Nemaline myopathy as a cause of sleep hypoventilation

Two siblings, a 14.5-year-old boy and his 11.5-year-old sister, with congenital nemaline myopathy presented with severe respiratory failure and, in the case of the older patient, with cor pulmonale and systemic hypertension. The children were treated initially by continuous mechanical ventilation, but after a few weeks they only required ventilation at night. At the start of treatment, both were found to have a decreased ventilatory response to CO2 which apparently improved during 4 to 5 years of follow-up treatment. It has not been possible to wean them from nocturnal mechanical ventilation, but during the daytime they attend school and function almost normally. It is postulated that respiratory failure in nemaline myopathy may not be related to the severity of the muscle weakness but may result from a disturbance of the feedback required for normal control of breathing.     

儿童型杆状体肌病2例临床、病理和基因研究

本文报道经肌肉病理及基因诊断确诊的儿童型杆状体肌病2例。2例患者均幼儿期起病,以肌肉无力为首发表现,病程长,进展缓慢。2例患者的肌肉病理光镜均发现Gomori染色及HE染色肌纤维胞浆内尤其肌膜下杆状物质沉积;电镜检查可见致密杆状体位于肌纤维肌膜下,与肌纤维长轴平行,部分肌纤维肌丝灶性溶解、坏死;基因检测发现两患儿分别存在杆状体肌病两种最常见的基因突变：ACTA1基因杂合突变（c.1013A > C）和NEB基因复合杂合突变（c.18676C > T及c.9812C > A）。杆状体肌病是一种常色体显性或隐性遗传的少见肌病,肌细胞胞浆中的杆状体是特征性肌肉病理改变。病理诊断和基因诊断是诊断杆状体肌病的金标准。     

线状体肌病1例报告并文献复习

目的 探讨线状体肌病的临床、病理特点和目前相关研究.方法 分析1例线状体肌病患儿临床表现、病理活检、电镜超微结构观察并结合文献复习.结果 患儿5岁时出现双下肢无力,病情进展缓慢,近端肌和远端肌均有受累.血清酶学正常,肌电图示所检肌肉无自发电位,神经传导均有不同程度异常.肌肉病理改变为肌纤维萎缩变细小,间质有少量纤维组织及脂肪细胞增生取代萎缩消失的肌纤维,肌纤维横纹清晰可见,无炎症细胞浸润.超微结构观察:核旁肌纤维中可见线状体,肌纤维呈灶性断裂缺失,肌纤维间隙增宽,肌萎缩,线粒体基本正常,未见线粒体内出现类晶体物,肌原纤维损害,肌丝溶解融合不清,部分局部可见肌节受挤压而排列紊乱或消失.通过电镜观察,结合临床,诊断为线状体肌病.结论 肌肉病理活检是确诊线状体肌病的唯一方法,而电镜为最后诊断该病的先决条件.     

Severe neonatal centronuclear (myotubular) myopathy: an X-linked recessive disorder

Prenatal onset and rapidly fatal course of centronuclear myopathy are described in four male newborns including two brothers. Diagnosis was established by muscle biopsy within the first week of life in two and at autopsy in the two other patients: Central nuclei, central aggregation of oxydative enzyme activity in the majority of muscle fibers and type 1 fibre hypotrophy were demonstrated. Prenatal manifestation included polyhydramnios, reduced fetal movements and breech presentation. All four newborns developed respiratory insufficiency requiring artificial ventilation immediately after birth. Severe muscular weakness and hypotonia as well as hardly elicitable grasping, deep tendon reflexes and Moro response were noticed. Additional findings included high arched palate, joint contractures, thin ribs, lung hypoplasia, abundant skin and cryptorchidism. In two families, the pedigree contains other affected males, suggesting X-linked inheritance. Seven female carriers were clinically healthy and one of them showed normal muscle histology. Fourteen previously published neonatal cases of centronuclear myopathy are reviewed and compared with our findings. This severe perinatal form of centronuclear myopathy has to be considered in male fetuses and newborns with polyhydramnios and respiratory failure due to muscular weakness or in infants who died of unexplained postnatal asphyxia. Diagnosis should be established by muscle biopsy.     

Nemaline myopathy: an unusual course]

A girl presents immediately post partum with postures and movements typical for severe muscular hypotonia (floppy infant). Her sucking and swallowing abilities are reduced. There is marked drooling. Broad alveolar ridges give the impression of a high-arched palate. Floppy infant-screening (muscle enzymes, EMG, NCV) was within normal ranges apart from a slight elevation of aldolase. Muscle biopsy performed at the age of two years revealed the diagnosis of nemaline myopathy. An onset of the disease with severe muscular hypotonia during neonatal period usually is linked with rapidly progressing, mostly lethal outcome. Our patient--in contrast--seems to suffer from a mild form.     

A new case of severe congenital nemaline myopathy

The case of a neonate with a rapidly fatal course of nemaline myopathy is reported. Neonatal history and clinical findings suggested a postasphyxia syndrome, but dependence on mechanical ventilation in the absence of severe brain damage or evidence of heart and lung involvement prompted us to perform a muscle biopsy. The typical rod-shaped bodies of nemaline myopathy were observed in skeletal and heart muscle which is unusual in infantile forms. Neonatal bone fractures, which have not been reported previously, were detected. Due to the rapid evolution of the neonatal form, many of these patients may die undiagnosed in the perinatal period, the families remaining unaware of the existence of the genetic disorder. Therefore, if severe hypotonia persists in a neonate, together with dependence on assisted breathing, specific examinations, such as muscle enzyme determination, NCV, EMG and if indicated, muscle biopsy should be performed to rule out neuromuscular disease.     

Respiratory deterioration during growth hormone therapy in a case of congenital nemaline myopathy

Congenital nemaline myopathy (CNM) is generally classified as a non-progressive or slowly progressive neuromuscular disease. We describe a boy with CNM and an isolated partial growth hormone (GH) deficiency. From the onset of GH therapy his respiratory capacity deteriorated rapidly. The possible association between this deterioration and GH therapy is discussed.     

Danon disease with typical early-onset cardiomyopathy in a male: focus on a novel LAMP-2 mutation

Abstract:  We report a case of a 16-yr-old male with Danon disease caused by a novel mutation in the LAMP-2 gene. Mutations in the LAMP-2 gene result in the absence of LAMP-2 on immunohistochemical staining of muscle tissue, thus defining Danon disease, a rare X-linked myopathy. It is characterized clinically by HCM or left ventricular hypertrophy, a WPW pattern on ECG, variable degrees of muscular weakness (skeletal myopathy), mental retardation, and retinal changes. The patient presented with severe skeletal muscular weakness and respiratory failure. He also had a history of two OHTs, the first one for severe HCM and the second for allograft rejection. The patient's myopathy was initially presumed to be exclusively related to steroid-induced "critical care myopathy." However, further evaluation with a thigh muscle biopsy revealed autophagic vacuoles with sarcolemnal features suggestive of a lysosomal storage disorder. DNA analysis ultimately identified a previously unreported hemizygous IVS6+3_+6delGAGT splice site deletion mutation in the LAMP-2 gene located within the 5' splice site of intron 6, consistent with Danon disease.     

Muscle weakness as presenting symptom of osteogenesis imperfecta

A young boy presented with severe muscle weakness of his legs at the age of 2 years. Muscle morphology and computer tomography imaging findings were compatible with a metabolic myopathy. Additional investigation showed an osteopenic skeleton and signs of healing fractures. A skin biopsy showed an abnormal electrophoresis pattern of collagen, consistent with a variant of osteogenesis imperfecta. The patient improved with intravenous treatment with pamidronate.     

Gastroesophageal reflux associated with nemaline myopathy of infancy

A severe infantile form of nemaline myopathy has a high mortality rate when untreated because of subsequent malnutrition and respiratory failure. Three infants with this condition demonstrated persistent vomiting, poor weight gain, and recurrent pneumonias. Esophageal manometry demonstrated decreased lower esophageal sphincter pressures and low amplitude peristalsis; 24-hour esophageal pH monitoring revealed significant gastroesophageal reflux. Medical therapy was ineffective in relieving symptoms. After antireflux surgery, vomiting and respiratory symptoms ceased, and there was no longer significant gastroesophageal reflux during pH monitoring. Our experience indicates that in some infants with nemaline myopathy a severe form of gastroesophageal reflux develops that is not responsive to medical therapy. Early surgical intervention may decrease life-threatening complications associated with gastroesophageal reflux in these infants.     

Ehlers-Danlos Syndrome Type VI in a 17-Year-Old Iranian Boy with Severe Muscular Weakness – A Diagnostic Challenge?

Background

The Ehlers-Danlos syndrome type VI (EDSVI) is an autosomal recessive connective tissue disease which is characterized by severe hypotonia at birth, progressive kyphoscoliosis, skin hyperelasticity and fragility, joint hypermobility and (sub-)luxations, microcornea, rupture of arteries and the eye globe, and osteopenia. The enzyme collagen lysyl hydroxylase (LH1) is deficient in these patients due to mutations in the PLOD1 gene.

Case Presentation

We report a 17-year-old boy, born to related parents, with severe kyphoscoliosis, scar formation, joint hypermobility and multiple dislocations, muscular weakness, rupture of an ocular globe, and a history of severe infantile hypotonia. EDS VI was suspected clinically and confirmed by an elevated ratio of urinary total lysyl pyridinoline to hydroxylysyl pyridinoline, abnormal electrophoretic mobility of the α-collagen chains, and mutation analysis.

Conclusion

Because of the high rate of consanguineous marriages in Iran and, as a consequence thereof, an increased rate of autosomal recessive disorders, we urge physicians to consider EDS VI in the differential diagnosis of severe infantile hypotonia and muscular weakness, a disorder which can easily be confirmed by the analysis of urinary pyridinolines that is highly specific, sensitive, robust, fast, non-invasive, and inexpensive.     

Hypokalemic rhabdomyolysis in a child with 11-hydroxylase deficiency

Myopathy is a well-recognized complication of persistent hypokalemia. Although hypokalemic myopathy may be due to divers diseases or to drug administration, hypokalemic rhabdomyolysis as a complication of under-treated 11-hydroxylase deficiency has not previously been described in the literature. We describe a 10-year-old boy with under-treated 11-hydroxylase deficiency who developed rhabdomyolysis following severe hypokalemia. Patients with under-treated 11-hydroxylase deficiency may present with hypokalemia in association with muscle weakness; if serum potassium is markedly low, rhabdomyolysis may occur. Hypokalemia-induced rhabdomyolysis should be carefully followed.     

Rod myopathy. A fatal neonatal case

A new lethal case of nemaline myopathy is reported. Muscle biopsy at 20 days of age permitted the diagnosis but this boy died at the 35th day of life. In a review of the literature (15 similar cases) the authors analyse the diagnostic, histopathogenic, genetic and evolutive aspects of this heterogeneous disorder, apparently less "benign" than previously thought.     

Sodium valproate — Induced skeletal myopathy

The authors report a case of skeletal myopathy in a four-year-old boy on long-term sodium valproate therapy for secondary epilepsy due to neurocysticercosis. He presented with clinical features of limb girdle weakness. EMG revealed features of myopathy. Carnitine deficiency due to sodium valproate was suspected and plasma carnitine levels were found to be low. Sodium valproate was withdrawn. L-carnitine supplementation resulted in marked clinical recovery as well as rise in plasma carnitine levels.     

Severe Neonatal Nemaline Myopathy—Histological and Histochemical Studies of Respiratory Muscles—

The histological and histochemical findings in the respiratory muscles of a patient with severe neonatal nemaline myopathy are described. The patient suffered from frequent pneumonia associated with vomiting due to gastroesophageal reflux and died at 3 months from respiratory failure. The diaphragm was moderately involved and the intercostal muscles mildly involved. Core/targetoid structures were observed in the diaphragm and intercostal muscles.     

Vimentin/desmin Immunoreactivity of Myofibres in Developmental Myopathies

Immunoreactivity for the intermediate filament proteins vimentin and desmin was studied in muscle biopsies of 33 children with neuromuscular diseases and in postmortem muscle of 15 fetuses and neonates at 8–42 weeks gestation. Fetal myotubes exhibited strong reactions for vimentin and desmin; reactivity was still present, though weaker, by 31 weeks and was no longer demonstrable at term. In X-linked myotubular myopathy (5 cases) myofibres showed strong reactivity for both vimentin and desmin; in myotonic dystrophy desmin but not vimentin had strong reactivity in myofibres of neonates and children. A similar but much weaker pattern of desmin reactivity was seen in nemaline rod disease and in congenital muscle fibre-type disproportion. The small myofibres in spinal muscular atrophy were reactive for both vimentin and desmin, as were regenerating myofibres in Duchenne muscular dystrophy and dermatomyositis. Acridine orange fluorochrome distinguished vimentin/desmin-reactive myofibres that were regenerating from those of developmental myopathies because the RNA fluorescence was strong in regenerating myofibres and in fetal myotubes, but was absent from myofibres in developmental disorders of muscle. A failure to regress of fetal cytoskeletal proteins may contribute to the apparent arrest in morphogenesis of myofibres. These stains are useful in studying the muscle biopsies of children with developmental myopathies because they demonstrate an aspect of muscle maturation not detected by standard histochemical methods.     

Multicore myopathy with restrictive cardiomyopathy

A 10-y-old girl is presented who suffered mild muscular weakness and exercise intolerance from the age of 1 y onwards, with progression appearing from the age of about 8 y. Multicore myopathy and restrictive cardiomyopathy were diagnosed. Literature concerning the coexistence of multicore myopathy and cardiomyopathy is reviewed.     

A new congenital myopathy in a Norwegian family

A 6-y-old boy presented with a mild, and apparently non-progressive, congenital myopathy, primarily affecting explosive movements such as running and jumping. Five other cases, spanning four generations, were identified in his family. A dominant inheritance pattern was suggested. Quadriceps muscle histology showed a selective type II fibre atrophy, which is otherwise considered a non-specific change associated with a number of conditions. Conclusion: A Norwegian boy with an inherited muscle weakness is presented. Based on clinical and laboratory investigations, and in light of the inheritance pattern, a previously undescribed congenital myopathy is suggested.     

Mutations in the Nebulin Gene in a Child with Nemaline (Rod) Myopathy

Nemaline myopathy, also called rod myopathy, is a relatively common congenital myopathy and probably second in incidence only to central core disease. The mainstay of diagnosis is histopathology, but detection of the causative mutation is mandatory for determining the mode of inheritance and for prenatal diagnosis. The authors report two siblings with nemaline myopathy caused by mutations in the nebulin gene.     

Articulation disorder as the initial manifestation of facioscapulohumeral muscular dystrophy in childhood

A five year old boy who had received logopedic treatment for more than two years was seen as an outpatient because of speech retardation. He presented with myopathic face, incomplete closure of both lids and severe weakness of facial muscles, bilateral winging of scapulae and hyperlordosis. Extraocular and pharyngeal muscles were not affected. Motor and sensory nerve fibre conductions and electromyography were within normal limits. CPK was moderately elevated (320 U/I). Muscle biopsy of right deltoid muscle revealed unspecific myopathic changes. The patients brother aged 7 also presented with facial weakness, elevated CPK and neurogenic changes in EMG of deltoid muscle. Both parents were clinically and electrophysiologically unremarkable. Although problems to speak distinctly are usually not the first manifestation, we found in this family facio-scapulo-humeral muscular dystrophy.