MPEI (Migrating Partial Epilepsy of Infancy)

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Niamh's Journey

Overview

Migrating Partial Epilepsy of Infancy (MPEI) or Migrating Partial Seizures of Infancy (MPSI) as it more commonly referred to in medical papers, is a very rare type of epilepsy which is belived to affect less than 100 children worldwide.

Seizures start in very early childhood, often from the first few weeks of life, and all affected children will have started having seizures by six months of age.

In the first few weeks of life, seizures may not occur regularly, however very rapidly they increase in frequency to the point where they may occur 10, 50 or even 100 (or more) times a day, every day.

Affected children have both partial and generalized seizures and may also have infantile spasms. The pattern, appearance and duration of these seizures changes regularly making it a very difficult condition to manage.

Affected children go through noticeable "good" periods where seizures may disappear for a few days or weeks. This may be followed or preceded by "bad" periods where seizures may be almost continuous - with no obvious explanation.

All children have considerably delayed development and some have numerous other medical issues.

No single common cause has been found to explain this type of epilepsy. For the majority of children, all blood and urine tests, skin and muscle biopsies are normal.
It is not believed to be due to any ‘birth injury’ and it does not routinely run in families (although affected siblings have been observed on rare occasions).

It is currently known that the underlying genetic basis of this epilepsy syndrome is not the same for every child, which is why children with this condition do not all respond in the same way to treatment.

It is agreed however, that all children with this condition display similar symptoms and progression of their condition, and whatever the underlying genetic fault within the child, the outward presentation of this condition shows remarkable homology between affected children.

It is also believed that MPEI may display a range of severities, which is demonstrated by the age of seizure onset, the range of learned skills and age of mortality of children with this condition.

It has been reported that if the seizures can be controlled for a number of months, it is possible that the child may show some developmental progress, however in our experience this has not been the case. Obtaining seizure freedom in this condition is very rare (but possible). In other cases, seizures have been seen to stabilize or gradually burn out over a number of years. Developmental issues however remain.

How Common is MPEI

MPEI is believed to affect 0.11 children in 100,000 - that's just over 1 affected child per one million children born.

Up until 2012, only 100 cases had been published in the medical literature since MPSI was first described in 1995. 15-20 of these are from the UK.

A research group at Great Ormond Children's Hospital in the UK have recently completed a survey of MPSI in the UK and Ireland via the British Paediatric Neurology Surveillance Unit (BPNSU). The local paediatric neurologist was asked via email whether they had seen any children with MPSI and then completed an anonymous questionnaire with information about clinical features, investigation results and EEG reports.

This was the first national case series, although series of 15 to 17 patients from individual centres from different parts of the world have previously been published in the medical literature. Results of this study and other MPSI published papers can be found in the Research Papers pages.

Global collaborations are ongoing and will continue to yield valuable information about the global incidence of this condition.

What Causes MPEI

There have been several theories proposed in the past.

Firstly, some believed that there might be a problem with the neurotransmitters (chemical substances responsible for signaling between nerve cells) in the brain, as this would explain why all of the brain could be affected. However treatments such as bromides (which are thought to act via neurotransmitters) have not been effective in all patients and measurement of neurotransmitter levels done in some of the previously reported cases have been normal.

Another possibility was a problem with the channels in the cell membrane which regulate the flow of sodium and potassium in and out of cells. Mutations in these genes, causing conditions known as channelopathies, have in recent years been found to be the cause of several different epilepsy syndromes such as Dravet syndrome also known as severe myoclonic epilepsy of infancy (SMEI).

Other possibilities that have been considered include metabolic conditions including mitochondrial diseases - however most previously reported cases of MPSI have been extensively investigated including blood, urine, cerebrospinal fluid testing and muscle biopsy and no biochemical abnormalities have been found.

It is believed that some cases of MPSI have an inherited basis. Most likely, a faulty gene might have been passed down from each parent, resulting in an affected child.
It is also possible that the occurrence might be spontaneous i.e. might have just occurred by chance in the child affected. This has been considerd as there are limited reports of affected siblings.

Recent research undetaken by Dr Amy Mctague et al (Brain 2013) has identified faulty genes in a number of affected children, which are believed to be the cause of their MPSI. Further work is currently being undertaken to see whether these mutations were inherited from the parents or happened spontaneously and only in that child.

Research evidence indicates that there is more than one genetic abnormality that can cause MPSI. This also explains the varying symptoms between affected children and why for some the onset is severe with death often occurring in the first few years of life whilst others have a more gradual onset, with less additional complications.

Genetic Causes To Date

Several genetic causes for MPSI have now been identified:

- SCN1A (which also causes Dravet syndrome),
- SLC25A22 (which also causes early myoclonic epilepsy),
- PLCB1 (which also causes West syndrome),

In 2012 a new gene was discovered called KCNT1, which codes for a potassium channel.
In a group of 12 children with MPSI, 6 were found to have changes in this gene so it seems likely that it is an important gene in MPSI.

Most recently in April 2013 a family with 2 affected children with MPSI were found to have mutations in TBC1D24, a gene which affects nerve growth within the brain.

MPEI Website Links