Juvenile Myoclonic Epilepsy
Juvenile myoclonic epilepsy (JME) is an idiopathic, hereditary, and generalized form of epilepsy. JME accounts for approximately 5%-10% of all cases of epilepsy. JME usually manifests between 12 and 18 years of age. JME is characterized by the presence of absence (20-40%), myoclonic (100%), and generalized tonic-clonic (GTC) (85-90%) seizures.
Clinical Features
Myoclonic seizures are the defining feature and are required for the diagnosis of JME and very rarely can be the only type of seizure present. Typically absence seizures are the first to occur in JME. They usually occur 3 to 5 years before the onset of myoclonic or GTC seizures and can happen as early as 5 to 6 years old. Myoclonic seizures present with short, bilateral jerking motions of the arms and legs that do not cause consciousness to be lost and often occurs 30 minutes to an hour after waking up in the morning. JME is typically triggered by sleep loss, alcohol consumption, mental stress, worry, and exhaustion. GTC seizures typically develop many months after myoclonic seizures begin. About 30-40% of JME patients are photosensitive and these patients tend to have earlier onset of seizures. There is an increased prevalence of psychiatric disorders, including anxiety, mood disorder, and personality disorders in patients with JME.
EEG
Fig. 1: 5Hz predominantly bifrontal polyspike and wave discharges
MRI
a number of quantitative
MRI studies have reported focal or regional abnormalities of the subcortical and cortical grey matter, particularly the thalamus and frontal cortex, in
JME patients
Genetics
Differential Diagnosis
Differential diagnosis includes childhood or juvenile absence epilepsy, eyelid myoclonia with absences, progressive myoclonic epilepsy, photosensitive occipital epilepsy, epilepsy with grand mal seizures upon awakening, hypnogogic myoclonus (hypnic jerk), and non-epileptic seizures.
Treatment / Management
Most patients respond to monotherapy with Valproic acid which is the drug of choice
levetiracetam, lamotrigine, topiramate, and zonisamide are other options
Lamotrigine can worsen myoclonic seizures but is still effective in controlling other seizure types in
JME
Clonazepam is also effective against myoclonic seizures
Carbamazepine, oxcarbazepine, phenytoin (sodium channel blocking agents) are contraindicated since they can worsen myoclonic and absence seizures.
vigabatrin, tiagabine, gabapentin, pregabalin, and primidone are also avoided
JME becomes intractable in a small number of patients who would need combination therapy with Vagal nerve stimulation (VNS) also as an option.
JME needs life long treatment with AEDs
Avoidance of triggers is important - alcohol, fatigue,stress, sleep deprivation, flashing lights etc
References
1.
a
Trinka E, Kienpointner G, Unterberger I, Luef G, Bauer G, Doering LB, Doering S. Psychiatric comorbidity in juvenile myoclonic epilepsy. Epilepsia. 2006 Dec;47(12):2086-91. doi: 10.1111/j.1528-1167.2006.00828.x.
[PMID: 17201708] [DOI: 10.1111/j.1528-1167.2006.00828.x]
2.
a
Tae WS, Kim SH, Joo EY, Han SJ, Kim IY, Kim SI, Lee J, Hong SB. Cortical thickness abnormality in juvenile myoclonic epilepsy. J Neurol. 2008 Apr;255(4):561-6. doi: 10.1007/s00415-008-0745-6. Epub 2008 Jan 31.
[PMID: 18227991] [DOI: 10.1007/s00415-008-0745-6]
4.
a,
b
Delgado-Escueta AV, Koeleman BPC, Bailey JN, Medina MT, DurĂ³n RM. The quest for juvenile myoclonic epilepsy genes. Epilepsy Behav. 2013 Jul;28 Suppl 1:S52-7. doi: 10.1016/j.yebeh.2012.06.033.
[PMID: 23756480] [DOI: 10.1016/j.yebeh.2012.06.033]