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Progressive Myoclonus Epilepsies

Etiologies: Considering genetic, metabolic or immune factors, some diseases, such as neuronal ceroid lipofuscinosis (which can be caused by PPT1, TPP1, CLN3, DNAC5, CLN5, CLN6, MFSD8, CLN8, CTSD, GRN, ATP14A2, CTSF, KCD7 and other gene variants), Unverricht Lundborg disease (which can be caused by CSTB gene variation, 90% of which is the unstable amplification of the dodecameric repeat (CCC-CGC-CCC-GCG) in the 5' promoter region, the sequence is generally 2-3 copies, and patients can have more than 30 copies), Lafora disease (caused by EPM2A or EPM2B gene mutation), sialidoses (caused by NEU1 gene mutation, of which type I is also known as myoclonic syndrome with cherry red spot), myoclonic epilepsy with ragged red fibers (MERRF), Alpers syndrome, Dentatorubo-pallidoluysian atrophy (due to ATN1 gene variation, caused by unstable amplification of CAG repeat sequence of exon 5 of the gene, with normal repeat times of 7-23, and patients can be amplified to 49-75), neuronopathic Gaucher's disease (due to GD1 gene variation), Niemann Pick disease type C (due to NPC1 and NPC2 gene variation), action-myoclonus-renal failure syndrome (due to SCARB2 gene variation) , Progressive myoclonic ataxia syndrome (caused by PRICKLE1 gene variation), Beihai progressive myoclonic epilepsy (caused by GOSR2 gene variation), KCNC1 gene mutation related progressive myoclonic epilepsy, KCTD7 gene mutation related progressive myoclonic epilepsy, muscle atrophy progressive myoclonic epilepsy (caused by ASAH1 gene variation), CARS2 gene mutation related progressive myoclonic epilepsy, familial encephalopathy with neuroserpin inclusions bodies (due to SERPINI1 gene variation), GM2 gangliosidoses, early-onset Alzheimers, juvenile Huntingtons, pantothenate-kinase associated neurodegeneration (formerly known as Hallervorden Spatz disease), Krabbe leukoencephalopathy, neuraxial dystrophy, atypical inclusion body disease, celiac disease, tetrahydrobiopterin deficiency and TBC1D24 gene mutation can also lead progressive myoclonic epilepsy [1-4].

Age of onset: Variable, depending on the underlying etiology.

Seizure characteristics: may vary depending on the underlying etiology, the madatory seizures are myoclonic seizures (in addition to epileptic myoclonus, it can also be mixed with abnormal movement components of cerebellum or extrapyramidal system), with or without generalized tonic clonic seizures, and progressive neurological function and mental intelligence decline [1-2].

EEG: The manifestations of different causes will vary. In general, background: may be normal at onset, progressive slowing of the background occurs over time. Interictal: some patients can see generalized or multifocal discharge. Ictal: some myoclonus and EEG paroxysmal electrical activity may have a good correlation, and some may not have a significant correlation [1-2].

Brain MRI: Variable, depending on the underlying etiology.

Developmental progress: Progressive cognitive decline often occurs.

 

 

Reference

  1. Panayiotopoulos.  癫痫综合征及临床治疗.  北京 : 人民卫生出版社, 2012.
  2. 刘晓燕.  临床脑电图学. 第2版.  北京 : 人民卫生出版社, 2017.
  3. Bhat, S. and S. Ganesh, New discoveries in progressive myoclonus epilepsies: a clinical outlook. Expert Rev Neurother, 2018. 18(8): p. 649-667.
  4. Zhang, J., et al., Infantile epilepsy with multifocal myoclonus caused by TBC1D24 mutations. Seizure, 2019. 69: p. 228-234.