Myoclonic epilepsy

Myoclonic epilepsy refers to a family of epilepsies that present with myoclonus.[1] It starts in both sides of the body at once,[2] and last for more than a second or two.[1] When myoclonic jerks are occasionally associated with abnormal brain wave activity, it can be categorized as myoclonic seizure.[1] If the abnormal brain wave activity is persistent and results from ongoing seizures, then a diagnosis of myoclonic epilepsy may be considered. Myoclonic seizures frequently occur in day-to-day life.[3] During sleep, abrupt jerks and hiccups occurred.[3]

Myoclonic epilepsy
SpecialtyNeurology

Myoclonic jerks are typical without regularity.[4] Myoclonus can be a source of substantial disability with impairment in daily activities.[4] . Myoclonus can be termed positive or negative, A sudden muscle contraction is known as "positive myoclonus," and a brief loss of muscular tone is known as "negative myoclonus".[4] Myoclonus which occurred at rest indicates the source as a spinal or brainstem.[4] Myoclonus which is action induced indicates the source as cortical.[4] . Focal and multifocal jerk which happened during voluntary action is an example of typical cortical myoclonus.[4] Myoclonic seizures mostly can bee seen in people with generalized or genetic epilepsy.[5] Because of its quick occurrence Myoclonic epilepsy some times can not be observed.[3] Sometimes it is mistaken as tics or clumsiness.[3]

Signs and symptoms

Myoclonus can be described as brief jerks of the body;[6] it can involve any part of the body, but it is mostly seen in limbs or facial muscles. The jerks are usually involuntary and can lead to falls. EEG is used to read brain wave activity. Spike activity produced from the brain is usually correlated with brief jerks seen on EMG or excessive muscle artifact. They usually occur without detectable loss of consciousness and may be generalized, regional or focal on the EEG tracing. Myoclonus jerks can be epileptic or not epileptic. Epileptic myoclonus is an elementary electroclinical manifestation of epilepsy involving descending neurons, whose spatial (spread) or temporal (self-sustained repetition) amplification can trigger overt epileptic activity.[6]

The probable symptoms of myoclonic epilepsy are:[5]

  • Brief Moment-They last for a very brief moment.[5] During epilepsy, muscle contractions caused tighten up of muscles, which lasts for fraction of a second.[5]
  • Small Groups of Muscles-They usually happen to small groups of muscles, including muscles of arms, legs, and face.[5]
  • Limited Numbers-They happen in limited numbers.[5] A myoclonic seizure usually happened once, but sometimes more than once.[5]
  • Certain Circumstances: They’re more likely under certain circumstances, like early morning when a person wakes up, in a very tired and sleepy state, stressed and anxious, or after alcohol consumption.[5]
  • Usual Awareness: People are usually aware of epilepsy loss of consciousness or awareness doesn’t happen with myoclonic seizures like other seizures.[5]

Causes

The exact cause of myoclonic epilepsy is unknown.[3] Some conditions or circumstances that leads to myoclonic epilepsy can be as follows:[5]

  • Brain tumor
  • Brain infection (meningitis or encephalitis)
  • Reduced oxygen to the brain
  • Cerebral hypoxia (lack of oxygen).
  • Severe concussion
  • traumatic brain injury
  • Degenerative brain diseases like Alzheimer’s disease or frontotemporal dementia.
  • Drugs and alcohol abuse
  • Drug or alcohol withdrawal
  • Infections like encephalitis or meningitis
  • Metabolic problems, like hyperglycemia or hypoglycemia
  • Toxic levels of metals like lithium[5][3]

Diagnosis

There are two syndromes and several related disorders.

Juvenile

Juvenile myoclonic epilepsy is responsible for 7% of cases of epilepsy.[7] Seizures usually begin around puberty and usually have a genetic basis.[7] Seizures can be stimulus-selective, with flashing lights being one of the most common triggers.[7]

Progressive

Progressive myoclonus epilepsy is a disease associated with myoclonus, epileptic seizures, and other problems with walking or speaking. These symptoms often worsen over time and can be fatal.[8]

MERRF syndrome is also known as myoclonic epilepsy with ragged-red fibers. This rare inherited disorder affects muscles cells.[9] Features of MERRF, along with myoclonus epilepsy seizures, include ataxia, peripheral neuropathy, and dementia.[9]

Lafora disease is also known as Lafora progressive myoclonus epilepsy, which is an autosomal recessive inherited disorder involving recurrent seizures and degradation of mental capabilities.[10] Lafora disease usually occurs in late childhood and usually leads to death around 10 years after first signs of the disease.[10]

Unverricht-Lundborg disease is an autosomal recessive inherited disorder seen in individuals as young as six years.[11] It is associated with possible loss of consciousness, rigidity, ataxia, dysarthria, declination of mental functioning, and involuntary shaking.[11]

Neuronal ceroid lipofuscinosis is a group of diseases that cause blindness, loss of mental abilities, and loss of movement.[12] All diseases in this group are lysosomal-storage disorders that also lead to death roughly ten years after onset of the disease.[12]

Lennox–Gastaut syndrome is often associated with intellectual deficits as well as a lack of response to anti-epileptic drugs.[13] It usually begins in the first years of life.[13]

Reticular reflex myoclonus is a generalized form of epilepsy originating from the brain stem. Jerks associated with the disorder can affect all muscles on the body or be selective in certain areas.[8] Jerks can be triggered by voluntary movement or be stimulus-selective.[8]

Differential diagnosis

Myoclonic jerks that are not epileptic may be due to a nervous system disorder or other metabolic abnormalities that may arise in renal (e.g. hyperuraemia) and liver failure (e.g. high ammonia states).

References
  1. "Myoclonic Seizures". Epilepsy Foundation.
  2. "Myoclonic seizure: Causes, symptoms, and treatment". www.medicalnewstoday.com. 30 June 2021.
  3. "Articles". Cedars-Sinai.
  4. "Myoclonus". Physiopedia.
  5. "Myoclonic Seizure: What It Is, Symptoms & Treatment". Cleveland Clinic.
  6. Wyllie, Elaine (2006). The Treatment of Epilepsy. Lippincott, Williams and Wilkins. ISBN 0-7817-4995-6.
  7. Juvenile Myoclonic Epilepsy: Characteristics and Treatment". Epilepsy.com.
  8. Myoclonus Fact Sheet. National Institute of Neurological Disorders and Stroke.
  9. "Myoclonic epilepsy with ragged-red fibers". Genetics Home Reference.
  10. "Lafora progressive myoclonus epilepsy". Genetics Home Reference.
  11. "Unverricht-Lundborg disease". Genetics Home Reference.
  12. Mole, S. E.; Williams, R. E.; Adam, M. P.; Mirzaa, G. M.; Pagon, R. A.; Wallace, S. E.; Bean LJH; Gripp, K. W.; Amemiya, A. (1993). "Neuronal Ceroid-Lipofuscinoses – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY". Neuronal Ceroid-Lipofuscinoses. GeneReviews. PMID 20301601.
  13. Niedermeyer, Ernst (1992). "Epileptic Syndromes: A Remarkable Contribution of EEG to Epileptology". American Journal of EEG Technology (32): 10–12.
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