Ventilatory support in facioscapulohumeral muscular dystrophy

Respiratory insufficiency due to respiratory muscle weakness is a common complication of many neuromuscular diseases. The prevalence of respiratory failure in facioscapulohumeral muscular dystrophy (FSHD) is unknown. The authors identified 10 FSHD patients on nocturnal ventilatory support at home, representing approximately 1% of the Dutch FSHD population. Severe muscle disease, wheelchair dependency, and kyphoscoliosis appeared to be risk factors for respiratory failure.     

Leadless intracardiac transcatheter pacing system: 20 months follow up in adult Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked muscular dystrophy in relation with dystrophin deficient. Heart and respiratory function are classically involved and affect long-term prognosis. Significant atrio-ventricular block may occur in some patients. Implantation of traditional pacemaker may be challenging in patients with tracheotomy and on permanent home mechanical ventilation. We report the first case of a successful leadless intra-cardiac trans-catheter pacing system implantation in an adult DMD on wheelchair and on permanent home mechanical ventilation.     

Congenital Muscular Dystrophy Presenting with Respiratory Failure

Respiratory failure is an unusual initial manifestation of congenital muscular dystrophy. The authors describe a case of congenital muscular dystrophy in a patient presenting with rhabdomyolysis at birth. Despite an initially poor prognosis, aggressive respiratory therapy during the neonatal period permitted normal subsequent development. The muscular dystrophy predominantly involved the respiratory muscles.     

A case of rigid spine syndrome associated with severe respiratory failure]

Rigid spine syndrome (RSS) is clinically characterized by progressive limitation of flexion of the spine and contractures of other joints. We herein report a 27-year-old man with RSS, who underwent tracheotomy because of severe restrictive respiratory failure. He had limitation of neck flexion and proximal muscle weakness from early childhood and was diagnosed as having muscular dystrophy at 16 years old. He was suffered from dyspnea and his first tracheotomy was performed at 24 years old. Two years later, the second tracheotomy was done because his respiratory failure was aggravated. He had limitation of spine flexion, scoliosis, but no limited range of elbow and wrist joints movement except mild contracture of ankle joints. Serum CK level was elevated to 590 IU/L. Repeated ECG examinations showed negative T wave but no conduction block. In his family, his parents and brother had neither similar clinical symptoms nor heart block. Chest X-ray study showed elevated diaphragm and enlarged heart shadow (CTR = 65%). Percent VC and FEV1 in sitting position were 14.6% and 100%, respectively. Arterial blood gas analysis showed PaO2 of 34.2 mmHg and PaCO2 of 77.2 mmHg. The density of paraspinal muscle in CT scan was severely decreased. Needle EMG showed myogenic change. Muscle biopsy from left biceps brachii showed myopathic change with mild type 2 fiber grouping. After the second tracheotomy, he was on a respiratory during sleep but mostly off in the daytime. His clinical features are different from Emery-Dreifuss muscular dystrophy because he had no heart conduction block and no family history, but progressive respiratory failure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Respiratory management in muscular dystrophies

Respiratory failure is a major contributor to immobility and mortality in progressive muscular dystrophies. The severity of pulmonary impairment and the stage at which it develops differ according to the type of muscular dystrophy. Appropriate respiratory management for each type should be considered. In Duchenne muscular dystrophy (DMD), respiratory impairment manifests in the late teens, and assisted mechanical ventilation is administered. Noninvasive positive-pressure ventilation (NIPPV) has increased the median survival of patients with DMD by 10 year and improved quality of life. In myotonic dystrophy (MyD), the causes of respiratory failure can involve both the central and the peripheral nervous systems in addition to respiratory muscles. Nocturnal desaturation is more severe in MyD than in other muscular dystrophies with similar degrees of respiratory muscle weakness. Cognitive impairment should be taken into account in the management of MyD patients. NIPPV does not appear to improve survival of MyD. Guidelines for DMD have been published. Respiratory function should be assessed serially by measuring forced vital capacity, oxyhemoglobin saturation, peak cough flow, and end-tidal CO₂ level. A respiratory action plan should be enacted with increasing disease severity. Therapeutic measures comprise airway clearance, respiratory muscle training, noninvasive nocturnal ventilation, daytime noninvasive ventilation, and continuous invasive ventilation. At the advanced stage of respiratory failure, attention should be paid to complications related to long-term mechanical ventilation, such as pneumothorax and tracheal hemorrhage. Discussing about end-of-life care among the patient, family, and physician is important before mechanical ventilatory support is required.     

Management of end stage respiratory failure in Duchenne muscular dystrophy

There were 31 Duchenne patients placed on overnight mouth intermittent positive pressure ventilation for severe respiratory insufficiency at the average age of 19.9 years. Most patients had vital capacities less than 200 cc at their last evaluations. Of these, 23 patients are alive at the average age of 27 years and live in the community, although they are dependent on assisted ventilation 24 hours a day. There were 8 patients who died at the average age of 30 years. Although normocapnic during the day, the presence of symptomatic nocturnal hypoventilation or pCO2 over 55 mmHg documented by continuous overnight capnograph study indicates the need for introducing overnight respiratory assistance. Mouth intermittent positive pressure ventilation alone or in combination with other techniques of ventilatory assistance can prolong life while allowing optimal function, attainment of higher levels of education, and home management of patients with Duchenne muscular dystrophy.     

RESPIRATORY MUSCLE TRAINING IN DUCHENNE MUSCULAR DYSTROPHY

Eighteen boys with Duchenne muscular dystrophy were entered into trials to assess the effects of specific ventilatory strength and endurance training programmes. The findings showed an improvement in ventilatory muscle endurance but not in strength as a result of specific respiratory muscle training. The clinical significance of these findings is uncertain, however, and needs further evaluation.     

Ventilatory response in myotonic dystrophy

Patients with myotonic dystrophy often develop respiratory failure caused by alveolar hypoventilation. Abnormalities in the ventilatory response to hypoxia and hypercapnia may explain this phenomenon. Accordingly, hypoxic and hypercapnic responses were measured in seven patients with myotonic dystrophy who had only mild respiratory muscle weakness. Hypoxic response was significantly reduced, while hypercapnic response was affected more irregularly. It is possible that the high incidence of respiratory failure in such patients is related to decreased hypoxic ventilatory response, occurring because of an underlying neurogenic deficit.     

Secretion and clinical significance of atrial natriuretic peptide in patients with muscular dystrophy

In patients with Duchenne muscular dystrophy (DMD), heart failure appears in later stage of the disease due to myocardial degeneration and respiratory insufficiency, and sometimes causes death. However, there have been no adequate parameters which can be used easily to evaluate the grade of heart failure in DMD, except cardiac enlargement and pulmonary congestion observed by chest X-ray picture. Thus, we measured the plasma concentrations of atrial natriuretic peptide (ANP) in the patients with muscular dystrophy of various types, and studied a relationship between plasma ANP concentration and heart failure, expecting that it could be an index of heart failure in DMD patients. The plasma ANP concentrations in patients with DMD were 35.5 +/- 3.3pg/ml (mean +/- SE) and higher than in normal subjects (19.3 +/- 1.0pg/ml). In the patients with limb-girdle muscular dystrophy, facioscapulohumeral muscular dystrophy and neurogenic muscular atrophy, the plasma ANP concentration showed a tendency to elevate. However, no elevation of plasma ANP levels was observed in the patients with other types of muscular dystrophy. In DMD, number of the patients having a high plasma ANP concentration was increased with progress of disability grade, and decrease in serum creatine kinase activity and serum myoglobin concentration. There was a significant correlation (p less than 0.01) between plasma ANP concentration and cardiothoracic ratio or PEP/LVET, but no correlation between the concentration and respiratory failure. Immunohistochemistry of the atrial cardiac muscle of an autopsied DMD case revealed many ANP-positive atrial muscle cells, indicating the preservation of ANP-secreting function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chronic respiratory failure in limb-girdle muscular dystrophy: Successful long-term therapy with nasal bilevel positive airway pressure

Chronic respiratory failure is a major factor contributing to mortality in progressive neuromuscular disorders. Among the muscular dystrophies, respiratory failure most commonly occurs with Duchenne dystrophy, while in Becker, limb-girdle, and facioscapulo-humeral dystrophies, respiratory failure is infrequent and generally occurs in the more severe cases that have progressed to a nonambulatory, advanced functional stage. We report two brothers with a myopathic disease in which the distribution of weakness, initial clinical course, heredity, and muscle pathology most closely resembled a limb-girdle type of dystrophy. Both brothers, however, presented with chronic alveolar hypoventilation and respiratory failure when their locomotor disabilities were still mild. Respiratory failure was reversed, and satisfactory ventilation has been maintained for more than a year using a type of non-invasive intermittent positive pressure ventilation, with a bilevel positive airway pressure device (Bi-PAP), administered through a nasal mask during sleeping hours. These cases demonstrate an unusual presentation of limb-girdle dystrophy, and document that nocturnal, nasal administration of continuous airway pressure using the Bi-PAP device may be sufficient to maintain adequate long-term ventilation in some patients with neuromuscular causes of respiratory failure, and thus significantly improve quality of life and delay the need for more complex or invasive forms of assisted ventilation.     

Clinical and molecular characterization of patients with limb-girdle muscular dystrophy type 2I

BACKGROUND: Limb-girdle muscular dystrophy type 2I is caused by mutations in the fukutin-related protein gene (FKRP). FKRP encodes a putative glycosyltransferase protein that is involved in alpha-dystroglycan glycosylation. OBJECTIVES: To identify patients with limb-girdle muscular dystrophy type 2I and to derive genotype-phenotype correlations. DESIGN: Two hundred fourteen patients who showed muscle histopathologic features consistent with muscular dystrophy or myopathy of unknown etiology were studied. The entire 1.5-kilobase FKRP coding sequence from patient DNA was analyzed using denaturing high-performance liquid chromatography of overlapping polymerase chain reaction products, followed by direct sequencing of heteroduplexes. RESULTS: Thirteen patients with limb-girdle muscular dystrophy type 2I (6% of all patients tested) were identified by FKRP mutation analysis, and 7 additional patients were identified by family screening. Six missense mutations (1 novel) were identified. The 826C>A nucleotide change was a common mutation, present in 35% of the mutated chromosomes. Clinical presentations included asymptomatic hyperCKemia, severe early-onset muscular dystrophy, and mild late-onset muscular dystrophy. Dilated cardiomyopathy and ventilatory impairment were frequent features. Significant intrafamilial and interfamilial clinical variability was observed. CONCLUSIONS: FKRP mutations are a frequent cause of limb-girdle muscular dystrophies. The degree of respiratory and cardiac insufficiency in patients did not correlate with the severity of muscle involvement. The finding of 2 asymptomatic patients with FKRP mutations suggests that modulating factors may ameliorate the clinical phenotype.     

An overexpression of fibroblast growth factor (FGF) and FGF receptor 4 in a severe clinical phenotype of facioscapulohumeral muscular dystrophy

We evaluated the expression of a select panel of growth factors and their receptors, including fibroblast growth factor 1 (FGF-1), fibroblast growth factor 2 (FGF-2), platelet-derived growth factor (PDGF), FGF receptor 1 (FGF-R1), FGF receptor 3 (FGF-R3), FGF receptor 4 (FGF-R4), PDGF receptor alpha (PDGF-Ralpha), PDGF receptor beta (PDGF-Rbeta), and heparan sulfate proteoglycan (HSPG), in muscle biopsy specimens from nine facioscapulohumeral muscular dystrophy (FSHD) patients using immunohistochemistry. Two cases of Duchenne-type muscular dystrophy (DMD), two of Becker-type muscular dystrophy (BMD), and one of limb-girdle-type muscular dystrophy (LGMD) were also investigated. Widespread immunostaining for FGF-1 and FGF-2 on the sarcolemma and overexpression of FGF-R4 in endomysial and perimysial connective tissue were seen in one patient with a severe clinical phenotype of FSHD who had respiratory failure. Standard histochemistry in this patient revealed marked interstitial fibrosis and lobulated fibers. The overexpression of FGF and FGF-R4 in this severe FSHD case may be associated with the muscle fibrosis and disease severity.     

Prandial hypoxia in progressive muscular dystrophy]

Progressive muscular dystrophy patients often show progressive body weight loss in early adolescence. This severe body weight loss frequently causes superior mesenteric artery syndrome which may result in a fatal outcome. We performed prandial pulse oximetry and found 12 out of 35 Duchenne muscular dystrophy patients, 1 out of 2 Becker muscular dystrophy patients and 1 out of 3 Limb-Girdle muscular dystrophy patients showed prandial hypoxia with tachycardia. The patients became tired and eating habits were easily interrupted resulting in progressive body weight loss. Nasal administration of 0.2L/min oxygen to 2 Duchenne muscular dystrophy patients, and nasal intermittent positive pressure ventilation to 2 Duchenne muscular dystrophy patients, 1 Becker muscular dystrophy patient and 1 Limb-Girdle muscular dystrophy patient for 15-30 minutes before eating improved the prandial hypoxia and halted the progression of body weight loss. This prandial hypoxia is one of the earliest signs of respiratory failure in progressive muscular dystrophy.     

Depressed left ventricular contractile reserve diagnosed by dobutamine stress echocardiography in a patient with Duchenne muscular dystrophy

Cardiomyopathy is a leading cause of death in patients with Duchenne muscular dystrophy. Congestive heart failure is often sub-clinical and unrecognized as a result of the severe physical limitations of this patient population. We report the case of a 16-year-old boy with Duchenne muscular dystrophy who demonstrated normal left ventricular systolic function at rest by screening transthoracic echocardiogram. This patient, however, was noted to have depressed left ventricular contractile reserve by dobutamine stress echocardiography. Dobutamine stress echocardiography can have an important role in unmasking subclinical heart failure in this patient population.     

Efficacy and tolerance of gastrostomy feeding in Japanese muscular dystrophy patients

Although muscular dystrophy patients often have feeding difficulty and need long-term enteral nutrition, only a few reports have described gastrostomy feeding in these patients. This study was designed to evaluate the efficacy and tolerance of gastrostomy feeding in patients with muscular dystrophy. We performed a retrospective, multicenter study on 144 patients with muscular dystrophy who received gastrostomy feeding between 2007 and 2009 in 25 neuromuscular centers in Japan. There were 77 Duchenne muscular dystrophy (median age at gastrostomy placement 26 years, range 13-47 years), 40 myotonic dystrophy (median age 54.5 years, range 13-70 years), 11 Fukuyama congenital muscular dystrophy (median age 22 years, range 13-29 years), 5 limb girdle muscular dystrophy (median age 62 years, range 43-78 years), and 5 facioscapulohumeral muscular dystrophy (median age 52 years, range 28-67 years) patients. Many benefits including amelioration of malnutrition, swallowing difficulty and respiratory status were observed after the introduction of gastrostomy feeding. Especially in patients with Duchenne muscular dystrophy, mean body weight significantly increased after gastrostomy placement. Although most complications, which are commonly observed in other populations, were tolerable, respiratory failure and peritonitis were important concerns. These findings suggest that gastrostomy placement at an appropriate time is advisable in patients with muscular dystrophy.     

Familial facioscapulohumeral muscular dystrophy: phenotypic diversity and genetic abnormality

We report two cases showing facioscapulohumeral muscular dystrophy (FSHD) with phenotypic diversity but the same genetic abnormality detected by a p13E-11 probe. The proband, a 26-year-old woman, showed an early onset, tortuosity of retinal arterioles and respiratory failure. The 53-year-old mother of the proband had limb-girdle (L-G) type muscular weakness with very mild facial involvement. Muscle biopsy showed perivascular cell infiltration in both patients. These cases suggest that the phenotypic diversity ranges from L-G type weakness to severe respiratory failure in FSHD family.     

Spinal cord limb motor neurones in muscular dystrophy

Using a technique previously described by two of the authors of counting the total numbers of limb motor neurones in the lumbosacral enlargement of the spinal cord, 9 cases previously diagnosed as examples of muscular dystrophy have been studied at autopsy. In 6 established cases of muscular dystrophy of the Duchenne type the total numbers of motor neurones were normal, except in 1 case in which focal loss of neurones in several spinal cord segments was attributed to a previous attack of poliomyelitis. Variable chromatolysis of neurones and increase of glial cells were also noted in these cases but the latter change may in part have been due to “crowding” of cells resulting from shortening of the lumbosacral segments. In 1 other case previously diagnosed as an example of Duchenne muscular dystrophy, the findings at autopsy were those of spinal muscular atrophy but in fact investigation in life shortly before death had led to revision of the clinical diagnosis in this case to one of the Kugelberg-Welander syndrome. In 1 other case, diagnosed in life as an example of limb-girdle muscular dystrophy, the reduction of limb motor neurones found at autopsy indicated that the patient had been suffering from chronic spinal muscular atrophy. In the final case of this series in whom diagnoses of peroneal muscular atrophy, spinal muscular atrophy and distal muscular dystrophy had been entertained during life, the total numbers of limb motor neurones in the lumbo-sacral cord were only just below the lower limit of normal and it was concluded that the patient had been suffering from distal muscular dystrophy.Histological changes of widespread myocardial fibrosis indicative of cardiomyopathy were found in all 6 cases of Duchenne type muscular dystrophy but also in the case of spinal muscular atrophy of the Kugelberg-Welander type and in the patient with distal muscular dystrophy. The possibility that such a cardiomyopathy could be the result of an autoimmune process due to the production of circulating antibodies which attack cardiac muscle in patients suffering from any disease giving longstanding and progressive destruction of voluntary muscle is raised.     

Selenoprotein N muscular dystrophy: differential diagnosis for early-onset limited mobility of the spine

Early spinal rigidity is a nonspecific feature reported in diseases such as neuromuscular and central movement disorders. We present a male patient with rigid spine muscular dystrophy caused by newly identified compound heterozygote mutations of the selenoprotein N gene and discuss this disease as a possible differential diagnosis for early-onset reduced spine mobility. Rigid spine muscular dystrophy is a rare myopathy presenting in childhood with a typical combination of stable or slowly progressive mild to moderate muscle weakness, limitation in flexion of the spine, and progressive restrictive ventilatory disorder. The clinical features of our patient include early-onset rigidity of his spine, scoliosis, mild muscular weakness predominantly of neck and trunk flexors, and restrictive ventilatory disorder. Biopsy of the biceps muscle revealed nonspecific myopathic changes, and molecular analysis confirmed the diagnosis of rigid spine muscular dystrophy. Thus, neuromuscular diseases such as muscular dystrophy must be considered in all patients presenting with early spinal rigidity, and genetic determination is a possible way to determine the diagnosis.     

Pulmonary function and electromyographic study of respiratory muscles in myotonic dystrophy

Ten adult myotonic dystrophy patients underwent measurements of lung function, maximal dynamic and static ventilatory efforts, and respiratory muscle electromyography (EMG). EMG studies were performed during spontaneous breathing or when subjects breathed through high inspiratory or expiratory resistive loads. Present results show that (1) a moderate restriction of lung volumes with hypoxemia plus normocapnia is often observed; (2) patients sustain dynamic ventilatory efforts more easily than static work; and (3) abnormalities in respiratory muscle EMG exist with spontaneous expiratory and inspiratory intercostal activities during quiet breathing and changes in muscular response to resistive loads. Inspiratory loading evokes contraction of expiratory muscles, with a marked decrease in inspiratory activities. Expiratory resistive loads prolong the diaphragmatic contraction throughout the expiratory time, and in some patients, relaxation of the diaphragm does not occur during the loaded run. These EMG data suggest that the reciprocal inhibition among respiratory neurons is enhanced in myotonic dystrophy and that myotonia also occurs in the diaphragm when loads oppose its relaxation.