Presentation, clinical course, and outcome of the congenital form of myotonic dystrophy

Childhood muscular dystrophies

Infancy- and childhood-onset muscular dystrophies are associated with a characteristic distribution and progression of motor dysfunction. The underlying causes of progressive childhood muscular dystrophies are heterogeneous involving diverse genetic pathways and genes that encode proteins of the plasma membrane, extracellular matrix, sarcomere, and nuclear membrane components. The prototypical clinicopathological features in an affected child may be adequate to fully distinguish it from other likely diagnoses based on four common features: (1) weakness and wasting of pelvic-femoral and scapular muscles with involvement of heart muscle; (2) elevation of serum muscle enzymes in particular serum creatine kinase; (3) necrosis and regeneration of myofibers; and (4) molecular neurogenetic assessment particularly utilizing next-generation sequencing of the genome of the likeliest candidates genes in an index case or family proband. A number of different animal models of therapeutic strategies have been developed for gene transfer therapy, but so far these techniques have not yet entered clinical practice. Treatment remains for the most part symptomatic with the goal of ameliorating locomotor and cardiorespiratory manifestations of the disease.

Respiratory outcomes in children with congenital myotonic dystrophy

PURPOSE

Congenital myotonic dystrophy (CDM) results in hypotonia and acute respiratory distress at birth. Previous studies show that prolonged periods of intubation (>4 weeks) correlate with increased mortality rates. The objective is to describe the use and duration of respiratory support in newborns with CDM and how these relate to mortality.

METHODS

A retrospective chart review was performed at a tertiary pediatric hospital among children with confirmed diagnosis of CDM. The main outcome measures were: mortality, duration of invasive mechanical ventilation (IMV) and non-invasive partial pressure ventilation (NIPPV), along with long-term use of respiratory support and equipment.

RESULTS

A total of 18 subjects met inclusion criteria, 83%.f which had documented respiratory distress at birth, 39%.equired NIPPV, and 50%.equired intubation in the neonatal period. The earliest NIPPV was initiated at day one of life, and the latest extubation to NIPPV was at 17 days of life.

CONCLUSION

This cohort required IMV for shorter periods with earlier transitions to NIPPV which suggests a possible change in practice and earlier transition to NIPPV recently. Further data are needed to determine if there is a possible correlation between the need for NIPPV/IMV and mortality rates.

Deciphering the mechanisms underlying brain alterations and cognitive impairment in congenital myotonic dystrophy

Myotonic dystrophy type 1 (DM1) is a multisystemic and heterogeneous disorder caused by the expansion of CTG repeats in the 3' UTR of the myotonic dystrophy protein kinase (DMPK) gene. There is a congenital form (CDM1) of the disease characterized by severe hypotonia, respiratory insufficiency as well as developmental delays and intellectual disabilities. CDM1 infants manifest important brain structure abnormalities present from birth while, in contrast, older patients with adult-onset DM1 often present neurodegenerative features and milder progressive cognitive deficits. Promising therapies targeting central molecular mechanisms contributing to the symptoms of adult-onset DM1 are currently in development, but their relevance for treating cognitive impairment in CDM1, which seems to be a partially distinct neurodevelopmental disorder, remain to be elucidated. Here, we provide an update on the clinical presentation of CDM1 and review recent in vitro and in vivo models that have provided meaningful insights on its consequences in development, with a particular focus on the brain. We discuss how enhanced toxic gain-of-function of the mutated DMPK transcripts with larger CUG repeats and the resulting dysregulation of RNA-binding proteins may affect the developing cortex in utero. Because the methylation of CpG islets flanking the trinucleotide repeats has emerged as a strong biomarker of CDM1, we highlight the need to investigate the tissue-specific impacts of these chromatin modifications in the brain. Finally, we outline promising potential therapeutic treatments for CDM1 and propose future in vitro and in vivo models with great potential to shed light on this disease.

Chylothorax as a complication of congenital myotonic dystrophy: A retrospective cohort study

BACKGROUND

The association between congenital myotonic dystrophy (CMD) and chylothorax is poorly recognized.

AIMS

To evaluate the proportion of chylothorax in infants with CMD compared to its prevalence in infants without CMD.

STUDY DESIGN

Single-center, retrospective, cohort study.

SUBJECTS

Infants managed at a neonatal intensive care unit from 2003 to 2019.

OUTCOME MEASURES

CMD was diagnosed using Southern blot for the quantification of CTG repeats in the dystrophia myotonica protein kinase (DMPK) gene. Prenatal and postnatal data of eligible infants with CMD were collected from the patients' medical records. The primary outcome was the proportion of chylothorax.

RESULTS

While the proportion of chylothorax in eligible infants without CMD was 0.25% (27/10714), that in infants with CMD was 50% (5/10; odds ratio (OR), 386.3; 95% confidence interval (CI), 84.4-1850.8; P < 0.001). The variables that were significantly different between infants with CMD with chylothorax and those without chylothorax were as follows: maternal age (33.0 vs. 24.8; P = 0.005), polyhydramnios (5/5 vs 1/5; P = 0.034), number of CTG repeats (1980 vs. 1500; P = 0.038), duration of invasive mechanical ventilation (220 vs. 2, P = 0.009), and duration of hospitalization (217.2 vs 68.0; P = 0.014). The mortality rate of all eligible infants with CMD was 5/10 (50%). No variables were significantly associated with mortality.

CONCLUSIONS

The proportion of chylothorax in infants with CMD was significantly higher than that in infants without CMD. Furthermore, the proportion was higher than that reported in previous studies on congenital chylothorax. This suggests that chylothorax may be frequently experienced in the clinical course of CMD.

Guidelines for genetic testing of muscle and neuromuscular junction disorders

Despite recent advances in the understanding of inherited muscle and neuromuscular junction diseases, as well as the advent of a wide range of genetic tests, patients continue to face delays in diagnosis of sometimes treatable disorders. These guidelines outline an approach to genetic testing in such disorders. Initially, a patient's phenotype is evaluated to identify myopathies requiring directed testing, including myotonic dystrophies, facioscapulohumeral muscular dystrophy, oculopharyngeal muscular dystrophy, mitochondrial myopathies, dystrophinopathies, and oculopharyngodistal myopathy. Initial investigation in the remaining patients is generally a comprehensive gene panel by next-generation sequencing. Broad panels have a higher diagnostic yield and can be cost-effective. Due to extensive phenotypic overlap and treatment implications, genes responsible for congenital myasthenic syndromes should be included when evaluating myopathy patients. For patients whose initial genetic testing is negative or inconclusive, phenotypic re-evaluation is warranted, along with consideration of genes and variants not included initially, as well as their acquired mimickers.

12-Month progression of motor and functional outcomes in congenital myotonic dystrophy

BACKGROUND

We aim to describe 12-mo functional and motor outcome performance in a cohort of participants with congenital myotonic dystrophy (CDM).

METHODS

CDM participants performed the 6 Minute Walk Test (6MWT), 10 Meter Run, 4 Stair Climb, Grip Strength, and Lip Force at baseline and 12-mo visits. Parents completed the Vineland Adaptive Behavior Scale.

RESULTS

Forty-seven participants, aged 0 to 13 y old, with CDM were enrolled. 6MWT, 10 Meter Run, and 4 Stair Climb were completed in >85% of eligible participants. The only significant difference between mean baseline and 12-mo performance was an improvement in 6MWT in children 3-6 y old (P = .008). This age group also had the largest mean % improvement in performance in all other timed functional testing. In children >7 y, the slope of change on timed functional tests decreased or plateaued, with further reductions in performance in children ≥10 y. Participants with CTG repeat lengths <500 did not perform differently than those with repeat lengths >1000.

CONCLUSIONS

The 6MWT, 10 Meter Run, and 4 Stair Climb were the most feasible measures. Our findings are consistent with the clinical profile and prior cross-sectional data, helping to establish reasonable expectations of functional trajectories in this population as well as identifying points in which therapeutic interventions may be best studied. Further study of outcomes in children >10 y old and <3 y is warranted, but this new information will assist planning of clinical trials in the CDM population.

Central nervous system involvement in arthrogryposis multiplex congenita: Overview of causes, diagnosis, and care

Arthrogryposis or AMC, arthrogryposis multiplex congenita, is defined as multiple congenital joint contractures in more than two joints and in different body areas. The common cause of all AMC is lack of movement in utero, which in turn can have different causes, one of which is CNS involvement. Intellectual disability/CNS involvement is found in approximately 25% of all AMC. AMC with CNS involvement includes a large number of genetic syndromes. So far, more than 400 genes have been identified as linked to AMC, with and without CNS involvement. A number of neonatally lethal syndromes and syndromes resulting in severe disability due to CNS malfunction belong to this group of syndromes. There are several X-linked disorders with AMC, which are primarily related to intellectual disability. A number of neuromuscular disorders may include AMC and CNS/brain involvement. Careful clinical evaluation by a geneticist and a pediatrician/pediatric neurologist is the first step in making a specific diagnosis. Further investigations may include MRI of the brain and spinal cord, electroencephalogram, blood chemistry for muscle enzymes, other organ investigations (ophtalmology, cardiology, gastrointestinal, and genitourinary systems). Nerve conduction studies, electromyogram, and muscle pathology may be of help when there is associated peripheral nervous system involvement. But most importantly, genetic investigations with targeted or rather whole exome or genome sequencing should be performed. A correct diagnosis is important in planning adequate treatment, in genetic counselling and also for future understanding of pathogenic mechanisms and possible new treatments. A multidiciplinary team is needed both in investigation and treatment.

Human iPSC Models to Study Orphan Diseases: Muscular Dystrophies

Purpose of Review

Muscular dystrophies (MDs) are a spectrum of muscle disorders, which are caused by a number of gene mutations. The studies of MDs are limited due to lack of appropriate models, except for Duchenne muscular dystrophy (DMD), myotonic dystrophy type 1 (DM1), facioscapulohumeral muscular dystrophy (FSHD), and certain type of limb-girdle muscular dystrophy (LGMD). Human induced pluripotent stem cell (iPSC) technologies are emerging to offer a useful model for mechanistic studies, drug discovery, and cell-based therapy to supplement in vivo animal models. This review will focus on current applications of iPSC as disease models of MDs for studies of pathogenic mechanisms and therapeutic development.

Recent Findings

Many and more human disease-specific iPSCs have been or being established, which carry the natural mutation of MDs with human genomic background. These iPSCs can be differentiated into specific cell types affected in a particular MDs such as skeletal muscle progenitor cells, skeletal muscle fibers, and cardiomyocytes. Human iPSCs are particularly useful for studies of the pathogenicity at the early stage or developmental phase of MDs. High-throughput screening using disease-specific human iPSCs has become a powerful technology in drug discovery. While MD iPSCs have been generated for cell-based replacement therapy, recent advances in genome editing technologies enabled correction of genetic mutations in these cells in culture, raising hope for in vivo genome therapy, which offers a fundamental cure for these daunting inherited MDs.

Summary

Human disease-specific iPSC models for MDs are emerging as an additional tool to current disease models for elucidating disease mechanisms and developing therapeutic intervention.

Physical function and mobility in children with congenital myotonic dystrophy

INTRODUCTION

Congenital myotonic dystrophy (CDM) occurs when symptoms of myotonic dystrophy present at birth. In this study we evaluated the relationship between physical function, muscle mass, and age to provide an assessment of the disease and help prepare for therapeutic trials.

METHODS

CDM participants performed timed functional tests (TFTs), the first 2 minutes of 6-minute walk tests (2/6MWTs), and myometry tests, and also performed dual-energy X-ray absorption (DEXA) scans. Healthy controls (HCs) performed TFTs, 6MWTs, and myometry.

RESULTS

Thirty-seven children with CDM and 27 HCs (age range 3-13 years) participated in the study. There were significant differences in the 10-meter walk (11.3 seconds in CDM vs. 6.8 seconds in HC) and 2MWT (91 meters in CDM vs. 193 meters in HCs). DEXA lean mass of the right arm correlated with grip strength (r = 0.91), and lean mass of the right leg correlated with 6MWT (r = 0.62).

CONCLUSION

Children with CDM have significant limitations in strength and mobility. The tests performed were reliable, and lean muscle mass may serve as a useful biomarker. Muscle Nerve 56: 224-229, 2017.

Genome modification leads to phenotype reversal in human myotonic dystrophy type 1 induced pluripotent stem cell-derived neural stem cells

Myotonic dystrophy type 1 (DM1) is caused by expanded CTG repeats in the 3'-untranslated region (3' UTR) of the DMPK gene. Correcting the mutation in DM1 stem cells would be an important step toward autologous stem cell therapy. The objective of this study is to demonstrate in vitro genome editing to prevent production of toxic mutant transcripts and reverse phenotypes in DM1 stem cells. Genome editing was performed in DM1 neural stem cells (NSCs) derived from human DM1 induced pluripotent stem (iPS) cells. An editing cassette containing SV40/bGH polyA signals was integrated upstream of the CTG repeats by TALEN-mediated homologous recombination (HR). The expression of mutant CUG repeats transcript was monitored by nuclear RNA foci, the molecular hallmarks of DM1, using RNA fluorescence in situ hybridization. Alternative splicing of microtubule-associated protein tau (MAPT) and muscleblind-like (MBNL) proteins were analyzed to further monitor the phenotype reversal after genome modification. The cassette was successfully inserted into DMPK intron 9 and this genomic modification led to complete disappearance of nuclear RNA foci. MAPT and MBNL 1, 2 aberrant splicing in DM1 NSCs were reversed to normal pattern in genome-modified NSCs. Genome modification by integration of exogenous polyA signals upstream of the DMPK CTG repeat expansion prevents the production of toxic RNA and leads to phenotype reversal in human DM1 iPS-cells derived stem cells. Our data provide proof-of-principle evidence that genome modification may be used to generate genetically modified progenitor cells as a first step toward autologous cell transfer therapy for DM1.

Congenital and infantile myotonic dystrophy

Myotonic dystrophy (DM) encompasses two gene defects, DM1 (myotonic dystrophy type 1) being currently the sole disorder leading to a childhood form of the disease. As consequence of the non coding unstable CTG repeat expansion mutation, DM1 presents as an extremely wide and diverse clinical continuum ranging from antenatal to late adult forms, the complexity of the disease being reinforced by multisystemic involvement. The congenital form appears as the most severe end of the phenotypic spectrum and may include marked neonatal hypotonia, respiratory failure, facial diplegia, contractures, and mental retardation. Brain involvement is the hallmark of childhood-onset DM1, distinguished by a normal neonatal period, with learning difficulties as the main presenting symptom, resulting from various degrees of mental delay, psychopathological manifestations, speech defects, hypersomnolence, and fatigue. In contrast, muscle weakness remains usually moderate in childhood, limited to facial weakness, ptosis, and dysarthria, until a decline from the second decade. Orthopedic manifestations including kyphoscoliosis and equinovarus may require surgery. Other organs involvement includes frequent abdominal symptoms, whereas endocrine disturbance is rare. Symptomatic cardiac arrhythmia, mainly exercise-induced, can be observed. While current treatment is mainly symptomatic, future clinical trials are expected following significant progress in pathophysiology and the recent development of molecular therapy approaches.

Generation of neural cells from DM1 induced pluripotent stem cells as cellular model for the study of central nervous system neuropathogenesis

Dystrophia myotonica type 1 (DM1) is an autosomal dominant multisystem disorder. The pathogenesis of central nervous system (CNS) involvement is poorly understood. Disease-specific induced pluripotent stem cell (iPSC) lines would provide an alternative model. In this study, we generated two DM1 lines and a normal iPSC line from dermal fibroblasts by retroviral transduction of Yamanaka's four factors (hOct4, hSox2, hKlf4, and hc-Myc). Both DM1 and control iPSC clones showed typical human embryonic stem cell (hESC) growth patterns with a high nuclear-to-cytoplasm ratio. The iPSC colonies maintained the same growth pattern through subsequent passages. All iPSC lines expressed stem cell markers and differentiated into cells derived from three embryonic germ layers. All iPSC lines underwent normal neural differentiation. Intranuclear RNA foci, a hallmark of DM1, were detected in DM1 iPSCs, neural stem cells (NSCs), and terminally differentiated neurons and astrocytes. In conclusion, we have successfully established disease-specific human DM1 iPSC lines, NSCs, and neuronal lineages with pathognomonic intranuclear RNA foci, which offer an unlimited cell resource for CNS mechanistic studies and a translational platform for therapeutic development.

Congenital myotonic dystrophy: Canadian population-based surveillance study

OBJECTIVES

To determine the incidence and neonatal morbidity and mortality of congenital myotonic dystrophy (CDM) in Canada.

STUDY DESIGN

The study has 2 phases. A 5-year prospective monthly surveillance of incident cases of CDM conducted via the Canadian Pediatric Surveillance Program, from March 1, 2005-February 28, 2010, and a 5-year cohort study of eligible incident cases, which is ongoing and not the subject of this report.

RESULTS

A total of 121 cases were reported, with 38 confirmed as CDM. The incidence of CDM in Canada is 2.1/100,000 (1/47,619) live births. The cases were reported from 8 provinces and 1 territory. The highest reported incidence was Ontario with 15, followed by British Columbia with 7, and Quebec with 6. External validation of cases was performed. The trinucleotide repeat level varied from 550-3100. Twenty-two (58%) of the children were the index cases for their families. Seventeen children are currently enrolled in the ongoing cohort study.

CONCLUSION

Surveillance and prospective examination of CDM at a population level is important, as the impact of this rare disease is systemic, chronic, and associated with significant morbidity and mortality throughout childhood.

Autism spectrum conditions in myotonic dystrophy type 1: a study on 57 individuals with congenital and childhood forms

Myotonic dystrophy type 1 (DM1) is an autosomal dominant disorder, caused by an expansion of a CTG triplet repeat in the DMPK gene. The aims of the present study were to classify a cohort of children with DM1, to describe their neuropsychiatric problems and cognitive level, to estimate the size of the CTG expansion, and to correlate the molecular findings with the neuropsychiatric problems. Fifty-seven children and adolescents (26 females; 31 males) with DM1 (CTG repeats > 40) were included in the study. The following instruments were used: Autism Diagnostic Interview-Revised (ADI-R), 5-15, Griffiths Mental Development Scales, and the Wechsler Scales. Based on age at onset and presenting symptoms, the children were divided into four DM1 groups; severe congenital (n = 19), mild congenital (n = 18), childhood (n = 18), and classical DM1 (n = 2). Forty-nine percent had an autism spectrum disorder (ASD) and autistic disorder was the most common diagnosis present in 35% of the subjects. Eighty-six percent of the individuals with DM1 had mental retardation (MR), most of them moderate or severe MR. ASD was significantly correlated with the DM1 form; the more severe the form of DM1, the higher the frequency of ASD. The frequency of ASD increased with increasing CTG repeat expansions. ASD and/or other neuropsychiatric disorders such as attention deficit hyperactivity disorder, and Tourette's disorder were found in 54% of the total DM1 group. In conclusion, awareness of ASD comorbidity in DM1 is essential. Further studies are warranted to elucidate the molecular etiology causing neurodevelopmental symptoms such as ASD and MR in DM1.

Myotonic dystrophy type I in childhood Long-term evolution in patients surviving the neonatal period

In a retrospective study, 32 patients with myotonic dystrophy, including congenital (n=17) and infantile/juvenile forms (n=15) were studied during a long follow-up lasting 7-28 years (median: 17 years). The clinical presentation was extremely variable; however, a continuum did exist between severe and less severe congenital forms, and later-onset forms, without genotype-phenotype correlation. We observed some unusual presentations, such as 3 cases of isolated club-feet during the neonatal period, and 7 patients (23%) with a completely isolated mental deficiency, language delay and school failure, who only completed the clinical picture several years later. Wechsler scale testing was performed in all cases, and repeated with 8 patients. It demonstrated a decrease in intellectual abilities in 5 patients, suggesting the possibility of a degenerative cerebral process occurring in these children. This decrease has also been reported in some adult cases. This study illustrates the extremely heterogeneous clinical presentation of myotonic dystrophy in childhood.

Myotonic dystrophy: muscle involvement in relation to disease type and size of expanded CTG-repeat sequence

This study aimed to: classify a cohort of children and adolescents with myotonic dystrophy (dystrophia myotonica: DM) into congenital and childhood onset forms; estimate CTG expansion size; and quantify muscle strength, contractures, and motor function in children with DM and compare results with those of controls. Participants were clinically examined, medical records were reviewed, and isometric muscle strength, contractures, and motor function were measured. Participants were: 42 children with DM (18 females, 24 males; mean age 8y 9mo [SD 4y 7mo], range 10mo to 17y) and 42 age- and sex-matched, healthy controls. Children with DM were divided into three groups: severe congenital (n=13), mild congenital (n=15), and childhood (n=14). Children with childhood DM were significantly weaker than controls (wrist and ankle dorsiflexors [p=0.0044, p=0.0044 respectively]; hip abductors and flexors [p=0.0464, p=0.0217]; and knee flexors and extensors: [p=0.0382, p=0.0033]). Children with mild congenital DM were significantly weaker than controls in all assessed muscle groups. Contractures and skeletal deformities were more frequent at time of investigation than at birth, suggesting that foot and spine deformities in particular increase over time. Motor function score was significantly lower for children with DM than for controls. Children with severe congenital DM had the lowest motor function, with correlation between motor function and size of CTG repeat (p=-0.743). Children found jumping, heel standing, and head lifting the most difficult items to perform but few had difficulty walking, running, or stair climbing. DM in children is a heterogeneous disorder with a wide spectrum of muscle involvement, and owing to increased risk of contractures and skeletal deformities, regular follow-ups are recommended.

Congenital myotonic dystrophy: assisted ventilation duration and outcome

OBJECTIVE

To clarify the relationship between initial assisted ventilation duration and outcome for patients with congenital myotonic dystrophy (CDM).

METHODS

A retrospective chart review was conducted of cases of CDM that presented to the Children's Hospital of Eastern Ontario (Ottawa, Ontario, Canada) between 1980 and 2000. Inclusion criteria were conclusive testing for CDM and clinical presentation in the first 30 days of life. Duration of assisted ventilation, morbidity, mortality, and developmental outcome were measured.

RESULTS

A total of 23 children met the inclusion criteria. One child died at 5 days of age, and 2 others had withdrawal of ventilation. The remaining 20 children were divided into 2 groups on the basis of whether they needed > or <30 days of ventilation. In the first year of life, 25% mortality was noted in the children with prolonged ventilation, whereas no child in the short ventilation duration group died. After 1 year of age, 1 child in each group died with follow-up of 2 to 16 years. The children with prolonged ventilation needed more hospitalizations. Delays were noted in development in both groups of children at ages 1, 3, and 6 years; however, there was an improvement in motor and language scores over time in all children. Children who required ventilation for <30 days had better motor, language, and activities of daily living scores at all ages.

CONCLUSIONS

Children with CDM with prolonged ventilation experienced 25% mortality in the first year. The use of a specific time period of ventilation to decide on withdrawal of therapy must be reconsidered given these findings. Prolonged ventilation was followed by greater morbidity and developmental delay than children with shorter ventilation duration.

Genetic diseases of muscle

In the last twenty years, the genetic basis for most of the inherited myopathies and muscular dystrophies has been unveiled. Diseases have been found to result from loss of function of structural components of the muscle basal lamina (e.g., MCD1A), sarcolemma (e.g., the sarcoglycanopathies), nucleus (e.g., EDMD) and sarcomere (e.g., the nemaline myopathies). A few have been associated with abnormalities in the genes for muscle enzymes (e.g., calpain and fukutin). Alternate mechanisms of pathogenesis have also recently been suggested by mutations lying outside of coding regions, such as the "field effect" of chromosomal mutations in DM2. In the future, we will likely identify the genes responsible for the remaining disorders, including many of the distal myopathies. In addition, we may also find skeletal muscle diseases associated with some of the presently non-implicated muscle proteins: syntropin, dystrobrevin, epsilon-sarcoglycan and sarcospan. The next steps may be to identify and understand the relationship of modifier genes producing the phenotypic heterogeneity of many of these diseases and to characterize those and other targets for therapeutic intervention, whether by gene therapy or by pharmacological treatment.

Congenital neonatal myotonic dystrophy with persistent pulmonary hypertension and coma: a difficult diagnosis

The fulminant forms of congenital myotonic dystrophy, which rapidly lead to death, are difficult to diagnose. The case described illustrates the roles of persistent pulmonary hypertension in such a fatal form.

Hydrocephalus and cognitive decline in myotonic dystrophy: case report and literature review

Myotonic dystrophy is a rare genetic neuromuscular disorder with multisystem involvement. Hydrocephalus and cognitive deterioration are not commonly considered part of adult-onset myotonic dystrophy. This report describes a case of progressive distal muscle weakness, cognitive decline, and longstanding ventricular enlargement. Review of the literature suggests that hydrocephalus may be associated with myotonic dystrophy while progressive cognitive decline is rare in the adult form of the disease.

Congenital myotonic dystrophy requiring prolonged endotracheal and noninvasive assisted ventilation: not a uniformly fatal condition

In this report we present two infants with congenital myotonic dystrophy (CMD) who were successfully weaned from prolonged ventilatory support using nasal continuous positive airway pressure (N-CPAP). The first infant received 127 days of endotracheal mechanical ventilation as part of 141 days of total ventilatory support, including N-CPAP; the second infant received 27 days of endotracheal mechanical ventilation as part of 84 days of total ventilatory support. Noninvasive N-CPAP facilitated weaning these two infants from ventilatory support, thereby minimizing the morbidity associated with prolonged intubation. The developmental outcomes of our two infants were comparable to infants not requiring prolonged endotracheal mechanical ventilation. We suggest that this noninvasive modality of ventilatory support may be advantageous in the management and beneficial to the outcome of infants with CMD who are respirator-dependent >30 days.

Pneumoperitoneum complicating mechanical ventilation in congenital myotonic dystrophy

Pneumoperitoneum is known as a disease caused by perforation of the gastrointestinal tract, but it has also been reported as a complication of mechanical ventilation. In a case of congenital myotonic dystrophy (CMyD), mechanical ventilation was performed to treat severe respiratory distress starting at birth, and then pneumomediastinum and pneumoperitoneum developed as complications 5 days after birth. The fact that the pneumoperitoneum improved when the ventilation pressure was reduced and the patient's course was observed, allowed us to rule out gastrointestinal perforation. It appeared that hypoplasia of the diaphragm may have been involved in the progression of pneumomediastinum to pneumoperitoneum in this patient. Mechanical ventilation is performed on many occasions in CMyD, and the development of pneumoperitoneum secondary to pulmonary air leak should always be borne in mind.