Pediatric Movement Disorders - Myoclonus

Etiology

Physiological:
Sleep myoclonus, benign myoclonus of infancy

Essential Myoclonus:
Familial essential myoclonus, essential myoclonus-dystonia, stimulus-sensitive myoclonus

Epileptic:
Juvenile myoclonic epilepsy, progressive myoclonic epilepsies, epilepsia partialis continua, Rasmussen's encephalitis, early infantile myoclonic encephalopathy, infantile spasms (West syndrome), Lennox-Gastaut syndrome, benign familial myoclonic epilepsy, Angelman syndrome

Symptomatic:

• Fixed injury:
  Carbon-monoxide poisoning; hypoxic injury or near-drowning (Lance-Adams syndrome); heatstroke; trauma; stroke; electrocution


• Storage/Degenerative:
  Sialidoses (cherry-red-spot myoclonus); lipidosis; lysosomal storage disease (Niemann-Pick type C, Tay-Sachs, Sandhoff's); other storage disorders (neuronal ceroid lipofuscinosis); pantothenate kinase associated neurodegenerative disease (PKAN, formerly neuronal brain iron accumulation type 1, formerly Hallervorden-Spatz disease); Wilson's disease; Lafora body disease; Rett syndrome; Baltic myoclonus; spinocerebellar ataxias (SCAs); dentatorubropallidoluysian atrophy (DRPLA); multiple sclerosis; mitochondrial disorders (e.g., myoclonic epilepsy with ragged-red fibers [MERRF] and others)


• Infections/Para-infectious:
  New-variant Creutzfeldt-Jacob disease (nvCJD); subacute sclerosing panencephalitis (SSPE); viral encephalitis; streptococcus


• Endocrine:
  Hyperthyroidism, hyponatremia, hypoglycemia


• Structural:
  Tumors that irritate the brain in a direct manner, tumors that release chemicals into the blood (as in abdominal or thoracic neuroblastoma [which causes the opsoclonus-myoclonus-ataxia syndrome]); palatal myoclonus (with injury to the Guillain-Mollaret triangle in the brainstem or cerebellum)


• Drug-induced/toxins:
  Anti-seizure medications (e.g., valproate, carbamazepine, etc.); antidepressants (e.g., amitryptaline, nortryptaline, desipramine, fluoxetine, sertraline, lithium, etc.); stimulants (e.g., amphetamine, dexedrine, methylphenidate, some asthma inhalers, caffeine, etc.); liver toxic medications; respiratory depressants; corticosteroids; amiodarone; acyclovir; bismuth; thallium; L-dopa


• Associated with systemic illness:
  Dialysis, renal failure, liver failure, pulmonary disease, carbon dioxide intoxication