MERRF; Myoclonus with Epilepsy with Ragged Red Fibers; MERRF Syndrome; Myoencephalopathy Ragged Red Fiber Disease; Fukuhara syndrome; Myoclonic epilepsy associated with ragged red fibers; Myoencephalopathy ragged-red fiber disease

Myoclonic Epilepsy with Ragged Red Fibers (MERRF) is a rare inherited neurometabolic disorder that affects the central nervous system, skeletal muscles, and other body systems. Characteristic abnormal muscle cells appear as ragged red fibers when stained and viewed under a microscope.

Diagnostic testing:

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  Muscle biopsy with pathology report documenting structurally abnormal mitochondria;

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  CT/MRI for cerebral atrophy;

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  EEG for seizure activity;

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  Blood serum testing for elevated lactate levels; and

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  Hearing and vision testing.

Physical findings:

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  Neurological dysfunction including cerebellar ataxia;

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  Myoclonic seizures (brief, sudden twitching muscle spasms);

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  Progressive spasticity;

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  Dementia;

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  Muscle atrophy with muscle weakness;

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  Neuropathy;

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  Optic atrophy; and

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  Short stature.

ICD-9: 277.87

Signs and symptoms of this disorder mostly appear during childhood or adolescence, although sometimes after age 20. Clinical course is variable, from slowly progressive to rapidly downhill.

There is no current cure for MERRF and treatment is supportive. Medications may be prescribed for seizures and to control muscle movement. Physical therapy and occupational therapy can be used to extend the range of muscle movement and improve dexterity. Vitamin therapies such as riboflavin, coenzyme Q, and carnitine may provide subjective improvement in fatigue and energy levels in some individuals.

Suggested MER for Evaluation:

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  Clinical history and examination that describes the diagnostic features of the impairment, and physical and cognitive findings;

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  Muscle biopsy showing the presence of ragged red fibers;

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  Imaging studies such as CT or MRI; and

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  EEG results, vision or hearing testing may be helpful.

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