Epilepsy, myoclonic

Myoclonic epilepsy with ragged-red fibers (MERPF) is a rare syndrome which shows clear maternal inheritance and a variable clinical pattern including progressive myoclonus, cerebellar ataxia, dementia, and muscle weakness. It is associated with an A-to-G transition at position 8344 of the tRNA Lys gene in the mtDNA. The mutation is heteroplasmic and produces similar multicomplex deficiencies as are seen in KSS. 

Juvenile myoclonic epilepsy (JME) A primary generalized epilepsy syndrome that usually starts in the early to middle teenage years and has a strong familial component. Patients have myoclonic jerks and tonic-clonic seizures and may also have absence seizures. 

Myoclonic Not mentioned Lamotrigine Valproate Valproate Topiramate (children with severe myoclonic epilepsy of infancy) Second-line Clobazam6 Clonazepam Lamotrigine Levetiracetam Piracetam6 Topiramate... 

BC, a 22-year-old woman, was diagnosed 2 years ago with juvenile myoclonic epilepsy. She has been treated with valproate 1500 mg/day. Since starting valproate she has gained 45 pounds (20.5 kg), continues to have occasional myoclonic jerks, had a generalized tonic-clonic seizure 3 months ago, and is sexually active. Additionally, she complains of easily falling asleep during the day. Due to adverse effects, poor seizure control, and the risk of birth defects with valproate, the decision is made to switch to a different antiepileptic drug. 

Generalized epilepsy with febrile seizures plus (GEFS+), severe myoclonic epilepsy of infancy (SMEI)... 

Myoclonic epilepsy with ragged red fibers (MERRF) Mitochondrial tRNAi>,s... 

MERRF (myoclonic epilepsy with ragged red fibers) Is characterized by weakness on exertion, ataxia, and associated deafness and Is due to mutation of the mitochondrial tRNA gene. 

In normal dosages juvenile myoclonic epilepsy may be induced with lamotrigine. 

The clinical symptoms of mitochondrial diseases are highly varied and include seizures, vomiting, deafness, dementia, stroke-like episodes, and short stature. Although there are many types of mitochondrial disorders, four of the most common types are as follows Kearns-Sayre syndrome, Leber s hereditary optic atrophy, MELAS (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes) and MERRE (myoclonic epilepsy with ragged red fibres). 

It is indicated in typical and atypical absence seizure, infantile spasms, myoclonic epilepsy, atonic seizures, minor motor seizures of childhood, refractory grandmal epilepsy or temporal lobe epilepsy and seizures not controlled by conventional antiepileptics. 

Specific myoclonic syndromes are usually treated with valproate an intravenous formulation can be used acutely if needed. It is nonsedating and can be dramatically effective. Other patients respond to clonazepam, nitrazepam, or other benzodiazepines, although high doses may be necessary, with accompanying drowsiness. Zonisamide and levetiracetam may be useful. Another specific myoclonic syndrome, juvenile myoclonic epilepsy, can be aggravated by phenytoin or carbamazepine valproate is the drug of choice followed by lamotrigine and topiramate. 

Polarographic studies can also be used to screen for much more specific defects suspected in some patients, such as impaired mitochondrial glutamate transport in cultured skin fibroblasts from patients presenting with neonatal myoclonic epilepsy [64]. 

Table 8. CACNB4 ( i, ) Functional results for mutations associated with JME= juvenile myoclonic epilepsy, GE = generalized epilepsy and EA = episodic ataxia...

Generalized tonic-clonic seizures (grand mal) Juvenile myoclonic epilepsy Reflex epilepsy... 

Valproate is now the most commonly used antiepileptic drug worldwide. It is the drug of choice in primary generalized epilepsy, particularly in the treatment of generalized absence, myoclonus and tonic-clonic seizures. Valproate is the drug of first choice in atypical absence and atonic seizures, for Lennox-Gastaut syndrome and myoclonic epilepsy. 

---