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juvenile myoclonic epilepsy (of Janz)
Epidemiology:
- begins in healthy individuals between 8 & 20 years of age
- one of the most common forms of generalized epilepsy in adults [1]
Genetics:
1) linked to a marker on chromosome 6
2) associated with defects in GABRA1
3) often a family history of similar seizures
4) type 1 associated with defects in EFHC1 gene
5) associated with defects in CACNB4
Clinical manifestations:
1) manifestations begin in adolescence (type 1)
2) myoclonic jerks, ranging from
a) massive bilateral spasms with falling to
b) minor isolated muscle jerking (may go unrecognized) [1]
3) generalized tonic-clonic seizures
4) myoclonic jerks & seizures generally occur after awakening
5) absence seizures may also occur
6) early morning clumbsiness may be reported
7) symptoms triggered by sleep deprivation & fatigue
8) symptoms may be triggered by alcohol [1]
Laboratory:
- electroencephalogram (EEG)
- generalized spikes, 4-6 Hz spike wave complexes & multiple spike discharges
Management:
- responds well to valproic acid
- lifelong anticonvulcant therapy [1]
General
myoclonic epilepsy
Database Correlations
OMIM correlations
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16,
17, 18, 19. American College of Physicians, Philadelphia 1998, 2009,
2012, 2015, 2018, 2021.
- OMIM :accession 606904
- Genton P, Gelisse P.
Juvenile myoclonic epilepsy.
Arch Neurol. 2001 Sep;58(9):1487-90.
PMID: 11559326