OBJECTIVEMitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a progressive, multisystem affected mitochondrial disease associated with a number of disease-related defective genes. MELAS has unpredictable presentations and clinical course, and it can be commonly misdiagnosed as encephalitis, cerebral infarction, or brain neoplasms. This review aimed to update the diagnosis progress in MELAS, which may provide better understanding of the disease nature and help make the right diagnosis as well.

DATA SOURCESThe data used in this review came from published peer review articles from October 1984 to October 2014, which were obtained from PubMed. The search term is "MELAS".

STUDY SELECTIONInformation selected from those reported studies is mainly based on the progress on clinical features, blood biochemistry, neuroimaging, muscle biopsy, and genetics in diagnosing MELAS.

RESULTSMELAS has a wide heterogeneity in genetics and clinical manifestations. The relationship between mutations and phenotypes remains unclear. Advanced serial functional magnetic resonance imaging (MRI) can provide directional information on this disease. Muscle biopsy has meaningful value in diagnosing MELAS, which shows the presence of ragged red fibers and mosaic appearance of cytochrome oxidase negative fibers. Genetic studies have reported that approximately 80% of MELAS cases are caused by the mutation m.3243A>G of the mitochondrial transfer RNA (Leu (UUR)) gene (MT-TL1).

CONCLUSIONSMELAS involves multiple systems with variable clinical symptoms and recurrent episodes. The prognosis of MELAS patients depends on timely diagnosis. Therefore, overall diagnosis of MELAS should be based on the maternal inheritance family history, clinical manifestation, and findings from serial MRI, muscle biopsy, and genetics.

Schizophrenia-like psychiatric symptoms in patients with MELAS are rarely reported. A 34-year-old male was admitted because of visual hallucinations, persecutory delusions and generalized seizure. He also presented with repeated headache, vomiting, and left homonymous hemianopsia. We report a 34-year-male with MELAS presenting psychiatric symptoms before the establishment of the diagnosis by gene analysis.
Adult ; Delusions ; Diagnosis ; Hallucinations ; Headache ; Hemianopsia ; Humans ; Male ; MELAS Syndrome* ; Schizophrenia ; Seizures ; Vomiting

Adolescent ; Adult ; Child ; Humans ; MELAS Syndrome ; diagnosis ; pathology ; Magnetic Resonance Imaging ; Male ; Tomography, X-Ray Computed

An 18-year-woman was referred with seizure activity and global aphasia. Diagnosis of MELAS syndrome with left temporo-parieto-occipital infarction was confirmed by gene analysis. Global aphasia was improved completely. Right temporal infarction developed after 5 months. Diagnosis of pure word deafness was made in view of impaired verbal comprehension in presence of adequate reading, writing, spontaneous speaking, and well preserved environmental sound perception. MRI findings of the patient support the hypothesis of the pathway of non-verbal hearing in previous reports.
Aphasia ; Comprehension ; Deafness* ; Diagnosis ; Hearing ; Hearing Loss, Central ; Humans ; Infarction ; Magnetic Resonance Imaging ; MELAS Syndrome* ; Seizures ; Writing

PURPOSE: The disease entity mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is characterized by an early onset of stroke-like episodes. MELAS is the most dominant subtype of mitochondrial disease. Molecular genetic testing is important in the diagnosis of MELAS. The mitochondrial DNA (mtDNA) 3243A>G mutation is found in 80% of MELAS patients. Nevertheless, molecular analysis alone may be insufficient to diagnose MELAS because of mtDNA heteroplasmy. This study aimed to evaluate whether muscle biopsy is useful in MELAS patients as an initial diagnostic evaluation method. MATERIALS AND METHODS: The medical records of patients who were diagnosed with MELAS at the Department of Pediatrics of Gangnam Severance Hospital between January 2006 and January 2017 were reviewed. The study population included 12 patients. They were divided into two subgroups according to whether the results of muscle pathology were in accordance with mitochondrial diseases. Clinical variables, diagnostic evaluations, and clinical outcomes were compared between the two groups. RESULTS: Of the 12 patients, seven were muscle pathology-positive for mitochondrial disease. No statistically significant difference in clinical data was observed between the groups that were muscle pathology-positive and muscle pathology-negative for mtDNA 3243A>G mutation. Additionally, the patients with weakness as the initial symptom were all muscle pathology-positive. CONCLUSION: The usefulness of muscle biopsy appears to be limited to an initial confirmative diagnostic evaluation of MELAS. Muscle biopsy can provide some information in MELAS patients with weakness not confirmed by genetic testing.
Biopsy* ; Diagnosis ; DNA, Mitochondrial ; Genetic Testing ; Humans ; Medical Records ; MELAS Syndrome* ; Methods ; Mitochondrial Diseases ; Mitochondrial Encephalomyopathies* ; Molecular Biology ; Pathology ; Pediatrics

DNA, Mitochondrial ; genetics ; Humans ; MELAS Syndrome ; diagnosis ; diagnostic imaging ; genetics ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Mutation ; genetics

We report the clinical and MR manifestations of an 18 year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. Recurrent status epilepticus caused reversible cytotoxic edema on diffusion-weighted images (DWI). Initial and one month follow-up MR spectroscopy, after seizure control, showed some discrepancies in the ratio of metabolites. N-acetylaspartate (NAA) partially recovered (NAA/creatine (Cr) ratio: 1.27-->1.84). This was because of a normalization of decreased NAA due to cellular dysfunction as a result of status epilepticus. A low ratio of NAA/Cr due to abnormal mitochondria remained in the decreased state. Reversible NAA/Cr ratios in the acute lesion suggested that NAA reflects the neuronal function as well as the level of neuronal structural damage. The altered NAA/Cr ratio better correlated with the abnormal signal intensity area of T2-weighted images (T2WI) and DWI than the lactate (Lac)/Cr ratio. With conservative treatment with anti-epileptics not accompanied by coenzyme Q or sodium dichloroacetate, lactate persistently increased (Lac/Cr ratio: 1.01-->1.21) because of the continued production of lactate in cells with respiratory deficiency, which is the main pathology of MELAS.
Adolescence ; Aspartic Acid/metabolism ; Aspartic Acid/analogs & derivatives* ; Brain/metabolism ; Case Report ; Creatine/metabolism ; Diffusion ; Female ; Human ; MELAS Syndrome/metabolism ; MELAS Syndrome/diagnosis* ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a maternally inherited mitochondrial disorder of which m.3243A>G is the most commonly associated mutation, resulting in an inability to meet the energy requirements of various organs. MELAS poses a diagnostic challenge owing to its multiple organ involvement and great clinical variability due to its heteroplasmic nature. We report three cases from a family who were initially misdiagnosed with myasthenia gravis or undiagnosed. Although there is no optimal consensus treatment approach for patients with MELAS because of the disease's heterogeneity, our 21-year-long therapy regimen of l-arginine, l-carnitine, and coenzyme Q10 supplementation combined with dietary management appeared to provide noticeable protection from the symptoms and complications. Prompt early diagnosis is important, as optimal multidisciplinary management and early intervention may improve outcomes.
Acidosis, Lactic ; Arginine ; Carnitine ; Consensus ; DNA, Mitochondrial ; Early Diagnosis ; Early Intervention (Education) ; Follow-Up Studies ; Humans ; MELAS Syndrome ; Mitochondrial Diseases ; Myasthenia Gravis ; Population Characteristics

Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome presents with various clinical features, including seizures, stroke-like episodes, encephalopathy, myopathy, cardiac involvement, and diabetes. However, due to its clinical heterogeneity, the diagnosis of MELAS syndrome is complex and difficult. The present report describes an 18-year-old male who was diagnosed with MELAS syndrome following the onset of type 1 diabetes. The patient had suffered from ataxia, mental retardation, and recurrent headaches for several years; following hospitalization for loss of consciousness, he was treated for cerebellar atrophy and Wolf-Parkinson-White (WPW) syndrome. Although the patient had no history of lactic acidosis, the recent onset of type 1 diabetes and his medical history of encephalopathy and WPW syndrome suggested MELAS syndrome. The diagnosis of MELAS syndrome was confirmed by molecular genetic testing, which revealed a point mutation (A3243G) in the patient's mitochondrial DNA.
Acidosis, Lactic ; Adolescent ; Ataxia ; Atrophy ; Diabetes Mellitus, Type 1* ; Diagnosis ; DNA, Mitochondrial ; Headache ; Hospitalization ; Humans ; Intellectual Disability ; Male ; MELAS Syndrome* ; Molecular Biology ; Muscular Diseases ; Point Mutation ; Population Characteristics ; Seizures ; Unconsciousness ; Wolff-Parkinson-White Syndrome

According to the recently published reports about mitochondrial diseasbl the clinical manifestations are more various than expected. There have been no clinical studies covering whole spectrum of mitochond7iral disease except a few case reports in our country. The authors performed this studies to understand the various clinical and laboratory findings of mitochondrial disease and the usefulness of current tools for the diagnosis of mitochondrial diseases. We reviewed retrospectively the clinical, laboratory and pathologic findings of mitochondrial disease. The diagnosis of mitochondrial disease was based on clinical manifestations, 'ragged-red fiber' in Gomori stainging, and/or abnormal mitochondrial morphologies on electron microscopy. Twenty one patients were diagnosed as mitochondrial disease. Their clinical diagnosis included 7 MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes); 3 MERRF (myoclonic epilepsy with ragged red fibers); 2 KSS (Kearns-Sayre syndrome); 7 CPEO (chronic progressive external ophthalmoplegia); and 2 mitochondrial myopathy. The usefulness of electrodiagnostic studies, such as EMG, NCV and FEG, were limited in some patients. The muscle biopsy showed ragged red fibers in 10 of 15 sampled examined. Eleven patients had abnormal serum lactic acid level. The authors found that the mitochondrial disease revealed broad clinical spectrum and clinically available diagnostic tests, such as serum lactate and light microscopic examination showed limited value. Therefore, to evaluate the mitochondrial dysfunction with systemic involvement may be desirable to depend on sensitive and specific methods including succinate dehydrogenase (SDH) staining, electron microscopy and biologic studies of mitochondrial DNA.
Acidosis, Lactic ; Biopsy ; Diagnosis ; Diagnostic Tests, Routine ; DNA, Mitochondrial ; Epilepsy ; Humans ; Lactic Acid ; MELAS Syndrome ; MERRF Syndrome ; Microscopy, Electron ; Mitochondrial Diseases* ; Mitochondrial Myopathies ; Muscular Diseases ; Ophthalmoplegia, Chronic Progressive External ; Retrospective Studies ; Succinate Dehydrogenase