Myoclonus epilepsy with ragged-red fiber (MERRF) patients present with symptoms related to the central and peripheral nervous system, ocular and cardiovascular apparatus and subcutaneous tissues. The main trait of this disease is myoclonus, consisting of involuntary, brief, sudden spasms affecting extremities. Other peripheral nervous system involvement signs include muscle weakness, as an expression of myopathy, progressive muscular spasticity, peripheral neuropathy, optic nerve atrophy or progressive external ophthalmoplegia and hearing loss. Central nervous system involvement causes seizures, ataxia, depression [1] and dementia, as well as the presence of pyramidal signs on evaluation.

The cardiovascular system is involved with patients developing a form of dilative cardiomyopathy after a period of normal development [2]. Affected individuals also have heart rhythm abnormalities, a type of preexcitation syndrome known as Wolff-Parkinson-White syndrome, premature ventricular contractions, incomplete left bundle branch block and other, unrelated findings such as a short stature, lipomas, abdominal pain, recurrent vomiting, fatigue, exercise intolerance, dyspnea (caused by lactic acid accumulation) and pigmentary retinopathy. Cardiac involvement may progress to subclinical left ventricular dysfunction or overt heart failure. Cases of stroke [3] [4] or stroke-like episodes [5] have also been described. This condition may also be associated with other diseases, such as atypical Charcot-Marie-Tooth and Leigh syndrome, diabetes mellitus and migraine headaches [6].

Other unusual manifestations include spasmodic dysphonia [7], acute demyelinating disease [8] and sudden infant death syndrome [9].

• Epilepsy

  Myoclonic epilepsy with red ragged fibers (MERRF). Reference article, Radiopaedia.org (Accessed on 28 Mar 2023) https://doi.org/10.53347/rID-39666 Myoclonic epilepsy with red ragged fibers (MERRF) is a rare, multisystem mitochondrial disorder. [radiopaedia.org]

  MERRF syndrome (or myoclonic epilepsy with ragged red fibers ) is a mitochondrial disease. [ipfs.io]

  Abstract The treatment of progressive myoclonic epilepsy (PME) is largely empirical, even though valproic acid (VPA) is usually considered the drug of first choice. [jns-journal.com]

  The present study reports the case of a 25-year-old male with mitochondrial encephalomyopathy, who presented with myoclonic epilepsy. [spandidos-publications.com]

  ^ Online Mendelian Inheritance in Man (OMIM): MYOCLONIC EPILEPSY ASSOCIATED WITH RAGGED-RED FIBERS; MERRF - 545000 ^ a b c Zeviani M, Muntoni F, Savarese N, et al. (1993). [en.wikipedia.org]

• Sudden Infant Death Syndrome

  Other unusual manifestations include spasmodic dysphonia, acute demyelinating disease and sudden infant death syndrome. [symptoma.com]

  Unusual manifestations in individuals with the m.8344A>G pathogenic variant in MT-TK include the following: Sudden infant death syndrome (SIDS) in an infant girl who had an unsuspected cardiomyopathy with the histologic features of histiocytoid cardiomyopathy [ncbi.nlm.nih.gov]

• Vomiting

  […] their most prominent features: MELAS (Mitochondrial encephalomyopathy, Lactic acidosis, and Stroke-like episodes) MERRF (Myoclonic epilepsy with Ragged red fibers) MELAS syndrome signs and symptoms: muscle weakness and pain recurrent headaches seizures vomiting [medschool.lsuhsc.edu]

  […] abnormalities, a type of preexcitation syndrome known as Wolff-Parkinson-White syndrome, premature ventricular contractions, incomplete left bundle branch block and other, unrelated findings such as a short stature, lipomas, abdominal pain, recurrent vomiting [symptoma.com]

  MELAS can lead to stroke-like episodes at a young age (usually before 40), seizures, dementia, headaches, vomiting, unsteadiness, and ill effects from exercise. [mitochondrialdiseases.org]

  Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) Onset: Childhood to early adulthood Symptoms: MELAS causes recurrent stroke-like episodes in the brain, migraine-type headaches, vomiting and seizures, and can lead to permanent [mda.org]

  The patient might have also had a gastrointestinal condition which could have been due to liver disease, as well as episodes of nausea or vomiting. [en.wikipedia.org]

• Nausea

  The patient might have also had a gastrointestinal condition which could have been due to liver disease, as well as episodes of nausea or vomiting. [en.wikipedia.org]

  […] headache/migraine, developmental delay, regression, dementia, tremo r, bradykinesia, retinopathy, optic atrophy, ophthalmoplegia Constitutional: exercise intolerance, growth failure, microcephaly, cachexia, lac tic acidosis, hyperalaninemia, SIDS GI: nausea [slideshare.net]

  She presented with a complex phenotype characterized by progressive cerebellar ataxia, frequent myoclonus seizures, recurrent stroke-like episodes, migraine-like headaches with nausea and vomiting, and elevated resting lactate blood level. [link.springer.com]

  […] psychiatrist, ophthalmologist There is no medication to slow the progression of the disease and treatments only target at controlling the symptoms Lactic acidosis is treated by sodium bicarbonate or sodium citrate Antiemetic drugs are used to treat nausea [lhsc.on.ca]

• Tachycardia

  On hospital day 22, the patient was transferred to the hospital floor from the ICU due to improved tachycardia and decreased O2 demand. [clinmedjournals.org]

  Click Here to download this mito profile (PDF) Links: NINDS OMIM, X-linked: OMIM, Adult-onset: OMIM Symptoms: Hypermetabolism, with fever, heat intolerance, profuse perspiration, polyphagia, polydipsia, ragged-red fibers, and resting tachycardia. [umdf.org]

• Hypotension

  […] and multiple myocardial infarctions with an implanted cardio defibrillator, and dysphagia with G-tube dependence who presented to the emergency department in May of 2020 as a transfer from a skilled nursing facility with respiratory distress, severe hypotension [clinmedjournals.org]

• Hearing Impairment

  Among them, action myoclonus was seen in five; short stature, muscle weakness, and mental retardation in four; lactic acidosis, hearing impairment, and ataxia in two; and seizures in one. [ncbi.nlm.nih.gov]

  The disease also can cause hearing impairment and short stature. [mda.org]

  Hearing aids and cochlear implants can improve hearing impairments. Physical therapy, occupational therapy and aerobic exercise may help to improve muscle weakness, stiffness, and motor function. [rarediseases.org]

• Night Blindness

  Symptoms LHON can result in complete blindness in one or both eyes, within about 6 months of initial symptoms. [lhsc.on.ca]

• Myopathy

  S2CID 12265373. ^ a b "Mitochondrial myopathies: Clinical features and diagnosis". www.uptodate.com. [en.wikipedia.org]

  Onset is in the neonatal period, with mental deterioration, intention tremor, myoclonic epilepsy, spasticity, ataxia, muscle weakness and atrophy, myopathy, and sensory neural hearing loss. [accessanesthesiology.mhmedical.com]

  Abstract A report is given of an association of dyssynergia cerebellaris myoclonica associated with Friedreich's ataxia and mitochondrial myopathy in 2 patients. [ncbi.nlm.nih.gov]

  Mitochondrial respiratory chain disorder Myoclonus epilepsy AND ragged red fibers Myoclonus epilepsy and ragged red fibers syndrome Myopathy, mitochondrial Neurogenic muscle weakness, ataxia and retinitis pigmentosa Pearson's syndrome R Kearns-Sayre [icd9data.com]

  Involuntary muscle twitches, generalized epilepsy, and cerebellar ataxia — these symptoms are typically indicative of a mitochondrial myopathy. [mitochondrialdiseasenews.com]

• Muscle Weakness

  Among them, action myoclonus was seen in five; short stature, muscle weakness, and mental retardation in four; lactic acidosis, hearing impairment, and ataxia in two; and seizures in one. [ncbi.nlm.nih.gov]

  […] headaches seizures vomiting abdominal pain hearing loss stroke-like episodes MERRF syndrome signs and symptoms: muscle twitches muscle weakness (abnormal muscle cells are ragged red figers) recurrent seizures uncoordinated movements hearing loss vision [medschool.lsuhsc.edu]

  Physical findings : Neurological dysfunction including cerebellar ataxia, dementia, muscle atrophy with muscle weakness, neuropathy, optic atrophy, and short stature. [secure.ssa.gov]

  Onset is in the neonatal period, with mental deterioration, intention tremor, myoclonic epilepsy, spasticity, ataxia, muscle weakness and atrophy, myopathy, and sensory neural hearing loss. [accessanesthesiology.mhmedical.com]

• Myoclonus

  Limited efficacy of levetiracetam on myoclonus of different etiologies. [jns-journal.com]

  […] based on clinical symptoms (myoclonus, epilepsy, ataxia) and ragged-red fibers on muscle biopsy 3. [radiopaedia.org]

  […] fibers (disorder) Myoclonus epilepsy AND ragged red fibers (disorder) Myoclonus with epilepsy and with Ragged Red Fibers (MERRF syndrome) myoclonic epilepsy with ragged red fibers Fukuhara syndrome Myoclonus with epilepsy and with Ragged Red Fibers Myoclonic [wikidata.org]

  It has been observed that patients with MERRF syndrome will primarily display myoclonus as a first symptom. [en.wikipedia.org]

  A Case of Myoclonus Epilepsy and Ragged-red Fiber Syndrome 서울대 신경과 A Case of Myoclonus Epilepsy and Ragged-red Fiber Syndrome Byung Gon Kim, M.D., Beom Seok Jeon, M.D. [jkna.org]

• Seizure

  MERRF is characterized by myoclonic seizures (brief, sudden twitching muscle spasms), weakness (myopathy), cerebellar ataxia, progressive spasticity and dementia. [secure.ssa.gov]

  The primary features displayed on a person with MERRF include myoclonus, seizures, cerebellar ataxia, myopathy,[3] and ragged red fibers (RRF) on muscle biopsy, leading to the disease's name. [en.wikipedia.org]

  The most frequent seizure type in MERRF is generalised myoclonic seizure but also focal myoclonic, focal atonic, generalised tonic-clonic, generalised atonic, generalised myoclonic-atonic, typical absences, or tonic-clonic seizures of unknown onset have [ncbi.nlm.nih.gov]

  The most frequent symptom is myoclonic seizures that are usually sudden, brief, jerking spasms that can affect the limbs or the entire body. [accessanesthesiology.mhmedical.com]

  The clinical features of MERRF syndrome are myoclonus, seizure, dementia, ataxia, neuropathy, myopathy, deafness, and lipouta. The patients with MERRF syndrome have a point mutation in mitochondrial DNA at 8344 or 8356 nucleotide. [jkna.org]

• Cerebellar Ataxia

  Patients usually present in late adolescence or early adulthood with 1-3 myoclonus epilepsy cerebellar ataxia intellectual disability vision and/or hearing loss cardiomyopathy with Wolff-Parkinson-White syndrome short stature The diagnosis of MERRF is [radiopaedia.org]

  MERRF is characterized by myoclonic seizures (brief, sudden twitching muscle spasms), weakness (myopathy), cerebellar ataxia, progressive spasticity and dementia. [secure.ssa.gov]

  He later showed cerebellar ataxia, peripheral neuropathy, and cognitive dysfunction. Skeletal muscle biopsy failed to demonstrate ragged-red fibers. He was diagnosed as MERRF syndrome by the mitochondrial DNA analysis. [jkna.org]

  Abstract Myoclonic epilepsy and ragged-red fibers (MERRF) syndrome is a rare disorder characterized by myoclonus, muscle weakness, cerebellar ataxia, heart conduction block, and dementia. [ncbi.nlm.nih.gov]

• Generalized Seizure

  Abstract Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a mitochondrial disorder characterized by myoclonus epilepsy, generalized seizures, ataxia and myopathy. [ncbi.nlm.nih.gov]

  At the age of 20 years, clear symptoms of MERRF syndrome developed, including myoclonic seizures, generalized tonic-clonic seizures, and paroxysmal hearing disturbance. [omim.org]

  […] syndromes that feature several kinds of generalized seizures. [emedicine.medscape.com]

• Limb Weakness

  Case report A 25-year-old male presented with paroxysmal left upper limb tics and weakness that had been ongoing for two years. [spandidos-publications.com]

  Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) Onset: Usually before age 20 Symptoms: This disorder causes PEO, ptosis (droopy eyelids), limb weakness and gastrointestinal (digestive) problems, including chronic diarrhea and abdominal pain [mda.org]

  Exercise intolerance, limb weakness, hearing loss, and diabetes may also precede the occurrence of the stroke-like episodes. [umdf.org]

  An individual with the MT-TF m.611G>A pathogenic variant had mild truncal and proximal limb weakness, cerebellar ataxia, bilateral Babinski sign, and frequent myoclonic jerks [ Mancuso et al 2004 ]. Table 2. [ncbi.nlm.nih.gov]

The diagnosis of MERRF is indicated by clinical examination and confirmed by molecular genetic testing and microscopic examination of the muscle biopsy specimen with modified Gomori trichrome or succinate dehydrogenase staining. This last method will show the presence of cytochrome c oxidase negative muscle fibers and ragged red fibers, while genetic tests will detect mitochondrial deoxyribonucleic acid mutations in white blood cells, urine, saliva, hair follicles, skin or muscle.

Blood workup reveals increased lactate and pyruvate concentrations in the blood and cerebrospinal fluid [10], which also has high protein concentration [11]. Creatine kinase levels may be slightly increased [12], but this is not a specific disease characteristic.

Brain imaging techniques like magnetic resonance imaging are able to diagnose stroke, brainstem atrophy [13], cerebellar atrophy [14] and basal ganglia calcification [15], while magnetic resonance spectroscopy detects brain lactate levels.

The electrocardiogram highlights rhythm and conduction abnormalities, if present. The electroencephalogram usually reveals generalized spike and wave discharges or focal epileptiform waves. The electromyogram and nerve conduction velocity may have either a myogenic or neurogenic aspect.

Genetic analysis may reveal MT-TL1, MT-TK, MT-TP, MT-TF or MT-TI mutations. Combined respiratory chain defects [16] and cytochrome c oxidase deficiency [17] have also been described.

• Focal Epileptiform Discharges

  Electroencephalogram (EEG) usually shows generalized spike and wave discharges with background slowing, but focal epileptiform discharges may also be seen. Electrocardiogram often shows pre-excitation; heart block has not been described. [ncbi.nlm.nih.gov]

• Epileptiform Activity

  The EEG of patients with MERRF usually exhibits variation in the degree of slowing of background activity and generalized epileptiform activity, which may worsen with intermittent photic stimulation 27, 33, 49, 50, 51. [doi.org]

  Generalized epileptiform discharges in 84.2% of patients, while focal discharges were present in ten patients. One of the patient had multifocal epileptiform activity. [bioline.org.br]

  The EEG of patients with MERRF usually exhibits variation in the degree of slowing of background activity and generalized epileptiform activity, which may worsen with intermittent photic stimulation2727. [scielo.br]

• Muscle Biopsy showing Ragged-Red Fibers

  Patients exhibit myoclonus epilepsy (involuntary muscle contractions) and show signs of ragged-red fibers in muscle biopsy. Less prevalent symptoms include deafness, exercise intolerance, dementia, and cardiomyopathies. [mitochondrialdiseasenews.com]

• Muscle Biopsy Abnormal

  Biopsy: Abnormal mitochondria from under the muscle tissue membrane appear as “ragged red fibres” under a microscope Chemical staining identifies diseased mitochondria, appearing as “ragged red fibres”. [lhsc.on.ca]

Abstract The treatment of progressive myoclonic epilepsy (PME) is largely empirical, even though valproic acid (VPA) is usually considered the drug of first choice. [jns-journal.com]

Many genes are involved. [2] These include: MT-TK [3] MT-TL1 MT-TH [4] MT-TS1 [5] MT-TS2 MT-TF [6] Treatment Like many mitochondrial diseases, there is no cure for MERRF and treatment is primarily symptomatic. [ipfs.io]

The treatment of progressive myoclonic epilepsy (PME) is largely empirical, even though valproic acid (VPA) is usually considered the drug of first choice. [ncbi.nlm.nih.gov]

[citation needed] Treatment[edit] Like many mitochondrial diseases, there is no cure for MERRF, no matter the means for diagnosis of the disease. The treatment is primarily symptomatic. [en.wikipedia.org]

Prognosis The prognosis for patients with MERRF syndrome is globally poor because of the progressive nature of the disease. [orpha.net]

Prognosis The prognosis depends heavily on the underlying etiology and the epilepsy syndrome. Patients with a benign syndrome typically respond well to medication and may outgrow their epilepsy. [emedicine.medscape.com]

Prognosis is generally quite poor. [lhsc.on.ca]

Genes involved include MT-TK, MT-TL1, MT-TH, MT-TS1, MT-TS2, and MT-TF.[1] Differentiating MERRF syndrome from Other Diseases Epidemiology and Demographics Risk Factors Screening Natural History, Complications, and Prognosis Diagnosis Diagnostic Criteria [wikidoc.org]

Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. [icd10coded.com]

Limited efficacy of levetiracetam on myoclonus of different etiologies. [jns-journal.com]

Department of Neurology, College of Medicine, Seoul National University Abstract Myoclonus epilepsy and ragged-red fiber (MERRF) syndrome is one of the common etiologies of progressive myoclonus epilepsy. [jkna.org]

Etiology Seizures associated with early myoclonic encephalopathy can be due to a number of etiologies. [emedicine.medscape.com]

Etiology MERRF syndrome is caused by mutations in the mitochondrial DNA. Over 80% of individuals with MERRF syndrome carry the 8344A>G mutation in the lysine transfer RNA ( tRNA Lys ) gene ( MTTK ). [orpha.net]

The epidemiology of pathogenetic mitochondrial DNA mutations. Ann Neurol2000;48:188–93. ↵ Darin N, Oldfors A, Moslemi A-R, et al. [jnnp.bmj.com]

The epidemiology of mitochondrial disorders—past, present and future. Biochim Biophys Acta BBA - Bioenerg. 2004;1659(2):115-120. doi:10.1016/j.bbabio.2004.09.005 11. Hameed S, Tadi P. Myoclonic Epilepsy and Ragged Red Fibers. In: StatPearls. [eyewiki.aao.org]

Summary Epidemiology The prevalence in the general population of Europe has been estimated at 0.9 in 100 000, but the disease seems to be more common in the USA. [orpha.net]

Epidemiology 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. [ncbi.nlm.nih.gov]

Pathophysiology Defect of the respiratory chain enzymes, mainly complexes I and IV. Diagnosis Clinical and laboratory confirmation of elevated pyruvate and lactate. [accessanesthesiology.mhmedical.com]

View Article : Google Scholar : PubMed/NCBI 5 De la Mata M, Garrido-Maraver J, Cotán D, et al: Recovery of MERRF fibroblasts and cybrids pathophysiology by coenzyme Q10. Neurotherapeutics. 9:446–463. 2012. [spandidos-publications.com]

[…] following characteristics: progressive myoclonic epilepsy clumps of diseased mitochondria accumulate in the subsarcolemmal region of the muscle fiber and appear as "ragged-red fibers" when muscle is stained with modified Gomori trichrome stain short stature Pathophysiology [wikidoc.org]

Familial mitochondrial encephalomyopathy (MERRF): genetic, pathophysiological and biochemical characterization of a mitochondrial DNA disease. Cell. 1988 ;55: 601 – 610. Google Scholar | Crossref | Medline | ISI 13. [doi.org]

This model is useful to clarify the pathophysiology and biomolecular mechanisms of MERRF syndrome. [nature.com]

Import of a tRNALys with a mutation in the anticodon preventing recognition of the lysine codons does not lead to any rescue, whereas downregulation of the transgenic tRNAs by small interfering RNA (siRNA) transiently abolishes the functional rescue, [ncbi.nlm.nih.gov]

Patients are usually prescribed therapeutic compounds to alleviate symptoms, but these do not prevent the disease from progressing. [mitochondrialdiseasenews.com]

Although higher proportions of the mutation in the blood of the mother result in a higher risk of having a child with severe phenotype, there are many examples of extreme segregation of the mutation from mother to child, which prevent efficient genetic [orpha.net]

Demographics Risk Factors Screening Natural History, Complications, and Prognosis Diagnosis Diagnostic Criteria History and Symptoms Physical Examination Laboratory Findings Imaging Findings Other Diagnostic Studies Treatment Medical Therapy Surgery Prevention [wikidoc.org]

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