doctors specialize in conditions affecting the nervous system (brain, spinal cord and nerves).

What are the signs and symptoms of pediatric myoclonus?

Myoclonus looks different from child to child. Some children have quick, random jerks in one muscle. Others have larger movements that affect several parts of the body.

Myoclonus can affect the:

• Arms

• Legs

• Face, mouth, tongue or throat

• Diaphragm (muscle wall that separates the chest cavity from the belly)

Movements may:

• Happen once in a while or many times a day

• Come in bursts or clusters

• Be triggered by sudden noise, light, stress or tiredness

• Be felt by your child, even if you don’t see them

Contact your child’s health care provider if:

• The movements get worse or don’t go away.

• Your child loses movement skills, such as walking, or starts dropping objects often.

• The movements cause falls or get in the way of your child’s day-to-day functioning.

How is pediatric myoclonus diagnosed?

At Children’s Health, our myoclonus team includes pediatric neurologists who specialize in movement disorders and epilepsy. We begin with a thorough evaluation of your child, including a physical exam. We'll ask you about your child's medical history and watch their movements. It’s very helpful if you can record and bring videos of your child's movements to the appointment.

Our team uses the latest diagnostic tools to understand what’s causing your child’s symptoms. For some tests, our Child Life specialists can work with your child to help them be ready and ease their fears.

Depending on what we learn in our evaluation, your child may need one or more diagnostic tests, such as:

• Electroencephalogram (EEG): This painless test records the brain’s electrical activity. It helps doctors see whether seizures or unusual brain wave patterns are causing the movements.

• Magnetic resonance imaging (MRI): MRI uses powerful magnets and radio waves to create detailed pictures of the brain. It can show whether structural changes or injuries may be causing the movements.

• Electromyography (EMG): EMG uses small sensors to measure the electrical activity of muscles. This test shows how muscles react and where the movements start (in the brain, spinal cord or nerves).

• Somatosensory evoked potentials (SEP): This test measures how the brain responds to touch or other stimulation. It helps identify the type of myoclonus and where it begins in the nervous system.

• Genetic testing: Genes are the set of instructions in our body that tells our body how to function. A blood or saliva sample can show whether your child has a gene change that may be causing myoclonus. Genetic counselors at Children’s Health guide families through this process.

What causes pediatric myoclonus?

Myoclonus can develop for many reasons. Sometimes the cause is unknown. Often, it’s a symptom of another condition, such as:

• Hiccups, sleep starts and other causes of benign and sleep myoclonus

• Epilepsy and seizure disorders

• Genetic syndromes, such as mitochondrial disease

• Metabolic disorders, such as kidney failure and liver failure

• Exposure to toxic substances, such as medications or chemicals

• Neurological (central nervous system) conditions, such as stroke, multiple sclerosis, spinal cord injury or lack of oxygen

How is pediatric myoclonus treated?

At Children’s Health, our pediatric neurology team tailors a treatment plan to your child. Treatment focuses on addressing the cause of myoclonus and relieving symptoms.

Some children with benign or sleep myoclonus don’t need treatment at all. For myoclonus related to epilepsy, our nationally recognized Level 4 Pediatric Epilepsy Center offers the highest level of care.

Families can feel confident knowing that, whatever the cause, we provide the full range of treatment options to support your child.

Nonsurgical treatments for myoclonus

• Medications: Anti-seizure medicines are often the first treatment for myoclonus. They can reduce or control movements caused by both epileptic and nonepileptic myoclonus. Other medications reduce symptoms by slowing down the central nervous system.

• Supportive therapies: Physical therapy and occupational therapy can help with balance, coordination and daily activities. Speech therapy may help children with myoclonus that affects the face, mouth or throat.

• Ketogenic diet: This eating plan can help some children with myoclonus caused by seizures. Registered dietitians at Children’s Health work with you on this high-fat, low-carbohydrate diet.

Medical devices and surgery

• Medical devices: If medicines aren’t enough, our team may recommend advanced devices. These include deep brain stimulation, responsive neurostimulation and vagus nerve stimulation.

• Surgery: Our neurology team works closely with neurosurgeons to treat children with seizures that cause myoclonus. We operate to treat the part of the brain where seizures begin.