Mitochondrial Encephalomyopathy With Lactic Acidosis And Stroke-like Episodes Research Articles

Clinical Reasoning: A 17-Year-Old Girl With Progressive Cognitive Impairment.

A 17-year-old girl presented with a long history of cognitive impairment, personality and behavioral changes, dysarthria, and paroxysmal lower-extremity weakness. She was initially suspected of having mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes because of stroke-like symptoms, such as episodic lower-extremity weakness, as well as abnormal brain MRI findings of generalized cerebral atrophy, extensive high-intensity lesions in the cortex and subcortical white matter on fluid-attenuated inversion recovery images, decreased N-acetyl aspartate/creatine ratio, and a lactate peak in the focal area on spectrum images. However, there were no relatives with similar presentations in the family of the patient. The whole mitochondrial genome and whole-exome sequencing did not suggest pathogenic mutations, and no abnormalities were found in the blood or CSF lactate levels. In this case, we detail the clinical manifestations, diagnostic workup, and imaging findings. This case highlights the importance of assessing cognitive function and the relevant differential diagnoses in an adolescent with cognitive impairment.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS): Special MRI features

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS): Special MRI features

Late-onset mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes syndrome with mitochondrial DNA 3243A>G mutation masquerading as autoimmune encephalitis: A case report

Here, we present a unique case of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, which initially appeared to be autoimmune encephalitis and was ultimately confirmed as MELAS with the mitochondrial DNA 3243A>G mutation. A 58-year-old female presented with acute-onset speech impediment and auditory hallucinations, symmetrical bitemporal lobe abnormalities, clinical and laboratory findings, and a lack of relevant prodromal history, which suggested diagnosis of autoimmune encephalitis. Further work-up, in conjunction with the patient's medical history, family history, and lactate peak on brain lesions on magnetic resonance imaging, suggested a mitochondrial disorder. Mitochondrial genome analysis revealed the m.3243A>G variant in the MT-TL1 gene, which led to a diagnosis of MELAS syndrome. This case underscores the importance of considering MELAS as a potential cause of autoimmune encephalitis even if patients are over 40 years of age, as the symptoms and signs are atypical for MELAS syndrome.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes syndrome: a case report

ABSTRACT A biopsy of gastrocnemius muscle from a patient with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome was studied histologically in semithin sections stained by hematoxylin-and-eosin (H&E) and toluidine blue, and ultrathin sections by transmission electron microscopy (TEM). H&E stain demonstrated typical ragged-red fibers (RRFs) and affected fibers in fascicles. Toluidine-blue stain showed an irregular meshwork in the center of RRFs. TEM demonstrated damaged myofibrils and variations in mitochondrial structure in RRFs and affected fibers. Dense mitochondria were compacted with cristae and pleomorphic electron-dense inclusions. Lucent mitochondria included paracrystalline inclusions with a parking lot appearance. At high magnification, the paracrystalline inclusions were composed of plates that paralleled and connected with mitochondrial cristae. These observations indicated that electron-dense granular and paracrystalline inclusions resulted from cristal degeneration and overlapping in mitochondria in MELAS syndrome.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes with an MT-TL1 m.3243A>G point mutation: Neuroradiological features and their implications for underlying pathogenesis.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is one of the most common inherited mitochondrial disorders. Due to the high clinical and genetic heterogeneity of MELAS, it is still a major challenge for clinicians to accurately diagnose the disease at an early stage. Herein, we evaluated the neuroimaging findings of MELAS with an m.3243A>G mutation in MT-TL1 and analyzed the possible underlying pathogenesis of stroke-like episodes. Fifty-nine imaging studies in 24 patients who had a confirmed genetic diagnosis of m.3243A>G (MT-TL1; tRNA Leu) associated with MELAS were reviewed in our case series. The anatomic location, morphological features, signal/intensity characteristics and temporal evolution of lesions were analyzed on magnetic resonance imaging (MRI), and computed tomography (CT) images. The supplying vessels and metabolite content of the lesions were also evaluated by using MR angiography (MRA)/CT angiography (CTA), and MR spectroscopy (MRS), respectively. The lesions were most commonly located in the posterior brain, with 37 (37/59, 63%) in the occipital lobe, 32 (32/59, 54%) in the parietal lobe, and 30 (30/59, 51%) in the temporal lobe. The signal characteristics of the lesions varied and evolved over time. Bilateral basal ganglia calcifications were found in 6 of 9 (67%) patients who underwent CT. Cerebral and cerebellar atrophy were found in 38/59 (64%) and 40/59 (68%) patients, respectively. Lesion polymorphism was found in 37/59 (63%) studies. MRS showed elevated lactate doublet peaks in 9/10 (90%) cases. MRA or CTA revealed that the lesion-related arteries were slightly dilated compared with those of the contralateral side in 4 of 6 (67%) cases. The imaging features of MELAS vary depending on the disease stage. Polymorphic lesions in a single imaging examination should be considered a diagnostic clue for MELAS. Stroke-like episodes may be involved in a complex pathogenetic process, including mitochondrial angiopathy, mitochondrial cytopathy, and neuronal excitotoxicity.

Mitochondrial Impairment: A Common Motif in Neuropsychiatric Presentation? The Link to the Tryptophan-Kynurenine Metabolic System.

Nearly half a century has passed since the discovery of cytoplasmic inheritance of human chloramphenicol resistance. The inheritance was then revealed to take place maternally by mitochondrial DNA (mtDNA). Later, a number of mutations in mtDNA were identified as a cause of severe inheritable metabolic diseases with neurological manifestation, and the impairment of mitochondrial functions has been probed in the pathogenesis of a wide range of illnesses including neurodegenerative diseases. Recently, a growing number of preclinical studies have revealed that animal behaviors are influenced by the impairment of mitochondrial functions and possibly by the loss of mitochondrial stress resilience. Indeed, as high as 54% of patients with one of the most common primary mitochondrial diseases, mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, present psychiatric symptoms including cognitive impairment, mood disorder, anxiety, and psychosis. Mitochondria are multifunctional organelles which produce cellular energy and play a major role in other cellular functions including homeostasis, cellular signaling, and gene expression, among others. Mitochondrial functions are observed to be compromised and to become less resilient under continuous stress. Meanwhile, stress and inflammation have been linked to the activation of the tryptophan (Trp)–kynurenine (KYN) metabolic system, which observably contributes to the development of pathological conditions including neurological and psychiatric disorders. This review discusses the functions of mitochondria and the Trp-KYN system, the interaction of the Trp-KYN system with mitochondria, and the current understanding of the involvement of mitochondria and the Trp-KYN system in preclinical and clinical studies of major neurological and psychiatric diseases.

Clinical features, pathogenesis, and management of stroke-like episodes due to MELAS.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a disease that should be considered as a differential diagnosis to acute ischemic stroke taking into account its onset pattern and neurological symptoms, which are similar to those of an ischemic stroke. Technological advancements in neuroimaging modalities have greatly facilitated differential diagnosis between stroke and MELAS on diagnostic imaging. Stroke-like episodes inMELAShave the following features: (1) symptoms are neurolocalized according to lesion site; (2) epileptic seizures are often present; (3) lesion distribution is inconsistent with vascular territory; (4) lesions are common in the posterior brain regions; (5) lesions continuously develop in adjacent sites over several weeks or months; (6) neurological symptoms and stroke-like lesions tend to be reversible, as presented on magnetic resonance imaging; (7) the rate of recurrence is high; and; (8) brain dysfunction and atrophy are slowly progressive. The m.3243ANG mutation in the MT-TL1 gene encoding the mitochondrial tRNALeu(UUR) is most commonly associated with MELAS. Although the precise pathophysiology is still unclear, one possible hypothesis for these episodes is a neuronal hyperexcitability theory, including neuron-astrocyte uncoupling. Supplementation, such as with L-arginine or taurine, has been proposed as preventive treatments for stroke-like episodes. As this disease is still untreatable and devastating, numerous drugs are being tested, and new gene therapies hold great promise for the future. This article contributes to the understanding of MELAS and its implications for clinical practice, by deepening their insight into the latest pathophysiological hypotheses and therapeutic developments.

Mitochondrial Diabetes: The Clinical Spectrum of MIDD and MELAS in Association With the A3243G Mutation

Abstract Introduction: Maternally inherited diabetes and deafness (MIDD) is a multisystem disorder characterized by insulinopenia and sensorineural hearing loss. This rare form of monogenic diabetes is most commonly associated with the A3243G mutation of mitochondrial DNA (mtDNA). The same mutation is seen in 80 percent of patients with MELAS (Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes). MIDD and MELAS have overlapping features suggesting a continuum of expression for the A3243G mutation. Clinical Case: A 41-year-old male was referred for genetic testing and counseling by his ophthalmologist following detection of bilateral punched-out retinal pigment epithelium (RPE) lesions on routine exam. His medical history was significant for type 1 diabetes mellitus (T1DM) diagnosed at the age of 21 and bilateral sensorineural hearing loss diagnosed at the age of 38. The referral was triggered by patient reported family history of MELAS in two of his brothers who were both diagnosed at the age of 10 and died at the ages of 20 and 27. Whether the patient was previously tested during early childhood remains unclear. His medical history was negative for stroke-like episodes or seizures. Neurologic evaluation revealed mild fluent aphasia with paraphasic errors and some comprehension difficulties. MRI of the brain without contrast showed no focus of restricted diffusion. Mitochondrial DNA sequence analysis was performed. A pathogenic variant (m.3243 A>G) was detected in the MT-TL1 gene at approximately 25% heteroplasmy. The patient was advised to avoid metformin given increased risk for lactic acidosis. He was also instructed against use of statins. At the age of 45, the patient presented to the emergency department (ED) with a complaint of headache, vertigo and incoordination. Physical examination revealed left homonymous hemianopsia, right horizontal nystagmus and bilateral upper extremity dysmetria. MRI of the brain without contrast showed a large area of predominantly cortical restricted diffusion involving the right temporal and occipital region with associated T2/FLAIR hyper-intensity. Cross over between the PCA and MCA territories was suggestive of a stroke-like episode related to MELAS. The patient received a bolus of IV arginine at 0.5 g/kg followed by an IV infusion of 0.5 g/kg/day for 3 days. He was later transitioned to oral arginine 5g three times daily and was discharged to a rehab facility. Clinical Lesson: This case demonstrates the evolution of MIDD to MELAS, supporting the concept that both syndromes represent a spectrum of the same disease. A few case reports describe the progression of MIDD to MELAS. Why some patients develop MELAS and others develop MIDD is unclear but may be related to heteroplasmy. Early identification of MIDD and MELAS is crucial given associated comorbidities and unique management issues.

Different Phenotypes Caused by the Unique Mutation in the Same Family with Mitochondrial Encephalomyopathy

Background and Objective: Mitochondrial encephalomyopathies represent a clinically heterogeneous group of disorders resulting from abnormal mitochondrial function. This study investigates the clinical and genetic characteristics of families with mitochondrial encephalomyopathy. Methods: The clinical manifestations, biopsy and gene detection were retrospectively analyzed for four probands with definitively diagnosed mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) from three families with MELAS and/or maternally inherited diabetes and deafness (MIDD). Results: The initial symptoms of probands were convulsive headache and/or epilepsy. The members of the three families also had diabetes, deafness, muscle weakness and short statures. Typical characteristics were indicated by muscle biopsy and gene detection in all. Conclusion: We reveal that the same family can have MIDD and MELAS cases, which clearly show that the unique mutation may cause different syndromes in one family. Neurologists should take into account more possibilities and phenotypes in screening and genetic counselling for the families of probands.

Different Phenotypes Caused by the Unique Mutation in the Same Family with Mitochondrial Encephalomyopathy

<p><strong>Background and Objective:</strong>  Mitochondrial encephalomyopathies represent a clinically heterogeneous group of disorders resulting from abnormal mitochondrial function. This study investigates the clinical and genetic characteristics of families with mitochondrial encephalomyopathy.</p>
 <p><strong>Methods: </strong> The clinical manifestations, biopsy and gene detection were retrospectively analyzed for four probands with definitively diagnosed mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) from three families with MELAS and/or maternally inherited diabetes and deafness (MIDD).</p>
 <p><strong>Results:</strong>  The initial symptoms of probands were convulsive headache and/or epilepsy. The members of the three families also had diabetes, deafness, muscle weakness and short statures. Typical characteristics were indicated by muscle biopsy and gene detection in all.</p>
 <p><strong>Conclusion:</strong>  We reveal that the same family can have MIDD and MELAS cases, which clearly show that the unique mutation may cause different syndromes in one family. Neurologists should take into account more possibilities and phenotypes in screening and genetic counselling for the families of probands.</p>

Aphasic status epilepticus in a tertiary referral center in Turkey: Clinical features, etiology, and outcome

ObjectiveAphasic status epilepticus (ASE), although rare, may often remain underdiagnosed. We aimed to report the patients diagnosed with ASE and describe their clinical presentation, etiology, electrophysiological findings, neuroimaging, treatment options, and outcome. MethodsWe retrospectively analyzed a series of 28 patients diagnosed with ASE between January 2010 and August 2019 in our tertiary referral center. We reviewed medical files, patient charts, and short- and long-term intermittent electroencephalogram (EEG) recordings. Demographical, historical, clinical, neuroimaging, electrophysiological parameters, administered antiseizure medications, and prognosis of all patients were recorded. Furthermore, EEGs were re-evaluated according to Salzburg criteria. ResultsMost patients presented with tumors (n = 11) and cerebrovascular disease (CVD) (n = 11), while the rest were diagnosed with hyperglycemia (n = 2), autoimmune encephalitis (n = 1), remote intracranial abscess (n = 1), mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) attack (n = 1), or unknown cause (n = 1). Seventy-one percent of patients had prior history of epilepsy. The most common EEG findings were rhythmic delta activity with fluctuation and epileptiform discharges ≤ 2.5 Hz with spatiotemporal evolution (66 %). Magnetic resonance imaging (MRI) and EEG findings indicated dominant hemisphere involvement in all patients. No casualties occurred; 71 % patients exhibited total recovery, while 29 % had mild-moderate sequela aphasia. None of the patients received aggressive treatment for ASE. SignificanceA relatively higher number of ASE patients could be contributed to the literature through this study. ASE should be considered in patients with prolonged unexplained aphasia, especially with pre-existing risk factors, such as prior history of epilepsy, structural lesion, and metabolic disorders accompanied by concordant EEG findings. Although the underlying cause is a determining prognostic factor, this study shows a significant number of patients with complete remission; thus, the prognosis of ASE may be considered more favorable than other types of nonconvulsive status epilepticus.

Altered Dynamic Functional Connectivity in Patients With Mitochondrial Encephalomyopathy With Lactic Acidosis and Stroke-Like Episodes (MELAS) at Acute and Chronic Stages: Shared and Specific Brain Connectivity Abnormalities.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a rare maternally inherited genetic disease; however, little is known about its underlying brain basis. Furthermore, the dynamic functional connectivity (dFC) of brain networks in MELAS has not been explored. To investigate the abnormalities of dFC in patients with MELAS at the acute and chronic stages, and to determine the possible relations between dynamic connectivity alterations and volumes of stroke-like lesions (SLLs). Prospective. Twenty-two MELAS patients at the acute stage, 23 MELAS patients at the chronic stage, and 22 healthy controls. Single-shot gradient-recalled echo planar imaging (EPI) sequence at 3T. Dynamic FC states were estimated using the sliding window approach and k-means clustering analyses. Combined with graph theory, the topological properties of the dFC network were also accessed. Permutation test, Pearson correlation coefficient, and false discovery rate correction. We identified four dFC states and found that MELAS patients (especially at the acute stage) spent more time in a state with weaker connectivity (state 1) and less time in states with stronger connectivity. In addition, volumes of acute SLLs were positively correlated with mean dwell time in state 1 (r = 0.539, P < 0.05) and negatively correlated with the number of transitions (r = -0.520, P < 0.05). Furthermore, MELAS patients at the acute stage exhibited significantly increased global efficiency (P < 0.01) and decreased local efficiency (P < 0.001) compared to the controls and the patients at the chronic stage. Patients at the chronic stage only showed significantly (P < 0.001) decreased local efficiency compared to the controls. Our findings suggest similar and distinct dFC alterations in MELAS patents at the acute and chronic stages, providing novel insights for understanding the neuropathological mechanisms of MELAS. Level of Evidence 2 Technical Efficacy Stage Stage 2 J. MAGN. RESON. IMAGING 2021;53:427-436.

Topological reorganization of brain functional networks in patients with mitochondrial encephalomyopathy with lactic acidosis and stroke‐like episodes

Mitochondrial encephalomyopathy with lactic acidosis and stroke‐like episodes (MELAS) is a rare maternally inherited genetic disease; however, little is known about its underlying brain basis. Furthermore, the topological organization of brain functional network in MELAS has not been explored. Here, 45 patients with MELAS (22 at acute stage, 23 at chronic stage) and 22 normal controls were studied using resting- state functional magnetic resonance imaging and graph theory analysis approaches. Topological properties of brain functional networks including global and nodal metrics, rich club organization and modularity were analyzed. At the global level, MELAS patients exhibited reduced clustering coefficient, normalized clustering coefficient, normalized characteristic path length and local network efficiency compared with the controls. At the nodal level, several nodes with abnormal degree centrality and nodal efficiency were detected in MELAS patients, and the distribution of these nodes was partly consistent with the stroke-like lesions. For rich club organization, rich club nodes were reorganized and the connections among them were decreased in MELAS patients. Modularity analysis revealed that MELAS patents had altered intra- or inter-modular connections in default mode network, fronto-parietal network, sensorimotor network, occipital network and cerebellum network. Notably, the patients at acute stage showed more obvious changes in these topological properties than the patients at chronic stage. These findings indicated that MELAS patients, particularly those at acute stage, exhibited topological reorganization of the whole-brain functional network. This study may help us to understand the neuropathological mechanisms of MELAS.

Acute Cortical Lesions in MELAS Syndrome: Anatomic Distribution, Symmetry, and Evolution.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is a rare mitochondrial disorder affecting children and young adults. Stroke-like episodes are often associated with acute cortical lesions in the posterior cerebral cortex and are classically described as asymmetric and transient. In this study we assessed the anatomic distribution of acute cortical lesions, the incidence of symmetry, and the temporal evolution of lesions. This was a retrospective cohort study of patients who had a confirmed genetic diagnosis of a pathogenic variant associated with MELAS and MR imaging performed at our center (2006-2018). Each MR imaging study was assessed for new lesions using T1, T2, FLAIR, DWI, ADC, and SWI. The anatomic location, symmetry, and temporal evolution of lesions were analyzed. Eight patients with the same pathogenic variant of MELAS (MT-TL1 m.3243A>G) with 31 MR imaging studies were included. Forty-one new lesions were identified in 17 of the studies (5 deep, 36 cortical). Cortical lesions most commonly affected the primary visual cortex, the middle-third of the primary somatosensory cortex, and the primary auditory cortex. Thirty of 36 cortical lesions had acute cortical diffusion restriction, of which 21 developed cortical laminar necrosis on subacute imaging. Six of 11 studies with multiple lesions showed symmetric cortical involvement. Acute cortical lesions in MELAS most commonly affect the primary visual, somatosensory, and auditory cortices, all regions of high neuronal density and metabolic demand. The most common pattern of temporal evolution is acute cortical diffusion restriction with subacute cortical laminar necrosis and chronic volume loss. Symmetric involvement is more common than previously described.

M itochondrial c erebellar a taxia, r enal failure, n europathy, and e ncephalopathy (MCARNE)

Mitochondrial NADH dehydrogenase 5 (MT-ND5) Asp393Asn missense mutation is established to cause mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS).1,2 We describe a case and family with this mutation and a divergent phenotype that eluded diagnosis. We suggest an expanded nomenclature, m itochondrial c erebellar a taxia, r enal failure, n europathy, and e ncephalopathy (MCARNE).

Mitochondriale Erkrankungen

Mitochondrial diseases (MD) are caused by mutations in the mitochondrial DNA or nuclear DNA. The clinical manifestation is often most severe in tissues with high energy demands. The most common MDs are Leber's hereditary optic neuropathy (LHON), chronic progressive external ophthalmoplegia (CPEO) and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS). Therapeutic approaches for MD include bridging of respiratory chain defects, pharmacological stimulation of mitochondrial metabolism, supplementation of deficient factors and symptomatic treatment. Initial gene therapeutic approaches for causal treatment have already reached the clinical development stage. This article provides an introduction to MD, asummary of the most important syndromes and an overview over established and innovative therapeutic approaches.

Late-Onset Melas with Midd: An Uncommon Age of Presentation

Objective: Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes caused by a mutation in mitochondrial DNA, usually a point mutation at position 3243 in the leucine tRNA gene. This same mutation can cause a rare but severe syndrome called mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS). Methods: We describe a case of MIDD with acute mitochondrial decompensation that progressed to MELAS. Results: A 63-year-old male with MIDD and a history of hypoglycemic seizures presented for evaluation of altered mental status with fever, tachycardia, hypotension, and somnolence. His history was also significant for deafness and cochlear implants. The physical exam results were consistent with mild, proximal muscle wasting. The initial workup was concerning for sepsis and a urinary tract infection. Laboratory evaluation revealed lactic acidosis with normal white cell count, liver enzymes, and ammonia level. After fluid resuscitation and 4 days of broad-spectrum...

Mitochondrial Disorder: Maternally Inherited Diabetes and Deafness.

Patients with maternally inherited diabetes and deafness (MIDD) have insulin-dependent diabetes with relatively low BMI; usually the onset of the diabetes is during the third or fourth decade of life and it is associated with progressive neurosensory deafness. The fundus shows circumferentially oriented but discontinuous patches of RPE and choriocapillaris (CC) atrophy around the macula, within the arcades (Figs. 31.1 and 31.2). Sometimes even hyperpigmentation can be seen, also around the optic nerve, or pattern-like dystrophy may occur. Vision is usually good, about 20/40 or better. Fundus autofluorescence (FAF) shows decreased AF in the areas of RPE atrophy, surrounded by a zone of speckled AF. No generalized retinal dysfunction is seen on full-field electroretinography (ERG), but pattern ERG or multifocal ERG shows abnormal function. Asymptomatic maternal relatives harboring the mutation may show pigmentary changes, hearing loss, and in some, diabetes. Another disorder associated with the same A3243G mitochondrial DNA (mtDNA) mutation as MIDD is Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like episodes (MELAS). The stroke-like episode (such as hemiplegia) occurs at about 5-15 years of age, and severe encephalopathy may cause death at a young age. Patients may also experience headache, vomiting, visual field defects, or cortical blindness.

Survival analysis of a cohort of Chinese patients with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) based on clinical features

BackgroundMitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a common mitochondrial syndrome. The aim of this study was to conduct a survival analysis based on the clinical features of a Chinese MELAS patient cohort. MethodsThis is a retrospective single-center study. The MELAS patients were followed up for 1–8years (median 4years). The disease severity was evaluated by the modified Rankin Scale (mRS). The survival analysis was performed using Kaplan-Meier analysis and Cox proportional hazards model. ResultsA total of 138 subjects were enrolled, and the median disease duration was 7years [interquartile range (IQR) 4–11years]. The stroke-like episodes were the most common initial symptoms (70.3%). Seventeen (17.3%) subjects lost to follow-up. Of the 121 subjects who successfully completed the follow-up, 28 subjects died (mortality rate 23.1%). An acute stroke-like episode and/or status epilepticus were the predominant causes of death (42.9%). Among the surviving patients (n=93), 39.8% (37/93) required assistance in daily life (mRS scores 3–5). The mRS scores were inversely correlated with the age of onset (r=−0.28, P=0.0022) but not with the disease duration (r=0.10, P=0.2709). The survival rate declined mainly within 12years after the disease onset. The stroke-like episode as the initial symptom was an independent risk factor for death (hazard ratio=2.86, 95% CI 1.03–7.94, P=0.043). ConclusionsMELAS had high mortality and morbidity in this cohort of Chinese patients. The early onset of stroke-like episodes might indicate the more severe form of the disease, highlighting the importance of management of stroke-like episodes to improve the prognosis.

Clinical analysis of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes in children

Objective To investigate the clinical, imaging, pathological and molecular biological features of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes(MELAS) in children. Methods The clinical, imaging, pathological and molecular biological features of 12 children with MELAS diagnosed through muscle biopsy or gene sequencing in the Fifth Affiliated Hospital of Zhengzhou University from January 2011 to December 2015 were retrospectively analyzed. Results (1) Clinical features: the main manifestations included headache and vomiting in 11 cases, epileptic seizures in 9 cases, short stature in 8 cases, hairy in 7 cases, intolerance fatigue in 7 cases, cognitive decline in 7 cases, visual disturbance in 6 cases, hearing disturbance in 6 cases, and 5 cases had positive family history.In addition, 7 cases had the serum lactic acid level increase in a rest for 10 min after exercise.(2) Imaging features: 4 cases showed bilateral basal ganglia calcification symmetry in 8 patients who underwent head CT scan.The most frequently involved parts of the lesion were occipital in 10 cases, temporal in 9 cases and parietal lobe in 7 cases in stroke-like episodes.The lesions were lamellar necrosis.The abnormal areas by MRI showed low signal intensity on T1 weighted imaging, high signal intensity on T2 weighted imaging and fluid attenuated inversion recovery, high or equal signal intensity on diffusion weighted imaging, high or low signal intensity on apparent diffusion coefficient; the lactate peak significantly increased on magnetic resonance spectroscopy.The distribution was not in accordance with the control region of the cerebral vessels.Dynamic observation revealed that the lesions were reversible and migratory.(3) Myopathological features: muscle biopsy was performed in all children, and ragged-red fibers were found in 10 cases by improved Gomori staining, strongly succinate dehydrogenase-reactive were found in 9 cases, and the lipid droplets slightly increased in 8 cases by oil red O staining.Besides, the crystalline inclusion bodies in mitochondria were arranged in a parking lot pattern in 9 cases by electromicroscope.(4) Molecular biological characteristics: the mitochondrial gene mutations were analyzed in peripheral blood of 9 children and their parents, including 8 cases with A3243G mutation and 1 case with G13513A mutation.Five mothers had the same A3243G mutation site in 8 cases. Conclusions Children with MELAS have complex and varied clinical manifestations and certain characteristic of neuroimaging.Moreover, muscle pathology and gene sequencing have important diagnostic value.Fully understanding the clinical, muscle pathology, imaging and molecular biological characteristics of children with MELAS can be helpful to the early diagnosis and treatment, also reduce misdiagnosis. Key words: Mitochondrial encephalomyopathy; Lactic acidosis; Stroke-like episodes; Clinical manifestation