KEARNS-SAYRE SYNDROME MASQUERADING AS MYASTHENIA GRAVIS

PURPOSE

Kearns-Sayre syndrome (KSS) is a mitochondrial DNA deletion syndrome that is characterized by the triad of onset commonly before age 20, pigmentary retinopathy, and chronic progressive external ophthalmoplegia. Here, we present a case of KSS masquerading as myasthenia gravis.

METHODS

Case report.

RESULTS

A 15-year-old boy with a presumed diagnosis of myasthenia gravis presented with blurry vision, ophthalmoplegia, and ptosis. He was found to have a mitochondrial pigmentary retinopathy and was eventually diagnosed with KSS after mitochondrial DNA sequencing revealed a novel large-scale deletion of 7.9 kb of mitochondrial DNA from nucleotides 6,578 to 14,460.

CONCLUSION

We report a case of KSS found to have a novel large-scale mitochondrial DNA deletion. The presence of a mitochondrial pigmentary retinopathy found on dilated examination led to reconsideration of the previous diagnosis of myasthenia gravis and ultimately led to the correct diagnosis of KSS.

Ophthalmologic school-based screening revealing Kearns-Sayre syndrome: a case report

Kearns-Sayre syndrome is a rare mitochondrial disorder. It had a triad of features, including progressive external ophthalmoplegia, pigmentary retinopathy, and an alteration of cardiac conduction. The ocular manifestations include bilateral ptosis, progressive external ophthalmoplegia, and atypical pigmentary retinopathy. We report the case of a 9-year-old Moroccan patient who has been diagnosed with Kearns-Sayre syndrome during an ophthalmologic school-based screening. This case highlights the interest of school-based screening in the diagnosis and management of a rare disease.

Pediatric single large-scale mtDNA deletion syndromes: The power of patient reported outcomes

There is a limited understanding of system-level clinical outcomes and interventions associated with single large-scale mitochondrial DNA deletion syndromes (SLSMDS). Additionally, no research exists that describes patient reported outcomes (PROs) of children with SLSMDS. A global and observational registry was established to understand the multi-systemic course of SLSMDS and track clinical outcomes. The development and design of the registry is described. Demographic characteristics, history and diagnoses, and system level prevalence of problems and interventions are reported for 42 children. System level problems and interventions include information on the following body systems: audiology, cardiac, endocrine, gastrointestinal (including pancreatic and hepatobiliary system), hematological, metabolic, neurological (including autonomic, mobility, & learning), ophthalmic, psychiatric, renal, and respiratory. Results emphasize the need of patient registries and suggest that the diagnostic odyssey and burden of disease for children with SLSMDS is significant. System-level findings may help families and clinical providers with diagnosis, prognostication, and treatment. A multidisciplinary team of clinical experts with a central coordinating specialist for children with SLSMDS is recommended.

Ophthalmoplegia in Mitochondrial Disease

PURPOSE

To evaluate the classification, diagnosis, and natural course of ophthalmoplegia associated with mitochondrial disease.

MATERIALS AND METHODS

Among 372 patients with mitochondrial disease who visited our hospital between January 2006 and January 2016, 21 patients with ophthalmoplegia were retrospectively identified. Inclusion criteria included onset before 20 years of age, pigmentary retinopathy, and cardiac involvement. The 16 patients who were finally included in the study were divided into three groups according to disease type: Kearns-Sayre syndrome (KSS), KSS-like, and chronic progressive external ophthalmoplegia (CPEO).

RESULTS

The prevalences of clinical findings were as follows: ptosis and retinopathy, both over 80%; myopathy, including extraocular muscles, 75%; lactic acidosis, 71%; and elevated levels of serum creatine kinase, 47%. Half of the patients had normal magnetic resonance imaging findings. A biochemical enzyme assay revealed mitochondrial respiratory chain complex I defect as the most common (50%). The prevalence of abnormal muscle findings in light or electron microscopic examinations was 50% each, while that of large-scale mitochondrial DNA (mtDNA) deletions in a gene study was 25%. We compared the KSS and KSS-like groups with the CPEO patient group, which showed pigmentary retinopathy (p<0.001), cardiac conduction disease (p=0.013), and large-scale mtDNA deletions (p=0.038). KSS and KSS-like groups also had gastrointestinal tract disorders such as abnormal gastrointestinal motility (p=0.013) unlike the CPEO group.

CONCLUSION

Patients with KSS had gastrointestinal symptoms, which may indicate another aspect of systemic involvement. The presence of large-scale mtDNA deletions was an objective diagnostic factor for KSS and a gene study may be helpful for evaluating patients with KSS.

[MELAS: Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-Like Episodes]

Mitochondrial disease is caused by a deficiency in the energy supply to cells due to mitochondrial dysfunction. Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is a mitochondrial disease that presents with stroke-like episodes such as acute onset of neurological deficits and characteristic imaging findings. Stroke-like episodes in MELAS have the following features: 1) neurological deficits due to localization of lesions in the brain, 2) episodes often accompany epilepsy, 3) lesions do not follow the vascular supply area, 4) lesions are more often seen in the posterior brain than in the anterior brain, 5) lesions spread to an adjacent area in the brain, and 6) neurological symptoms often disappear together with imaging findings, but later relapse. About 80% of patients with MELAS have an A-to-G transition mutation at the nucleotide pair 3243 in the dihydrouridine loop of mitochondrial tRNA^Leu(UUR), which causes the absence of posttranscriptional taurine modification at the wobble nucleotide of mitochondrial tRNA^Leu(UUR) and disrupts protein synthesis. However, the precise pathophysiology of stroke-like episodes is under investigation, with possible hypotheses for these episodes including mitochondrial angiopathy, mitochondrial cytopathy, and neuron-astrocyte uncoupling. With regard to treatment, L-arginine and taurine have recently been suggested for relief of clinical symptoms.

Clinical manifestation of mitochondrial diseases

Mitochondrial disorders (MD) represent a clinically, biochemically and genetically heterogeneous group of diseases associated with dysfunction of the oxidative phosphorylation system and pyruvate dehydrogenase complex. Our aim was to illustrate the most common clinical presentation of MD on the example of selected diseases and syndromes. The minimal prevalence of MD is estimated as 1 to 5,000. MD may manifest at any age since birth until late-adulthood with acute manifestation or as a chronic progressive disease. Virtually any organ may be impaired, but the organs with the highest energetic demands are most frequently involved, including brain, muscle, heart and liver. Some MD may manifest as a characteristic cluster of clinical features (e.g. MELAS syndrome, Kearns-Sayre syndrome). Diagnostics includes detailed history, the comprehensive clinical examination, results of specialized examinations (especially cardiology, visual fundus examination, brain imaging, EMG), laboratory testing of body fluids (lactate, aminoacids, organic acids), and analysis of bioptic samples of muscle, skin, and liver, eventually. Normal lactate level in blood does not exclude the possibility of MD. Although the aimed molecular genetic analyses may be indicated in some of mitochondrial diseases, the methods of next generation sequencing come into focus. Examples of treatment are arginine supplementation in MELAS syndrome, ketogenic diet in pyruvate oxidation disorders or quinone analogs in patients with LHON. Conclusion: The clinical suspicion of a mitochondrial disorder is often delayed, or the disease remains undiagnosed. The correct diagnosis and adequate treatment can improve prognosis of the patient. Access to genetic counseling is also of great importance.

[Kearns-Sayre syndrome: ophthalmic manifestations]

The clinical case and genetic diagnosis of Kearns-Sayre syndrome (KSS) is described in a young patient. The findings included: ptosis, ocular motility disturbances, pigmentary retinopathy, as well as mitral insufficiency. A muscle biopsy revealed mitochondrial cytopathyand heteroplasmic mitochondrial DNA deletions. KSS is a rare neuromuscular disorder defined by a characteristic triad of progressive external ophthalmoplegia, pigmentary retinopathy and atrioventricular block. Early detection is essential to avoid potential cardiac complications.

[Diagnosis and therapy of mitochondrial diseases]

Mitochondrial diseases are a significant part of neuromuscular diseases. Majority of them is multisystemic disorder. The diagnosis can be established in more and more cases. Beyond the routine neurological examination imaging methods (MRI and MR-spectroscopy) and electrophysiology (EMG, ENG, EEG, evoked potential tests) might be helpful in setting the diagnosis. Raised blood lactate level supports the diagnosis. Muscle biopsy demonstrates mitochondrial abnormalities in the majority of cases. The positivity of genetic tests is low, because the amount of mitochondrial DNA alterations is different in tissues. Therefore other tissue than blood (mainly muscle) is necessary for genetic tests. The other reason is that the respiratory chain is under double -mitochondrial and nuclear - genetic control, and testing the nuclear genes are available only in selected laboratories. The treatment is limited, mainly symptomatic.

Kearns-Sayre syndrome presenting as somatomedin C deficiency and complete heart block

Kearns-Sayre syndrome (KSS) is a rare mitochondrial disease in which neuromuscular structures, endocrine glands, and cardiac conduction systems are most commonly involved. An 11-year-old boy was admitted with blurred consciousness, respiratory instability, and bradycardia of two-hour onset. He was immediately intubated. His medical history included growth retardation and myopic refractive defect for six years, therapy for somatomedin C deficiency for 15 months, and bilateral ptosis for three months. On physical examination, he was unconscious, had a peak heart rate of 40/min, blood pressure of 60/20 mmHg, and a weak pulse. Laboratory findings showed elevated blood lactate and blood pyruvate levels and an increased lactate/pyruvate ratio. The electrocardiogram showed complete atrioventricular block and echocardiography showed mitral valve prolapse. Following implantation of a temporary transvenous cardiac pacemaker, his heart rate and clinical condition improved. Further analysis with cranial magnetic resonance (MR) imaging demonstrated hyperintense signal changes in the subcortical white matter of the two cerebral hemispheres, bilateral thalamus, putamen, cerebral peduncles, dorsal medulla, and midbrain. The typical clinical and MR findings confirmed the initial diagnosis of KSS. A permanent cardiac pacemaker was implanted into the right ventricle.

A novel mitochondrial DNA deletion in a Chinese girl with Kearns-Sayre syndrome

Kearns-Sayre syndrome is a rare disorder often caused by mitochondrial DNA rearrangement. The most commonly reported mitochondrial DNA deletion is 4977 bp in size spanning nucleotides 8469 and 13447. The clinical signs of Kearns-Sayre syndrome include chronic progressive external ophthalmoplegia, retinitis pigmentosa, heart block and cerebellar ataxia, as well as other heterogeneous manifestations including neuromuscular problems and endocrine disorders. Cardiac conduction defects can develop insidiously, leading to sudden death sometimes if not promptly recognised. This report focuses on the diagnosis of Kearns-Sayre syndrome in a Chinese girl who presented initially with short stature, delayed puberty, insidious onset of ptosis and later with typical features of Kearns-Sayre syndrome including complete heart block. Genetic analysis disclosed a novel 7.2 kilobases deletion in muscle tissue. Mitochondrial diseases have heterogeneous phenotypes and mutational analysis has proven to be an effective tool for confirming the diagnosis.

Spinocerebellar ataxia type 7 mimicking Kearns–Sayre syndrome: A clinical diagnosis is desirable

Spinocerebellar ataxias are a group of autosomal dominant cerebellar degenerative disorders, which are characterized by clinical and genetic variability. Spinocerebellar ataxia type 7 (SCA7) is less variable in clinical presentation than other SCAs. We present a pediatric patient with 13 and 70 trinucleotide CAG repeats within SCA7 gene and no family history, whose presentation mimicked Kearns-Sayre syndrome (KSS). We review the differential diagnosis of cerebellar ataxia with vision loss secondary to retinal pigmentary dystrophy. This paper supports concept of a desirable clinical diagnosis to avoid multiple genetic or invasive testing in children with neurodegenerative disorders.

Clinical evolution of Kearns-Sayre syndrome with polyendocrinopathy and respiratory failure

BACKGROUND

The triad of progressive external ophthalmoplegia, atypical retinal pigmentation and cardiac conduction defects characterizes Kearns-Sayre syndrome (KSS), which is most often caused by a single, large deletion of mitochondrial DNA. Endocrine disease appears to be more common in KSS than in other mitochondrial diseases.

MATERIALS, METHODS AND RESULTS

A patient presenting with KSS developed Addison's disease, hypothyroidism and glucose intolerance. Thyroid peroxidase antibodies and adrenal 21-hydroxylase antibodies were identified. She developed acute respiratory failure requiring invasive ventilatory support, but improved and currently requires only non-invasive, nocturnal BiPAP treatment.

DISCUSSION AND CONCLUSION

This case confirms the association of KSS and endocrine dysfunction. Our finding of autoantibodies to thyroid and adrenal glands distinguishes this patient from most other published cases and suggests a potential synergy between the two disease mechanisms. In addition, we demonstrate that respiratory failure can be a treatable event in this disease.

The clinical diagnosis and molecular genetics of kearns-sayre syndrome: a complex mitochondrial encephalomyopathy

From the first description by Kearns and Sayre in 1958, this syndrome has been diagnosed in several hundred patients. However, the labile character of its clinical manifestations makes diagnosis difficult and delayed. Only recently, some thirty years from the first diagnosis, have we recognized mitochondrial DNA rearrangements as the molecular basis of the disease. This has lead to increasing interest in the contribution which mtDNA deletions make to Kearns-Sayre Syndrome (KSS) and other disorders. Although the true prevalence of this syndrome in the general population is unknown, a basic awareness of the KSS phenotype, as well as of the essential elements of patient evaluation is important for appropriate patient management. Although methods of assessing patients for mtDNA rearrangements are well developed, ambiguity in patient diagnosis often remains even after detailed, multisystem testing. Advances in our understanding of the genetic background and the tissue specific effects of mtDNA deletions, in addition to resolving the inheritance pattern, will also increase our ability to diagnose, manage and counsel patients with this disorder.

Persistent diffusion abnormalities in the brain stem of three children with mitochondrial diseases

We report 2 children (patients 1 and 2) with Kearns-Sayre syndrome and 1 (patient 3) with Leigh syndrome, who underwent serial diffusion-weighted MR imaging (DWI) studies for 2.8 (patient 1), 4.2 (patient 2), and 1.0 years (patient 3). The DWI revealed the persistent hyperintense signals in the pontine and mesencephalic tegmenta. The apparent diffusion coefficient in the affected regions remained constantly low, suggesting that cytotoxic edema and spongiform degenerations may compose these brain stem lesions.

[The outcome of pregnancy and delivery in primigravid pregnancy with Kearn-Sayre's syndrome]

The Kearn-Sayre's syndrome is an uncommon, non-hereditary disease which belongs to the group of mitochondrial myopathy. The characteristic symptoms of this syndrome often appear before the age of 20. In this report we describe the outcome of primigravid pregnancy of a 33 year old woman with early diagnosed Kearn-Sayre's syndrome.

Unusual clinical presentation of a patient carrying a novel single 1.8 kb deletion of mitochondrial DNA

Kearns-Sayre syndrome (KSS) is a mitochondrial encephalomyopathy characterized by progressive external ophthalmoplegia (PEO), pigmentary retinopathy and onset before the age of 20 years. Cerebellar ataxia, as well as short stature and increased protein content in the cerebrospinal fluid, are frequent additional symptoms. A single large mitochondrial (mt) DNA deletion of 4,977 bp is the most common molecular defect in KSS. Recently, different mutations have also been associated with incomplete, KSS-like phenotypes. We describe the unusual clinical presentation of a patient carrying a novel 1,814-bp deletion of mtDNA. In contrast with typical KSS, the clinical picture of this patient did not include either palpebral ptosis or PEO and was dominated by an ataxic syndrome.

Kearns-Sayre syndrome associated with trifascicular block and QT prolongation

Patients suffering from Kearns-Sayre syndrome (KSS) often develop conduction defects that may lead to syncope or sudden cardiac death. The association of conduction abnormalities with prolonged QT interval in these patients is very rare. We describe a patient with KSS and diabetes mellitus who suffered a torsades de pointes-induced syncopal attack, in the presence of trifascicular block and QT prolongation (QTc: 574 ms). The patient was successfully treated with permanent pacing. This case highlights that torsades de pointes represents a potential mechanism of syncope or sudden cardiac death in patients with KSS.

[Cardiac involvement in Kearns-Sayre syndrome]

The mitochondrial cytopathies or oxidative-phosphorylation diseases are a diverse group of disorders that result from the structural, biochemical, or genetic derangement of mitochondria. Because mitochondrial dysfunction can affect the most highly energy-dependent organs, cardiac involvement is frequent in these diseases. To identify the clinical features of Kearns-Sayre syndrome, an entity associated with this group of diseases, we evaluated cardiac structure and function in 5 patients with Kearns-Sayre syndrome and followed the clinical course of these patients for 5 years.

'Cerebral palsy' due to mitochondrial cytopathy

Two children aged 10 and 13 years with initially static motor problems, diagnosed as cerebral palsy, were found to have respiratory chain defects after developing a progressive course and multisystem involvement. Mitochondrial cytopathies should be considered in the differential diagnosis of cerebral palsy.

[Kearns-Sayre syndrome associated with growth hormone deficiency]

The Authors report a 10 years old boy with Kearns-Sayre syndrome and growth hormone (GH) deficiency. The patient was treated with human recombinant GH for 6 months but the growth velocity/year did not change. The Authors report a brief review of the literature on the ethiopatogenesis of GH deficiency observed in this patient is given.

Sustained polymorphic ventricular tachycardia unassociated with QT prolongation or bradycardia in the Kearns-Sayre syndrome

Cardiac dysfunction, including congestive heart failure and impulse conduction abnormalities, have been implicated in the sudden death of patients suffering from the Kearns-Sayre syndrome. This report describes a 29-year-old woman who suffered syncopal episodes due to sustained polymorphic VT. Sustained polymorphic VT was not associated with prolongation of the QT interval or bradycardia on the ECG. The implantation of a cardioverter defibrillator should be considered in this syndrome.

[Diagnostic and therapeutic problems in chronic progressive external ophthalmoplegia (CPEO)]

BACKGROUND

Strictly speaking, CPEO is defined as paralysis of the external ocular muscles combined with ptosis. In Kearns-Sayre syndrome additional neurological or muscular deficits can be observed, sometimes even decades after the onset of ocular symptoms.

METHOD

Three patients with classical CPEO and one patient with Kearns-Sayre syndrome where included in the present study. The clinical examinations included electromyography, various serological parameters and histological biopsies.

RESULTS

The onset of ocular symptoms with divergent strabism and ptosis could be dated back to the age of 7, 27, 38 and 44 years starting on one eye and progressing slowly over years to both eyes. In the Kearns-Sayre syndrome patient a general decrease in cardio-respiratory fitness and occasional collapses were noted. In three patients ptosis and strabism surgery led to the relief of the ocular symptoms.

CONCLUSIONS

In CPEO respectively Kearns-Sayre syndrome the onset of the disease is variable. The final correct diagnosis is often delayed due to the mild beginning of the symptoms and the slow progression of the paralyses. Early EMG and muscle biopsy examination may facilitate the diagnosis.

Bilateral spontaneous corneal perforation associated with complete external ophthalmoplegia in mitochondrial myopathy (kearns-sayre syndrome)

PURPOSE

Mutations of mitochondrial DNA can lead to a variety of pheno- and genotypically heterogeneous diseases. Kearns-Sayre syndrome is caused by the deletion of several mitochondrial genes. The syndrome is characterized by chronic progressive external ophthalmoplegia, tapetoretinal degeneration, and severe generalized myopathy.

CASE REPORT

We report on a 36-year-old female patient with Kearns-Sayre syndrome, confirmed by biochemistry, histology, and genetics. Over a period of 10 years, progressive ophthalmoplegia led to recurrent conjunctivitis, keratitis, and corneal ulceration. Almost total external ophthalmoplegia including involvement of the orbicularis oculi muscles was observed. Despite advanced ptosis, there was lagophthalmos of 2 mm with near complete extinction of globe motility in both eyes. The left eye showed a peripheral corneal perforation parallel to the lower limbus. After successful penetrating keratoplasty in the left eye, despite preventive measures, a peripheral corneal perforation also occurred in the right eye. Penetrating keratoplasty was therefore also performed on the right eye. To achieve a satisfactory functional result, large-diameter transplants were necessary in both eyes. To prevent immune reactions, cyclosporine therapy was initiated prophylactically. Sixteen and 9 months after penetrating keratoplasty, the corrected visual acuity was 20/60 in the right eye and 20/100 in the left eye, with clear transplants on both sides.

DISCUSSION

Patients with progressive ophthalmoplegia require thorough neurologic investigation and evaluation. Lagophthalmos in the presence of almost absent globe motility requires extensive preventive measures to avoid exposure keratitis. In spite of this, in the presented case, corneal perforation of the second eye could not be prevented.

[Pigmented retinopathy as a presenting sign of mitochondrial encephalomyopathy without external ophthalmoplegia]

BACKGROUND

Mitochondrial encephalomyopathies result from deletions in the nuclear or mitochondrial (mt) DNA. Deletions in the mtDNA are often sporadic. Mitochondriopathies are commonly associated with chronic progessive external ophthalmoplegia (CPEO). Here we describe a patient with a structural mtDNA aberration whose presenting sign was impaired visual acuity in the presence of a pigmented retinopathy but lack of impaired ocular motility.

PATIENT

A 7-year-old girl presented with impaired visual acuity (0.4 OD and 0.5 OS), coarse hyperpigmentation of the posterior pole and diffuse hyperpigmentation with irregular depigmentation in the periphery. Scotopic and photopic as well as multifocal ERG were abnormal. Further symptoms included an incomplete inner ear deafness, ataxia, lapses of coordination and an intention tremor. Compared with her twin sister, the patient's speech was less modulated and slower. MRI scanning disclosed symmetric changes of density in the basal ganglia and nucleus dentatus as well as in the brainstem. ECG yielded no evidence of an AV-node block. Molecular biological analysis showed a structural rearrangement of the mtDNA.

CONCLUSIONS

Mitochondrial encephalomyopathies in early ages may present with pronounced retinal changes in the absence of external ophthalmoplegia.Therefore, it appears prudent to include a neuropediatric evaluation as well as a mutation screening of the mtDNA in the evaluation of pediatric patients with diffuse non-specific pigmented retinopathies.

[Pulmonary thromboembolism as a late complication of mitochondrial myopathy (Kearns-Sayer syndrome ]

A case of pulmonary thromboembolism with transient pulmonary hypertension of a rare cause is presented. In 24-year-old woman myasthenia was recognised on the ground of ptosis and fixation of eyes muscles from the 14th year of age. The treatment with mestinon was ineffective. Before planned thymectomy serious disturbances of heart rhythm and conduction were confirmed. Stimulator was implanted and thymectomy was done. No improvement of neurological state was observed despite the treatment with mestinone and prednisone. When she was 30 years old disease of lung appeared with fever, cough and parenchymal and pleural lesions of right lung. Antibiotic therapy was ineffective. CT scan and US examination revealed large thrombus inside the right auricle connected with stimulator electrodes. Embolisation of right pulmonary arteria was confirmed also. Treatment with heparin was ineffective and thrombectomy was performed. Exact neurological examination stated that the patient had no typical symptoms of myasthenia and that symptoms related with eyes and heart could be result of mitochondrial myopathy. Diagnosis was confirmed by EMG examination and muscle biopsy.

Corneal decompensation in a boy with Kearns-Sayre syndrome

This paper describes the clinical history of a young boy with Kearns-Sayre syndrome. The first presenting symptom of Kearns-Sayre syndrome in this boy was corneal edema with photophobia and tearing.

Severe mitochondrial cytopathy with complete A-V block, PEO, and mtDNA deletions

We describe a 17-year-old male with neurologic and cardiovascular disorders characterized by complete atrioventricular block and a mitochondrial cytopathy with clinical, structural, biochemical, and molecular features shared by chronic progressive external ophthalmoplegia and Kearns-Sayre syndrome. The patient's manifestations included progressive external ophthalmoplegia, bilateral ptosis, muscle weakness, delayed development, and progressive hearing loss with multiple mitochondrial DNA deletions, including an abundant 11-kb novel deletion and reduced specific activities of respiratory complexes I, III, and IV present in skeletal muscle. Ultrastructural analysis of biopsied muscle revealed a heterogenous mixture of normal and abnormal mitochondria with unusual cristae. This unique mitochondrial DNA deletion, which eliminates the origin of mitochondrial DNA replication for the light strand, may be responsible for generating an intermediate clinical phenotype.

Mitochondrial disease mimicking polymyositis: a case report

The authors report on a 34-year-old woman who had developed severe weakness and reduction in grip strength in both upper and lower limbs. Laboratory blood tests revealed increased levels of muscle enzyme. The presence of progressive bilateral ptosis and external ophthalmoplegia raised the suspicion of a mitochondrial disease, subsequently confirmed by deltoid biopsy and genetic analysis of mitochondrial DNA that showed a deletion indicative of Kearns-Sayre syndrome. In this report we emphasise the need for a differential diagnosis between myositis and other myopathies, particularly the mitochondrial ones.

Neurological mitochondrial cytopathies

The mitochondrial cytopathies are genetically and phenotypically heterogeneous group of disorders caused by structural and functional abnormalities in mitochondria. To the best of our knowledge, there are very few studies published from India till date. Selected and confirmed fourteen cases of neurological mitochondrial cytopathies with different clinical syndromes admitted between 1997 and 2000 are being reported. There were 8 male and 6 female patients. The mean age was 24.42+/-11.18 years (range 4-40 years). Twelve patients could be categorized into well-defined syndromes, while two belonged to undefined group. In the defined syndrome categories, three patients had MELAS (mitochondrial encephalopathy, lactic acidosis and stroke like episodes), three had MERRF (myoclonic epilepsy and ragged red fibre myopathy), three cases had KSS (Kearns-Sayre Syndrome) and three were diagnosed to be suffering from mitochondrial myopathy. In the uncategorized group, one case presented with paroxysmal kinesogenic dystonia and the other manifested with generalized chorea alone. Serum lactic acid level was significantly increased in all the patients (fasting 28.96+/-4.59 mg%, post exercise 41.02+/-4.93 mg%). Muscle biopsy was done in all cases. Succinic dehydrogenase staining of muscle tissue showed subsarcolemmal accumulation of mitochondria in 12 cases. Mitochondrial DNA study could be performed in one case only and it did not reveal any mutation at nucleotides 3243 and 8344. MRI brain showed multiple infarcts in MELAS, hyperintensities in putaminal areas in chorea and bilateral cerebellar atrophy in MERRF.

Alarming atrioventricular block and mitral valve prolapse in the Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a multisystem mitochondrial disorder characterized by the invariant triad: onset before 20, progressive external ophthalmoplegia and pigmentary retinal degeneration, plus at least one of the following: complete (or not) heart block, cereberal dysfunction and CSF protein above 100 mg/dl. Autopsies from patients with KSS revealed widespread tissue distribution mtDNA deletions. These deletions result in significantly lower activities of the enzymes of the respiratory chain. The same deletion of mitochondrial DNA present in skeletal muscle is found in myocardial tissue. An 18-year-old girl diagnosed with the KSS was admitted to our hospital because of an upper respiratory tract infection and dysphagia. ECG showed cardiac conduction defects. The patient had no history of syncope. At her surface ECG there was a complete RBBB (QRS duration approximately 130 ms), a clockwise rotation with an axis of approximately 90 degrees and a slight QT prolongation (420 ms). Echocardiography showed prolapse with thickening and degeneration of both mitral valve leaflets but without mitral regurgitation. The patient was started on a diet rich in potassium and pharmaceutical therapy with magnesium oxide (240 mg of elemental Mg p.o. per day), 1 g of calcium carbonate t.i.d., vitamin D (calcitriol 0.25 microg p.o. per day) and coenzyme Q(10) 100 mg daily and discharged 6 days later with slightly improved biochemical profile but apparent clinical improvement. Urgent pacemaker implantation was decided but unfortunately the patient died due to acute cardiac arrest 10 days later.

[Disorders of mitochondrial energy metabolism in patients with the Kearns-Sayre syndrome]

BACKGROUND

Kearns-Sayre syndrome is a multisystem disorder caused by rearrangements of mitochondrial genome including various deletions and/or duplications. The aim of the study is to analyse the impact of mitochondrial DNA (mtDNA) deletions on the mitochondrial energetic metabolism in five patients with Kearns-Sayre syndrome.

METHODS AND RESULTS

The course of the disease is progressive in all patients. All of them have bilateral ptosis and external opthalmoplegia, four have retinitis pigmentosa, three have progressive muscle weakness and three have pacemaker because of complete A-V heart block. One patient underwent renal transplantation at the age of 12 because of a chronic renal failure. Southern blot analysis in muscle tissue revealed large scale heteroplasmic mtDNA deletions (3-7.4 kb) in all patients, the number of mutated copies of mtDNA ranged from 50 to 70%. Spectrophotometric measurements of respiratory chain complexes activities in muscle tissue revealed various combinations of defects of complex III, IV and I + III activities in all patients. Nevertheless, the lactic acidosis was permanently present only in one patient. Ragged-red fibers were found in two patients.

CONCLUSIONS

Although the diagnostic of Kearns-Sayre syndrome is based on clinical features, molecular analysis of mtDNA is necessary to confirm the diagnosis. The prognosis of the disease is unfavourable and co-operation between the patient and various specialists is necessary for the treatment, which is currently only symptomatic.

[Kearns-Sayre syndrome: pediatric neuroradiologic findings in computed tomography and magnetic resonance imaging]

Clinical presentation of mitochondrial disorders is heterogeneous because the affected organs are those depending on a high rate of aerobic metabolism. They can appear at any age and evolution is progressive. Signs that guide diagnostic suspicion, especially in the pediatric age group, are heterogeneous clinical presentation and multisystem involvement. Within the spectrum of diseases caused by mitochondrial myopathy, there are clearly defined syndromes such as Kearns-Sayre syndrome. Muscle biopsy shows ragged red fibers and approximately 80 % of patients present sporadic deletions in mitochondrial DNA. Imaging studies reveal areas of hypointensity in basal ganglia and midbrain that are not visible after administration of contrast enhancement in computed tomography, and symmetric T2 hyperintensity lesions in these areas in magnetic resonance imaging. We present a patient with Kearns-Sayre syndrome, in whom radiological alterations were helpful in reaching the diagnosis.

[Mitochondrial diseases in adults]

PURPOSE

Mitochondrial diseases have numerous phenotypic expression, and form an heterogeneous group of genetic diseases in which the production of energy fails. Well known in childhood, these mitochondrial diseases can onset in adulthood and may remain unrecognized. We propose a recent review (Medline 1981-2001) of the literature on adult forms of mitochondriopathies, illustrated with a typical case report.

CURRENT KNOWLEDGE AND KEY POINTS

Mitochondrial diseases have numerous phenotypic expression in adulthood. Principles of diagnosis are i) recognize a phenotype, ii) prove the mitochondrial abnormalities, iii) realize a genetical analysis. Main varieties of adult phenotypes are studied and separated in 1) skeletal muscular involvement, ocular myopathies above all; 2) mitochondrial cardiomyopathies; 3) neurological involvement (MERRF, MELAS, NARP, MNGIE syndromes); 4) endocrinological involvement and diabetes mellitus; 5) multisystemic diseases with a particular focus on Kearns Sayre syndrome.

FUTURE PROSPECTS AND PROJECTS

Phenotypic analysis of a patient with mitochondrial disease is not simple. A "multi-tissues" involvement is the main characteristic feature. Faced with such patients, replacement therapy, genomic therapy and genetic advice are evoked.

Recognition of mitochondrial DNA deletion syndrome with non-neuromuscular multisystemic manifestation

PURPOSE

To correlate the molecular characteristics of the mtDNA deletions with clinical phenotypes.

METHODS

Southern analysis and polymerase chain reaction (PCR)/DNA sequencing were used to determine the size and location of deletions in 16 patients with mtDNA deletion syndrome. An additional 48 reported cases from the literature were also included in the statistical analysis.

RESULTS

The common 5-kb deletion is found in eight of nine patients with Kearns-Sayre syndrome (KSS), mitochondrial myopathies (MM), or progressive external ophthalmoplegia (PEO). The rare/novel deletions were found in six of seven patients with extra-neuromuscular multisystemic manifestations and infantile/early childhood onset.

CONCLUSIONS

Patients with mtDNA deletion syndrome who manifest non-neuromuscular multisystemic disorders at a very young age usually harbor mutant mtDNA with novel or rare deletions in every tissue analyzed. For this group of patients, it is possible to use the less invasive blood specimens instead of muscle biopsies for molecular diagnosis. Overwhelmingly, the common 5-kb deletion is mostly seen in the muscle specimens of patients with KSS and age of onset after the second decade of life.

Progressive sensorineural hearing loss in children with mitochondrial encephalomyopathies

OBJECTIVE

Mitochondrial disorders are responsible for a variety of neurological syndromes. Specific mitochondrial DNA mutations have been identified recently in some of these rare disorders. Clinical symptoms may occur in different organs to various extent; often they are associated with progressive hearing loss. The aims of this study were to determine incidence, onset, and characteristics of hearing loss in children with mitochondrial encephalomyopathies and to investigate a possible correlation between the degree of hearing loss and neurological symptoms. In addition, we investigated the prognostic value of hearing loss as a predictor of the disease.

STUDY DESIGN

From August 1992 to September 1998, 29 patients ranging in age from 5 to 23 years (mean years) were studied. These children were hospitalized for diagnostic purposes in the neuropediatric department.

METHODS

The mitochondrial disorder was diagnosed by clinical and laboratory testings, including analysis of the mtDNA. Audiological evaluation consisted of measurements of pure-tone and speech audiometry, tympanometry, and acoustic refle- threshold testing, auditory brainstem response, and evoked as well as distortion-product otoacoustic emissions.

RESULTS

A sensorineural hearing loss was identified in 12 children. Three of these were diagnosed as having classic Kearns-Sayre syndrome; five as having multisystem KSS; two as having the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS); one as having KSS-MELAS overlap syndrome; and one as having Friedreich ataxia. Longitudinal testing was performed in seven children, and in all of them a progression of the hearing loss could be demonstrated. Audiological test results in all 12 children suggested cochlear as well as retrocochlear origin of the hearing loss presenting independently from the severity of hearing impairment. No correlation between the characteristics and degrees of hearing loss and the number and severity of clinical neurological symptoms could be found.

CONCLUSIONS

The present study demonstrated a high incidence (42%) of sensorineural hearing loss in children with mitochondrial encephalomyopathies. The progressive nature of the hearing impairment was confirmed by a significant correlation between the duration in years and severity of hearing loss in the children. The hearing loss does not have a prognostic value for the progression of the disorder. Based on our findings, we recommend regular audiometric examinations in patients with mitochondrial disorders.

Transient improvement of pyruvate metabolism after coenzyme Q therapy in Kearns-Sayre syndrome: MRS study

Coenzyme Q therapy has been used to support metabolic derangements in patients with mitochondrial encephalomyopathies. Biochemical analysis of the living human brain can be performed by magnetic resonance spectroscopy (MRS). We report upon a KSS patient who was serially imaged with localized proton MRS to monitor the efficacy of CoQ treatment. A 17-year-old girl with KSS was serially imaged with localized proton MRS performed on a GE 1.5 T SIGNA MRI/MRS system. The elevated lactate contents of lesions decreased after one month of CoQ therapy but were re-elevated 10 months after treatment. We conclude that MRS presents us with a powerful tool for monitoring the effects of therapeutic trials in mitochondrial encephalomyopathies.

Kearns Sayre syndrome: an atypical presentation

Kearns Sayre syndrome is a rare presentation which usually involves a triad of factors: external ophthalmoplegia, retinal pigmentary degeneration, and heart block. We present a clinically and histopathologically confirmed case of Kearns Sayre syndrome that involved no retinal pathology.

[Progressive ptosis in children as a presenting sign of Kearns-Sayre syndrome]

Mitochondrial encephalopathies represent a heterogeneous group of various neurological syndromes caused by defects in mitochondrial metabolism. All clinical syndromes can be subdivided by type of biochemical defect into 3 subgroups: defective oxidation, defects in pyruvate metabolism and various defects in the respiratory chain. We present a 12-year-old girl admitted for evaluation of progressive ptosis over a period of 3 years, diagnosed as having the rare mitochondrial encephalopathy, Kearns-Sayre syndrome.

Mitochondrial diseases in children: neuroradiological and clinical features in 17 patients

Mitochondrial diseases result from structural, biochemical or genetic defects of mitochondria, which contain the respiratory chain. They usually affect children and young adults. We report the CT and MRI findings in 17 patients under 14 years of age, the youngest reported to date, with various mitochondrial diseases. Although imaging studies may be normal negative in the early stages, follow-up usually shows many abnormalities, which depend on clinical status and the disease. We have recognised a spectrum of findings that can be divided into four patterns: nonspecific myelin lesions (8/17); grey-matter nuclei involvement (6/17); a leukodystrophic pattern; and calcification of the brain (1/17), although mixed forms, particularly myelin and grey-matter lesions are frequent.

MRI of the brain in the Kearns-Sayre syndrome: report of four cases and a review

We report brain MRI findings in four patients with typical Kearns-Sayre syndrome (KSS) and correlate them with clinical manifestations. MRI was interpreted as normal in two patients; cerebral and cerebellar atrophy was seen in the other two. On T2-weighted spin-echo images, two patients had high-signal lesions bilaterally in subcortical white matter, thalamus and brain stem. In one patient, the white matter lesion extended into the deep cerebral white matter and the cerebellum was also affected. The other also had bilateral high-signal lesions in the globus pallidus. There was little correlation between neurological deficits and MRI findings. A review of the literature revealed that 10 of the 13 patients with typical KSS previously studied had bilateral subcortical white-matter lesions on T2-weighted images; at least 7 also had high-signal lesions in the brain stem, globus pallidus, thalamus or cerebellum. Although MRI may be normal or show atrophy, the characteristic finding in KSS is a combination of the high-signal foci in subcortical cerebral white matter and in the brain stem, globus pallidus or thalamus.

Patient with Kearns-Sayre syndrome exhibiting abnormal magnetic resonance image of the brain

A 33-year-old Japanese man had Kearns-Sayre syndrome (KSS), which consists of the triad of external ophthalmoplegia, heart block, and "salt-and-pepper" retinopathy. The other systemic manifestations included sensorineural hearing loss, slight generalized muscle weakness, cerebellar ataxia, and elevated levels of cerebrospinal fluid protein. He exhibited a heteroplasmic mitochondrial DNA deletion of approximately 9 kb between the cytochrome c oxidase subunit 1 and cytochrome b genes. In the authors' experience, this deletion is one of the longest to be observed in such patients. His fundi were characterized bilaterally by white flecks in the inner layers of retina at the midperiphery. Visual evoked potentials showed delayed latency in the P100 component. The tibial somatosensory evoked potential revealed a marked prolongation of interpeak latency between the N20 and P40 components. Brain magnetic resonance images revealed high-intensity foci in several regions on T2-weighted images. Electrophysiological and magnetic resonance imaging findings suggested an involvement of the white matter of the central nervous system in this patient that was not reflected in the clinical findings.

[Kearns-Sayre syndrome]

The authors describe a rare group of symptoms, resulting in progressive external ophthalmoplegia, retinal pigment epithelial dysfunction and cardiac conduction disturbance. The illness belongs to the group of mitochondrial cytopathies. The case extends over the diagnostic possibilities, with special attention on electromyographic diagnostic, clinical symptoms, pathomechanism of the disease, and the therapic possibilities.

Mitochondrial DNA deletion with Kearns Sayre syndrome in a child with Addison disease

Kearns Sayre syndrome (KSS) is a multisystem disorder with a confounding variety of clinical manifestations, including ocular myopathy, pigmentary retinopathy, heart block and ataxia. Endocrinopathies are common in KSS, including growth hormone deficiency, hypogonadism, diabetes mellitus and hypoparathyroidism. A variety of deletions of mitochondrial DNA (mtDNA) are found in most cases. We report on a 5-year-old boy with Addison disease in whom further investigation revealed a 4.9 kilobase mtDNA deletion and KSS. Later he developed severe lactic acidosis and expired.

CONCLUSION

The degree of mutant mtDNA heteroplasmy in various tissues on autopsy did not correlate well with the clinical manifestations, although this may be due at least in part to replacement with other tissue types. Our report is the first of non-autoimmune Addison disease in KSS and patients with KSS should be evaluated for adrenal insufficiency. Early recognition of adrenal insufficiency is crucial to prevent mortality from this cause.