Symposium on the musculoskeletal aspects of Marfan syndrome: meeting report and state of the science

The Musculoskeletal Manifestations of Marfan Syndrome: Diagnosis, Impact, and Management

Purpose of Review

Marfan syndrome (MFS) is an autosomal dominant heritable disorder of fibrillin-1 (FBN1) with predominantly ocular, cardiovascular, and musculoskeletal manifestations that has a population prevalence of approximately 1 in 5–10,000 (Chiu et al. Mayo Clin Proc. 89(1):34–42, 146, Dietz 3, Loeys et al. J Med Genet. 47(7):476–85, 4).

Recent Findings

The vascular complications of MFS still pose the greatest threat, but effective management options, such as regular cardiac monitoring and elective surgical intervention, have reduced the risk of life-threatening cardiovascular events, such as aortic dissection. Although cardiovascular morbidity and mortality remains high, these improvements in cardiovascular management have extended the life expectancy of those with MFS by perhaps 30–50 years from an estimated mean of 32 years in 1972 (Dietz 3, Gott et al. Eur J Cardio-thoracic Surg. 10(3):149–58, 147, Murdoch et al. N Engl J Med. 286(15):804–8, 148). The musculoskeletal manifestations of MFS, which to date have received less attention, can also have a significant impact on the quality of life and are likely to become more important as the age of the Marfan syndrome population increases (Hasan et al. Int J Clin Pract. 61(8):1308–1320, 127). In addition, musculoskeletal manifestations are often critically important in the diagnosis of MFS.

Summary

Here, we review the main clinically relevant and diagnostically useful musculoskeletal features of MFS, which together contribute to the “systemic features score” (referred to hereafter as systemic score), part of the revised Ghent nosology for MFS. We discuss current treatment strategies and highlight the need for a multidisciplinary approach to diagnosis and management. Finally, we review new pharmacological approaches that may be disease modifying and could help to improve the outcome for individuals with this syndrome.

Artificial intelligence-based analysis of body composition in Marfan: skeletal muscle density and psoas muscle index predict aortic enlargement

BACKGROUND

Patients with Marfan syndrome are at risk for aortic enlargement and are routinely monitored by computed tomography (CT) imaging. The purpose of this study is to analyse body composition using artificial intelligence (AI)-based tissue segmentation in patients with Marfan syndrome in order to identify possible predictors of progressive aortic enlargement.

METHODS

In this study, the body composition of 25 patients aged ≤50 years with Marfan syndrome and no prior aortic repair was analysed at the third lumbar vertebra (L3) level from a retrospective dataset using an AI-based software tool (Visage Imaging). All patients underwent electrocardiography-triggered CT of the aorta twice within 2 years for suspected progression of aortic disease, suspected dissection, and/or pre-operative evaluation. Progression of aortic enlargement was defined as an increase in diameter at the aortic sinus or the ascending aorta of at least 2 mm. Patients meeting this definition were assigned to the 'progressive aortic enlargement' group (proAE group) and patients with stable diameters to the 'stable aortic enlargement' group (staAE group). Statistical analysis was performed using the Mann-Whitney U test. Two possible body composition predictors of aortic enlargement-skeletal muscle density (SMD) and psoas muscle index (PMI)-were analysed further using multivariant logistic regression analysis. Aortic enlargement was defined as the dependent variant, whereas PMI, SMD, age, sex, body mass index (BMI), beta blocker medication, and time interval between CT scans were defined as independent variants.

RESULTS

There were 13 patients in the proAE group and 12 patients in the staAE group. AI-based automated analysis of body composition at L3 revealed a significantly increased SMD measured in Hounsfield units (HUs) in patients with aortic enlargement (proAE group: 50.0 ± 8.6 HU vs. staAE group: 39.0 ± 15.0 HU; P = 0.03). PMI also trended towards higher values in the proAE group (proAE group: 6.8 ± 2.3 vs. staAE group: 5.6 ± 1.3; P = 0.19). Multivariate logistic regression revealed significant prediction of aortic enlargement for SMD (P = 0.05) and PMI (P = 0.04).

CONCLUSIONS

Artificial intelligence-based analysis of body composition at L3 in Marfan patients is feasible and easily available from CT angiography. Analysis of body composition at L3 revealed significantly higher SMD in patients with progressive aortic enlargement. PMI and SMD significantly predicted aortic enlargement in these patients. Using body composition as a predictor of progressive aortic enlargement may contribute information for risk stratification regarding follow-up intervals and the need for aortic repair.

Marfan syndrome in children: correlation between musculoskeletal features and cardiac Z-score

We investigated the correlation between the musculoskeletal features and the cardiovascular anomalies in pediatric patients affected by Marfan syndrome, in order to identify possible orthopedic deformities that could be a warning sign for severe aortic dilatation. Moreover, we analyzed the role of the orthopedic aspects in the early diagnosis of the disease in a pediatric population. Seventy-two patients from 3 to 14 years of age, underwent interdisciplinary evaluation that included an orthopedic and cardiological examination. At the orthopedic examination, we analyzed the musculoskeletal features included in the systemic score of the revised Ghent criteria. Cardiological evaluation included a transthoracic echocardiography with definition of the cardiac Z-score, which is an index that evaluates aortic diameter. A statistical analysis was performed. We identified a statistically significant correlation between the presence of pectus excavatum and cardiac Z-score ≥3 (P = 0.022). Clinically, this data means that pectus excavatum is frequently observed in patients with larger aortic root diameter. On the contrary, no statistically significant correlation was found between the other investigated musculoskeletal features and a pathological Z-score. In the pediatric population, the diagnosis of Marfan syndrome remains difficult because many clinical manifestations are age-dependent and the Ghent criteria, usually used for adults, are not reliable in children. Our results show that the presence of pectus excavatum could help in the early identification of patients at greater risk of developing possibly fatal aortic disease. However, it is always indicated to screen all patients with Marfan syndrome for cardiac abnormalities, even in absence of pectus excavatum.

Orthopaedic Aspects of Marfan Syndrome: The Experience of a Referral Center for Diagnosis of Rare Diseases

Marfan syndrome is caused by mutations in the fibrillin-1 gene (FBN1). The most important features affect the cardiovascular system, eyes, and skeleton. The aim of this study was to report the most frequent musculoskeletal alterations observed in 146 patients affected by Marfan syndrome. Fifty-four patients (37%) underwent cardiac surgery and 11 of them received emergent surgery for acute aortic dissection. Ectopia lentis was found in 68 patients (47%) whereas myopia above 3D occurred in 46 patients (32%). Musculoskeletal anomalies were observed in all patients with Marfan syndrome. In 88 patients (60.2%), the associated “wrist and thumb sign” was present; in 58 patients (39.7%), pectus carinatum deformity; in 44 patients (30.1%), pectus excavatum; in 49 patients (33.5%), severe flatfoot; in 31 patients (21.2%), hindfoot deformity; in 54 patients (36.9%), reduced US/LS ratio or increased arm span-height ratio; in 37 patients (25.3%), scoliosis or thoracolumbar kyphosis; in 22 patients (15%), reduced elbow extension (170° or less). Acetabular protrusion was ascertained on radiographs in 27 patients (18.4%). Orthopaedic aspects of the disease are very important for an early diagnosis; however, we have not observed definite correlations between the extent of orthopaedic involvement and aortic complications.

Participation of oleic acid in the formation of the aortic aneurysm in Marfan syndrome patients

Marfan syndrome (MFS) is associated with progressive aortic dilatation and endothelial dysfunction that lead to early acute dissection and rupture of the aorta and sudden death. Alteration in fatty acid (FA) metabolism can stimulate nitric oxide (NO) overproduction which increases the activity of the inducible form of NO synthase (iNOS) that is involved in endothelial dysfunction. We evaluated the participation of FA in the formation of thoracic aneurysms in MFS and its relation to the iNOS. Oleic acid (OA), iNOS, citrulline, nitrates and nitrites, TGF-β1, TNF-α, monounsaturated FA and NO synthase activity were significantly increased (p<0.05) in tissue from the aortas of MFS. Saturated FA, eNOS and HDL were significantly decreased (p<0.05). Arachidonic acid, delta-9 desaturase tended to increase and histological examination showed an increase in cystic necrosis, elastic fibers and collagen in MFS. The increase in OA contributes to the altered pathway of iNOS, which favors endothelial dysfunction and formation of the aortic aneurysms in MFS.

Synovial joints: from development to homeostasis

Synovial joint morphogenesis occurs through the condensation of mesenchymal cells into a non-cartilaginous region known as the interzone and the specification of progenitor cells that commit to the articular fate. Although several signaling molecules are expressed by the interzone, the mechanism is poorly understood. For treatments of cartilage injuries, it is critical to discover the presence of joint progenitor cells in adult tissues and their expression gene pattern. Potential stem cell niches have been found in different joint regions, such as the surface zone of articular cartilage, synovium, and groove of Ranvier. Inherited joint malformations as well as joint-degenerating conditions are often associated with other skeletal defects and may be seen as the failure of morphogenic factors to establish the correct microenvironment in cartilage and bone. Therefore, exploring how joints form can help us understand how cartilage and bone are damaged and develop drugs to reactivate this developing mechanism.

Systematic review of the psychosocial aspects of living with Marfan syndrome

The purpose of this study was to explore the literature on the psychosocial aspects of Marfan syndrome (MFS), to critically appraise and to synthesize relevant literature. A mixed-method systematic review was performed by searching the published literature databases using available medical, psychological, pedagogical and social databases and other sources. All studies that addressed psychosocial aspects of MFS, published in peer-reviewed journals were assessed. Of 81 search results, 15 articles (four articles based on same study population) satisfied the eligibility criteria. All studies were cross-sectional; no intervention or randomized controlled trial (RCT) studies were found. Most studies were of small sample sizes, had low response rate or participants without a verified diagnosis. Despite these limitations, all studies described, that MFS has a significant impact on the psychosocial aspects of people's lives: Decreased quality of life; challenges in education, work and family life, depression and anxiety. Some studies indicated that the subjective perception of discomfort did not necessarily match the medical severity of a disease. The research of the psychosocial aspects of MFS is limited in size and quality. More research is needed on the psychosocial aspects of MFS in samples with a verified diagnosis to develop evidence-based knowledge and appropriate guidelines.

Ten-year clinical and imaging follow-up of dural ectasia in adults with Marfan syndrome

BACKGROUND CONTEXT

Dural ectasia in the lumbosacral spine is a common feature of Marfan syndrome and is associated with low back pain and surgical complications, but its natural history is unknown.

PURPOSE

To evaluate the natural history of dural ectasia in adults with Marfan syndrome by determining if, over time, symptoms associated with dural ectasia worsen, dural ectasia imaging findings worsen, or spondylolisthesis/spondylolysis develops or worsens.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

For our prospective follow-up study, we enrolled 20 patients with Marfan syndrome and dural ectasia who, from 1998 through 1999, had undergone magnetic resonance imaging (MRI) and computed tomography (CT) of the lumbosacral spine and had completed the Oswestry Disability Index (ODI) questionnaire. Of the 20, five did not meet the inclusion criterion of a completed 2009 ODI questionnaire and were excluded. The remaining 15 patients (mean age, 49.6 years; mean follow-up, 10.5 years) formed our study group.

OUTCOME MEASURES

The ODI, MRI-based qualitative and quantitative measurements, CT-based quantitative measurements.

METHODS

We performed matched-pair analyses via Student t test and Wilcoxon signed-rank test of the ODI scores (15 pairs), dural volume of L5-S2 (eight pairs), dural sac ratio (DSR) of L4-S2 (nine pairs), development/progression of spondolysthesis/spondylolysis (11 pairs), and Fattori qualitative grading of dural ectasia size (10 pairs). Significance was set at p<.05.

RESULTS

We found no statistical differences in the 1998/1999 and 2009 ODI scores (25.8 vs. 22.2 points), dural volume (70.4 vs. 73.9 cm(3)), or DSR (0.68, 0.78, 2.04, and 58.1 vs. 0.69, 0.83, 2.30, and 70.20). There was also no development or progression of spondylolisthesis/spondylolysis and no increase in dural ectasia size.

CONCLUSIONS

During this 10-year period, the natural history of dural ectasia in adults with Marfan syndrome was not associated with a significant increase in ODI scores, dural ectasia size, or with the development/progression of spondylolisthesis or spondylolysis.

Diverticulitis complicated by fistulous communication of sigmoid colon with anterior sacral meningocele in a patient with Marfan syndrome

Rare in the general public, dural ectasia is a common finding in patients with Marfan syndrome. Complications are not frequent but include constipation, urinary retention, and meningitis. Presented here is a case of bacterial meningitis secondary to fistulous communication between a sacral meningocele and sigmoid colon in the setting of diverticulitis.

Dural ectasia in individuals with Marfan-like features but exclusion of mutations in the genes FBN1, TGFBR1 and TGFBR2

Mutations in the genes FBN1, TGFBR1, and TGFBR2 can result in heritable connective tissue disorders comprising the Marfan syndrome and the Loeys-Dietz syndrome. Dural ectasia is a characteristic manifestation of both syndromes. However, dural ectasia has not yet been investigated in connective tissue disorders that are unrelated to mutations in the FBN1, TGFBR1 or TGFBR2 genes. Here, we assessed dural ectasia in 33 individuals both with typical manifestations of heritable connective tissue disease and in whom mutations in all three genes had been excluded. We identified 19 individuals with dural ectasia (58%), who exhibited major skeletal manifestations of the Marfan syndrome more frequently than the remaining 14 persons without dural ectasia (p = 0.06). Moreover, only persons with dural ectasia fulfilled clinical criteria of the Marfan syndrome (p = 0.01). Conversely, aortic aneurysm (12 patients; p = 0.8), aortic dissection (five patients; p = 0.1), spontaneous dissection of the carotid arteries (five patients; p = 1), and mitral valve prolapse (13 patients; p = 0.4) were similarly frequent irrespective of dural ectasia. We conclude that dural ectasia is a marker for connective tissue disease which coincides with skeletal rather than with cardiovascular manifestations, and which may involve currently uncharacterized pathogenetic mechanisms and syndromes.

Radicular dysfunction due to spinal deformities in Marfan syndrome at older age: three case reports

Marfan syndrome is a inherited connective tissue disorder due to mutations in fibrillin-1. It presents with cardiovascular, ocular, skeletal, pulmonary and dural signs and symptoms. Some of the symptoms of later onset are those associated with scoliosis and dural ectasia. This is the enlargement of the neural canal especially in the lower lumbar and sacral region and occurs in over 90% of Marfan patients. We here report three patients with lumbar and/or sacral radiculopathy due to (kypho)scoliosis and dural ectasia with spinal meningeal cysts. The pain, muscle weakness, muscle atrophy, and sensory disturbances illustrate the severe neurological complications which may occur in Marfan syndrome, especially at later age. Awareness of these complications and development of management protocols is essential since life expectancy of Marfan patients has increased. Marfan syndrome might gradually become recognized as an inherited connective tissue disorder with potentially severe neurological complications during ageing.

Scoliosis in pediatric patients: comorbid disorders and screening

Scoliosis is one of the most commonly encountered pediatric spinal deformities. Knowledge of comorbid disorders associated with scoliosis is required in order to rule out other serious conditions. A thorough knowledge of the clinical scenarios associated with each of these disorders will help guide the pediatric practitioner in their work-up of associated conditions and possible further referrals. The aim of this review is to discuss the comorbidities associated with scoliosis and review appropriate screening tools aiding diagnosis.

Fibrillin-rich microfibrils - structural and instructive determinants of mammalian development and physiology

Fibrillin-rich microfibrils have emerged recently as an informative model system in which to study fundamental questions related to extracellular matrix biology and connective tissue pathophysiology. As a result, these studies have yielded novel clinical concepts and promising therapeutic strategies. These achievements have been based on the realization from studies of genetically engineered mice that mutations in fibrillin-rich microfibrils impair both the structural integrity of connective tissues and signaling events by TGF-beta/BMP superfamily members. In this view, fibrillin-rich microfibrils represent architectural assemblies that specify the concentration and timely release of local effectors of morphogenesis and tissue remodeling, in addition to conferring structural integrity to individual organ systems. This review summarizes the evidence supporting our current understanding of the structural and instructive roles that fibrillin-rich microfibrils play during embryonic development and in human diseases.

Marfan-like skeletal phenotype in the tight skin (Tsk) mouse

Tight skin (Tsk) is an autosomal dominant mutation located on mouse chromosome 2 and is associated with an intragenic duplication of the fibrillin 1 (Fbn1) gene. Mutant mice (Tsk/+) display a tightness of skin in the interscapular region, lung emphysema, myocardial hypertrophy, skeletal overgrowth, and kyphosis. It is hypothesized in this study that in Tsk mice the mutation in Fbn1 alters bone cell metabolism. A detailed study of the Tsk skeletal phenotype revealed that Tsk mice have significantly longer femurs and axial skeleton as well as vertebral abnormalities. Cortical and trabecular bone volumes were significantly decreased in Tsk femurs from 2- and 4-month-old mice (13% and 39%, respectively) as well as trabecular thickness, number, connectivity, and surface area. These skeletal differences were also associated with a reduction in bone mineral density in mutant mice. Expression of the osteoblast-specific genes Col1a1, BSP and OC was examined in marrow stromal cell cultures at various time points. A decrease in the rate of maturation of the Tsk cells was indicated by a delay in the appearance of OC expression. These initial experiments demonstrated a significant role of the fibrillin 1 protein in the extracellular matrix of bone cells.