Late-onset facioscapulohumeral muscular dystrophy type 1 in previously undiagnosed families: Presenting clinical features in an often-misdiagnosed disorder

INTRODUCTION/AIMS

In our experience, patients with late-onset facioscapulohumeral muscular dystrophy type 1 (FSHD1) are frequently misdiagnosed, some for many years. The aim of this report is to document this clinical experience including the presenting symptoms and misdiagnoses and to discuss the challenges in diagnosing patients with late-onset FSHD1.

METHODS

We performed a retrospective medical record review and recorded clinical data on patients with a genetically confirmed diagnosis of FSHD1, who began to have symptoms at 50 years of age or older, and either had no family history of FSHD1 or had a history of an undiagnosed weakness in a family member.

RESULTS

Thirteen patients, 7 men and 6 women, met the study inclusion criteria. Age of onset ranged from 52 to 74 (mean, 59.8) years, age of diagnosis ranged from 54 to 80 (mean, 66.5) years, and duration of symptoms from onset to diagnosis was 1 to 15 (mean, 6.7) years. Prior diagnoses included lumbosacral polyradiculopathy in five (38%); statin-related myopathy in two (15%); and one each of polymyositis, inclusion-body myositis, distal myopathy, limb-girdle muscular dystrophy, unspecific myopathy, and unspecified scapular winging. For eight patients (62%), family history was suspected in deceased members or if by confirmed DNA test postdiagnosis.

DISCUSSION

The diagnosis of late-onset FSHD1 is often delayed by many years with patients frequently receiving misdiagnoses. FSHD1 may not be considered in the differential diagnosis of late-onset weakness due to its rarity and because its clinical features are subtler, nonspecific, and mimic other neuromuscular disorders.

Trunk muscle dysfunction in patients with myotonic dystrophy type 2 and its contribution to chronic low back pain

Introduction

Myotonic dystrophy type 2 (MD2) presents with a varied manifestation. Even though the myopathy in these patients is more widespread, axial musculature involvement is one of the most prominent conditions. MD2 patients also often report chronic low back pain (CLBP). The purpose of this study was to evaluate trunk muscle function, including respiratory muscles, in patients with MD2 and to compare it with healthy controls, to determine the occurrence of CLBP in patients with MD2, and to assess whether trunk muscle dysfunction increases the risk of CLBP in these patients.

Methods

We enrolled 40 MD2 patients (age range 23 to 76 years, 26 women). A comprehensive battery of tests was used to evaluate trunk muscle function. The tests consisted of quantitative muscle strength testing of low back extensor muscles and respiratory muscles and the assessment of trunk muscle endurance. A neurological evaluation contained procedures assessing the distribution of muscle weakness, myotonia, and pain, and used questionnaires focused on these items and on disability, depression, and physical activity.

Results

The results of this study suggest that patients with MD2 show significant dysfunction of the trunk muscles, including the respiratory muscles, expressed by decreased muscle strength and endurance. The prevalence of CLBP in patients with MD2 was 52.5%. Based on our analysis, the only independent significant risk factor for CLBP in these patients was maximal isometric lower back extensor strength in a prone position ≤ 15.8 kg (OR = 37.3). Other possible risk factors were severity of myotonia and reduced physical activity.

Conclusion

Outcomes of this study highlighted the presence of axial muscle dysfunction, respiratory muscle weakness, and frequent occurrence of CLBP together with its risk factors in patients with MD2. We believe that the findings of this study may help in management and prevention programs for patients with MD2.

Myofibrillar myopathy: a rare but important differential diagnosis of camptocormia in a patient with Parkinson's Disease

Here we report on a patient with Parkinson's Disease and camptocormia due to Myofibrillar Myopathy Type 3. By leading the reader through the clinical reasoning process and highlighting the respective red flags we aim to increase the readers' awareness for the differential diagnosis of camptocormia.

New genomic insights into the conformation of Lipizzan horses

Conformation traits are important selection criteria in equine breeding, as they describe the exterior aspects of the horse (height, joint angles, shape). However, the genetic architecture of conformation is not well understood, as data of these traits mainly consist of subjective evaluation scores. Here, we performed genome-wide association studies on two-dimensional shape data of Lipizzan horses. Based on this data, we identified significant quantitative trait loci (QTL) associated with cresty neck on equine chromosome (ECA)16 within the MAGI1 gene, and with type, hereby differentiating heavy from light horses on ECA5 within the POU2F1 gene. Both genes were previously described to affect growth, muscling and fatty deposits in sheep, cattle and pigs. Furthermore, we pin-pointed another suggestive QTL on ECA21, near the PTGER4 gene, associated with human ankylosing spondylitis, for shape differences in the back and pelvis (roach back vs sway back). Further differences in the shape of the back and abdomen were suggestively associated with the RYR1 gene, involved in core muscle weakness in humans. Therefore, we demonstrated that horse shape space data enhance the genomic investigations of horse conformation.

Clinical Reasoning: Adult Patient Presenting With Spine Pain Following a Motor Vehicle Accident

A 52-year-old woman with a complex medical history, including a history of consanguinity, developed refractory uncontrollable spine pain after a motor vehicle accident 2 years before presentation. There were no well-defined findings on clinical examination. She was found to have mildly elevated serum creatine phosphokinase levels, and spine imaging revealed fatty replacement and atrophy affecting predominantly lumbar paraspinal muscles. Initial EMG sampling of multiple limb muscles was normal. However, a follow-up concentric needle examination sampling paraspinal and trunk muscles showed abundant myotonic discharges, fibrillations and positive sharp waves, and myopathic motor unit action potential changes. This pattern of neurophysiologic abnormalities prompted the search for a myopathic disorder, which was ultimately confirmed with additional studies. This case highlights the critical role of neurophysiologic evaluation of paraspinal and other trunk muscles in the disambiguation of clinical and imaging data, helping to establish the diagnosis of a rare but treatable myopathy at early disease stages.

Lumbar Kinematics Assessment of Patients with Chronic Low Back Pain in Three Bridge Tests Using Miniaturized Sensors

Lumbar muscle atrophy, diminished strength, stamina, and increased fatigability have been associated with chronic nonspecific low back pain (LBP). When evaluating patients with LBP, trunk or core stability, provided by the performance and coordination of trunk muscles, appears to be essential. Several clinical tests have been developed to identify deficiencies in trunk performance, demonstrating high levels of validity and reproducibility. The most frequently prescribed tests for assessing the core body muscles are the prone plank bridge test (PBT), the side bridge test (SBT), and the supine bridge test (SUBT). However, quantitative assessments of the kinematics of the lumbar spine during their execution have not yet been conducted. The purpose of our study was to provide objective biomechanical data for the assessment of LBP patients. The lumbar spine ranges of motion of 22 healthy subjects (Group A) and 25 patients diagnosed with chronic LBP (Group B) were measured using two inertial measurement units during the execution of the PBT, SUBT, and SBT. Statistically significant differences between the two groups were found in all three tests' kinematic patterns. This quantitative assessment of lumbar spine motion transforms the three bridge tests into an objective biomechanical diagnostic tool for LPBs that may be used to assess the efficacy of applied rehabilitation programs.

Atypical presentations of inclusion body myositis: Clinical characteristics and long-term outcomes

INTRODUCTIONS/AIMS

Inclusion body myositis (IBM) typically presents with progressive weakness preferentially involving finger flexors and quadriceps. Atypical presentations have been less commonly reported. Here, we aim to describe the clinical characteristics and long-term outcomes of IBM patients with atypical presentations.

METHODS

We retrospectively searched the Mayo Clinic medical records to identify IBM patients with atypical disease onset, seen between 2015 and 2020.

RESULTS

We identified 357 IBM patients, of whom 50 (14%) had an atypical presentation. Thirty-eight patients were diagnosed with IBM because they fulfilled one of the European Neuromuscular Center diagnostic categories at a later stage, 10 had all IBM histopathological features, and 2 were diagnosed on the basis of clinical and laboratory data. The most common presentation was dysphagia (50%), followed by asymptomatic hyperCKemia (24%; CK, creatine kinase), then foot drop (12%). 6% of patients presented with proximal arm weakness, 4% with axial weakness and 4% with facial diplegia. Median time from symptom onset to diagnosis was 9 y. Median age at diagnosis was 70.5 y. 16% of patients needed a walking aid. When tested, 86.5% of patients had impaired swallowing and 56% had elevated cytosolic nucleotidase-1A antibodies. Only 1/26 patients who received immunotherapy had minimal improvement. Upon follow-up, most patients had generalization of their weakness with a decline in their strength summated score of 0.082/mo.

DISCUSSION

A significant proportion of IBM patients may have an atypical presentation. Recognition of such heterogeneity could improve early diagnosis, prevent unnecessary immunotherapy, and provide insight for future diagnostic criteria development and clinical trials.

Whole-body magnetic resonance imaging in limb girdle muscular dystrophy type R1/2A: correlation with clinical scores

INTRODUCTION/AIM

The most common limb girdle muscular dystrophy (LGMD) worldwide is LGMD type R1 (LGMDR1). The aim of this study was to correlate the magnetic resonance imaging (MRI) findings with functional scores and to describe the whole-body MRI (WBMRI) pattern in a LGMDR1 Brazilian cohort.

METHODS

LGMDR1 patients under follow-up in three centers were referred for the study. Clinical data were collected and a functional evaluation was performed, consisting of Gardner-Medwin and Walton (GMW) and Brooke scales. All patients underwent a WBMRI study (1.5T) with axial T1 and STIR images. Fifty-one muscles were semiquantitatively assessed regarding fatty infiltration and muscle edema.

RESULTS

The study group consisted of 18 patients. The highest fatty infiltration scores involved the serratus anterior, biceps femoris long head, adductor magnus and lumbar erector spinae. There was a latero-medial and caudo-cranial descending gradient of involvement of the paravertebral muscles, with erector spinae being significantly more affected than the transversospinalis muscles (p<0.05). A striped appearance that has been dubbed the "pseudocollagen sign" was present in 72% of the patients. There was a positive correlation between the MRI score and GMW (Rho:0.83) and Brooke (Rho:0.53) scores.

DISCUSSION

WBMRI in LGMDR1 allows a global patient evaluation including involvement of the paraspinal muscles, usually an underestimated feature in the clinical and imaging study of myopathies. Knowledge of the WBMRI pattern of LGMDR1 involvement can be useful in the diagnostic approach and in future studies to identify the best target muscles to serve as outcome measures in clinical trials.

HIGH PREVALENCE OF PARASPINAL MUSCLE INVOLVEMENT IN ADULTS WITH McARDLE DISEASE

INTRODUCTION/AIMS

Very few studies analyzing the pattern of muscle involvement in magnetic resonance imaging (MRI) of patients with McArdle disease have been reported to date. We aimed to examine the pattern of muscle fat replacement in patients with McArdle disease.

METHODS

We performed a retrospective study including all patients with genetically confirmed McArdle disease followed in our center from January 2010 to March 2021. Clinical data were collected from the medical record. Whole-body MRI was performed as part of the diagnostic evaluation. The distribution of muscle fat replacement and its severity were analyzed.

RESULTS

Nine patients were included. Median age at onset was 7 years (range:5-58) and median age at the time when MRI was performed was 57.3 years (range 37.2-72.8). At physical examination 4 patients had permanent weakness: in 3 the weakness was limited to paraspinal muscles whereas in one the weakness involved the paraspinal and proximal upper limb muscles. Muscle MRI showed abnormalities in 6 of the 7 studied patients. In all of them fat replacement of paravertebral muscles was found. Other muscles frequently affected were the tongue in 3, subscapularis in 3, and long head of biceps femoris and semimembranosus in 2.

DISCUSSION

Our findings suggest that paraspinal muscle involvement is common in McArdle disease and support the need to include this disease in the differential diagnosis of the causes of paraspinal muscle weakness. Involvement of the tongue and subscapularis are also frequent in McArdle disease. This article is protected by copyright. All rights reserved.

Axial muscle involvement in patients with Limb girdle muscular dystrophy type R9

INTRODUCTION/AIMS

Limb girdle muscular dystrophy type R9 (LGMDR9) is characterized by progressive weakness of the shoulder and hip girdles. Involvement of proximal extremity muscles is well-described whereas information about axial muscle involvement is lacking. It is important to recognize the involvement of axial muscles to understand functional challenges for the patients. The aim of this study was to investigate the involvement of axial and leg muscles in patients with LGMDR9.

METHODS

This observational, cross-sectional study investigated fat replacement of axial and leg muscles in 14 patients with LGMDR9 and 13 matched, healthy controls using quantitative MRI (Dixon technique). We investigated paraspinal muscles at three levels, psoas major at the lumbar level, and leg muscles in the thigh and calf. Trunk strength was assessed with stationary dynamometry and manual muscle tests.

RESULTS

Patients with LGMDR9 had significantly increased fat replacement of all investigated axial muscles compared with healthy controls (p < 0.05). Trunk extension and flexion strength were significantly reduced in patients. Extension strength correlated negatively with mean fat fraction of paraspinal muscles. Fat fractions of all investigated leg muscles were significantly increased vs. controls, with the posterior thigh muscles being the most severely affected.

DISCUSSION

Patients with LGMDR9 have severe involvement of their axial muscles and correspondingly have reduced trunk extension and flexion strength. Our findings define the axial muscles as some of the most severely involved muscle groups in LGMDR9, which should be considered in the clinical management of the disorder and monitoring of disease progression.

Assessment of Lumbar Extensor Muscles in the Context of Trunk Function, a Pilot Study in Healthy Individuals

A comprehensive assessment of trunk function, including the lumbar extensor muscles, appears to be important in various conditions affecting axial musculature. This pilot cross-sectional observational study aimed to define a battery of tests that comprehensively assess trunk muscle function (strength and muscular endurance). Sixty subjects without low back pain (LBP) underwent measurement of isometric lower back extensor strength using a hand-held dynamometer (HHD) in three positions; measurement of respiratory muscle strength; and Biering-Sørensen, prone-plank, and side-bridge tests. The repeatability, short-term and long-term reliability using the HHD device in different postural positions was confirmed. The greatest isometric lower back extensor strength was generated in the sitting position by male subjects. Time of effort in the Biering-Sørensen test was longer in women and older subgroups than in men and younger individuals, although this was not the case for the other two muscular endurance tests. This pilot monitoring of trunk muscle strength and endurance in healthy volunteers may lead to a better understanding of trunk muscle function. Based on this methodological background, the authors aim to use the defined battery of tests in their further studies in a group of patients with LBP and certain neuromuscular diseases to verify its usefulness in clinical practice.

Anti-Ku Antibody-Positive Myositis Presenting as a Wide Range of Axial Myopathies and Myocarditis: A Case Report and Review of the Literature

Idiopathic inflammatory myopathies (IIMs) are autoimmune diseases predominantly affecting proximal muscles; paraspinal muscle involvement is relatively rare. Because paraspinal myopathies do not always cause clinically-evident symptoms, the diagnosis of IIMs with axial myopathies can be challenging. Anti-Ku autoantibodies, initially reported in polymyositis/systemic sclerosis overlap syndrome, are myositis-associated antibodies (MAAs) observed in patients with a wide variety of connective tissue diseases (CTDs). Few reports have been published demonstrating predominant axial myopathy in IIM patients with anti-Ku antibodies. Herein, we investigated a previously healthy Japanese woman in her early 70s who presented with Raynaud's phenomenon, back pain, and exertional dyspnea. The creatine kinase (CK) was elevated and antinuclear antibody staining was positive, but myositis-specific antibodies (MSAs) were negative. Magnetic resonance imaging (MRI) revealed myocarditis and a wide range of axial muscle inflammation, including bilateral thoracolumbar paraspinal, infraspinatus, and trapezius muscles. The muscle biopsy was consistent with IIM. In addition, anti-Ku antibody was positive. Administration of prednisolone and tacrolimus quickly alleviated the symptoms and the CK level returned to normal. The diagnosis of IIM was arduous in this case because she did not present with camptocormia, muscle weakness involving the proximal limbs was not apparent, and MSAs were negative. Whether axial myopathy and myocarditis are more prevalent in IIM patients with than without anti-Ku antibodies is uncertain. Clinicians should suspect axial myopathy and MAAs, such as anti-Ku antibodies, especially in patients in whom muscle weakness of the proximal limbs is not noticeable.

Whole-body muscle MRI in McArdle disease

This study describes muscle involvement on whole-body MRI (WB-MRI) scans at different stages of McArdle disease. WB-MRI was performed on fifteen genetically confirmed McArdle disease patients between ages 25 to 80. The degree of fatty substitution was scored for 60 muscles using Mercuri's classification. All patients reported an intolerance to exercise and episodes of rhabdomyolysis. A mild fixed muscle weakness was observed in 13/15 patients with neck flexor weakness in 7/15 cases, and proximal muscle weakness in 6/15 cases. A moderate scapular winging was observed in five patients. A careful review of the MRI scans, as well as hierarchical clustering of patients by Mercuri scores, pointed out recurrent muscle changes particularly in the subscapularis, anterior serratus, erector spinae and quadratus femoris muscles. WB-MRI imaging provides clinically relevant information and is a useful tool to orient toward the diagnosis of McArdle disease.

Muscle involvement assessed by quantitative magnetic resonance imaging in patients with anoctamin 5 deficiency

OBJECTIVE

Using magnetic resonance imaging (MRI) and stationary dynamometry, the aim was to investigate the muscle affection in paraspinal muscles and lower extremities and compare the muscle affection in men and women with anoctamin 5 (ANO5) deficiency.

METHODS

Seventeen patients (seven women) with pathogenic ANO5-mutations were included. Quantitative muscle fat fraction of back and leg muscles were assessed by Dixon MRI. Muscle strength was assessed by stationary dynamometer. Results were compared with 11 matched, healthy controls.

RESULTS

Muscle involvement pattern in men with ANO5-deficiency is characterized by a severe fat replacement of hamstrings, adductor and gastrocnemius muscles, while paraspinal muscles are only mildly affected, while preserved gracilis and sartorius muscles were hypertrophied. Women with ANO5-myopathy, of the same age as male patients, were very mildly affected, showing muscle affection and strength resembling that found in healthy persons, with the exception of the gluteus minimus and medius and gastrocnemii muscles that were significantly replaced by fat. Although individual muscles showed clear asymmetric involvement in a few muscle groups, the overall muscle involvement was symmetric.

CONCLUSIONS

Patients with ANO5-deficiency have relatively preserved paraspinal muscles on imaging and only mild reduction of trunk extension strength in men only. Our study quantifies the large difference in muscle affection in lower extremity between women and men with ANO5-deficiency. The clinical notion is that affection may be very asymmetric in ANO5-deficiency, but the present study shows that while this may be true for a few muscles, the general impression is that muscle affection is very symmetric.

Patients With Becker Muscular Dystrophy Have Severe Paraspinal Muscle Involvement

Introduction: Paraspinal muscles are important for gross motor functions. Impairment of these muscles can lead to poor postural control and ambulation difficulty. Little knowledge exists about the involvement of paraspinal muscles in Becker muscular dystrophy.

Objective: In this cross-sectional study, we investigated the involvement of paraspinal muscles with quantitative trunk strength measure and quantitative muscle MRI.

Methods and Materials: Eighteen patients with Becker muscular dystrophy underwent trunk, hip, and thigh strength assessment using a Biodex dynamometer and an MRI Dixon scan. Fourteen age- and body mass index-matched healthy men were included for comparison.

Results: Muscle fat fraction (FF) of the paraspinal muscles (multifidus and erector spinae) was higher in participants with Becker muscular dystrophy vs. healthy controls at all three examined spinal levels (C6, Th12, and L4/L5) (p < 0.05). There was a strong and inverse correlation between paraspinal muscle FF and trunk extension strength (ρ = −0.829, p < 0.001), gluteus maximus FF and hip extension strength (ρ = −0.701, p = 0.005), FF of the knee extensor muscles (quadriceps and sartorius) and knee extension strength (ρ = −0.842, p < 0.001), and FF of the knee flexor muscles (hamstring muscles) and knee flexion strength (ρ = −0.864, p < 0.001). Fat fraction of the paraspinal muscles also correlated with muscle FF of the thigh muscles and lower leg muscles.

Conclusion: In conclusion, patients with Becker muscular dystrophy demonstrate severe paraspinal muscular involvement indicated by low back extension strength and high levels of fat replacement, which parallel involvement of lower limb muscles. Assessment of paraspinal muscle strength and fat replacement may serve as a possible biomarker for both the clinical management and further study of the disease.

MR imaging of inherited myopathies: a review and proposal of imaging algorithms

PURPOSE OF REVIEW

The aims of this review are to discuss the imaging modalities used to assess muscle changes in myopathies, to provide an overview of the inherited myopathies focusing on their patterns of muscle involvement in magnetic resonance imaging (MR), and to propose up-to-date imaging-based diagnostic algorithms that can help in the diagnostic workup.

CONCLUSION

Familiarization with the most common and specific patterns of muscular involvement in inherited myopathies is very important for radiologists and neurologists, as imaging plays a significant role in diagnosis and follow-up of these patients.

KEY POINTS

• Imaging is an increasingly important tool for diagnosis and follow-up in the setting of inherited myopathies. • Knowledge of the most common imaging patterns of muscle involvement in inherited myopathies is valuable for both radiologists and neurologists. • In this review, we present imaging-based algorithms that can help in the diagnostic workup of myopathies.

Deep phenotyping of an international series of patients with late-onset dysferlinopathy

BACKGROUND

To describe the clinical, pathological, and molecular characteristics of late-onset (LO) dysferlinopathy patients.

METHODS

Retrospective series of patients with LO dysferlinopathy, defined by an age at onset of symptoms ≥30 years, from neuromuscular centers in France and the International Clinical Outcome Study for dysferlinopathy (COS). Patients with early-onset (EO) dysferlinopathy (<30 years) were randomly selected from the COS study as a control group, and the North Star Assessment for Dysferlinopathy (NSAD) and Activity Limitation (ACTIVLIM) scores were used to assess functionality. Muscle biopsies obtained from 11 LO and 11 EO patients were revisited.

RESULTS

Forty-eight patients with LO dysferlinopathy were included (28 females). Median age at onset of symptoms was 37 (range 30-57) years and most patients showed a limb-girdle (n = 26) or distal (n = 10) phenotype. However, compared with EO dysferlinopathy patients (n = 48), LO patients more frequently showed atypical phenotypes (7 vs. 1; p = 0.014), including camptocormia, lower creatine kinase levels (2855 vs. 4394 U/L; p = 0.01), and higher NSAD (p = 0.008) and ACTIVLIM scores (p = 0.016). Loss of ambulation in LO patients tended to occur later (23 ± 4.4 years after disease onset vs. 16.3 ± 6.8 years; p = 0.064). Muscle biopsy of LO patients more frequently showed an atypical pattern (unspecific myopathic changes) as well as significantly less necrosis regeneration and inflammation. Although LO patients more frequently showed missense variants (39.8% vs. 23.9%; p = 0.021), no differences in dysferlin protein expression were found on Western blot.

CONCLUSIONS

Late-onset dysferlinopathy patients show a higher frequency of atypical presentations, are less severely affected, and show milder dystrophic changes in muscle biopsy.

Late-onset camptocormia caused by a heterozygous in-frame CAPN3 deletion

Camptocormia is defined by a pathological involuntary flexion of the thoracic and lumbar spine that is fully reducible in the supine position. Although originally described as a manifestation of conversion disorder, it is more commonly caused by a wide range of neurological diseases, in particular movement and neuromuscular disorders. We describe here a rare case of late onset camptocormia caused by autosomal dominant calpainopathy due to a heterozygous in-frame deletion in CAPN3 leading to loss of a single lysin amino acid in the catalytic domain of calpain-3. Creatine kinase levels, electromyography, and thigh muscle MRI were normal. Muscle biopsy did not show lobulated fibers and calpain-3 protein expression was not decreased, but in vitro functional assays showed impaired proteolytic function of. Lys254del CAPN3. Autosomal dominant calpainopathy should be considered in the differential diagnosis of late onset camptocormia and unexplained paravertebral myopathies even in presence of normal creatine kinase levels, and in absence of lobulated fibers, of decreased calpain-3 protein expression, and of muscle limb involvement.

Spinal surgery for a late-onset axial myopathy

Axial myopathies with paraspinal predominance usually present with dropped head, abnormal posture or rigidity of the spine. Management of axial myopathy can be difficult and there is little data in the literature about surgical treatment. We discuss a case of axial myopathy with late-onset scoliosis and dropped head, focusing on the surgical management of the case.

Large genotype-phenotype study in carriers of D4Z4 borderline alleles provides guidance for facioscapulohumeral muscular dystrophy diagnosis

Facioscapulohumeral muscular dystrophy (FSHD) is a myopathy with prevalence of 1 in 20,000. Almost all patients affected by FSHD carry deletions of an integral number of tandem 3.3 kilobase repeats, termed D4Z4, located on chromosome 4q35. Assessment of size of D4Z4 alleles is commonly used for FSHD diagnosis. However, the extended molecular testing has expanded the spectrum of clinical phenotypes. In particular, D4Z4 alleles with 9–10 repeat have been found in healthy individuals, in subjects with FSHD or affected by other myopathies. These findings weakened the strict relationship between observed phenotypes and their underlying genotypes, complicating the interpretation of molecular findings for diagnosis and genetic counseling. In light of the wide clinical variability detected in carriers of D4Z4 alleles with 9–10 repeats, we applied a standardized methodology, the Comprehensive Clinical Evaluation Form (CCEF), to describe and characterize the phenotype of 244 individuals carrying D4Z4 alleles with 9–10 repeats (134 index cases and 110 relatives). The study shows that 54.5% of index cases display a classical FSHD phenotype with typical facial and scapular muscle weakness, whereas 20.1% present incomplete phenotype with facial weakness or scapular girdle weakness, 6.7% display minor signs such as winged scapula or hyperCKemia, without functional motor impairment, and 18.7% of index cases show more complex phenotypes with atypical clinical features. Family studies revealed that 70.9% of relatives carrying 9–10 D4Z4 reduced alleles has no motor impairment, whereas a few relatives (10.0%) display a classical FSHD phenotype. Importantly all relatives of index cases with no FSHD phenotype were healthy carriers. These data establish the low penetrance of D4Z4 alleles with 9–10 repeats. We recommend the use of CCEF for the standardized clinical assessment integrated by family studies and further molecular investigation for appropriate diagnosis and genetic counseling. Especially in presence of atypical phenotypes and/or sporadic cases with all healthy relatives is not possible to perform conclusive diagnosis of FSHD, but all these cases need further studies for a proper diagnosis, to search novel causative genetic defects or investigate environmental factors or co-morbidities that may trigger the pathogenic process. These evidences are also fundamental for the stratification of patients eligible for clinical trials. Our work reinforces the value of large genotype–phenotype studies to define criteria for clinical practice and genetic counseling in rare diseases.

Axial muscle weakness

Axial myopathy is a rare neuromuscular disorder characterised by selective involvement of the paraspinal muscles, and presenting either as a bent spine and/or dropped head syndrome. The axial muscles can be involved in various conditions, including neuromuscular disease, movement disorders, spinal disease and metabolic disorders. There have been recent descriptions of disorders with selective axial muscle involvement, but overall axial myopathy remains under-recognised. Here, we review disorders of axial muscle function, provide guidance on interpreting axial muscles imaging and suggest a diagnostic algorithm to evaluate patients with axial muscles weakness.

Quantitative electromyography: Normative data in paraspinal muscles

BACKGROUND

Quantitative electromyography of paraspinal muscle is a valuable diagnostic tool, but normative data are lacking.

METHODS

Needle electromyography (EMG) was obtained in 65 healthy subjects (49% men, 51% women) aged 21 to 82 years at C7, Th10, and L5 segments bilaterally. The incidence of spontaneous activity; motor unit potential (MUP) amplitudes, durations, and the incidence of polyphasic potentials; and the recruitment pattern at maximal voluntary contraction (MVC) were evaluated.

RESULTS

The incidence of fibrillation potentials was similar to limb muscles. The mean MUP duration and amplitude, and the amplitude at MVC increased caudally, while the incidence of polyphasic potentials was similar at all levels. EMG parameters did not correlate with sex or age.

CONCLUSIONS

In contrast to limb muscles, EMG parameters did not change with age, while polyphasic potentials were more frequent in paraspinal muscle than in limb muscles. The EMG gradient suggests larger motor units at more caudal segments.

Camptocormia as the presenting symptom in sporadic late onset nemaline myopathy: a case report

Background

Camptocormia has been reported in a plethora of diseases comprising disorders of the central nervous system, the peripheral nervous system, and the neuromuscular junction as well as hereditary and acquired myopathies. In sporadic late onset nemaline myopathy concomitant axial myopathy is common, but reports about camptocormia as the only presenting symptom in this condition are very rare. Notably, sporadic late onset nemaline myopathy is a potentially treatable condition in particular when associated with monoclonal gammopathy of unknown significance, HIV or rheumatological disorders.

Case presentation

We report the case of a 62-year-old female patient, who presented with slowly progressive camptocormia. Comprehensive work-up including neurological work-up, laboratory tests, MR-imaging, muscle biopsy and genetic testing led to the diagnosis of sporadic late onset nemaline myopathy.

Conclusions

Our case report highlights that sporadic late onset nemaline myopathy has to be considered in patients presenting with isolated camptocormia and comprehensive work-up of camptocormia is mandatory to ascertain the individual diagnosis, especially in consideration of treatable conditions.

Pompe disease: what are we missing?

Pompe disease is a multisystemic metabolic disorder caused by a deficiency of lysosomal acid alpha-glucosidase (GAA) leading to progressive accumulation of lysosomal glycogen, lysosomal swelling and rupture in all tissues of the human body. Furthermore, autophagic buildup, organelle abnormalities, and energy deficit are regularly observed. Enzyme replacement therapy has been available for patients living with Pompe disease for more than 15 years. Although our disease knowledge has grown enormously, we still have multiple challenges to overcome. Here, I will discuss unmet clinical needs, neglected or overlooked aspects of the pathophysiology, and issues related to future therapies.

MRI of trunk muscles and motor and respiratory function in patients with myotonic dystrophy type 1

Background

Myotonic Dystrophy 1 (DM1) causes progressive myopathy of extremity muscles. DM1 may also affect muscles of the trunk. The aim of this study was to investigate fat infiltration and muscle size in trunk muscles in DM1 patients, and in an age and gender matched control group. Further, explore how fat infiltration and degree of atrophy in these muscles are associated with motor and respiratory function in DM1 patients.

Method

We measured fat infiltration and trunk muscle size by MRI in 20 patients with genetically confirmed classic form of DM1, and compared these cases with 20 healthy, age and gender matched controls. In the DM1 group, we investigated correlations between MRI findings and clinical measures of muscle strength, mobility and respiration. We used sum scores for fat infiltration and muscle size in trunk flexors and trunk extensors in the analysis of group differences and correlations.

Results

Significant differences between cases and controls were present for fat infiltration in trunk flexors (p = 0.001) and trunk extensors (p = < 0.001), and for muscle size in trunk flexors (p = 0.002) and trunk extensors (p = 0.030). Fat infiltration in trunk flexors were significant correlated to back extension strength (rho = − 0.523 p = 0.018), while muscle size in trunk flexors was significantly correlated to trunk flexion strength (rho = 0.506 p = 0.023). Fat infiltration in trunk flexors was significantly correlated with lower general mobility (rho = − 0.628, p = 0.003), reduced balance (rho = 0.630, p < 0.003) and forced vital capacity (rho − 0.487 p = 0.040).

Conclusions

Trunk muscles in DM1 patients had significant higher levels of fat infiltration and reduced muscle size compared to age and gender matched controls. In DM1 patients, fat infiltration was associated with reduced muscle strength, mobility, balance and lung function, while muscle size was associated with reduced muscle strength and lung function. These findings are of importance for clinical management of the disease and could be useful additional outcome measures in future intervention studies.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1357-8) contains supplementary material, which is available to authorized users.

Recessive PYROXD1 mutations cause adult-onset limb-girdle-type muscular dystrophy

Objective

To describe adult-onset limb-girdle-type muscular dystrophy caused by biallelic variants in the PYROXD1 gene, which has been recently linked to early-onset congenital myofibrillar myopathy.

Methods

Whole exome sequencing was performed for adult-onset neuromuscular disease patients with no molecular diagnosis. Patients with PYROXD1 variants underwent clinical characterization, lower limb muscle MRI, muscle biopsy and spirometry. A yeast complementation assay was used to determine the biochemical consequences of the genetic variants.

Results

We identified four patients with biallelic PYROXD1 variants. Three patients, who had symptom onset in their 20s or 30s, were homozygous for the previously described p.Asn155Ser. The fourth patient, with symptom onset at age 49, was compound heterozygous for p.Asn155Ser variant and previously unknown p.Tyr354Cys. All patients presented with a LGMD-type phenotype of symmetric muscle weakness and wasting. Symptoms started in proximal muscles of the lower limbs, and progressed slowly to involve also upper limbs in a proximal-predominant fashion. All patients remained ambulant past the age of 60. They had restrictive lung disease but no cardiac impairment. Muscle MRI showed strong involvement of anterolateral thigh muscles. Muscle biopsy displayed chronic myopathic changes. Yeast complementation assay demonstrated the p.Tyr354Cys mutation to impair PYROXD1 oxidoreductase ability.

Conclusion

PYROXD1 variants can cause an adult-onset slowly progressive LGMD-type phenotype.

Electronic supplementary material

The online version of this article (10.1007/s00415-018-9137-8) contains supplementary material, which is available to authorized users.

Facioscapulohumeral Dystrophy in Childhood: A Nationwide Natural History Study

OBJECTIVE

Facioscapulohumeral dystrophy (FSHD) is one of the most frequent heritable muscular dystrophies, with a large variety in age at onset and disease severity. The natural history and molecular characteristics of FSHD in childhood are incompletely understood. Our objective is to clinically and genetically characterize FSHD in childhood.

METHODS

We performed a nationwide, single-investigator, natural history study on FSHD in childhood.

RESULTS

Multiple-source recruitment resulted in 32 patients with FSHD (0-17 years), leading to an estimated prevalence of 1 in 100,000 children in The Netherlands. This series of 32 children with FSHD revealed a heterogeneous phenotype and genotype in childhood. The phenotypic hallmarks of FSHD in childhood are: facial weakness with normal or only mildly affected motor performance, decreased functional exercise capacity (6-minute walk test), lumbar hyperlordosis, and increased echo intensity on muscle ultrasonography. In addition, pain and fatigue were frequent and patients experienced a lower quality of life compared to healthy peers. In contrast to the literature on early-onset FSHD, systemic features such as hearing loss and retinal and cardiac abnormalities were infrequent and subclinical, and epilepsy and intellectual disability were absent. Genotypically, patients had a mean D4Z4 repeat array of 5 units (range, 2-9), and 14% of the mutations were de novo.

INTERPRETATION

FSHD in childhood is more prevalent than previously known and the genotype resembles classic FSHD. Importantly, FSHD mainly affects functional exercise capacity and quality of life in children. As such, these results are paramount for counseling, clinical management, and stratification in clinical research. Ann Neurol 2018;84:635-645.

Chemotherapy dosing and toxicity in a patient with muscular dystrophy

BACKGROUND

Chemotherapy dosing has traditionally been based on a body surface area (BSA) calculation despite BSA dosing being problematic in a number of conditions, such as renal failure, liver failure, obesity, and sarcopenia. This case highlights another condition in which BSA dosing is problematic.

CASE

A 57-year-old man with limb-girdle muscular dystrophy presents with stage IIA inoperable squamous cell carcinoma of the lung. He is treated with chemotherapy and radiotherapy with curative intent but develops significant chemotherapy related toxicity affecting chemotherapy scheduling and dosing. Later, his cancer progresses, and he is commenced on palliative chemotherapy resulting in further significant chemotherapy toxicity.

CONCLUSION

Sarcopenia is known to increase risk of chemotherapy toxicity. This case postulates that changes in muscle mass seen in muscular dystrophy increases risk of chemotherapy toxicity, similar to sarcopenia.

Limb girdle muscular dystrophies: classification, clinical spectrum and emerging therapies

PURPOSE OF REVIEW

The aim of the study was to describe the clinical spectrum of limb girdle muscular dystrophies (LGMDs), the pitfalls of the current classification system for LGMDs, and emerging therapies for these conditions.

RECENT FINDINGS

Close to half of all LGMD subtypes have been discovered within the last 6 years of the 21-year-period in which the current classification system for LGMD has existed. The number of letters for annotation of new recessive LGMD conditions is exhausted, and multiple already classified LGMDs do not strictly fulfill diagnostic criteria for LGMD or are registered in other classification systems for muscle disease. On the contrary, diseases that fulfill classical criteria for LGMD have found no place in the LGMD classification system. These shortcomings call for revision/creation of a new classification system for LGMD. The rapidly expanding gene sequencing capabilities have helped to speed up new LGMD discoveries, and unveiled pheno-/genotype relations. Parallel to this progress in identifying new LGMD subtypes, emerging therapies for LGMDs are under way, but no disease-specific treatment is yet available for nonexperimental use.

SUMMARY

The field of LGMD is rapidly developing from a diagnostic and therapeutic viewpoint, but a uniform and universally agreed classification system for LGMDs is needed.

Successful treatment using rituximab in a patient with refractory polymyositis complicated by scleroderma renal crisis

Corticosteroids are the first-line treatment for patients with inflammatory myopathies. Myositis can be a clinical feature of scleroderma (polymyositis-scleroderma overlap syndrome), and treatment of this syndrome is a challenge for clinicians because moderate to high doses of corticosteroids are considered a risk factor for development of acute kidney injury in affected patients. We report here the case of a 56-year-old woman with scleroderma who developed polymyositis and was successfully treated with rituximab. Initial treatment of the polymyositis with prednisolone 40 mg/day was rapidly tapered to 2.5 mg/day due to development of scleroderma renal crisis, for which four weekly infusions of rituximab (500 mg; off-label) were given. She responded well to rituximab in addition to prednisolone 2.5 mg/day. Rituximab may improve inflammatory myopathies, even in cases where high-dose corticosteroids should be avoided due to complications. Rituximab should be considered as a treatment option in cases of refractory polymyositis.

Muscle MRI in neutral lipid storage disease (NLSD)

Neutral lipid storage disease (NLSD) is a rare inherited disorder of lipid metabolism resulting in lipid droplets accumulation in different tissues. Skeletal muscle could be affected in both two different form of disease: NLSD with myopathy (NLSD-M) and NLSD with ichthyosis (NLSD-I). We present the muscle imaging data of 12 patients from the Italian Network for NLSD: ten patients presenting NLSD-M and two patients with NLSD-I. In NLSD-M gluteus minimus, semimembranosus, soleus and gastrocnemius medialis in the lower limbs and infraspinatus in the upper limbs were the most affected muscles. Gracilis, sartorius, subscapularis, pectoralis, triceps brachii and sternocleidomastoid were spared. Muscle involvement was not homogenous and characteristic “patchy” replacement was observed in at least one muscle in all the patients. Half of the patients showed one or more STIR positive muscles. In both NLSD-I cases muscle involvement was not observed by T1-TSE sequences, but one of them showed positive STIR images in more than one muscle in the leg. Our data provides evidence that muscle imaging can identify characteristic alterations in NLSD-M, characterized by a specific pattern of muscle involvement with “patchy” areas of fatty replacement. Larger cohorts are needed to assess if a distinct pattern of muscle involvement exists also for NLSD-I.

Pathophysiological Concepts and Treatment of Camptocormia

Camptocormia is a disabling pathological, non-fixed, forward bending of the trunk. The clinical definition using only the bending angle is insufficient; it should include the subjectively perceived inability to stand upright, occurrence of back pain, typical individual complaints, and need for walking aids and compensatory signs (e.g. back-swept wing sign). Due to the heterogeneous etiologies of camptocormia a broad diagnostic approach is necessary. Camptocormia is most frequently encountered in movement disorders (PD and dystonia) and muscles diseases (myositis and myopathy, mainly facio-scapulo-humeral muscular dystrophy (FSHD)). The main diagnostic aim is to discover the etiology by looking for signs of the underlying disease in the neurological examination, EMG, muscle MRI and possibly biopsy. PD and probably myositic camptocormia can be divided into an acute and a chronic stage according to the duration of camptocormia and the findings in the short time inversion recovery (STIR) and T1 sequences of paravertebral muscle MRI. There is no established treatment of camptocormia resulting from any etiology. Case series suggest that deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) is effective in the acute but not the chronic stage of PD camptocormia. In chronic stages with degenerated muscles, treatment options are limited to orthoses, walking aids, physiotherapy and pain therapy. In acute myositic camptocormia an escalation strategy with different immunosuppressive drugs is recommended. In dystonic camptocormia, as in dystonia in general, case reports have shown botulinum toxin and DBS of the globus pallidus internus (GPi-DBS) to be effective. Camptocormia in connection with primary myopathies should be treated according to the underlying illness.