(MERRF) Myoclonic epilepsy with ragged red fibers – Fukuhara syndrome

Myoclonic epilepsy with ragged red fibers (MERRF) is a multisystem mitochondrial syndrome characterized by progressive myoclonus and seizures. Other features associated with MERRF include cerebellar ataxia, myopathy, cardiac arrhythmia, sensorineural hearing loss, optic atrophy, and dementia.

The epidemiologic data of MERRF is largely unknown, but it is widely considered that the prevalence of MERRF is probably less than 1:100,000. 

The symptomatic management of the complications is the cornerstone in patients with MERRF. Antiepileptic drugs are given for myoclonic seizures and epilepsy. Although sodium valproate is typically the recommended drug for myoclonic epilepsies, it should be used with caution in mitochondrial diseases as it inhibits carnitine uptake and may precipitate liver failure. Carbamazepine, oxcarbazepine, and phenytoin may worsen the myoclonic episodes. No head-to-head clinical drug trials are available for the treatment of epilepsy in patients with MERRF, but some authors recommend levetiracetam, topiramate, clonazepam, or zonisamide. Other complications, e.g., cardiac arrhythmia, deafness, and myopathy, are treated accordingly. It is also important to avoid drugs and toxins with adverse mitochondrial effects, for example, aminoglycoside antibiotics, linezolid, cigarettes, and alcohol.

Affected persons with MERRF and their asymptomatic at-risk relatives should have a regular follow-up (e.g., every 6-12 months initially) for disease monitoring and the appearance of new symptoms.

It is recommended to have annual neurologic (epilepsy control), ophthalmologic (for vision changes), cardiology (electrocardiogram and echocardiogram), and endocrinologic evaluations (for diabetes and thyroid problems). Physiotherapy, occupational therapy, and rehabilitation are important for improving the quality of life and prevent complications.

 

References 

  1. Lorenzoni PJ, Scola RH, Kay CS, Silvado CE, Werneck LC. When should MERRF (myoclonus epilepsy associated with ragged-red fibers) be the diagnosis? Arq Neuropsiquiatr. 2014 Oct;72(10):803-11.
  2. Finsterer J, Zarrouk-Mahjoub S. Management of epilepsy in MERRF syndrome. Seizure. 2017 Aug;50:166-170.
  3. DiMauro S, Hirano M. MERRF. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, editors. GeneReviews® [Internet]. University of Washington, Seattle; Seattle (WA): Jun 3, 2003.
  4. Fukuhara N, Tokiguchi S, Shirakawa K, Tsubaki T. Myoclonus epilepsy associated with ragged-red fibres (mitochondrial abnormalities ): disease entity or a syndrome? Light-and electron-microscopic studies of two cases and review of literature. J. Neurol. Sci. 1980 Jul;47(1):117-33.
  5. Hameed S, Tadi P. Myoclonic Epilepsy and Ragged Red Fibers (MERF) [Updated 2020 Mar 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555923/

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