Juvenile Myoclonic Epilepsy

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Background

Juvenile myoclonic epilepsy (JME) is an idiopathic generalized epileptic syndrome characterized by myoclonic jerks, generalized tonic-clonic seizures (GTCSs), and sometimes absence seizures. JME is relatively common and responds well to treatment with appropriate anticonvulsants.

Other keys to the diagnosis include normal intelligence, onset around adolescence, and a family history of the condition. GTCSs occur shortly after awakening or after precipitating factors such as sleep deprivation, alcohol use, or psychological stress. Patients usually require lifelong anticonvulsant therapy, but their overall prognosis is generally good.

Definition of juvenile myoclonic epilepsy

Since the first description of a probable case of JME in 1867,[1] various names have been applied to this condition.[2, 3, 4, 5] The term “juvenile myoclonic epilepsy” was proposed in 1975[6] and has been adopted by the International League Against Epilepsy (ILAE). Under the proposal for revised classification of epilepsies and epileptic syndromes, in 1989 the ILAE Commission on Classification and Terminology defined JME (impulsive petit mal) as follows.[7]

“Impulsive petit mal appears around puberty and is characterized by seizures with bilateral, single or repetitive, arrhythmic, irregular myoclonic jerks, predominantly in the arms. Jerks may cause some patients to fall suddenly. No disturbance of consciousness is noticeable. Often, there are GTCS and, less often infrequent absences. The seizures usually occur shortly after awakening and are often precipitated by sleep deprivation."

“Interictal and ictal EEG have rapid, generalized, often irregular spike-waves (SW) and polyspike-waves (PSW); there is no close phase correlation between EEG [electroencephalographic] spikes and jerks. Frequently the patients are photosensitive. The disorder may be inherited and sex distribution is equal. Response to appropriate drugs is good.”

For more information, see the following:

Pathophysiology

JME is an idiopathic generalized epilepsy syndrome. It is not associated with conditions such as head trauma, brain tumor, or encephalitis.

Results from routine pathologic analyses of brain specimens from patients with JME are typically normal. However, histology occasionally reveals increased numbers of partially dystropic neurons in the stratum moleculare, white matter, hippocampus, and cerebellar cortex; an indistinct boundary between the cortex and the subcortical white matter and between lamina 1 and 2 can also be found. These findings are termed microdysgenesia and have been interpreted as a manifestation of minimal developmental disturbances.

Some families have specific mutations that yield the clinical phenotype of JME. (See Etiology.) Known mutations include ion channel proteins, such as the beta-4 subunit of calcium channels and the chloride channel 2 protein.

One study of a large Canadian family with JME demonstrated increased gamma-aminobutyric acid (GABA)-A receptor subunit degradation from a mutation of the alpha1-subunit (A322D) of the GABA-A receptor.[8] This results in a decreased functional lifespan of the GABA-A receptor and consequent CNS hyperexcitability. A review article by MacDonald and Kang describes additional mechanisms that might result in hyperexcitability.[9]

In another study, there was a reduction in the regional binding potential to the dopamine transporter (DAT) in the substantia nigra and midbrain (but not in caudate or putamen) in a positron emission tomography (PET) study of patients with JME as compared with healthy controls.[10]

Etiology

The exact cause of JME remains unknown. Specific mutations in various genes have been identified with a complex mode of inheritance.[11] Most likely, multiple genes result in a similar electroclinical syndrome.

Mutations in genes encoding ion channels have been associated with JME, inclusive of the beta-4 calcium channel subunit (CACNB4), the GABA receptor subunit (GABRA1), and the chloride channel (CLCN2). Each of these channelopathies has been described in a single family, and all are rare causes of JME.[12]

Discussion by Suzuki et al[13] and Delgado-Escueta’s group[14] describe missense mutations of the myoclonin gene (EFHC1) in the EJM1 site at 6p12–p11. Calcium dysregulation versus abnormalities during cortical development may be the underlying reason for dysfunction in affected patients with JME and mutation in the EFHC1 gene. Gene dysfunction at other loci (EJM2, EJM3) are also being studied.

Genetic risk factors

Although JME is known to be an inherited disorder, the exact mode of inheritance is not clear. About a third of patients with JME have a positive family history of epilepsy. About 17-49% of patients with JME have relatives who have epileptic seizures, including parents (about 4%) and children (about 7%). The risk of expressing clinical JME might be slightly higher in female individuals than in male individuals and in relatives of people with JME. However, some studies have shown similar sex-related risks.

Although investigators in most studies have presumed that JME is an autosomal dominant condition (ie, 50% risk of inheritance), it has incomplete penetrance, which means that some individuals who inherit the JME gene or genes do not express clinical JME. However, their children may inherit the JME genes and express clinically obvious disease. To an untrained observer, the disease seems to skip generations. For relatives of a patient with JME, the risk of having clinically obvious JME is small: 3.4% in parents, 7% in siblings, and 6.6% in children.

Despite similar genetic burden, the phenotype of JME might vary among relatives, as in a case of identical twins in which the proband had JME (myoclonus and GTCSs) but the identical twin only had childhood absence epilepsy. A French-Canadian study of probands with JME demonstrated only an absence syndrome in 27% of relatives with seizures.[15]

Epidemiology

The incidence of JME in the general population is estimated to be 1 case per 1000-2000 people internationally. JME represents approximately 5-10% of all epilepsies; however, the exact figures may be higher, as the condition is often misdiagnosed.

Age-related differences in incidence

JME typically begins in adolescence. Although the age of onset varies from 6-36 years, symptoms typically begin in adolescents, with a peak age of 12-18 years. Why the onset of this genetic disorder is delayed until adolescence is unclear.

Myoclonic jerks, GTCSs, and absence seizures all have an age-related onset in JME. If absence seizures are a feature, they usually begin between the ages of 5 years and 16 years. Myoclonic jerks may follow 1-9 years later, usually around the age of 15 years. GTCSs typically appear a few years later than myoclonic jerks.

Sexual differences in incidence

Findings from some studies suggest that JME is slightly more prevalent among females than males. The reason is unknown. However, data from other studies indicate similar prevalences in both sexes.

Racial differences in incidence

No systematic racial differences have been observed. However, it is likely that some specific genetic mutations among the different types described in families with JME might be more prevalent among different racial groups. For example, the myoclonin (EFHC1) mutation has been found in 9-20% of Mexican-American families with JME but in only 3% of Japanese families with this disorder.[11]

Prognosis

In general, excellent seizure control can be achieved in JME patients with relatively low doses of appropriate anticonvulsants (eg, valproic acid). The risk of recurrence is higher than 80% if anticonvulsants are withdrawn; hence, lifelong treatment is usually necessary.

The severity of JME seizures appears to decrease in adulthood and senescence. Whether patients outgrow JME, as compared with other primary generalized epilepsies, at a late age (ie, >60 y) is unknown. However, in 1 author’s experience, older relatives of people with JME who have a history of seizures are often untreated and rarely have seizures. An epidemiologic study is needed to settle this issue. Rare cases of late-onset JME have been reported as late as the eighth decade of life.[16]

Camfield and Camfield conducted a long-term population-based study of patients with JME. Between 1977 and 1985, the 24 patients in Nova Scotia who developed JME by age 16 years were contacted 25 years later. In 17%, all seizure types in JME had resolved; in 13%, only myoclonus persisted. Nevertheless, many patients’ lives were complicated by depression, social isolation, unemployment, and social impulsiveness.[17]

Sudden unexpected death in epilepsy (SUDEP) and accidental morbidity and mortality have been observed in JME, as in other epileptic syndromes involving GTCSs.

Patient Education

The Epilepsy Foundation has a large selection of brochures and informational booklets for patients and their families. The American Epilepsy Society is the professional organization for people treating patients with epilepsy or for those doing research in this field.

For patient education resources, see the Brain and Nervous System Center, as well as Epilepsy.

History

Juvenile myoclonic epilepsy (JME) is diagnosed on the basis of clinical findings. Video-electroencephalography (EEG) monitoring of typical seizures is the criterion standard, but in the great majority of patients, a working diagnosis of probable JME is made on the basis of the clinical history.

Although observers’ descriptions of seizures are helpful, caution must be used regarding their validity. The most important element in the diagnosis of JME is the patient’s history. Any patient who presents with generalized tonic-clonic seizures (GTCSs) without an aura should be questioned about myoclonic jerks, the time of day when the seizures occurred, and any precipitating factors.

About 17-49% of patients have a family history of epilepsy. Symptoms usually begin in adolescence. The leading symptom is jerky movements that occur in the morning (typically, shortly after awakening) but might occur throughout the day, without loss of consciousness.

Patients may have myoclonic jerks plus other seizure types. In about 60% of patients, JME begins with myoclonic jerks, followed by the onset of relatively uncommon GTCSs a few years later. The finding of myoclonic jerks plus absence seizures and GTCSs is the next most common combination, occurring in approximately 30% of patients with JME. The combination of myoclonic jerks and absence seizures without GTCSs is rare, occurring in only 2% of patients.

Myoclonic jerks or seizures

Myoclonic jerks or seizures without impairment of consciousness are the cardinal symptoms of JME. Although an occasional strong myoclonic jerk may make patients momentarily seem to be “in a fog,” a key feature is that consciousness is preserved during these jerks.

The jerks are usually brief, bilateral, arrhythmic contractions that mainly involve the shoulders and arms. However, some patients report jerking in the lower limbs, trunk, or head. Some jerks occur unilaterally. In a video-EEG study, Hirano et al characterized myoclonic jerks in patients with JME as being more likely to occur in clusters, with distal predominance, and involving extension muscles.[18]

The frequency and intensity of myoclonic jerks may vary. For instance, they may be perceived only internally, as an electric shock–like sensation. If the jerks are violent, patients may throw objects they are holding or even fall to the floor. Myoclonic jerks can occur in rapid succession and even progress to myoclonic status epilepticus. However, more often a rapid succession of myoclonic jerks evolves into a primary GTCS.

Myoclonic jerks occur as the only seizure type in approximately 17% of patients with JME; the remaining patients have a combination of myoclonic jerks, GTCSs, and absence seizures. Myoclonic seizures tend to subside by the fourth decade,[19] but the other seizure types might persist.

Generalized tonic-clonic seizures

GTCSs occur in approximately 80% of patients with JME. The GTCSs seen in JME are typically symmetric, with a prolonged tonic phase that may lead to cyanosis and tongue biting.

GTCSs are sometimes preceded by a series of myoclonic jerks of increasing severity that evolve into an initial clonic phase of a GTCS. The GTCSs often cause a patient with JME to seek medical attention; in this setting, patients should be questioned specifically about myoclonic jerks because most patients do not mention them.

Absence seizures

In JME, absence seizures are somewhat less common than GTCSs. Janz reported that 28% of his patients with JME also had absence seizures.[4, 5] When absence seizures are a feature of JME, they are often the first clinical manifestation of the syndrome, with myoclonic jerks typically following 1-9 years later. A clue to this diagnosis is the development of GTCSs or myoclonic seizures within a couple of years after starting treatment with ethosuximide. Approximately 3-8% of children who present with absence seizures ultimately receive a diagnosis of JME.

In JME, absence seizures are typically short, lasting a few seconds, and usually not accompanied by motor signs.

The severity of absence seizures in JME is somewhat age dependent. When they appear in children younger than 10 years, absence seizures of JME are reported less often than those of childhood absence epilepsy. Some recollection of the ictal events is common, particularly in patients that have persistence of these seizures during adulthood. Automatism is rare.

When absence seizures of JME begin in children aged 10 years or older, they may be even less severe than they otherwise would be, with merely a brief interruption in the patient’s ability to concentrate. In a video-EEG monitoring study of patients with absence seizures, Sadleir et al found that patients with JME tend to have shorter seizures than patients with other epileptic syndromes with absences.[20]

Precipitating factors for seizures

Seizures of JME often are precipitated by (1) lack of sleep, (2) psychological stress, (3) alcohol consumption, and (4) noncompliance with medication regimens. These factors can be a particular problem in adolescents: staying up late at night to study or party can easily lead to myoclonic seizures or GTCS the next morning.

The time of day is also important because JME has a characteristic circadian pattern of activity. Myoclonic jerks, GTCSs, and absence seizures all tend to occur in the early morning after the patient awakens (though they also occur, to a lesser extent, in the evening when the patient is relaxing). When myoclonic jerks occur in the mornings, patients may have difficulty in eating breakfast or brushing their teeth. In some studies, nearly 90% of patients with JME had myoclonic jerks on awakening; the rest had either random jerks throughout the day or jerks at night.

In a study using transcranial magnetic stimulation (TMS) to examine the diurnal variability of cortical excitability, Badawy et al demonstrated that short and long intracortical inhibition was considerably more impaired in the mornings than in the afternoons in patients with JME.[21] This might suggest a biological basis for the clinical observation of increased seizure frequency within the first hour upon awakening in patients with JME.

Precipitating factors can be summarized as follows:

Physical Examination

Physical examination usually does not identify any abnormalities in patients with JME. Intelligence is normal; this observation is in contrast to findings with diseases such as progressive myoclonic epilepsies, in which progressive mental deterioration is the rule.

Comorbidities

Comorbidities associated with JME include psychiatric and neurologic disorders. Psychiatric comorbidities have been described often in patients with JME. In one study, 49% of patients with JME had a psychiatric comorbidity.[22] Anxiety and mood disorders were reported in 23% and 19% of patients with JME, respectively.

Neuropsychological testing of patients with JME has demonstrated selected frontal lobe dysfunction in tests such as the Wisconsin Card Sorting test and the Word Fluency test.[23] This dysfunction occurs despite having normal intelligence quotient (IQ) results obtained testing through conventional Wechsler testing. Impairment in executive function has also been reported.[24]

Approach Considerations

Typical electroencephalographic (EEG) abnormalities are highly supportive of the clinical diagnosis of juvenile myoclonic epilepsy (JME). Neuroimaging studies are typically normal in JME. Many clinicians believe that in the presence of an adequate supportive history, EEG abnormalities, normal intelligence, and normal neurologic findings, neuroimaging studies are unnecessary. However, the clinical scenario might not be as clear as the classical description would suggest.

Electroencephalography

The study of choice for confirming the clinical diagnosis of JME is sleep-deprived EEG with activation procedures (ie, hyperventilation, photic stimulation). A normal study does not rule out epilepsy or JME. Typical EEG abnormalities are highly supportive of the clinical diagnosis.

Interictal EEG

The typical interictal EEG abnormality consists of a generalized 4- to 6-Hz spike or polyspike and slow-wave discharges lasting 1-20 seconds (see the image below). Usually, 1-3 spikes precede each slow wave. When absence seizures are also present, 3-Hz spike-and-wave (SW) activity may be seen in addition to the polyspike-and-wave (PSW) pattern.


View Image

Findings in a man with a history of generalized tonic-clonic seizures (mostly nocturnal) and myoclonic jerks (mostly in the morning) since the age of ....

Treatment with medications clinically effective in JME might also reduce the frequency of interictal abnormalities. Levetiracetam adjunctive therapy in patients with JME increased the likelihood of a normal EEG from 8% to 53% after maintenance therapy was achieved. There was a decrease in frequency of interictal discharges and suppression of the paroxysms induced by photic stimulation.[25]

Ictal EEG

The ictal EEG associated with myoclonic jerks typically reveals 10- to 16-Hz polyspike discharges. These may be preceded by SW activity and are often followed by 1- to 3-Hz slow waves. The number of spikes is typically 5-20 and tends to be proportionately correlated with the clinical intensity of the seizure. These epileptic discharges may briefly persist, even after clinical activity has ceased. Seizures in patients with JME tend to be associated with polyspikes and disorganization of the paroxysm.[26]

Absence seizures of JME may be associated with ictal EEG patterns consisting of 3-Hz SW activity. Sometimes, these are preceded by 4- to 6-Hz PSW discharges, which slow to 3 Hz as the patient loses consciousness.

Background

Background activity of the EEG is normal in JME.

Activation

Hyperventilation and photic stimulation often facilitate the appearance of epileptiform discharges. Photic stimulation frequently precipitates SW patterns or a photoconvulsive response. Photosensitivity of EEG in patients with JME has been reported to be as high as 50% of the cases.[27] .

SW patterns by photic stimulation occur in 30% of patients with JME, compared with 18% of patients with childhood absence epilepsy, 13% of patients with epileptic seizures on awakening, and 7.5% of patients with juvenile absence epilepsy.

Other EEG findings

In addition to generalized epileptiform discharges, focal abnormalities may be found in 20-55% of patients with JME. These include focal slow waves, generalized discharges that evolve from a focal onset, and focal spikes or SW discharges. Ignorance of these changes may lead to one’s mistakenly ruling out the syndrome.

The etiology of these focal abnormalities is unclear. A possible explanation is structural changes in the cerebral cortex secondary to recurrent seizures or head injury; another is fluctuation in the refractoriness of the cortex to the influence of a spike/wave generator.

Morning EEG

A morning EEG has been proposed as a superior strategy to detect generalized epileptiform discharges in patients with JME. In this particular study, a morning awake EEG detected interictal epileptiform discharges in 69% of patients, whereas an afternoon awake EEG in the same patients demonstrated epileptiform discharges in fewer than 20% of patients.[28]

Video EEG

Video EEG monitoring in patients with atypical features of JME might be needed. In a one study, most people with JME only required no more than 2 days of stay to demonstrate diagnostic abnormalities in the EEG.[29]

A combined magnetoencephalography and EEG study demonstrated interictal spikes with localizations mainly in the central and premotor regions in patients with JME as compared with other absence syndromes.[30]

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) of the brain usually yields unremarkable results. This observation reflects the fact that JME is an idiopathic generalized epilepsy and is not caused by conditions such as brain tumors or encephalitis. However, quantitative morphometric studies using a voxel-based technique have shown some differences among patients with JME.

For example, decreased gray matter volume was found in thalami, insula cortices, and cerebellar hemispheres bilaterally in patients with JME. An increase in gray matter volume was observed in the right superior frontal, orbitofrontal, and medial frontal gyri of patients with JME as compared with age-matched controls. Patients with JME who are photosensitive had decreased gray matter volume in the visual cortex as compared with a control group; this was not found in patients with JME who were not photosensitive.[31, 32]

Some patients with brain MRIs, particularly if the MRIs are high-definition (or high-Tesla) studies, have shown minor abnormalities of cortical development. Tae et al reported reduction in the cortical thicknesses of frontal and temporal gyri in patients with JME.[33] However, these observations were not confirmed in the study by Roebling et al.[34]

Progressive thalamic atrophy was also reported in patients with JME by the same group.[35] The decreased thalamic volume has been confirmed by several other groups and might be related to executive function impairment.[36, 37, 38] Furthermore, studies using diffusion tension imaging (DTI) have also confirmed that abnormalities in the degree of thalamocortical fiber orientation and tissue anisotropy correlate with the frequency of generalized tonic-clonic seizures (GTCSs).[39]

Magnetic resonance spectroscopy (MRS) has also confirmed abnormalities in the thalamus and thalamocortical system of patients with JME.[40, 41] Functional MRI (fMRI) studies have not shown significant abnormalities in patients with JME.[34]

Despite these minor quantitative differences, the guidelines of the International League Against Epilepsy (ILAE) do not recommend routine neuroimaging studies in patients with JME.[42]

Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) has also been employed in this setting. Studies using TMS show abnormalities in cortical excitability in patients with JME.[43]

Approach Considerations

Medical therapy with anticonvulsants typically is needed (see Medication). Avoidance of precipitating events such as alcohol use and sleep deprivation may be useful but is not sufficient to control the seizures of juvenile myoclonic epilepsy (JME).

Go to Antiepileptic Drugs and Epilepsy and Seizures for complete information on these topics.

Anticonvulsant Therapy

The selection of antiepileptic drugs for the treatment of JME depends on several factors, including the patient’s comorbidities, preferences, previous history of adverse events, and gender. The US Food and Drug Administration (FDA) has not approved any anticonvulsant solely for the treatment of JME. In 2006, the FDA approved the adjunctive use of levetiracetam for the treatment of JME. Divalproex sodium has been approved as adjunctive therapy for patients with multiple seizure types that include absence seizures. However, many patients with JME do not have absence seizures.

In most patients with JME, seizures are well controlled with monotherapy. Valproic acid has been considered the treatment of choice for JME for many years, but epileptologists are increasingly using other choices as first-line therapies. Approximately 80% of patients with JME become seizure free with valproate monotherapy. Several studies using lamotrigine, topiramate, levetiracetam, and zonisamide have shown similar efficacy to that achieved with divalproex sodium, and in some cases better tolerability.[44]

Levetiracetam is useful for the treatment of myoclonic seizures.[45, 46] Noachtar et al demonstrated in a randomized, double-blinded, placebo-controlled trial that levetiracetam adjunctive therapy reduced all seizure types and myoclonic seizures in patients with JME.[47] Meta-analysis of 2 randomized controlled trials affirm that JME is highly responsive to treatment with levetiracetam.[48] Small, uncontrolled studies of levetiracetam monotherapy in JME suggest efficacy and tolerability.[49, 50]

Lamotrigine may also be useful in the treatment of JME. This agent is ideal for patients who cannot tolerate the adverse effects of valproate (eg, weight gain, tremor, stomach upset, and hair loss). In some patients, lamotrigine monotherapy controls seizures completely. However, recent evidence indicates that lamotrigine may exacerbate myoclonic jerks.

Data from a recent open-label study suggested that lamotrigine was better tolerated than valproate, with similar efficacy.[51] A European expert opinion study showed that lamotrigine was first-line choice for JME in adolescent females, whereas valproate was the first-line choice in adolescent males.[52]

Topiramate has been useful in the treatment of primary generalized seizures; it may effectively prevent the seizures of JME.[53]

Findings from an open-label study also suggested that zonisamide might be effective and well tolerated in patients with JME.[54]

In general, low doses of appropriate anticonvulsants are needed to successfully treat JME. Although treatment with phenytoin, carbamazepine, or phenobarbital may control some seizure components of JME (typically at high doses), these drugs may increase seizure frequency (eg, myoclonic exacerbation with carbamazepine) and occasionally precipitate new seizure types, such as absence seizures. However, they may be used in combination if the patient’s condition does not respond to other drugs.[55]

Clonazepam is often used during seizure exacerbations in patients with JME; however, it is inadequate as long-term treatment.

A patient’s medication should rarely be changed because he or she is not having seizures. In medical school, physicians are taught to treat patients and not serum concentrations. A low-dose requirement is not unusual; in fact, the great majority of patients with JME need relatively low levels of anticonvulsants to achieve adequate seizure control (as long as it is an appropriate medication for the syndrome).

A valproic-acid serum concentration of less than 20 mcg/mL is certainly a concern, and the patient’s spouse or other observer should be interviewed for confirmatory evidence that the patient is not having seizures.

Special considerations in pregnant women

Most of the time, when a neurologist examines a pregnant woman with epilepsy, it is after the first 6 weeks of gestation (ie, after the neural tube normally closes). That is one of the reasons why all women of childbearing age who are taking anticonvulsants should also take folic acid 1 mg/d.

In general, most epileptologists believe that the anticonvulsants that help that patient the most should be continued during pregnancy. Frequent monitoring of drug levels is recommended, as pregnancy induces clinically significant changes in drug metabolism, clearance, and volume of distribution. Women with JME are no different from other women who need to take anticonvulsants.

A great majority of children born to women taking anticonvulsant monotherapy are healthy. Valproic acid and divalproex sodium clearly pose a recognized risk of neural-tube defects (category D) that is higher than the risk associated with older anticonvulsants. Evidence suggests that supplementation with folic acid may decrease this risk.

Experience is limited with the newer anticonvulsants, including lamotrigine (category C), levetiracetam (category C), and topiramate (category C). Laboratory data indicate some teratogenicity with topiramate, but the effect in humans is unknown. Animal studies have revealed no evidence of teratogenicity related to lamotrigine. Lamotrigine is a weak folic-acid antagonist in the gut; therefore, folic-acid supplementation is required in women of childbearing age taking this drug.

Surgical Care

Surgical treatment is not indicated, because JME is a primary generalized epilepsy. Some uncontrolled studies have suggested that vagal nerve stimulation might be helpful for patients with intractable seizures of primary generalized onset, such as JME.

Modification of Activity

Seizure precautions include warnings about unpredictable lapses of consciousness due to seizures during a variety of activities, including the following:

Such precautions, including restrictions on driving, must be observed until seizures that impair consciousness are controlled (ie, the patient is seizure free) for the recommended period—typically 3-12 months, though the length varies from state to state in the United States. Patients with seizures cannot have a commercial driving license until they complete a seizure-free period of 5 years. In addition, patients with seizures are not permitted to fly aircraft.

Studies have shown that patients with JME experience decreases in quality of life similar to those experienced by patients with other epileptic syndromes.[56]

Patients with suspected seizures manifesting as lapses of consciousness during wakefulness should be educated and warned about seizure precautions. Documenting on the patient’s chart that driving and occupational hazards for people with seizures were discussed is helpful. Physicians should be aware of state regulations regarding driving, which vary considerably among states and nations.

Warnings should be tailored to each specific patient, and they should include factors such as seizure control, time of the occurrence of seizures, medication compliance, and the patient’s occupation, among other concerns.

Consultations

JME is rarely diagnosed in the primary care setting. Most often, an epileptologist diagnoses the condition after several years of inadequate treatment with medications such as carbamazepine or phenytoin.

Medication Summary

The goal of pharmacotherapy is to reduce morbidity and prevent complications.

The US Food and Drug Administration (FDA) has not approved any anticonvulsant solely for the treatment of juvenile myoclonic epilepsy (JME). In 2006, the FDA approved the adjunctive use of levetiracetam for the treatment of JME. Divalproex sodium has been approved as adjunctive therapy for patients with multiple seizure types that include absence seizures. However, many patients with JME do not have absence seizures.

In most patients with JME, seizures are well controlled with monotherapy. Valproic acid has been considered the treatment of choice for JME for many years, but epileptologists are increasingly using other choices as first-line therapies. Approximately 80% of patients with JME become seizure free with valproate monotherapy.

Valproic acid and derivatives (Depakote, Depakene, Stavzor)

Clinical Context:  Divalproex sodium is indicated for monotherapy or adjunctive therapy in simple and complex absence seizures and adjunctively in many seizure types, including absence. In clinical practice, it is often a first-line anticonvulsant in JME. It is metabolized to valproic acid.

Valproic acid (Depakene), in a rapid-release formulation, is available as a cap and syrup; Depacon is an intravenous (IV) formulation. Stavzor is available as a 125-, 250-, or 500-mg delayed-release tablet.

Studies of combination therapy suggest that in practice, patients starting divalproex monotherapy need a low starting dose and target doses close to about 10 mg/kg/d. In the elderly, clearance of unbound drug is decreased; lowered doses are needed. Children often require higher doses per weight than adults do; some children given combination therapy (with enzyme-inducing antiepileptic drugs [EIAEDs]) may need doses as high as 60 mg/kg/d.

Lamotrigine (Lamictal)

Clinical Context:  Lamotrigine is FDA-approved as add-on therapy in patients older than 16 years with partial seizures; it is recommended as adjunctive therapy in generalized seizures of Lennox-Gastaut syndrome in adults and children; it is also indicated for conversion to monotherapy after failure of at least 1 EIAED (eg, carbamazepine, phenytoin, phenobarbital). Several reports suggest that it is efficacious in JME and some of its seizure types; the present authors found benefit in some patients.

Lamotrigine is a well-tolerated anticonvulsant; it requires slow up-titration because of the risk of rash. It probably has fewer cognitive (ie, sedative) effects than most anticonvulsants do; some patients with JME have worsening of myoclonic jerks at low doses. In most patients, increasing the dose results in clinically significant improvement.

Serum concentrations of lamotrigine are useful in monitoring compliance and adjusting the dose; a few months into treatment, serum concentrations may decrease slightly because of enzymatic inducement in the liver. Conversion from EIAEDs can be faster than recommended. Conversion from (or add-on therapy with) valproic acid requires slow titration because valproic acid inhibits metabolism of lamotrigine. Starting at high doses may increase the incidence of rash.

No IV formulation is available.

Topiramate (Topamax)

Clinical Context:  Topiramate is indicated and FDA-approved as adjunctive therapy for adults and children with partial-onset seizures and primary GTCSs. It is approved for monotherapy in primary GTCSs. Some patients with JME have primary GTCSs but may also have myoclonic and absence seizures. Topiramate is available as a 25-, 100-, or 200-mg tablet and as a 15- or 25-mg sprinkle capsule.

Zonisamide (Zonegran)

Clinical Context:  Zonisamide is indicated for adjunctive treatment of partial seizures with or without secondary generalization. Evidence suggests effectiveness in myoclonic and other generalized seizure types as well.

Levetiracetam (Keppra)

Clinical Context:  Levetiracetam is indicated as adjunctive therapy for myoclonic seizures in adults and adolescents and in primary GTCSs. The mechanism of action is unknown but is presumed to involve binding to the SV2A site in synaptic terminals.

Class Summary

Anticonvulsants are the mainstay of therapy for JME. These agents are given to prevent myoclonic jerks or seizures, generalized tonic-clonic seizures (GTCSs), and absence seizures.

Author

Elizabeth Carroll, DO, Resident Physician, Department of Neurology, University of South Florida College of Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Jose E Cavazos, MD, PhD, FAAN, FANA, FACNS, Professor with Tenure, Departments of Neurology, Pharmacology, and Physiology, Assistant Dean for the MD/PhD Program, Program Director of the Clinical Neurophysiology Fellowship, University of Texas School of Medicine at San Antonio; Co-Director, South Texas Comprehensive Epilepsy Center, University Hospital System; Director, San Antonio Veterans Affairs Epilepsy Center of Excellence and Neurodiagnostic Centers, Audie L Murphy Veterans Affairs Medical Center

Disclosure: LGCH, Inc Ownership interest Consulting

Specialty Editors

Ramon Diaz-Arrastia, MD, PhD, Professor, Department of Neurology, University of Texas Southwestern Medical Center at Dallas, Southwestern Medical School; Director, North Texas TBI Research Center, Comprehensive Epilepsy Center, Parkland Memorial Hospital

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Chief Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, Tampa General Hospital, University of South Florida College of Medicine

Disclosure: UCB Pharma Honoraria Speaking, consulting; Lundbeck Honoraria Speaking, consulting; Cyberonics Honoraria Speaking, consulting; Glaxo Smith Kline Honoraria Speaking, consulting; Sleepmed/DigiTrace Honoraria Speaking, consulting; Sunovion Consulting fee None

Additional Contributors

Mark Spitz, MD Professor, Department of Neurology, University of Colorado Health Sciences Center

Mark Spitz, MD is a member of the following medical societies: American Academy of Neurology, American Clinical Neurophysiology Society, and American Epilepsy Society

Disclosure: pfizer Honoraria Speaking and teaching; ucb Honoraria Speaking and teaching; lumdbeck Honoraria Consulting

References

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Findings in a man with a history of generalized tonic-clonic seizures (mostly nocturnal) and myoclonic jerks (mostly in the morning) since the age of 14 years. Carbamazepine exacerbated his myoclonic seizures. Sleep-deprived EEG was digitally recorded and then plotted by using an analog paper machine. The patient was getting drowsy when this burst of polyspike and slow wave was recorded.

Findings in a man with a history of generalized tonic-clonic seizures (mostly nocturnal) and myoclonic jerks (mostly in the morning) since the age of 14 years. Carbamazepine exacerbated his myoclonic seizures. Sleep-deprived EEG was digitally recorded and then plotted by using an analog paper machine. The patient was getting drowsy when this burst of polyspike and slow wave was recorded.