Natural course of scoliosis in proximal spinal muscular atrophy type II and IIIa: descriptive clinical study with retrospective data collection of 126 patients

Scoliosis development in 5q-spinal muscular atrophy under disease modifying therapies

PURPOSE

5q-spinal muscular atrophy (SMA) is a treatable neuromuscular disorder associated with scoliosis in up to 90% of patients. New SMA therapies could mark a paradigm shift in scoliosis management, but their effects on scoliosis development remain unclear. This study aims to observe scoliosis progression in the current treatment landscape to inform management strategies.

METHODS

We conducted a cross-sectional retrospective analysis of 94 SMA patients treated at our center. Scoliosis development was evaluated in 75 patients using spine radiographs and electronic health records. Statistical analysis was performed using Python and GraphPad Prism. One-way ANOVA and Pearson correlation were used for group comparisons and correlation analysis, respectively.

RESULTS

Scoliosis parameters in 5q-SMA patients who had received either nusinersen, onasemnogene abeparvovec, risdiplam, or their combinations showed mean ages at scoliosis detection were 23.94, 55.52, and 168.11 months for SMA types 1, 2, and 3, respectively. Cobb angles at detection showed no significant intergroup differences. The mean ages at scoliosis surgery were 60, 88.43, and 124.8 months. Pelvic obliquity (PO) was highest in type 1 and lowest in type 3. A strong correlation (r = 0.9) was found between PO measurement techniques. HFMSE scores correlated moderately with scoliosis severity (r = -0.38), while CHOP-INTEND showed no correlation.

CONCLUSION

The observations made in this study suggest that the effects of SMA therapies do not prevent scoliosis development. The improved prognosis may lead to a growing cohort of SMA type 1 and 2 patients with early onset scoliosis who require early growth-friendly surgical interventions.

Spinal presentations in children with spinal muscular atrophy type 1 following gene therapy treatment with onasemnogene abeparvovec - The SMA REACH UK network experience

Spinal muscular atrophy (SMA) is a neuromuscular disorder of mainly early onset and variable severity. Prior to the introduction of disease modifying therapies (DMTs), children with SMA type 1 typically died before 2 years of age and management was primarily palliative. Onasemnogene abeparvovec (OA), nusinersen, and risdiplam are novel DMTs which ameliorate the effects of the underlying genetic defect at least partially making SMA a treatable condition. Survival and achievement of previously unmet developmental milestones result in treated SMA type 1 children spending more time upright than expected based on the natural history of the treatment-naïve condition. Consequently, spinal asymmetry and kyphosis, features not typically seen in untreated SMA type 1 children due to early mortality, are increasingly common complications. Precise data regarding their prevalence, severity, and management are currently limited. This study describes the spinal features and management in 75 children with SMA type 1 who received OA between March 2021 and December 2022. Retrospective analysis from SMA REACH UK data showed that 44/75 (59 %) clinically had spinal asymmetry and 37 (49 %) had kyphosis. This study aims to raise awareness of this important feature as part of the changed natural history of SMA type 1 post OA treatment.

Chest and spinal disease in patients with progressive neuromuscular disease

The chest and spine deformity in neuromuscular disease (NMDz) can impact respiratory mechanics and pulmonary function by changing the orientation of the muscles and joints of the respiratory system and placing them in a mechanically unfavorable position. This increases mechanical load on weak respiratory muscles and eventually can cause respiratory failure. Therefore, chest and spine deformity in NMDz will both lead to increased respiratory "load" and decreased respiratory muscle "pump", an exceptionally bad combination. While the current pharmacotherapies used for progressive neuromuscular disease focus on slowing progression, a similar approach has been used for decades in managing chest and spine deformity in patients with NMDz. There are, however, variable approaches to doing so and a recognition that not all "neuromuscular scoliosis" is the same and that each patient type (i.e. hypotonic vs. hypertonic) requires a different approach. Figuring out what approach to use requires both an understanding of the underlying pathophysiology of a particular neuromuscular condition and considering available options for and timing of surgical interventions. The remaining discussion will focus on hypotonic neuromuscular scoliosis.

Functional and Structural Changes in Patients with Spinal Muscular Atrophy Treated in Poland during 12-Month Follow-Up: A Prospective Cohort Study

Background: In recent years, rapid advances in diagnosis and treatment have been observed in spinal muscular atrophy (SMA) patients. The introduction of modern therapies and screening tests has significantly changed the clinical picture of the disease. The previous classification has, therefore, been replaced by new phenotypes: non-sitters, sitters, and walkers, defined by the patient's functional level. However, despite the change in the clinical picture of the disease, patients still suffer from accompanying structural disorders such as scoliosis or joint contractures. Their presence also significantly affects the acquisition of subsequent motor skills. Due to this, monitoring structural changes and ensuring therapists are aware of improvements or declines in patient functionality are essential components of clinical practice. This study aims to compare the assessment of structural and functional changes after a 12-month follow-up in SMA patients who have already experienced the effects of the disease and are now receiving modern therapy. Methods: We present a study of 34 SMA patients being treated with modern therapies and tested twice 12 months apart. The participants were tested using structural measurements and validated scales such as The Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) and Hammersmith Functional Motor Scale-Expanded (HFMSE). Results: During the 12-month follow-up, patients showed deteriorating, non-statistically significant structural changes. We also proved that patients showed a trend toward functional improvement. Analyzing the individual scale items, we distinguished which participants obtained the maximum score for a given parameter and no longer had an opportunity to improve during the second examination. Conclusions: Our study proved that most patients improved overall motor function. The examination of structural measurements should become a standard in the evaluation of SMA patients.

An interpretable data-driven prediction model to anticipate scoliosis in spinal muscular atrophy in the era of (gene-) therapies

5q-spinal muscular atrophy (SMA) is a neuromuscular disorder (NMD) that has become one of the first 5% treatable rare diseases. The efficacy of new SMA therapies is creating a dynamic SMA patient landscape, where disease progression and scoliosis development play a central role, however, remain difficult to anticipate. New approaches to anticipate disease progression and associated sequelae will be needed to continuously provide these patients the best standard of care. Here we developed an interpretable machine learning (ML) model that can function as an assistive tool in the anticipation of SMA-associated scoliosis based on disease progression markers. We collected longitudinal data from 86 genetically confirmed SMA patients. We selected six features routinely assessed over time to train a random forest classifier. The model achieved a mean accuracy of 0.77 (SD 0.2) and an average ROC AUC of 0.85 (SD 0.17). For class 1 'scoliosis' the average precision was 0.84 (SD 0.11), recall 0.89 (SD 0.22), F1-score of 0.85 (SD 0.17), respectively. Our trained model could predict scoliosis using selected disease progression markers and was consistent with the radiological measurements. During post validation, the model could predict scoliosis in patients who were unseen during training. We also demonstrate that rare disease data sets can be wrangled to build predictive ML models. Interpretable ML models can function as assistive tools in a changing disease landscape and have the potential to democratize expertise that is otherwise clustered at specialized centers.

Hip reduction surgery versus scoliosis correction in non-ambulant neuromuscular patients: which surgery is the first step?

PURPOSE

Children and young adults with neuromuscular disorders have a high incidence of both spine and hip deformities. The aim of this study was to evaluate the outcome of either primary scoliosis or hip surgery in children and young adults with neuromuscular disorders.

METHODS

A retrospective study was conducted on all children and young adults with neuromuscular-related synchronous hip subluxation/dislocation and scoliosis undergoing hip or scoliosis surgery in our institution between 2012 and 2021 with a minimum follow-up of 24 months. Demographic and operative data were collected; radiological parameters were measured preoperatively and postoperatively at final follow-up.

RESULTS

Forty neuromuscular patients with synchronous hip displacement and scoliosis were included. Twenty patients with an average age of10.2 years had hip correction surgery performed primarily, with a mean follow-up of 54.9 (24-96) months. The other 20 patients with an average age of 12.4 years had scoliosis correction first, with a mean follow-up of 40 (24-60) months. In the "Hip first" group, pelvic obliquity, hip MP and Cobb angle were 16.8°, 71%, and 49°, respectively. At final follow-up, the mean pelvic obliquity and Cobb angles significantly progressed to 27.2° (p = 0.003) and 82.2° (p = 0.001), respectively. Eighteen patients (90%) required scoliosis correction after the hip surgery. In the "Scoliosis first" group, the mean pelvic obliquity, hip MP and Cobb angle were 21.2°, 49% and 65.5°, respectively. At final follow-up, both pelvic obliquity and Cobb angle significantly improved to 8.44° (p = 0.002) and 23.4° (p = 0.001), respectively. In 11/20 (55%) patients, the hip MP had significantly increased following the spinal surgery to 62% (p = 0.001), but only 5/20 (25%) patients underwent hip surgery after scoliosis correction.

CONCLUSION

In neuromuscular patients presenting with synchronous hip displacement and scoliosis deformity, corrective scoliosis surgery is associated with a significant correction of pelvic obliquity and lower rates of secondary hip surgery. On the other hand, primary hip surgery does not reduce the risk of pelvic obliquity and scoliosis deformity progression.

Pain in Children and Adolescents with Spinal Muscular Atrophy: A Longitudinal Study from a Patient Registry

Spinal muscular atrophy (SMA) is a devastating genetic neurodegenerative disease caused by the insufficient production of Survival Motor Neuron (SMN) protein. It presents different phenotypes with frequent contractures and dislocations, scoliosis, and pain. This study aims to report the prevalence and description of pain and how it affects daily life by analyzing a new ad hoc questionnaire. An observational study of patients under 18 years of age with SMA was conducted at two referral centers in Spain. Data were analyzed using a descriptive analysis and a Bayesian ordinal regression model to assess the association with clinical and demographic variables. Fifty-one individuals were included in this study, 27% of whom reported pain with a median duration of 5.2 years and a mean Visual Analogic Scale (VAS) score of 5. Notably, 77% were receiving disease-modifying treatment, with more than 50% receiving analgesic treatment. The Bayesian model showed that functional status, lower limb contractures, and number of visits have a high probability (>90%) of influencing pain. Thus, the prevalence of pain in the SMA population under 18 years is substantial, and its presence could be associated with lower limb contractures, better functional status, and higher RULM (Revised Upper Limb Module) scores.

Feasibility analysis of intrathecal administration strategy of nusinersen based on Cobb angle in children with spinal muscular atrophy

AIM

This retro-prospective observational study described the experience in lumbar puncture procedures in children with spinal muscular atrophy (SMA) with and without neuromuscular scoliosis in a single center. The technical feasibility of intrathecal nusinersen administration was the main limiting factor.

STUDY DESIGN

A total of 457 technically successful intrathecal injections based on a hierarchical strategy in Cobb angle were reviewed in 81 SMA children aged 0.75-13.5 years who were referred for nusinersen injections in our hospital from October 2019 to December 2022.

RESULTS

Under local anesthesia, conventional lumbar puncture was performed on 47 patients without spinal deformity (Cobb angle of 0-10°) and 20 patients with moderate scoliosis (Cobb angle of 10-50°). Ultrasound-assisted lumbar puncture was performed on 12 patients with moderate scoliosis but lordosis. A combination of ultrasound imaging and three-dimensional CT under sedation was performed in the remaining 14 patients with severe scoliosis (Cobb angle >50°). No severe complications were found.

CONCLUSION

Cobb angle is an important basis for intrathecal administration of nusinersen. It is feasible and suitable to carry out intrathecal nusinersen injection under ultrasound combined with three-dimensional CT imaging for children with severe scoliosis.

Nusinersen Treatment of Children with Later-Onset Spinal Muscular Atrophy and Scoliosis Is Associated with Improvements or Stabilization of Motor Function

Nusinersen has been shown to improve or stabilize motor function in individuals with spinal muscular atrophy (SMA). We evaluated baseline scoliosis severity and motor function in nusinersen-treated non-ambulatory children with later-onset SMA. Post hoc analyses were conducted on 95 children initiating nusinersen treatment in the CHERISH study or SHINE long-term extension trial. Participants were categorized by baseline Cobb angle (first nusinersen dose): ≤10°, >10° to ≤20°, and >20° to <40° (no/mild/moderate scoliosis, respectively). Outcome measures included the Hammersmith Functional Motor Score-Expanded (HFMSE) and the Revised Upper Limb Module (RULM). Regression analysis determined the relationships between baseline scoliosis severity and later motor function. For children with no, mild, and moderate scoliosis, the mean increase in HFMSE from baseline to Day 930 was 6.0, 3.9, and 0.7 points, and in RULM was 6.1, 4.6, and 2.3 points. In the linear model, a 10° increase in baseline Cobb angle was significantly associated with a -1.4 (95% CI -2.6, -0.2) point decrease in HFMSE (p = 0.02) and a -1.2 (95% CI -2.1, -0.4) point decrease in RULM (p = 0.006) at Day 930. Treatment with nusinersen was associated with improvements/stabilization in motor function in all groups, with greater response in those with no/mild scoliosis at baseline.

Early Development of Spinal Deformities in Children Severely Affected with Spinal Muscular Atrophy after Gene Therapy with Onasemnogene Abeparvovec-Preliminary Results

Spinal muscular atrophy (SMA) is a rare genetic disorder, with the most common form being 5q SMA. Survival of children with severe SMA is poor, yet major advances have been made in recent years in pharmaceutical treatment, such as gene-therapy, which has improved patient survival. Therefore, clinical problems, such as the development of spinal deformities in these genetically treated SMA children represent an unknown challenge in clinical work. In a retrospective case series, the development of spinal deformities was analyzed in 16 SMA children (9 male, 7 female) treated with onasemnogene abeparvovec in two institutions during the years 2020 to 2022. Ten out of sixteen patients had a significant kyphosis, and nine out of sixteen patients had significant scoliosis, with the mean curvature angles of 24 ± 27° for scoliosis, and 69 ± 15° for kyphosis. Based on these preliminary data, it can be assumed that early-onset kyphosis presents a clinical challenge in gene-therapy-treated SMA children. Larger datasets with longer follow-up times need to be collected in order to verify these preliminary observations.

Clinical and Functional Characteristics of a New Phenotype of SMA Type I among a National Sample of Spanish Children: A Cross-Sectional Study

Spinal Muscular Atrophy (SMA) type I has classically presented extremely severe clinical features. New pharmacological treatments have led to a new phenotype of SMA. The aim of this study was to describe the current health and functional status of children with SMA. A cross-sectional study was conducted based on the STROBE guidelines. Patient questionnaires and standardized tools were used. A descriptive analysis was conducted establishing the proportions of subjects for each of the characteristics of interest. In total, 51 genetically confirmed SMA type I subjects were included. Fifty-seven percent received oral feeding, 33% received tube feeding and 10% combined both. Moreover, 21.6% had tracheostomies, and 9.8% needed more than 16 h/d ventilatory support. Regarding orthopedic status, 66.7% had scoliosis, and 68.6% had hip subluxation or dislocation. Up to 67% were able to sit independently, 23.5% walked with support and one child walked independently. Current SMA type I is a different entity from the classic phenotype but also from types II and III. In addition, no differences were found between SMA type I subgroups. These findings may enable the professionals involved in the care of these patients to improve their interventions in terms of prevention and rehabilitation measures for these children.

Needleless inhaled anesthesia with sevoflurane: Advantages of a simplified approach for children with spinal muscular atrophy undergoing intrathecal administration of nusinersen

BACKGROUND

Intrathecal nusinersen administration, a fundamental step in the treatment of spinal muscular atrophy, is challenging in children.

AIMS

This retrospective monocentric analysis of prospectively collected data evaluated the feasibility of needleless general anesthesia exclusively with sevoflurane, without imaging guidance, for children undergoing nusinersen administration in a 24-month period.

METHODS

Clinical data included demographics, type of spinal muscular atrophy, presence and severity of scoliosis. Primary outcome was defined by the number of predefined sentinel adverse events related to anesthesia. Secondary outcomes were assessed by duration of the procedure, number of lumbar puncture attempts, and number of failures. Other measures included number and type of moderate, minor and minimal adverse events, as well as number and type of puncture-related adverse events.

RESULTS

116 patients (mean age: 8.7 (SD 6.9) years; with scoliosis: 49.1%) underwent 250 lumbar punctures; two cases of prolonged desaturation, considered as sentinel adverse events, (0.8%) were recorded during anesthesia (primary outcome). None of the patients underwent orotracheal intubation nor required an unplanned admission in the Pediatric Intensive Care Unit. No patient required an unplanned or prolonged hospitalization after the procedure. Mean number of puncture attempts was 1.6 (SD 1.3), and mean duration of the procedure was 14.1 (SD 8.3) minutes. No failure in the drug administration occurred (secondary outcomes).

CONCLUSION

In this single-center experience, needleless general anesthesia with inhaled sevoflurane without imaging guidance has been shown to be feasible for children with spinal muscular atrophy undergoing lumbar puncture for nusinersen administration.

Prospective Analysis of Functional and Structural Changes in Patients with Spinal Muscular Atrophy-A Pilot Study

Spinal muscular atrophy (SMA) is a rare, autosomal recessive neuromuscular disease. Recent years have seen a significant development of therapeutic options for SMA patients. With the development of treatment methods, it has become necessary to adapt a physiotherapeutic approach to the evolving clinical picture of SMA patients. We presented an analysis of 40 SMA patients undergoing pharmacological treatment, examined twice in an average interval of 5 months. Twelve patients (non-sitters) were evaluated using CHOP-INTEND, while 28 (sitters) were tested using the Hammersmith scale. The research protocol consisted of measurements of upper and lower limb ranges of motion, and four tests for early detection of musculoskeletal changes. Both non-sitters and sitters patients showed motor improvement between the first and second examinations. Favorable changes in range of motion parameters were noted in most children, except for hip extension (HE) range, which deteriorated. An association was also observed between scale scores and the presence of contractures in the hip and knee joints depending on the group studied. Our findings showed that the presence of contractures at the hip and knee joint negatively affected functional improvement as measured by the scale scores.

Scoliosis in Spinal Muscular Atrophy Type 1 in the Nusinersen Era

Background and Objectives

The introduction of spinal muscular dystrophy (SMA)-modifying therapies, such as antisense oligonucleotide therapy, has changed the natural history of SMA. Most reports on treatment outcomes have focused on motor scores and respiratory function. The objective of this study is to document the development and progression of scoliosis in patients with SMA1 treated with nusinersen.

Methods

A descriptive single-center study was conducted in patients with SMA1 who were treated with nusinersen before 6 months of age. Data were collected on patients who met criteria, including age at the first nusinersen dose, number of nusinersen doses, degree of scoliosis, respiratory parameters, feeding route, and motor scores at baseline and follow-up. The Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) was subanalyzed using axial (AxS) and appendicular motor (ApS) scores to evaluate a possible correlation between scoliosis and axial muscle strength.

Results

From our cohort, 31 percent (11/35) of patients had a diagnosis of SMA1. Sixty-three percent (7/11) met the inclusion criteria. All patients (7/7) showed initial improvement in their CHOP-INTEND scores in correlation with improvement on the ApS. Despite this, most patients did not show improvement in the AxS. Subsequently, all patients developed scoliosis in the first year of life with Cobb angles that ranged between 18° and 60°. Furthermore, total CHOP-INTEND scores had dropped in 2 patients alongside the development of a Cobb angle of >40°.

Discussion

Despite the significant improvement in functional motor assessment in patients with SMA1, there is a progression of significant scoliosis despite treatment. Subsequently, lack or minimal improvement on the axial CHOP-INTEND scores may predict worsening on the total motor scores.

Protocol-driven early tracheal extubation in patients with flaccid neuromuscular scoliosis and pre-existing lung disease

PURPOSE

To review the results of a postoperative respiratory pathway for patients with muscular dystrophy (MD) and spinal muscular atrophy (SMA) undergoing spinal surgery.

METHODS

With IRB approval, a retrospective review was done on all patients with SMA and MD undergoing spinal surgery on a neuromuscular protocol. Baseline demographics, perioperative results, and long-term outcomes were collected. Per the protocol, patients remained intubated after surgery and were transported to the intensive care unit (ICU) for extubation. We present the results of protocol implementation and compare patients with MD to those with SMA.

RESULTS

Twenty-four patients were treated using the protocol. Average age was 13.1 years. Severe restrictive lung disease was present in 75% of patients. Nocturnal BiPAP was required in 68% of patients. Average number of instrumented levels was 17. All patients were immediately extubated upon entering the ICU. There were three respiratory complications and only was patient was re-intubated. Average ICU stay was 1.8 days and average hospital length of stay was 6.7 days. No differences in postoperative inspiratory or expiratory positive airway pressures were observed between the MD and SMA groups.

CONCLUSION

Through a multidisciplinary neuromuscular protocol, excellent clinical outcomes were achieved in patients with neuromuscular scoliosis and restrictive lung disease, with complication rates and length of stay significantly lower than previously published data.

LEVEL OF EVIDENCE

IV.

ANALYSIS OF PATIENTS SUBMITTED TO SURGICAL TREATMENT FOR NEUROMUSCULAR SCOLIOSIS WITH AND WITHOUT INTRAOPERATIVE TRACTION

ABSTRACT Objectives: To compare the surgical treatment of neuromuscular scoliosis (NMS) with and without intraoperative skull-skeletal traction (ISST) in terms of the degree of curve correction, surgical time, hospitalization time, screw density, use of blood products,and complications. Methods: A comparative retrospective study, in which we analyzed the medical records and radiographs of 17 patients who underwent surgical treatment for neuromuscular scoliosis (NMS). They were divided into two groups, with 9 and 8 patients operated with and without ISST, respectively, at a referral hospital specialized in the treatment of spinal deformitiesfrom 2019 to 2021. The categorical variables were analyzed using the Chi-squared test. Results: Among the 17 patients included in the study, there was a higher prevalence of women in the group without ISST (6 and 2) and of men in group with ISST (5 and 3). The ages of the patients in the two groups ranged from 8-19 years and from 11-29 years, respectively. The screw density used in the traction group averaged 66.33%±8.49 and 82.63%±17.25 in the non-traction group, a statistically significant differencewith a P-value of 0.036. The average percent correction was 76.81%±15.61 in the traction group as compared to an average of 66.39%±12.99 in the non-traction group. In addition, there were complications in 1 patient in each of the groups. Conclusions: Surgical treatment for NMS with ISST allows surgery using fewer blood products to maintain the same hematimetric level in the postoperative period. ISST also allows the use of a lower screw density to correct more severe deformities. Level of evidence III; Comparative retrospective study.

Current concepts in the treatment of neuromuscular scoliosis: clinical assessment, treatment options, and surgical outcomes

The development of spinal deformity in children with underlying neurodisability can affect their ability to function and impact on their quality of life, as well as compromise provision of nursing care. Patients with neuromuscular spinal deformity are among the most challenging due to the number and complexity of medical comorbidities that increase the risk for severe intraoperative or postoperative complications. A multidisciplinary approach is mandatory at every stage to ensure that all nonoperative measures have been applied, and that the treatment goals have been clearly defined and agreed with the family. This will involve input from multiple specialities, including allied healthcare professionals, such as physiotherapists and wheelchair services. Surgery should be considered when there is significant impact on the patients’ quality of life, which is usually due to poor sitting balance, back or costo-pelvic pain, respiratory complications, or problems with self-care and feeding. Meticulous preoperative assessment is required, along with careful consideration of the nature of the deformity and the problems that it is causing. Surgery can achieve good curve correction and results in high levels of satisfaction from the patients and their caregivers. Modern modular posterior instrumentation systems allow an effective deformity correction. However, the risks of surgery remain high, and involvement of the family at all stages of decision-making is required in order to balance the risks and anticipated gains of the procedure, and to select those patients who can mostly benefit from spinal correction.

Cholesterol-functionalized DNA/RNA heteroduplexes cross the blood-brain barrier and knock down genes in the rodent CNS

Achieving regulation of endogenous gene expression in the central nervous system (CNS) with antisense oligonucleotides (ASOs) administered systemically would facilitate the development of ASO-based therapies for neurological diseases. We demonstrate that DNA/RNA heteroduplex oligonucleotides (HDOs) conjugated to cholesterol or α-tocopherol at the 5' end of the RNA strand reach the CNS after subcutaneous or intravenous administration in mice and rats. The HDOs distribute throughout the brain, spinal cord and peripheral tissues and suppress the expression of four target genes by up to 90% in the CNS, whereas single-stranded ASOs conjugated to cholesterol have limited activity. Gene knockdown was observed in major CNS cell types and was greatest in neurons and microglial cells. Side effects, such as thrombocytopenia and focal brain necrosis, were limited by using subcutaneous delivery or by dividing intravenous injections. By crossing the blood-brain barrier more effectively, cholesterol-conjugated HDOs may overcome the limited efficacy of ASOs targeting the CNS without requiring intrathecal administration.

The Antisense Oligonucleotide Nusinersen for Treatment of Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a rare, autosomal recessive neuromuscular degenerative disease characterized by loss of spinal cord motor neurons leading to progressive muscle wasting. The most common pathology results from a homozygous disruption in the survival motor neuron 1 (SMN1) gene on chromosome 5q13 via deletion, conversion, or mutation. SMN2 is a near duplicate of SMN1 that can produce full-length SMN mRNA transcripts, but its overall production capability of these mRNA transcripts is lower than that seen in SMN1. This leads to lower levels of functional SMN protein within motor neurons. The FDA approved nusinersen in December 2016 to treat SMA associated with SMN1 gene mutation. It is administered directly to the central nervous system by intrathecal injection. An antisense oligonucleotide (ASO) drug, nusinersen, provides an upcoming and promising treatment option for SMA and represents a novel pharmacological approach with a mechanism of action relevant for other neurodegenerative disorders. Nusinersen begins with four initial loading doses that are followed by three maintenance doses per year. Three major studies (CHERISH, ENDEAR, and NURTURE) have shown to improve motor function in early and late-onset individuals and reduce the chances of ventilator requirements in pre-symptomatic infants. Studies investigating the timing of drug delivery in mouse models of SMA report the best outcomes when drugs are delivered early before any significant motor function is lost. Nusinersen is a novel therapeutic approach with consistent results in all three studies and is proof of the novel concept for treating SMA and other neurodegenerative disorders in the future.

Hybrid versus total sublaminar wires in patients with spinal muscular atrophy undergoing scoliosis surgery

Background

Early versions of spinal muscular atrophy (SMA) scoliosis correction surgery often involved sublaminar devices. Recently, the utilization of pedicle screws has gained much popularity. Pedicle screws are generally believed to provide additional deformity correction, but pedicle size and rotational deformity limit their application in the thoracic spine, resulting in a hybrid construct involving pedicle screws and sublaminar wire. Studies of the efficacy of hybrid instrumentation in SMA scoliosis are often limited by the scarcity of the disease itself. In this study, we aimed to compare the surgical outcomes between hybrid constructs involving pedicle screws and sublaminar wire and sublaminar wire alone in patients with SMA scoliosis.

Methods

We retrospectively reviewed the clinical records and radiographic assessments of patients with SMA scoliosis who underwent corrective surgery between 1993 and 2017. The radiographic assessments included deformity correction and progressive changes in the major curve angle, pelvic tilt (PT) and coronal balance (CB). The correction of deformities was observed postoperatively and at the patient’s 2-year follow-up to test the efficacy of each type of construct.

Results

Thirty-three patients were included in this study. There were 14 and 19 patients in the wiring and hybrid construct groups, respectively. The hybrid construct group demonstrated a higher major curve angle correction (50.5° ± 11.2° vs. 36.4° ± 8.4°, p < 0.001), a higher apical vertebral rotation correction (10.6° ± 3.9° vs. 4.8° ± 2.6°, p < 0.001), and a reduced progression of the major curve angle at the 2-year follow-up (5.1° ± 2.9° vs. 8.7° ± 4.8°, p < 0.001). A moderate correlation was observed between the magnitude of correction of the apical vertebral rotation angle and the major curve (r = 0.528, p = 0.002).

Conclusion

This study demonstrated that hybrid instrumentation can provide a greater magnitude of correction in major curve and apical rotation as well as less major curve progression than sublaminar wire instrumentation alone in patients with SMA scoliosis. Level of evidence III

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04737-0.

Minimally Invasive Fusionless Surgery for Scoliosis in Spinal Muscular Atrophy: Long-term Follow-up Results in a Series of 59 Patients

BACKGROUND

Treatment of spinal muscular atrophy (SMA) scoliosis has evolved in the last decade, with the emergence of fusionless surgical techniques that allow correction of the deformity before the end of growth spurt. These techniques are expected to delay definitive spine fusion and preserve trunk growth.

PURPOSE

The aim was to evaluate long-term clinical, radiologic, and respiratory outcomes of a minimally invasive fusionless surgery (MIFLS) in SMA scoliosis.

METHODS

All children affected with SMA scoliosis who underwent MIFLS in our department from 2011 to 2019 were included. The instrumentation consisted in a bilateral sliding rod construct from T1 to the sacrum, anchored proximally by double-hook claws and distally by iliosacral screws. Clinical, genetic, respiratory and radiographic data were retrospectively reviewed. A patient's satisfaction survey was performed.

RESULTS

A total of 59 children with genetic confirmation of SMA (9SMA1c, 47SMA2, and 3SMA3) underwent MIFLS at a mean age of 11±1.9 years. All of them were nonwalker at the time of surgery. Twenty-six were treated with intrathecal Nusinersen. Mean follow-up was 5.2 years (2 to 9.6 y). Mean major coronal curve improved from 79±15 to 41±16 degrees and pelvic obliquity decreased from 24±11 to 5.9±4 degrees. Mean space available for lung improved from 77% to 93%. Mechanical or infectious complications occurred in 9 patients, with removal of the implant in 1. 6 children required unplanned surgeries. Postoperative bracing was needed in 13 children. Mean gain weight 3 years after the first surgery was 6 kg. 91.5% of patients had a positive satisfaction of the surgery. There was no significant impact in respiratory function postoperatively. Only 30 children required rod lengthening procedures, with a mean interval between procedures of 1.9 years (0.5 to 3.7 y). No arthrodesis was required at last follow-up in any patient.

CONCLUSION

Bipolar MIFLS in SMA preserves spinal and thoracic growth without interference with respiratory function. It provides a significant correction of spinal deformity and pelvic obliquity, having a reduced rate of complications. The correction of spinal deformity was maintained at long term, not requiring definitive fusion at the end of growth.

LEVEL OF EVIDENCE

Level IV.

Motor Function of Children with SMA1 and SMA2 Depends on the Neck and Trunk Muscle Strength, Deformation of the Spine, and the Range of Motion in the Limb Joints

The purpose of this study was to investigate the functional relationships between selected ranges of motion of the neck, upper and lower limbs, the strength of the neck and trunk muscles, postural parameters, and the motor function of children with SMA1 and SMA2—27 children, aged 6 months-15 years, with genetically confirmed spinal muscular atrophy type 1 (19 children) and 2 (8 children) undergoing pharmacological treatment. All children were examined, according to the methodology, including the motor function evaluation, measurement of selected ranges of motion, assessment of postural parameters, and measurement of neck and trunk muscle strength. The functional status of 15 children was assessed with the CHOP INTEND (CHOP group) scale and of 12 children with the HFMSE (HFMSE group). The results obtained showed that, in children examined with the CHOP scale, greater limitation of flexion in the shoulder joints was observed. As the deformation of the chest increased, the functional abilities of children deteriorated. In participants examined with the CHOP group, the ranges of neck rotation decreased with the increase of the chest deformity. In the HFMSE group, the ranges of head rotation showed a strong relationship with some parameters of muscle strength and the sum of the R coefficients. Participants showed many significant relationships between the range of motion in the neck and joints of the limbs, with more significant relationships in the CHOP group. The following conclusions were made: motor skills of children with SMA depend on muscle strength, range of motion, and deformities of the spine and chest; the development of scoliosis adversely affects the motor function, ranges of motion, and muscle strength; and movement ranges are related to motor skills and strength values.

Sagittal Plane Deformities in Children with SMA2 following Posterior Spinal Instrumentation

This is a retrospective radiographic review to assess post-operative sagittal plane deformities in patients with Spinal Muscular Atrophy type 2 that had been treated with posterior spinal instrumentation. Thirty-two patients with a history of either spinal fusion (N = 20) or growing rods (N = 12) were identified with an average of 7.6 (2.1-16.6) years post-operative follow-up. Forty percent (13/32) of the patients were identified as having obvious "tucked chin" (N = 4), "tipped trunk" (N = 9), or both (N = 3). Sacral incidence was the only parameter that was statistically significant change between pre-operative or immediate post-operative measurements (66.9° vs. 55.2° p = 0.03). However, at final follow-up, the post-operative thoracic kyphosis had decreased over time in those that developed a subsequent sagittal deformity (24.2°) whereas it increased in those that did not (44.7°, p = 0.008). This decrease in thoracic kyphosis throughout the instrumented levels, resulted in a greater lordotic imbalance (30.4° vs. 5.6°, p = 0.001) throughout the instrumented levels in the group that developed the subsequent cervical or pelvic sagittal deformities. In conclusion, sagittal plane deformities commonly develop outside the instrumented levels in children with SMA type 2 following posterior spinal instrumentation and may be the result of lordotic imbalance that occurs through continued anterior growth following posterior instrumentation.

[Etiology, epidemiology, prognosis and biomechanical principles of neuromuscular scoliosis]

Deformity due to neuromuscular disease is often progressive and associated with reduced vital capacity. In general, all treatment should be performed in specialized centers, since invasive measures are associated with an increased morbidity compared to adolescent scoliosis. Derived from the etiology and the resulting biomechanical basis (characteristics), important aspects and considerations arise for all healthcare institutions from the examination interval to the duration of conservative therapy and initiation of surgical therapy. Proper monitoring and assessment are key components to identify curve progression and to achieve preservation or improvement of basic functions.

[Surgical strategies in the treatment of neuromuscular scoliosis]

As part of the underlying condition, neuromuscular scoliosis occurs in early childhood. Compared to idiopathic scoliosis, neuromuscular scoliosis shows a more rapid progress of deformity, which continues even after the end of growth. This progress and the associated complications can only be prevented by surgical treatment. Depending on the patient's age and the extent of the deformity, different strategies have been established: in early childhood, so-called "growing implants" are used, while between the ages of 10 to 12, definitive treatment by reposition and fusion of the deformity is the treatment of choice. In this review, we present different surgical strategies as well as indications for surgery and discuss challenges in the treatment of these complex deformities.

Scoliosis in Friedreich's ataxia: longitudinal characterization in a large heterogeneous cohort

OBJECTIVE

The objective of this study was to characterize the incidence and progression of scoliosis in the natural history of Friedreich's ataxia (FRDA) and document the factors leading to the requirement for corrective surgery.

METHODS

Data on the prevalence of scoliosis and scoliosis surgery from up to 17 years of follow-up collected during a large natural history study in FRDA (1116 patients at 4928 visits) were summarized descriptively and subjected to time to event analyses.

RESULTS

Well over 90% of early or typical FRDA patients (as determined by age of onset) developed intermediate to severe scoliosis, while patients with a later onset (>14 years) had no or much lower prevalence of scoliosis. Diagnosis of scoliosis occurs during the onset of ataxia and in rare cases even prior to that. Major progression follows throughout the growth phase and puberty, leading to the need for surgical intervention in more than 50% of individuals in the most severe subgroup. The youngest patients appear to delay surgery until the end of the growth period, leading to further progression before surgical intervention. Age of onset of FRDA before or after reaching 15 years sharply separated severe and relatively mild incidence and progression of scoliosis.

INTERPRETATION

Scoliosis is an important comorbidity of FRDA. Our comprehensive documentation of scoliosis progression in this natural history study provides a baseline for comparison as novel treatments become available.

Managing intrathecal administration of nusinersen in adolescents and adults with 5q-spinal muscular atrophy and previous spinal surgery

BACKGROUND

Spinal muscular atrophy (SMA) is a neurodegenerative disease of lower motor neurons associated with frequent occurrence of spinal deformity. Nusinersen is an antisense oligonucleotide that increases SMN protein level and is administrated by frequent intrathecal lumbar injections. Thus, spinal deformities and previous spinal surgery are important challenges for drug delivery in SMA.

OBJECTIVE

To report imaging methods used for Nusinersen injection in SMA patients.

METHODS

Nusinersen injection procedures in SMA types 2 and 3 patients who had previous spinal surgery were analyzed retrospectively to describe the imaging and puncture procedures, as well as the occurrence of complications.

RESULTS

Nine SMA patients (14 to 50 years old) underwent 57 lumbar punctures for nusinersen injection. Six patients had no interlaminar space available; in five of them, a transforaminal approach was used, and another one underwent a surgery to open a posterior bone window for the injections. Transforaminal puncture was performed using CT scan in three cases and fluoroscopy in the other two, with a similar success rate. One patient in the transforaminal group had post-procedure radiculitis, and another one had vagal reaction (hypotension). In three cases, with preserved interlaminar space, injections were performed by posterior interlaminar puncture, and only one adverse event was reported (post-puncture headache).

CONCLUSION

In SMA patients with previous spinal surgery, the use of imaging-guided intervention is necessary for administering intrathecal nusinersen. Transforaminal technique is indicated in patients for whom the interlaminar space is not available, and injections should always be guided by either CT or fluoroscopy.

Understanding European patient expectations towards current therapeutic development in spinal muscular atrophy

Following the 2017 approval of a first spinal muscular atrophy (SMA) treatment by the European Medicines Agency, SMA Europe launched a Europe-wide survey with the goal of understanding patients' treatment expectations, realities of daily living and access to clinical trials and therapy, and how this varied according to parameters such as age and disease severity. A response rate of 31% yielded 1474 completed surveys from 26 European countries. In line with findings from a 2015 SMA Europe-led survey, participants considered stabilization of their condition to be progress. Notably, responses indicated that the current classification of SMA at diagnosis by 'type' often does not reflect current mobility level. Large gaps in treatment access were identified that varied in particular between age and disease severity groups, yet there was high interest in clinical trial participation. In addition, alternative treatment options, including combination therapies, are now expectations. These perspectives should be central considerations through the research and development processes of new SMA therapies, through data generation and discussions on access to therapies. Results from this survey indicate that collaboration between stakeholders is essential to the foundation upon which innovative approaches for SMA treatments and access can be explored.

Evolving Surgical Management for Early-Onset Scoliosis in Spinal Muscular Atrophy Type 1 Given Improvements in Survival

CASE

We present a case of an 18-month-old child with early-onset scoliosis in the setting of spinal muscular atrophy (SMA) type 1 whose rapidly progressive scoliosis is successfully managed with magnetic growing rods, the youngest age of implantation in a patient with SMA we are currently aware of. Technical challenges, complications, and outcome are described in this case presentation.

CONCLUSION

Patients with SMA type 1 and early-onset scoliosis can be managed with growing-rod constructs given dramatic improvements in medical care that have expanded life expectancy.

Feeding difficulties in children and adolescents with spinal muscular atrophy type 2

Disease course of feeding difficulties in spinal muscular atrophy type 2 is not well documented. Disease-modifying therapies rapidly change the trajectory of motor function and survival in spinal muscular atrophy, but effects on co-morbidities like bulbar function are unknown. We analysed data concerning feeding problems and their standard of care treatment in 146 patients with spinal muscular atrophy type 2. Data were collected from two separate cohorts: one single-centre retrospective chart review study from the United Kingdom (London), and one prospective questionnaire-based multicentre study from Italy. Cumulatively feeding difficulties were present in 88 patients (60%) in these 2 cohorts. Median age at onset of problems was 6.5years (range 0-16.5 years). Eighty-two patients (60%) showed periods of underweight according to age adjusted body mass index, and thirty-six patients (25%) showed malnourishment with a significant drop on their weight curves. Enteral feeding was indicated in 23 out of 72 patients in the UK cohort (32%) because of weight loss, oropharyngeal dysphagia or aspiration. Gastrostomy and its placement was generally well tolerated, uncomplicated in 96%, never reversed and performed without Nissen fundoplication in 66% of patients. After gastrostomy chest infections improved in 80% and nutritional status (e.g., Body Mass Index) in 84% of patients. These results show that feeding difficulties are a common problem in spinal muscular atrophy type 2. Treatment strategies should be tailor-made on the symptoms and needs of the individual patient.

The impact of scoliosis surgery on pulmonary function in spinal muscular atrophy: a systematic review

Scoliosis often occurs coincident with pulmonary function deterioration in spinal muscular atrophy but a causal relationship has not yet been reliably established. A systematic literature review was performed, with pulmonary function testing being the primary outcome pre- and post-scoliosis surgery. Levels of evidence were determined and GRADE recommendations made. Ninety studies were identified with only 14 meeting inclusion criteria. Four studies were level III and the rest were level IV evidence. The average age at surgical intervention was 11.8 years (follow-up 6.1 years). Post-operative pulmonary function progressively declined for the majority of studies. Otherwise, pulmonary function: improved (two studies), were unchanged (two studies), had a decreased rate of decline (three studies), declined initially then returned to baseline (two studies). Respiratory and spine-based complications were common. Given the available evidence, the following GRADE C recommendations were made: (1) surgery is most often associated with decreases in pulmonary function; (2) the impact of surgery on pulmonary function is variable, but does not improve over pre-operative baseline; (3) surgery may result in a decreased rate of decline in pulmonary function post-operatively. Given this lack of evidence-based support, the risk-benefit balance should be taken into consideration when contemplating scoliosis surgery.

Point Prevalence and Associated Factors of Hip Displacement in Pediatric Patients With Mitochondrial Disease

Objective: Mitochondrial disease is a multisystem disorder resulting from mitochondrial dysfunction. Although musculoskeletal system is vulnerable to mitochondrial dysfunction, little information is available on orthopedic issues such as hip displacement and scoliosis in patients with mitochondrial disease. We aimed to examine the point prevalence of hip displacement and investigate the associated factors in patients with mitochondrial disease. Methods: We retrospectively reviewed the medical records and plain radiographs of patients diagnosed with mitochondrial disease between January 2006 and January 2019 at a single institution. Data, including patient age, sex, follow-up duration, syndromic diagnosis, and gross motor function were collected. Migration percentage was measured on the radiographs. The clinical and radiologic variables were compared between patients classified according to the presence of hip displacement and motor function level. Results: We included 225 patients (135 men, 90 women). The mean age at the latest follow-up was 11.1 years, and the mean follow-up duration was 7.0 years. Hip displacement was noted in 70 (31.1%) patients. The proportion of patients with Leigh disease (p = 0.007) and the ratio of non-ambulators (p < 0.001) were higher among patients with hip displacement. The proportion of patients with Leigh disease was higher in the non-ambulators than the ambulators. Conclusion: One-third of patients with mitochondrial disease developed hip displacement. Hip displacement was more common in non-ambulators or patients with hypertonia. Careful and serial monitoring for hip problems is required for non-ambulatory patients with mitochondrial disease who have increased muscle tone.

Scoliosis Surgery Significantly Impacts Motor Abilities in Higher-functioning Individuals with Spinal Muscular Atrophy1

BACKGROUND

Weakness affects motor performance and causes skeletal deformities in spinal muscular atrophy (SMA). Scoliosis surgery decision-making is based on curve progression, pulmonary function, and skeletal maturity. Benefits include quality of life, sitting balance, and endurance. Post-operative functional decline has not been formally assessed.

OBJECTIVE

To assess the impact of scoliosis surgery on motor function in SMA types 2 and 3.

METHODS

Prospective data were acquired during a multicenter natural history study. Seventeen participants (12 type 2, 5 type 3 with 4 of the 5 having lost the ability to ambulate) had motor function assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE) performed pre-operatively and at least 3 months post-operatively. Independent t-tests determined group differences based on post-operative HFMSE changes, age, and baseline HFMSE scores.

RESULTS

Three participants had minimal HFMSE changes (±2 points) representing stability (mean change = -0.7). Fourteen participants lost >3 points, representing a clinically meaningful progressive change (mean change = -12.1, SD = 8.9). No participant improved >2 points. There were no age differences between stable and progressive groups (p = 0.278), but there were significant differences between baseline HFMSE (p = 0.006) and change scores (p = 0.001). Post-operative changes were permanent over time.

CONCLUSIONS

Scoliosis surgery has an immediate impact on function. Baseline HFMSE scores anticipate post-operative loss as higher motor function scores were associated with worse decline. Instrumentation that includes fixation to the pelvis reduces flexibility, limiting the ability for compensatory maneuvers. These observations provide information to alert clinicians regarding surgical risk and to counsel families.

Cervical rotation, chest deformity and pelvic obliquity in patients with spinal muscular atrophy

Background

Musculoskeletal disorders are often observed in patients with spinal muscular atrophy (SMA). The aim of the study was to assess passive ranges of rotation in the cervical spine, chest deformity and pelvic obliquity in SMA patients, and to compare these results to the norms obtained in the group of healthy individuals. The second aim was to review these measurements and Cobb angle values for correlations in SMA patients.

Methods

The study included 74 patients with SMA and 89 healthy individuals aged 2 to 18 years. Cervical Rotation (CR), Supine Angle of Trunk Rotation (SATR) and Pelvic Obliquity (PO) tests were carried out.

Results

Cervical rotation ranges were significantly higher in the control group than in SMA patients (p < 0.05). Differences between cervical rotation ranges to the left and to the right were significantly larger in SMA I and SMA II groups than in healthy individuals (p = 0.000). Chest asymmetry and pelvic obliquity were bigger in SMA groups than in the control (p < 0.05). Significant correlations between cervical rotation measurements, chest deformity, pelvic obliquity and Cobb angle were found in SMA individuals, depending on the type.

Conclusions

The results of the study suggest that CR, SATR and PO tests may assist in the assessment of SMA patients in addition to the radiographic evaluation of the spine. Biomechanical relationships between disorders located in various skeletal structures should be taken into account in the treatment of SMA patients. Special attention should be given to assessing postural parameters in non- sitters and sitters. Treatment of patients with SMA and associated musculoskeletal disorders requires a multi-specialist approach.

Predictors for Deformity Progression in a Spinal Muscular Atrophy Cohort After Scoliosis Correction Surgery

STUDY DESIGN

This was a single-center, retrospective study.

OBJECTIVE

The objective of this study was to assess the risk factors for deformity progression after scoliosis correction surgery in spinal muscular atrophy (SMA) patients.

SUMMARY OF BACKGROUND DATA

Moderate residual postoperative scoliosis curve is common in SMA populations; however, the acceptable postoperative scoliosis curve for preventing deformity progression remains uncertain.

MATERIALS AND METHODS

Twenty-nine SMA patients undergoing scoliosis correction surgery were included. Scoliosis progression was defined as an increase of 10 degrees in the major curve of Cobb angle (MCCA); pelvic obliquity (PO) or concave-side hip progression was arbitrarily defined as an increase of ≥1 grade after surgery. Risk factors for deformity progression were examined using Cox proportional hazard models. The cumulative incidence rate of deformity progression was performed by the Kaplan-Meier survival analysis RESULTS:: The mean age at surgery was 13.3 years (range: 8-25 y) and the mean follow-up time was 7 years (range: 2-22.9 y). The mean MCCA was corrected from 69 to 34.6 degrees at initial follow-up and 42.2 degrees at the final follow-up. Postoperative MCCA (P=0.002) and PO (P=0.004) at initial follow-up were the risk factors for scoliosis progression. Postoperative MCCA at initial follow-up (P=0.007) and age at the time of surgery (P=0.017) were the risk factors for PO progression. Different cutoff points of postoperative MCCA at initial follow-up were compared for predicting deformity progression. We found the patient with postoperative MCCA of <30 degrees at initial follow-up had a significantly less cumulative incidence rate of progression than their counterparts for scoliosis (P=0.005), PO (P=0.023), and concave-side hip progressions (P=0.008).

CONCLUSIONS

We recommended that MCCA should be corrected to <30 degrees to prevent postoperative scoliosis, PO, and concave-side femoral head coverage percentage progressions. Patients receiving surgery earlier had less postoperative MCCA at initial follow-up but with no increase in the risk of postoperative scoliosis progression.

Early Results of a Management Algorithm for Collapsing Spine Deformity in Young Children (Below 10-Year Old) With Spinal Muscular Atrophy Type II

BACKGROUND

Progressive C-shaped scoliosis with marked pelvic obliquity is common to spinal muscular atrophy (SMA). Reducing the number of procedures with effective deformity control is critical to minimize the risk of pulmonary complications. This study reports the preliminary results of magnetically controlled growing rods (MCGR) in SMA-related collapsing spine deformity.

METHODS

Inclusion criteria for this retrospective review were: (1) SMA type 2 patients, (2) early onset scoliosis (below 10 y), (3) collapsing spine deformity with pelvic obliquity, (4) growth-friendly scoliosis treatment with MCGR, (5) in between 2014 and 2017. Extracted data included demographic and clinical information, radiologic parameters, surgical details, and final status of the patients.

RESULTS

A total of 11 patients (7 boys, 4 girls) were included. The average age at index surgery was 8.2 (6 to 10) years. Dual MCGR was implanted in 8 patients. In 3 patients, because of curve rigidity and inability of apex to be brought into the stable zone, apical fusion with gliding connectors (convexity) and a single MCGR (concavity) was preferred. Instrumentation included the pelvis in 9 and stopped at the lumbar spine (L3) in 2 patients at the index procedure. Average preoperative deformity of 81.8 degrees (66 to 115) decreased to 29 degrees (11 to 57) postoperatively and was 26 degrees at average 35 months (16 to 59). Pelvic obliquity of 20.9 degrees (11 to 30) decreased to 4.9 degrees (2 to 8) after index surgery and was 6.5 degrees (2 to 16) at the last follow-up. T1-S1 height of 329 mm (280 to 376) after index surgery increased to 356 mm (312 to 390) after 9.2 (4 to 20) outpatient lengthening. No neurologic, infectious, or implant-related complication was recorded. Distal adding-on deformity occurred in 2 patients without initial pelvic fixation.One patient deceased secondary to pneumonia at 16 months after surgery.

CONCLUSIONS

Short-term results indicate that MCGR may be a good option in SMA-associated collapsing spine deformity to reduce the burden of repetitive lengthening procedures. The authors recommend apical deformity control in the convex side in case of curve rigidity. In addition, including the pelvis in the instrumentation at index surgery is critical to prevent distal adding-on.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Treatment expectations and patient-reported outcomes of nusinersen therapy in adult spinal muscular atrophy

Background

The antisense-oligonucleotide (ASO) nusinersen has recently been approved as the first genetically modifying therapy for 5q-associated spinal muscular atrophy (SMA) based on randomized sham-controlled trials in infants and children. The efficacy in adults with long disease history and advanced disease status is still widely unknown; the same applies to specific expectations of adult SMA patients and to what extent they are met and may impact outcome measures.

Methods

In a longitudinal monocentric study in adult patients with SMA types 2–4, the Stanford Expectations of Treatment Scale (SETS) was assessed prior to and during nusinersen treatment. Treatment outcome was evaluated using patient-reported outcomes (PROs) as well as objectively quantifiable motor outcome measures.

Results

Adult SMA patients had high expectations of nusinersen treatment effectiveness regarding increase in muscle strength and disease stabilization. Via PROs, 75% stated improvements in muscle strength, endurance and independence under therapy which was in line with slight improvements in quantifiable motor scores during a  ten month observation period. In contrast, patients only expressed few negative expectations which further decreased during therapy.

Conclusions

This study showed mainly positive treatment expectations and PROs in patients undergoing nusinersen treatment along with measurable functional improvement in adult SMA patients. Moreover, treatment expectations did not significantly influence outcome measures.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09847-8) contains supplementary material, which is available to authorized users.

Clinical Implication of Dosimetry of Computed Tomography- and Fluoroscopy-Guided Intrathecal Therapy With Nusinersen in Adult Patients With Spinal Muscular Atrophy

Background: Spinal muscular atrophy (SMA) is a genetic disorder that leads to progressive tetraparesis. Nusinersen is the first approved drug for the treatment of SMA and is administered via intrathecal injections. Neuromyopathic scoliosis and spondylodesis can impede lumbar punctures, thus necessitating the use of radiological imaging. Furthermore, dosimetry of this potentially lifelong therapy should be supervised.

Methods: Fluoroscopy-assisted or computed tomography (CT)-guided intrathecal injections of nusinersen were performed in adult patients with SMA type 2 and 3. The mean effective dose was compared in patients with and without spondylodesis as well as in those with SMA type 2 and 3. The dosimetry was analyzed in relation to the motor function evaluated with the Revised Upper Limb module (RULM) score and the Hammersmith Functional Motor Scale-Expanded (HFMSE) score.

Results: Fifteen patients with SMA type 2 and 3 underwent radiological imaging-assisted intrathecal injections. The mean effective dose per CT-guided injection per patient was 2.59 (±1.67) mSv (n = 12). The mean dose area product (DAP) per fluoroscopy-guided injection per patient was 200.48 (±323.67) μGym² (n = 3). With increase in the number of injections, the effective dose (r = −0.23) (p < 0.05) and the DAP (r = −0.09) (p > 0.05) decreased. The mean effective dose in 4 patients without spinal fusion (SMA type 2) was 1.39 (±0.51) mSv, whereas that in 8 patients with spondylodesis (SMA type 2 and 3) was 3.21 (±1.73) mSv. The mean effective dose in 5 SMA type 2 patients with spondylodesis was 2.68 (±1.47) mSv (n = 5) and in 3 SMA type 3 patients was 4.00 (±1.82) mSv. Dosimetry did not show significant correlation with the clinical severity of the disease (RULM score: r = −0.045, p > 0.05 and HFMSE score: r = −0.001, p > 0.05).

Conclusions: In SMA type 2 and 3 patients undergoing radiological imaging-assisted injections, the effective dose and DAP decreased during therapy with nusinersen. The mean effective dose in patients with spondylodesis was higher than that in patients without spondylodesis. Dosimetry should be monitored carefully in order to detect and prevent unnecessary radiation exposure.

Intrathecal administration of nusinersen in adult and adolescent patients with spinal muscular atrophy and scoliosis: Transforaminal versus conventional approach

Spinal deformities and surgical correction of scoliosis can make intrathecal delivery of nusinersen very challenging. We aim to evaluate the feasibility and safety of intrathecal administration of nusinersen either via interlaminar or transforaminal approach in a cohort of adult and adolescent patients with spinal muscular atrophy (SMA). Twelve patients were treated with nusinersen in our center under CT-guidance; after a CT scan of the lumbar column, we identified a safe virtual trajectory for the needle and defined patients to address to the transforaminal approach (seven patients) or the interlaminar approach (five patients). Out of 47 procedures, all injections but one were successful. There was one adverse event (post-lumbar puncture syndrome) in the interlaminar approach group (out of 20 procedures) and four adverse events in TFA group (out of 27 procedures) including one serious adverse event, a subarachnoid hemorrhage that required hospitalization. Transforaminal approach can be considered an effective option for nusinersen administration but potentially associated with serious complications, therefore it should be recommended in very selected patients.

Natural course of scoliosis and lifetime risk of scoliosis surgery in spinal muscular atrophy

Objective

To investigate the natural course of scoliosis and to estimate lifetime probability of scoliosis surgery in spinal muscular atrophy (SMA).

Methods

We analyzed cross-sectional data from 283 patients from our population-based cohort study. Additional longitudinal data on scoliosis progression and spinal surgery were collected from 36 consecutive patients who received scoliosis surgery at our center.

Results

The lifetime probability of receiving scoliosis surgery was ≈80% in SMA types 1c and 2. Patients with type 2 who only learned to sit (type 2a) were significantly younger at time of surgery than those who learned to sit and stand (type 2b). The lifetime risk of surgery was lower in type 3a (40%) and strongly associated with age at loss of ambulation: 71% in patients losing ambulation before 10 years of age vs 22% losing ambulation after the age of 10 years (p = 0.005). In type 3a, preserving the ability to walk 1 year longer corresponded to a 15% decrease in lifetime risk of scoliosis surgery (hazard ratio 0.852, p = 0.017). Scoliosis development was characterized by initial slow progression, followed by acceleration in the 1.5- to 2-year period before surgery.

Conclusion

The lifetime probability of scoliosis surgery is high in SMA types 1c and 2 and depends on age at loss of ambulation in type 3. Motor milestones such as standing that are not part of the standard classification system are of additional predictive value. Our data may act as a reference to assess long-term effects of new SMA-specific therapies.

Current concepts in neuromuscular scoliosis

PURPOSE OF REVIEW

Spinal deformity is a common issue in pediatric patients with an underlying neurological diagnosis or syndrome. Management of neuromuscular scoliosis (NMS) is a major part of the orthopedic care of such patients, as the deformity is often progressive, and may affect gait, seating and positioning. In addition, untreated large spinal deformities may be associated with pain and/or cardiopulmonary issues over time.

RECENT FINDINGS

Recent changes in medical management of the underlying disease process appears to alter the natural history of certain neuromuscular conditions, and in the case of patients with Duchenne's muscular dystrophy significantly diminish the incidence of spinal deformity. In the most common diagnosis associated with NMS, cerebral palsy, there is evidence that despite a high complication rate, surgical management of spinal deformity is associated with measurable improvements in validated health-related quality-of-life measures. Spinal deformity is a common finding in patients with neurological diagnoses. It is important for those involved in the care of these patients to understand the natural history of NMS, as well as the potential risks and benefits to the patient and caregivers, of surgical and non-surgical interventions.

Reliability of four tests to assess body posture and the range of selected movements in individuals with spinal muscular atrophy

Background

The majority of individuals with spinal muscular atrophy (SMA) experience progressive skeletal deformities which may affect the quality of life and mobility. To date, no studies have evaluated the reliability of tests assessing body posture and joint mobility in SMA patients. The purpose of this study was to assess the reliability of Cervical Rotation test (CR), Supine Angle of Trunk Rotation test (SATR), Hip Extension test (HE) and Pelvic Obliquity test (PO) developed to evaluate the musculoskeletal system in SMA individuals.

Methods

Thirty individuals (12 girls and 18 boys) aged 4–15 with SMA type II (n = 24) and III (n = 6) confirmed by genetic examinations were qualified for the study. The participants were examined twice by three physiotherapists on the same day. The examination included four tests, i.e. CR, SATR, HE and PO tests aimed at assessing ranges of rotation in the cervical spine, chest deformities, ranges of hip extension and pelvis position while sitting. Statistical calculations were made with the use of statistical software IBM SPSS Statistics version 20. Reliability was assessed using the Intraclass Correlation Coefficient (ICC).

Results

Intraobserver reliability was excellent for CR (ICC range 0.839–0.911), SATR (ICC range 0.918–0.939 - the upper part of the sternum; ICC range 0.951–0.975 - the lower part of the sternum), HE (ICC range 0.988–0,991) and PO (ICC range 0.896–0.935) tests.

The interobserver ICC reached the excellent values in CR (ICC range 0.912–0.920), SATR (ICC = 0.888 - the upper part of the sternum, ICC = 0.951 - the lower part of the sternum), HE (ICC range 0.922–0.923) and PO (ICC = 0.928) tests.

Conclusions

CR, SATR, HE and PO tests are reliable and may be used for examining individuals with SMA. The application of these tests provides a possibility to detect early changes in the musculoskeletal system in children and adolescents and to assess the effectiveness of the implemented pharmacotherapy and rehabilitation.

Outcomes of Primary Posterior Spinal Fusion for Scoliosis in Spinal Muscular Atrophy: Clinical, Radiographic, and Pulmonary Outcomes and Complications

BACKGROUND

Spinal muscular atrophy (SMA) is a progressive neuromuscular disease commonly including progressive scoliosis resulting in severe deformity and negatively affecting pulmonary function. Surgical correction and stabilization of this progressive deformity is generally recommended; however, the timing and method of surgical fixation remains controversial.

METHODS

Retrospective review of clinical, radiographic, and pulmonary function data from 16 children with SMA and surgically treated scoliosis between 1985 and 2013. Radiographic data included direct measures of major curve, coronal balance, pelvic obliquity, T1-T12 height, T1-S1 height, and T1-rod length. Estimations of rib collapse, thoracic cavity shape, and space-available-for-lung (T6:T12, width ratio; T6:T10, rib-vertebral-angle difference ratios; and lung height) were determined. Eleven patients were able to complete pulmonary function testing. Results were compared with published outcomes for growing rod constructs.

RESULTS

Posterior spinal fusion was performed at an average age of 9.8±3.6 years. The mean age at most recent follow-up was 19.4 years (range, 10 to 37 y), with a mean follow-up of 10.1 years (range, 3.1 to 26 y). Radiographic measurements improved from preoperative to latest follow-up as follows: major curve, 78±20 degrees to 27±24 degrees; coronal balance, 4.1±4.0 cm to 1.9±2.2 cm; pelvic obliquity (median), 23 to 5 degrees; T1-T12 height, 19±3 cm to 22±3 cm; T1-S1 height, 31±7 cm to 36±6 cm; T1-rod length, 0.8±1.1 cm (postop) to 2.8±1.6 cm (final); and space-available-for-lung ratio, 0.88±0.26 to 0.95±0.25. Rib collapse continued throughout the follow-up period in all but 1 patient. Pulmonary function testing demonstrated a decrease in rate of decline in forced vital capacity and forced expiratory volume when comparing preoperative with postoperative rates. Mean length of stay was 7.8±4.4 days. Complications included reintubation for low tidal volumes (n=1), pneumonia (n=1), superficial wound breakdown (n=1), and superficial infection (n=1).

CONCLUSIONS

Definitive posterior spinal fusion for treatment of scoliosis associated with SMA is effective at controlling curve progression and pelvic obliquity without negatively impacting the space-available-for-lung ratio, trunk height, or pulmonary function at 10 years follow-up.

LEVEL OF EVIDENCE

Therapeutic Level IV.

Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder due to a defect in the survival motor neuron 1 (SMN1) gene. Its incidence is approximately 1 in 11,000 live births. In 2007, an International Conference on the Standard of Care for SMA published a consensus statement on SMA standard of care that has been widely used throughout the world. Here we report a two-part update of the topics covered in the previous recommendations. In part 1 we present the methods used to achieve these recommendations, and an update on diagnosis, rehabilitation, orthopedic and spinal management; and nutritional, swallowing and gastrointestinal management. Pulmonary management, acute care, other organ involvement, ethical issues, medications, and the impact of new treatments for SMA are discussed in part 2.

Emerging therapies and challenges in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a hereditary neurodegenerative disease with severity ranging from progressive infantile paralysis and premature death (type I) to limited motor neuron loss and normal life expectancy (type IV). Without disease‐modifying therapies, the impact is profound for patients and their families. Improved understanding of the molecular basis of SMA, disease pathogenesis, natural history, and recognition of the impact of standardized care on outcomes has yielded progress toward the development of novel therapeutic strategies and are summarized. Therapeutic strategies in the pipeline are appraised, ranging from SMN1 gene replacement to modulation of SMN2 encoded transcripts, to neuroprotection, to an expanding repertoire of peripheral targets, including muscle. With the advent of preliminary trial data, it can be reasonably anticipated that the SMA treatment landscape will transform significantly. Advancement in presymptomatic diagnosis and screening programs will be critical, with pilot newborn screening studies underway to facilitate preclinical diagnosis. The development of disease‐modifying therapies will necessitate monitoring programs to determine the long‐term impact, careful evaluation of combined treatments, and further acceleration of improvements in supportive care. In advance of upcoming clinical trial results, we consider the challenges and controversies related to the implementation of novel therapies for all patients and set the scene as the field prepares to enter an era of novel therapies. Ann Neurol 2017;81:355–368

Spontaneous Breathing Pattern as Respiratory Functional Outcome in Children with Spinal Muscular Atrophy (SMA)

Introduction

SMA is characterised by progressive motor and respiratory muscle weakness. We aimed to verify if in SMA children 1)each form is characterized by specific ventilatory and thoraco-abdominal pattern(VTAp) during quiet breathing(QB); 2)VTAp is affected by salbutamol therapy, currently suggested as standard treatment, or by the natural history(NH) of SMA; 3)the severity of global motor impairment linearly correlates with VTAp.

Materials and methods

VTAp was analysed on 32 SMA type I (SMA1,the most severe form), 51 type II (SMA2,the moderate), 8 type III (SMA3,the mildest) and 20 healthy (HC) using opto-electronic plethysmography. Spirometry, cough and motor function were measured in a subgroup of patients.

Results

In SMA1, a normal ventilation is obtained in supine position by rapid and shallow breathing with paradoxical ribcage motion. In SMA2, ventilation is within a normal range in seated position due to an increased respiratory rate(p<0.05) with reduced tidal volume(p<0.05) secondary to a poor contribution of pulmonary ribcage(%ΔV_RC,P, p<0.001). Salbutamol therapy had no effect on VTAp during QB(p>0.05) while tachypnea occurred in type I NH. A linear correlation(p<0.001) was found between motor function scales and VTAp.

Conclusion

A negative or reduced %ΔV_RC,P, indicative of ribcage muscle weakness, is a distinctive feature of SMA1 and SMA2 since infancy. Its quantitative assessment represents a non-invasive, non-volitional index that can be obtained in all children, even uncollaborative, and provides useful information on the action of ribcage muscles that are known to be affected by the disease.Low values of motor function scales indicate impairment of motor but also of respiratory function.

What's New in the Management of Neuromuscular Scoliosis

BACKGROUND

Patients with neuromuscular scoliosis (NMS) can pose treatment challenges related to medical comorbidities and altered spinopelvic anatomy. We reviewed the recent literature regarding evaluation and management of NMS patients and explored areas where further research is needed.

METHODS

We searched the PubMed database for all papers related to the treatment of NMS published from January 1, 2011 through July 31, 2014, yielding 70 papers.

RESULTS

A total of 39 papers contributed compelling new findings. Steroid treatment has been most promising in patients with Duchenne muscular dystrophy, leading to a significantly lower death rate, better pulmonary function, and longer independent ambulation. Growing rods in early-onset NMS were shown to result in significant improvements in major Cobb angles and pelvic obliquity, with low complication rates in patients with spinal muscular atrophy but high infection rates in those with cerebral palsy. Early reports of magnetic growing rods in NMS patients are favorable. Intraoperative neural monitoring is variable in this patient population; however, use of transcranial motor-evoked potentials in NMS patients seems to be safe. Blood loss is the highest in NMS patients when compared with all other diagnostic categories. However, tranexamic acid seems to significantly lower intraoperative blood loss. In a multicenter study, patients diagnosed with NMS had the highest surgical-site infection rate at 13.1%. Best-practice guidelines have been created regarding prevention of infection in NMS patients. Preoperative nutritional optimization and postoperative nutritional supplementation seem to help with lowering the infection rate in these patients.

CONCLUSIONS

There have been major advances in the management of NMS patients, but many challenges remain. Further multicenter studies and randomized clinical trials are needed, particularly in the areas of infection prophylaxis, nutritional optimization, improvement in intraoperative neural monitoring, and prevention of proximal junctional kyphosis.

LEVEL OF EVIDENCE

Level 4-literature review.

Delay in Diagnosis of Spinal Muscular Atrophy: A Systematic Literature Review

BACKGROUND

Spinal muscular atrophy is a rare genetic disease with devastating neurodegenerative consequences. Timing of diagnosis is crucial for spinal muscular atrophy because early diagnosis may lead to early supportive care and reduction in patient and caregiver stress. The purpose of this study was to examine the published literature for diagnostic delay in spinal muscular atrophy.

METHODS

A systematic literature search was conducted in the PubMed and Web of Science databases for studies published between 2000 and 2014 that listed any type of spinal muscular atrophy and without molecular, mouse, or pathology in the keywords. Mean and/or median age of onset and diagnosis and delay in diagnosis was extracted or calculated. All estimates were weighted by the number of patients and descriptive statistics are reported.

RESULTS

A total of 21 studies were included in the final analysis. The weighted mean (standard deviation) ages of onset were 2.5 (0.6), 8.3 (1.6), and 39.0 (32.6) months for spinal muscular atrophy types I, II, and III, respectively, and the weighted mean (standard deviation) ages of confirmed spinal muscular atrophy genetic diagnosis were 6.3 (2.2), 20.7 (2.6), and 50.3 (12.9) months, respectively, for types I, II, and III. For studies reporting both age of onset and diagnosis, the weighted diagnostic delay was 3.6, 14.3, and 43.6 months for types I, II, and III, respectively.

CONCLUSIONS

Diagnostic delay is common in spinal muscular atrophy. The length of delay varied by severity (type) of spinal muscular atrophy. Further studies evaluating this delay and tools such as newborn screening are warranted to end the diagnostic delay in spinal muscular atrophy.