Nemaline cardiomyopathy in a young adult: an ultraimmunohistochemical study and review of the literature

Respiratory treatment in a patient with nemaline myopathy

Respiratory involvement of nemaline myopathy is evident on the diaphragm and intercostal muscles function. The present case study aimed to describe the characteristics of the respiratory physiotherapeutic treatment in a patient with nemaline myopathy. Here, we describe a case of a 43-yearold woman with nemaline myopathy undergoing pulmonary rehabilitation during short hospital admission for an acute exacerbation. At the time of hospitalisation, the patient was already under oxygen therapy (1 L/min) and noninvasive home ventilation using bi-level positive airway pressure with a nasal interface. Supplementary therapeutic exercises were implemented in addition to daily nasal noninvasive ventilation. At discharge, ultrasound examination revealed increased diaphragm trophism if compared with data obtained at hospital admission.

Congenital myopathies are mainly associated with a mild cardiac phenotype

BACKGROUND

To evaluate the prevalence of cardiac involvement in patients with congenital myopathies and the association to specific genotypes.

METHODS

We evaluated patients with physical examination, electrocardiogram, echocardiography, and 48-h Holter monitoring. Follow-up was performed for major events.

RESULTS

We included 130 patients, 55 men (42%), with a mean age of 34 ± 17 years. A genetic diagnosis was established in 97 patients (75%). Right bundle branch block was observed in three patients: 2/34 patients with a ryanodine receptor 1 (RYR1) and 1/6 with a tropomyosin two gene (TPM2) gene mutation. Echocardiography showed left-ventricular hypertrophy in five patients: 2/17 and 3/34 patients with a Dynamin 2 (DNM2) and a RYR1 mutation, respectively. One patient with a myosin heavy-chain (MYH7) mutation had dilated cardiomyopathy and heart failure. On Holter monitoring, frequent ventricular premature contractions were observed in one patient with a DNM2 mutation. Two patients with a TPM2 and a RYR1 mutation, respectively, had a single short run of non-sustained ventricular tachycardia. Atrioventricular nodal re-entry tachycardia was observed in a 20-year-old man with an actin 1 gene mutation. During follow-up (median 8.4 years), four patients died, all of non-cardiac causes.

CONCLUSION

Congenital myopathies are generally associated with a mild cardiac phenotype. Our findings substantiate the literature and indicate that, except for patients with specific genotypes, such as MYH7 and TTN mutations, repeated cardiac assessments can be minimized, given a normal initial cardiac screening at time of diagnosis.

[Two cases of nemaline myopathy presenting with hypertrophy of distal limbs with prominent asymmetry]

Nemaline myopathy commonly presents with symmetrical proximal weakness. Here we report two cases of nemaline myopathy presenting with distal dominant involvement with prominent asymmetry. Case 1 was a 37-year-old man who recalled frequently falling down and had right calf atrophy since he was 3-years-old. He had right calf muscle atrophy and weakness and steppage gait; his cardiopulmonary function was normal. Case 2 was a 35-year-old man with right calf muscle atrophy and weakness since childhood. He had right dominant distal leg weakness and atrophy together with respiratory failure and started noninvasive positive pressure ventilation. He also developed cardiomyopathy and died from acute respiratory failure due to pneumonia at age 39. Both cases harbored compound heterozygous nebulin (NEB) mutations with c.20131 C>T:p.Arg6711Trp and a nonsense mutation. Nemaline myopathy associated with NEB mutations can present as distal dominant myopathy with prominent asymmetry.

Review of Cardiac Disease in Nemaline Myopathy

OBJECTIVES

Little is known about the type, frequency, severity, treatment, and outcome of cardiac disease in nemaline myopathy. This review summarizes and discusses findings concerning the type, prevalence, diagnosis, treatment, and outcome of cardiac involvement in nemaline myopathy.

METHODS

Review of publications about nemaline myopathy and cardiac disease.

RESULTS

Altogether, 35 patients with nemaline myopathy with cardiac disease were identified. Age at presentation ranged from 0 to 62 years. In 30 individuals whose gender was described, 22 were male and eight were female. Onset was congenital in 16 patients, infantile in five, and adult in four. Nine patients presented with dilated cardiomyopathy, six with hypertrophic cardiomyopathy, and one with nonspecific cardiomyopathy. Among those with cardiomyopathy, four developed heart failure. One patient experienced sudden cardiac death. A ventricular septal defect was described in two patients. Cardiac treatment included drugs for heart failure (eight patients), implantable cardioverter-defibrillator implantation (one patient), and heart transplant (three patients). Four patients received noninvasive positive-pressure ventilation and two continuous positive-pressure ventilation. The outcome was fatal in 11 patients.

CONCLUSIONS

Cardiac disease in nemaline myopathy manifests as cardiomyopathy leading to heart failure. If respiratory muscles are affected, the right side of the heart may be secondarily involved. Early detection of cardiac involvement is essential since effective treatment for cardiac disease in nemaline myopathy may be available.

Potential causes of sudden cardiac death in nemaline myopathy

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[Treatability of sporadic late onset nemaline myopathy]

Sporadic late onset nemaline myopathy (SLONM) is an extremely rare disorder which can be associated with monoclonal gammopathy of unclear significance (MGUS). Clinically SLONM appears mostly after the fourth decade of life as rapidly progressing tetraparesis, respiratory insufficiency and features, such as dropped head syndrome, facial and bulbar involvement. Diagnosis is confirmed by muscle biopsy with detection of nemaline bodies and also frequently lobulated fibres. Immunosuppressant and immunomodulating therapies have been shown to be ineffective but clinical improvement accompanied by disappearance of monoclonal gammopathy and even nemaline bodies was reported following autologous stem cell transplantation and chemotherapy with melphalan. This article presents the case of a 53-year-old man with a 4-year history of SLOMN with MGUS in which administration of intravenous immunoglobulin therapy (IVIG) was not successful in reversing gammopathy, histopathological changes or clinical symptoms.

Nemaline myopathy in a newborn infant: a rare muscle disorder

Nemaline myopathy (NM) is a genetically and clinically heterogeneous muscle disorder, defined by the presence of characteristic nemaline bodies on muscle biopsy. The disease has a wide spectrum of phenotypes, ranging from forms with neonatal onset and fatal outcome to asymptomatic forms. The neonatal form is severe and usually fatal. The clinical variability, with differing age of onset and severity of symptoms makes the diagnosis difficult during infancy. There is no curative treatment. L-tyrosine may prevent aspiration by reducing pharyngeal secretions and drooling. Most of the patients die from respiratory and cardiac failure. This article discusses a newborn infant who presented with generalized weakness and respiratory failure. Partial response to L-tyrosine treatment was noted. The case is worth presenting to remind clinicians of congenital myopathies in the differential diagnosis of floppy infant during neonatal period and to emphasize the importance of muscle biopsy in diagnosis.

Nemaline myopathy with dilated cardiomyopathy in childhood

We present a case of a 9-year-old boy with nemaline myopathy and dilated cardiomyopathy. The combination of nemaline myopathy and cardiomyopathy is rare, and this is the first reported case of dilated cardiomyopathy associated with childhood-onset nemaline myopathy. A novel mutation, p.W358C, in ACTA1 was detected in this patient. An unusual feature of this case was that the patient's cardiac failure developed during early childhood with no delay of gross motor milestones. The use of a β-blocker did not improve his clinical course, and the patient died 6 months after diagnosis of dilated cardiomyopathy. Congenital nonprogressive nemaline myopathy is not necessarily a benign disorder: deterioration can occur early in the course of dilated cardiomyopathy with neuromuscular disease, and careful clinical evaluation is therefore necessary.

Cardiomyopathy in neurological disorders

According to the American Heart Association, cardiomyopathies are classified as primary (solely or predominantly confined to heart muscle), secondary (those showing pathological myocardial involvement as part of a neuromuscular disorder) and those in which cardiomyopathy is the first/predominant manifestation of a neuromuscular disorder. Cardiomyopathies may be further classified as hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, or unclassified cardiomyopathy (noncompaction, Takotsubo-cardiomyopathy). This review focuses on secondary cardiomyopathies and those in which cardiomyopathy is the predominant manifestation of a myopathy. Any of them may cause neurological disease, and any of them may be a manifestation of a neurological disorder. Neurological disease most frequently caused by cardiomyopathies is ischemic stroke, followed by transitory ischemic attack, syncope, or vertigo. Neurological disease, which most frequently manifests with cardiomyopathies are the neuromuscular disorders. Most commonly associated with cardiomyopathies are muscular dystrophies, myofibrillar myopathies, congenital myopathies and metabolic myopathies. Management of neurological disease caused by cardiomyopathies is not at variance from the same neurological disorders due to other causes. Management of secondary cardiomyopathies is not different from that of cardiomyopathies due to other causes either. Patients with neuromuscular disorders require early cardiologic investigations and close follow-ups, patients with cardiomyopathies require neurological investigation and avoidance of muscle toxic medication if a neuromuscular disorder is diagnosed. Which patients with cardiomyopathy profit most from primary stroke prevention is unsolved and requires further investigations.

Clinical and pathological features of childhood-onset nemaline myopathy: a report of four cases

We examined whether immunological abnormalities can be found in the specimens of four childhood-onset nemaline myopathy (NM) patients without autoimmune diseases. Pathological examination revealed that nemaline rods were found in all specimens. The immunohistochemical results showed that CD4 positive cells and some other cells were gathered among the necrotic muscle fibers. We conclude that immunological abnormalities are present in the specimens of certain childhood-onset NM patients without autoimmune diseases. Further evaluation of the immunological changes is warranted in childhood-onset NM patients.

Stroke and Stroke-like Episodes in Muscle Disease

Background:

Though not obvious at a first glance, myopathies may be associated with ischemic stroke. Stroke-like episodes resemble ischemic stroke only to some extent but are a unique feature of certain mitochondrial disorders with a pathogenesis at variance from that of ischemic stroke. Only limited data are available about ischemic stroke in pri-mary myopathies and the management of stroke-like episodes in mitochondrial disorders. This review aims to summarize and discuss current knowledge about stroke in myopathies and to delineate stroke-like episodes from ischemic stroke.

Methods:

Literature review via PubMED using the search terms “stroke”, “cerebrovascular”, “ischemic event”, “stroke-like episode”, “stroke-mimic”, “mitochondrial disorder”.

Results:

Stroke in myopathies is most frequently cardioembolic due to atrial fibrillation or atrial flutter, dilated cardio-myopathy, or left-ventricular hypertrabeculation (noncompaction). The second most frequent cause of stroke in myopathies is angiopathy from atherosclerosis or vasculitis, which may be a feature of inflammatory myopathies. Athero-sclerosis may either result from classical risk factors, such as diabetes, arterial hypertension, hyperlpidemia, or smoking, associated with muscle disease, or may be an inherent feature of a mitochondrial disorder. In case of severe heart failure from cardiomyopathy as a manifestation of muscle disease low flow infarcts may occur. Thrombophilic stroke has been described in polymyositis and dermatomyositis in association with anti-phospholipid syndrome. Stroke-like episodes occur particularly in mitochondrial encephalopathy, lactacidosis and stroke-likeepisode syndrome but rarely also in Leigh-syndrome and other mitochondrial disorders. Stroke-like episodes are at variance from ischemic stroke, pathogenically, clinically and on imaging. They may be the manifestation of a vascular, metabolic or epileptic process and present with predominantly vasogenic but also cytotoxic edema on MRI. Differentiation between ischemic stroke and stroke-like episodes is essential in terms of management and prognosis. Management of ischemic stroke in patients with myopathy is not at variance from the treatment of ischemic stroke in non-myopathic patients. There is no standardized treatment of stroke-like episodes but there is increasing evidence that these patients profit from the administration of L-arginine and conse-quent antiepileptic treatment if associated with seizure activity.

Conclusions:

Ischemic stroke may be a complication of myopathy and needs to be delineated from stroke-like episodes, which are unique to mitochondrial disorders, particularly mitochondrial encephalopathy, lactacidosis and stroke-likeepisode syndrome. Ischemic stroke in myopathies is most frequently cardioembolic and treatment is not at variance from non-myopathic ischemic stroke. Treatment of stroke-like episodes is not standardized but seems to respond to L-arginine and adequate antiepileptic treatment.

In vitro analysis of rod composition and actin dynamics in inherited myopathies

Rods are the pathological hallmark of nemaline myopathy, but they can also occur as a secondary phenomenon in other disorders, including mitochondrial myopathies such as complex I deficiency. The mechanisms of rod formation are not well understood, particularly when rods occur in diverse disorders with very different structural and metabolic defects. We compared the characteristics of rods associated with abnormalities in structural components of skeletal muscle thin filament (3 mutations in the skeletal actin gene ACTA1) with those of rods induced by the metabolic cell stress of adenosine triphosphate depletion. C2C12 and NIH/3T3 cell culture models and immunocytochemistry were used to study rod composition and conformation. Fluorescent recovery after photobleaching was used to measure actin dynamics inside the rods. We demonstrate that not all rods are the same. Rods formed under different conditions contain a unique fingerprint of actin-binding proteins (cofilin and alpha-actinin) and display differences in actin dynamics that are specific to the mutation, to the cellular location of the rods (intranuclear vs cytoplasmic), and/or to the underlying pathological process (i.e. mutant actin or adenosine triphosphate depletion). Thus, rods likely represent a common morphological end point of a variety of different pathological processes, either structural or metabolic.

Idiopathic adult-onset nemaline myopathy presenting with isolated respiratory failure

Idiopathic adult-onset nemaline myopathy is a rare condition of unknown etiology that usually presents with proximal weakness. This case study reports a 60-year-old woman who presented with isolated type 2 respiratory failure secondary to bilateral hemidiaphragm weakness. A left vastus medialis muscle biopsy examined under light microscopy revealed appearances typical of nemaline myopathy. Electron microscopy confirmed the presence of nemaline rods in most muscle fibers, thus establishing idiopathic adult-onset nemaline myopathy as the cause of her respiratory failure. Our patient's presentation highlights the importance of considering neuromuscular weakness as a cause of respiratory failure. Unless appropriate tests are performed-including a muscle biopsy, if indicated-specific neuromuscular diseases are easily missed. This can lead to inappropriate counseling and treatment.

Mouse models for thin filament disease

Thin filament integrity is important for the ordered structure and function of skeletal muscles. Mutations within genes that encode thin filament and thin filament-associated proteins can cause muscle disruption, fiber atrophy and alter fiber type composition, leading to muscle weakness. Analyses of patient biopsy samples and tissue culture systems provide rapid methods for studying disease-causing mutations. However, there are limitations to these techniques. Although time consuming, many laboratories are generating and utilizing animal models, in particular the mouse, to study the disease process of various myopathies. This chapter reviews the use of mouse models for thin filament diseases of skeletal muscle and in particular, concentrates on what has been achieved through the generation and characterization of transgenic and knock-in mouse models for the congenital thin filament disease nemaline myopathy. We will review potential therapies that have been trialled on the nemaline models, providing indications for future directions for the treatment of nemaline myopathy patients and muscle weakness in general.

Primary myopathies and the heart

Myopathies are frequently not confined to the skeletal muscles but also involve other organs or tissues. One of the most frequently affected organ in addition to the skeletal muscle is the heart (cardiac involvement, CI). CI manifests as impulse generation or conduction defects, focal or diffuse myocardial thickening, dilation of the cardiac cavities, relaxation abnormality, hypertrophic, dilated, restrictive cardiomyopathy, apical form of hypertrophic cardiomyopathy, noncompaction, Takotsubo phenomenon, secondary valve insufficiency, intra-cardiac thrombus formation, or heart failure with systolic or diastolic dysfunction. CI occurs in dystrophinopathies, Emery-Dreifuss muscular dystrophy, facioscapulohumeral muscular dystrophy, limb girdle muscular dystrophies, laminopathies, congenital muscular dystrophies, myotonic dystrophies, congenital myopathies, metabolic myopathies, desminopathies, myofibrillar myopathy, Barth syndrome, McLeod syndrome, Senger's syndrome, and Bethlem myopathy. Patients with myopathy should be cardiologically investigated as soon as their neurological diagnosis is established, since supportive cardiac therapy is available, which markedly influences prognosis and outcome of CI in these patients.

Tropomyosins in skeletal muscle diseases

A number of congenital muscle diseases and disorders are caused by mutations in genes that encode the proteins present in or associated with the thin filaments of the muscle sarcomere. These genes include alpha-skeletal actin (ACTA1), beta-tropomyosin (TPM2), alpha-tropomyosin slow (TPM3), nebulin (NEB), troponin I fast (TNNI2), troponin T slow (TNNT1), troponin T fast (TNNT3) and cofilin (CFL2). Mutations in two of the four tropomyosin (Tm) genes, TPM2 and TPM3, result in at least three different skeletal muscle diseases and one disorder as distinguished by the presence of specific clinical features and/or structural abnormalities--nemaline myopathy (TPM2 and TPM3), distal arthrogryposis (TPM2), cap disease (TPM2) and congenital fiber type disproportion (TPM3). These diseases have overlapping clinical features and pathologies and there are cases of family members who have the same mutation, but different diseases (Table 1). The relatively recent discovery of nonmuscle or cytoskeletal Tms in skeletal muscle adds to this complexity since it is now possible that a disease-causing mutation could be in a striated isoform and a cytoskeletal isoform both present in muscle.

Congenital myopathies at their molecular dawning

The introduction and application of molecular techniques have commenced to influence and alter the nosology of congenital myopathies. Long-known entities such as nemaline myopathies, core diseases, and desmin-related myopathies have now been found to be caused by unequivocal mutations. Several of these mutations and their genes have been identified by analyzing aggregates of proteins within muscle fibers as a morphological hallmark as in desminopathy and actinopathy, the latter a subtype among the nemaline myopathies. Immunohistochemistry has played a crucial role in recognizing this new group of protein aggregate myopathies within the spectrum of congenital myopathies. It is to be expected that other congenital myopathies marked by inclusion bodies may turn out to be such protein aggregate myopathies, depending on analysis of individual proteins within these protein aggregates and their association with putative gene mutations.

Familial cardioneuromyopathy with hyaline masses and nemaline rods: a novel phenotype

Two siblings (patients 1 and 2) had adult-onset muscle weakness that was greater distally than proximally, as well as respiratory insufficiency, cardiomyopathy, and cervical spine anomalies. Electromyography studies indicated myopathy and findings consistent with neuropathy in both. In the deltoid muscle of patient 1 and the anterior tibial muscle of patient 2, myriad type 1 fibers harbored large, irregularly polygonal, and mostly central hyaline masses, small vacuoles, and nemaline rods flanking the hyaline masses or congregated under the sarcolemma. The hyaline masses are intensely congophilic; react strongly for desmin, alphaB-crystallin, alpha1-antichymotrypsin, and ubiquitin and variably for gelsolin and dystrophin; and are devoid of alpha-actinin, nebulin, titin, and slow myosin. The presence of ubiquitin, gelsolin, and fragmented filaments, and the absence of nebulin, titin, alpha-actinin, and slow myosin in the hyaline masses, signal nonlysosomal protein degradation. Ultrastructurally, the hyaline masses are composed of intermediate-density amorphous material intermingled with fragmented filaments and irregularly branching, pleomorphic, highly electron-dense material, resembling the hyaline structures of myofibrillar myopathy. We conclude that the pathological process in this syndrome is one that induces destruction of myofibrillar components, resulting in aggregation of the degraded residues in hyaline masses, and causes replication of Z disks, resulting in formation of nemaline rods.

Sarcomatoid carcinoma of the urinary bladder: 3 case reports

Three cases of sarcomatoid carcinoma of the urinary bladder are considered. The patients were 2 males, aged 68 and 81 years, and a 79-year-old female. Transurethral resection of the bladder tumor (TUR-BT) and consecutive radical cystectomy were performed in all patients. Local progression of bladder tumors just after TUR-BT was recognized in the 2 younger patients, each of whom died due to recurrence after radical cystectomy. Because of the extremely aggressive malignant potential of sarcomatoid carcinomas, the indications for TUR-BT should be carefully assessed and suitable therapeutic strategies should be examined further.