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Mitochondrial disorders

What is a syndrome?

A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.

Epilepsy Action has more information about seizure types, learning disabilities, and the EEG.

If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.

Epilepsy and mitochondrial disorders

The mitochondrial disorders are an uncommon group of conditions that are known as ‘metabolic disorders’.

There are many different types of mitochondrial disorders. The mitochondria are known as the ‘powerhouse of the cell’. All our organs (brain, nerves, muscles, heart, liver and so on) are made up of millions of cells. These cells can only work properly if the mitochondria in the cells work properly. The mitochondria are as important to the cells as the engine is to a car.

The organs with the most mitochondria are the brain, nerves, muscles and liver. Because of this, epilepsy occurs quite commonly in mitochondrial disorders. Most of the epilepsy starts in childhood and usually in the first two years of life. However, it can start within a few days of birth, or as late as the teenage years or even adult life.


The seizures can appear in different forms.The most common types are myoclonic, tonic-clonic, atonic, atypical absences, and focal (partial). However, other types of seizure may happen in mitochondrial disorders, including epileptic spasms.

When a focal or partial seizure happens, it may do so without stopping and can last for many hours or days. This is called ‘epilepsiapartialis continua’ (literally meaning ‘continuous partial epilepsy’). This type of seizure is seen in the mitochondrial disorders called ‘Alpers’ disease’ (after the German doctor who first described it), and Leigh’s disease (after the British doctor who first described it).


 A diagnosis of a mitochondrial disorder is considered in children where::

  • Their epilepsy begins in the first few months or years of life
  • Their epilepsy is not caused by any obvious infection or brain malformation
  • Their epilepsy does not respond to epilepsy medicines
  • They have delayed development
  • They have symptoms of other organs not working normally; this includes liver disease, poor weight gain or short stature

If the paediatrician thinks that the child might have a mitochondrial disorder, they will organise an EEG, MRI and other investigations. The EEG is not always helpful but it may show a pattern that is seen in one or two mitochondrial disorders. Two of these are Leigh’s disease and Alpers’ disease. The EEG pattern in both - but particularly Alpers’ disease - often shows a pattern called ‘periodic lateralising discharges or ‘PLEDS’ for short. An MRI brain scan may show abnormalities within the part of the brain called the ‘basal ganglia’. It may also show shrinkage of the brain (‘atrophy’). Blood tests and a lumbar puncture test may show high levels of lactate – which is one of the metabolic ‘waste products’ of the cell. A definite diagnosis may only be made by a muscle biopsy. Finally, genetic-testing (on DNA) might also be able to make a diagnosis of a particular type of mitochondrial disorder.

Epilepsy Action has more information about diagnosing epilepsy.


Treatment is nearly always necessary to treat the seizures in the mitochondrial disorders. However, the seizures may be very difficult to control. The most commonly used epilepsy medicines include the benzodiazepines (clonazepamand clobazam), levetiracetam, lamotrigine, piracetam, and vigabatrin. Sodium valproate can also be used, but preferably not in young infants or if the child has any liver disease because this might make the child seriously unwell. The ketogenic diet may sometimes be helpful in a few children, but this will again depend on the particular type of mitochondrial disorder. Epilepsy surgery is rarely able to help treat seizures in the mitochondrial disorders. 

Information about treatments for children can be found on the Medicines for Children website.

There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.

If your child has a mitochondrial disorder they may have prolonged or repeated seizures. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.


Most mitochondrial disorders are progressive. This means that the symptoms and the seizures will worsen over time. This worsening may happen over weeks, months or many years. How quickly the progression happens will depend on the particular type of mitochondrial disorder. The seizures in most mitochondrial disorders are usually very difficult to control. Unfortunately, for most mitochondrial disorders there is no specific treatment, such as diet or surgery, which can stop the seizures or stop the disorder from progressing.


Contact a Family
Freephone helpline (UK only): 0808 808 3555
Website: cafamily.org.uk
Email: info@cafamily.org.uk 


Epilepsy Action would like to thank

  • Dr Richard Appleton, and Dr Rachel Kneen, consultant paediatric neurologists at Alder Hey Children’s Hospital, Liverpool, UK and
  • Dr Stewart Macleod, consultant paediatric neurologist at Royal Hospital for Sick Children, Glasgow, UK.
    They have kindly prepared the information on this page. It is based on their own research, experience and expertise.

This information is exempt under the terms of The Information Standard.

  • Updated April 2014
    To be reviewed April 2017

Comments: read the 1 comments or add yours


I have jme but been on keppra 750mg twice a day and I have had two moments were all of a sudden I went stiff and stopped jerking and fell backwards and I've had my eyes shut but when I went to the doctors they said I probably fainted but I don't really faint could of this been a seizure or just a faint as a side affect of the medication


Submitted by rebecca unthank on