Juvenile myoclonic epilepsy is the most frequently encountered and most common of the generalized epilepsy syndromes. It is characterized by the presence of absence seizures, myoclonic seizures and generalized tonic-clonic seizures. Typically, the first seizure type to present are absence seizures that start anywhere between the ages of 5 and 16 years of age followed by myoclonic jerks about 1 to 9 years later, with an average age of 14 or 15 years. Generalized tonic-clonic seizures appear a few months later after that, although they can appear earlier and both males and females are affected equally.
The hallmark characteristics of juvenile myoclonic epilepsy are the presence of myoclonic jerks that occur on awakening from sleep either in the morning or from a nap. These jerks are the most prominent seizure type. They are typically described as shock-like, irregular and arrhythmic movements of both arms. Sometimes these movements are restricted only to the fingers making the patient or individual look clumsy or prone to dropping things. In almost 20% of individuals, these myoclonic jerks can be primarily on one side as opposed to both sides. Generalized tonic-clonic seizures are reported in nearly all patients and in about a third of individuals absence seizures are reported. A small percentage of patients may never develop a generalized tonic-clonic seizure. When the patient develops myoclonic jerks, they typically occur in clusters and may be the warning sign prior to the generalized tonic-clonic seizure.
The most concerning aspect of juvenile myoclonic epilepsy is the presence of a condition known as myoclonic status epilepticus. This is occurs primarily when an individual awakens and basically it is multiple myoclonic seizures that do not readily stop. It is precipitated by sleep deprivation or missing medications. All seizures, especially the myoclonic jerks, occur within 30 minutes to an hour of awakening. Myoclonic jerks rarely occur at any other time unless the individual is quite tired.
One of the most interesting aspects of juvenile myoclonic epilepsy is the fact that there are two very common seizure-precipitating factors related to this condition. Sleep deprivation and fatigue, primarily after excessive alcohol intake are the most powerful precipitants of myoclonic jerks and generalized tonic-clonic seizures in juvenile myoclonic epilepsy. Other common precipitating factors include mental stress, emotion, and in particular excitement or frustration.
Juvenile myoclonic epilepsy is a genetically determined syndrome. About 50-60% of families with juvenile myoclonic seizures report seizures in either a direct relative or a cousin. The inheritance is of a complex type, although there are certain subtypes of the condition that have distinct genetics that are associated with it.
The EEG is the most important test in making a diagnosis of juvenile myoclonic epilepsy. The EEG in untreated individuals is typically abnormal with what is known as a 3-6 Hz generalized polyspike and wave discharge. An example of this condition is reflected in the figure below.
MRIs are typically normal. 30% of patients may show a photoparoxysmal response or an abnormal EEG in response to flickering lights. It is important when someone has a question of juvenile myoclonic epilepsy that if a normal EEG is obtained, that an EEG capturing sleep and wakefulness is performed in order to make certain that the diagnosis has been accurately assessed.
According to Dr. Panayiotopoulous, in his book “The Epileptic Syndromes and Their Treatment: A Clinical Guide, generalized tonic-clonic seizures in juvenile myoclonic patients are usually preceded by myoclonic jerks if they occur the morning after:
A party to celebrate a birthday
Waking up early in the morning to travel for vacations, particularly after a late night.
Replacement of valproic acid with carbamazepine in women starting to have a family, and
Withdrawal of appropriate medications after many seizure-free years.
The treatment of juvenile myoclonic epilepsy starts with advice regarding lifestyle and avoidance of the precipitating factors. It is essential that one avoid alcohol indulgence. Avoiding for sleep deprivation is essential. It is important to have adequate rest and adequate outlets for emotional outbursts in order to mitigate the potential for seizures in these individuals. Valproic acid is the most effective anti-epileptic drug in the treatment of juvenile myoclonic epilepsy; however, it is not the appropriate choice of treatment for women of childbearing years.
Levetiracetam is another possible drug choice; however, it has not been well studied for all of the seizure types that occur within this syndrome. Levetiracetam is approved for use in the treatment of myoclonic seizures in juvenile myoclonic epilepsy. Lamotrigine is widely used for juvenile myoclonic epilepsy; however, it may lead to worsening of the myoclonic jerks even though it may be helpful for the generalized convulsions and absence seizures.
Clonazepam administered in small doses could be effective for myoclonic jerks; phenobarbital is another option; and lastly topiramate and zonisamide can be additional options, particularly in women of childbearing years.
Medications that should be avoided include: vigabatrin, tiagabine, gabapentin, pregabalin, phenytoin, oxcarbazepine, and carbamazepine. Carbamazepine, in particular, is not effective for myoclonic jerks and may actually aggravate this and absence seizures; however, carbamazepine and phenytoin may be useful for generalized convulsions.
With regard to the prognosis of this condition, it appears that seizures tend to improve after the fourth decade of life. Seizures are generally well controlled with medications in up to 90% of patients, and individuals who have multiple seizure types may require more medications in order to best help them. One of the most commonly asked question about this syndrome is how long does an individual need to be on drugs, especially if they become seizure free. It is likely that lifelong treatment with a seizure drug is usually necessary. Withdrawal could result in a relapse in seizure, even in patients who have been seizure free for many years with appropriate drugs. It appears that it is only in individuals with mild forms of the condition that one is able to reduce the dose of the medication slowly over months, particularly in older aged individuals who have been on this drug; however, persistence or recurrence of the myoclonic jerks does require that medications be restarted.
How can the Epilepsy Therapy Project help with juvenile myoclonic epilepsy?
The Epilepsy Therapy Project can be beneficial in the treatment and diagnosis of juvenile myoclonic epilepsy by: 1) The use of My Epilepsy Diary for more accurate seizure counts, both of the three different seizure types that are commonly encountered in this condition; 2) by educating the public about the various medications and diagnostic tools available for help in this condition; and 3) by helping to speed up the research and development of new drugs that may be helpful for the three seizure types and the syndrome in of itself for effective termination of all seizures.
Joseph Sirven, M.D.
Last Reviewed: 5/15/11
Article from the May 2011 Epilepsy.com Spotlight Newsletter. Other articles in this issue inclue:
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