Pediatric SMA patients with complex spinal anatomy: Implementation and evaluation of a decision-tree algorithm for administration of nusinersen

Characteristics of Patients With Spinal Muscular Atrophy Who Have Switched Treatments: A Multi-Center Experience in the United Kingdom

INTRODUCTION/AIMS

The evolving landscape of spinal muscular atrophy (SMA) treatment in the United Kingdom allows patients to switch, with health authority approval, from one treatment to another. This retrospective analysis explores the characteristics of pediatric patients across the United Kingdom who switched between available therapies that included nusinersen, risdiplam, and onasemnogene abeparvovec (OA).

METHODS

Demographic data were collected, along with indicators of disease severity and motor function scores for all pediatric patients registered with the SMA REACH UK database who received nusinersen or risdiplam as initial treatments.

RESULTS

Data were available for 375 patients across 19 sites. In total, 289 patients received nusinersen (of whom 21% switched to risdiplam and 16% to OA), and 86 patients received risdiplam (of whom 5% switched to OA). The top reported reasons for treatment changes were as follows: nusinersen to risdiplam: related to spine complexity (28/52), other difficulties related to administration (23/52); nusinersen to OA: parent preference (19/36), bridging to OA (14/36); risdiplam to OA: parent preference (2/2). After switching, no patients requested to go back to the initial treatment. No patients demonstrated deterioration beyond the expected disease trajectory prior to switching.

DISCUSSION

The availability of treatments in the United Kingdom has fundamentally influenced treatment choices, but deterioration in a treatment was not identified as a factor in switching treatments. Further work will be needed to investigate the long-term trajectory of these patients.

Scoliosis in spinal muscular atrophy in the era of disease-modifying therapy: a scoping review

Spinal muscular atrophy (SMA) frequently causes scoliosis (up to 90% of cases), due to weakened axial muscles impacting motor and respiratory function. While new SMA treatments improve motor function, their effect on scoliosis progression is unclear. This scoping review (2016-October 2024) analyzed literature from Pubmed, MEDLINE, EMBASE, and Scopus, focusing on studies of SMA, scoliosis, and treatment approaches. The aim of this work was to describe the clinical features and the possible therapeutic approaches of scoliosis in the "new population" of pharmacologically treated SMA patients. We included all types of SMA as well as all the approved disease modifying therapies (DMTs). The review found significant variability in scoliosis presentation and surgical intervention among different types of treated SMA patients. Early pharmacological treatment may slow scoliosis progression, particularly in Type II SMA. Interestingly, Type I SMA patients, who typically don't develop scoliosis due to severe hypotonia, showed an increased scoliosis onset. Larger studies are needed to fully evaluate the impact of different treatments on scoliosis progression in SMA, especially in Type I SMA patients, to establish updated standards of care.

Administration practices of and adherence to nusinersen in children with spinal muscular atrophy: a multicenter disease registry study in China

BACKGROUND

Nusinersen was the first approved disease modifying therapy (DMT) for spinal muscular atrophy (SMA). Intrathecal administration of nusinersen enables drug delivery directly to the central nervous system, where the motor neurons are located. Per the package insert, individuals with SMA receive 4 loading doses of nusinersen followed by maintenance doses every 4 months thereafter. The aim of this analysis was to investigate the administration practices of and adherence to nusinersen in Chinese children with SMA.

METHODS

Data were analyzed from a longitudinal, multicenter registry enrolling children with 5q-SMA in China. Information on nusinersen administration, including administration date, care setting, use of sedation and general anesthesia, method of administration, and use of imaging guidance before administration, was collected both retrospectively and prospectively. Adherence rate was calculated at dose and participant level. A dose was considered adherent if the inter-dose interval (for dose-level) and interval from the first dose (for participant-level) followed the standard dosing regimen, with a grace period of ± 7 days for Dose 2 to 4 and ± 28 days thereafter.

RESULTS

A total of 385 participants receiving nusinersen with a total of 2,415 doses were included in the study. The median (interquartile range) number of doses administered per participant was 6 (5-7). Over 99% of intrathecal injections were given in an inpatient setting. Only a few (n = 3, 0.1%) required general anesthesia, while 9% (n = 217) of doses were administered under the use of sedation. Interlaminar lumbar puncture (n = 2,407, 99.7%) was the most common method of administration, followed by cervical puncture (n = 5, 0.2%) and transforaminal lumbar puncture (n = 3, 0.1%). Over 90% of injections did not utilize any imaging guidance prior to administration, with ultrasound (n = 142, 5.9%) being the most commonly used imaging guidance. The adherence rate was 95.7% (1,943/2,030) at dose level and 81.0% (312/385) at participant level. The median inter-dose intervals aligned well with the dosing schedule, with 14 days for Doses 2 and 3, 35 days for Dose 4, and 114-124 days for maintenance doses thereafter.

CONCLUSIONS

Findings from the analysis demonstrated high real-world adherence to nusinersen in Chinese children with SMA.

Impact of Spinal Surgery on Intrathecal Nusinersen Injections in Pediatric Spinal Muscular Atrophy

BACKGROUND

Complex spinal deformities necessitate surgical interventions that may intervene with intrathecal injections in patients with spinal muscular atrophy (SMA). This study aimed to determine the effect of spinal deformity correction surgery on nusinersen administration.

METHODS

Pediatric patients with SMA, operated by a single surgeon, either via magnetically controlled growing rod (MCGR) or definitive fusion (DF) with skip instrumentation, were evaluated retrospectively in terms of safety and feasibility of intrathecal injections. Patients' and their parents' perspectives were evaluated through a questionnaire regarding any shift in the setting of injections.

RESULTS

Fourteen patients with 15 spinal surgeries (10 MCGR and 5 DF) were included. Eleven patients received intrathecal treatment both before and after the surgery. Preoperative (n=3) and postoperative (n=9) fluoroscopic guidance was required leading to a shift in the application settings in 6 patients. Of 106 preoperative injections, 15% required fluoroscopy and 2% required anesthesia. Postoperatively, of 88 injections, 73% required fluoroscopy and 26% required anesthesia. No patients discontinued intrathecal injections due to technical difficulties associated with the spinal surgery.

CONCLUSIONS

This study demonstrates that spinal surgery does not prevent safe and successful intrathecal nusinersen injections. In the DF group, the skip instrumentation technique provided access to interlaminal space for intrathecal injections. In either surgical group, no further auxillary approach was required. Modifications in the injection technique require an institutional approach, and concerns of patients and their families should be addressed accordingly.

LEVEL OF EVIDENCE

IV.

A horizontal and perpendicular interlaminar approach for intrathecal nusinersen injection in patients with spinal muscular atrophy and scoliosis: an observational study

BACKGROUND

Lumbar puncture is challenging for patients with scoliosis. Previous ultrasound-assisted techniques for lumbar puncture used the angle of the probe as the needle trajectory; however, reproducing the angle is difficult and increases the number of needle manipulations. In response, we developed a technique that eliminated both the craniocaudal and lateromedial angulation of the needle trajectory to overall improve this technique. We assessed the feasibility and safety of this method in patients with scoliosis and identify factors related to difficult lumbar puncture.

METHODS

Patients with spinal muscular atrophy and scoliosis who were referred to the anesthesia department for intrathecal nusinersen administrations were included. With a novel approach that utilized patient position and geometry, lumbar puncture was performed under ultrasound guidance. Success rates, performance times and adverse events were recorded. Clinical-demographic and spinal radiographic data pertaining to difficult procedures were analyzed.

RESULTS

Success was achieved in all 260 (100%) lumbar punctures for 44 patients, with first pass and first attempt success rates of 70% (183/260) and 87% (226/260), respectively. Adverse events were infrequent and benign. Higher BMI, greater skin dural sac depth and smaller interlaminar size might be associated with greater difficulty in lumbar puncture.

CONCLUSIONS

The novel ultrasound-assisted horizontal and perpendicular interlaminar needle trajectory approach is an effective and safe method for lumbar puncture in patients with spinal deformities. This method can be reliably performed at the bedside and avoids other more typical and complex imaging such as computed tomography guided procedure.

Analysis of the efficacy and adverse effects of nusinersen in the treatment of children with spinal muscular atrophy in China

OBJECTIVE

This study was based on a retrospective clinical observational cohort study of a two-center application of nusinersen in China to evaluate the clinical efficacy and adverse effects of nusinersen in the treatment of SMA (spinal muscular atrophy) Types 1-3.

METHODS

Clinical data from children with clinically and genetically confirmed 5qSMA from a double center in western China (the Second Affiliated Hospital of Xi'an Jiaotong University and the Second Hospital of West China of Sichuan University). All children were younger than 18 years of age. Patients were assessed for motor function and underwent blood and fluid tests before each nusinersen injection.

RESULTS

At 14-month follow-up, 100% of children had improved their HFMSE (Hammersmith Functional Motor Scale Expanded) score, 83.6% had improved their CHOP INTEND (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders) score, and 66.6% had improved their RULM (Revised Upper Limb Module) score by ≥3 points from baseline, and their 6MWT (6-min walk test) was 216.00 ± 52.08 m longer than at baseline. The age of the child at the start of treatment was negatively correlated with the clinical efficacy of nusinersen; the younger the child, the better the response to treatment. No significant adverse effects affecting the treatment and quality of life of the child were observed during the treatment of SMA with nusinersen.

CONCLUSION

This study concluded that nusinersen is clinically beneficial for children with SMA in western China, with mild adverse effects.

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.

Muscle impairment in MRI affect variability in treatment response to nusinersen in patients with spinal muscular atrophy type 2 and 3: A retrospective cohort study

BACKGROUND

Real-world data have shown variability in treatment responses to nusinersen in spinal muscular atrophy (SMA). We investigated whether the magnitude of muscle impairment assessed by magnetic resonance imaging (MRI) at baseline can predict the treatment response.

METHODS

We retrospectively assessed the clinical data in relevance to the thigh and pelvic MRI taken before the nusinersen treatment. A total of 16 patients with SMA types 2 and 3 (age = mean [SD]; 9.2 [4.6] year) receiving nusinersen treatment were enrolled. The T1-weighted MRI images of the pelvis and thigh were scored for muscle fatty infiltration and atrophy. The minimally clinically important difference (MCID) was considered as gaining at least 3 points of Hammersmith Functional Motor Scale-Expanded (HFMSE) from baseline.

RESULTS

Of these 16 individuals, 14 had been treated for at least 15 months with baseline data. At 15 months, seven individuals obtained MCID in HFMSE. Baseline muscle MRI score could not differentiate the two groups; however, individuals who obtained MCID had significantly less severe scoliosis. In addition, there was a significant and negative relationship between baseline MRI score and the change of score in HFMSE after 15 months of treatment. Further, baseline Cobb angle along with MRI score also indicated the correlation to the degree of change in motor function.

CONCLUSION

The degree of muscle damage may confer the variability in response to nusinersen in SMA types 2 and 3. Muscle MRI score along with the severity of scoliosis assessed at baseline may help to predict the motor function change.

Full-Length SMN Transcript in Extracellular Vesicles as Biomarker in Individuals with Spinal Muscular Atrophy Type 2 Treated with Nusinersen

BACKGROUND

Three therapeutic strategies have radically changed the therapeutic scenario for spinal muscular atrophy (SMA). However, therapeutic response differs between individuals. There is a need to identify biomarkers to further assess therapeutic response and to better understand which variables determine the extent of response.

METHODS

We conducted a study using an optimized digital droplet PCR-based method for the ultra-sensitive detection of SMN transcript in serum EVs from SMA 2 individuals treated with nusinersen over 14 months. In parallel, we investigated levels of serum and CSF neurofilament heavy chain (pNF-H) in the same cohort.

RESULTS

Expression of flSMN transcript in EVs of SMA 2 individuals prior to nusinersen was lower than in controls (0.40 vs 2.79 copies/ul; p < 0.05) and increased after 14 months of nusinersen (0.40 vs 1.11 copies/ul; p < 0.05). The increase in flSMN with nusinersen was significantly higher in younger individuals (p < 0.05). Serum pNF-h was higher in non-treated individuals with SMA 2 than in controls (230.72 vs 22.88 pg/ml; p < 0.05) and decreased with nusinersen (45.72 pg/ml at 6 months, 39.02 pg/ml at 14 months). CSF pNF-h in SMA 2 individuals also decreased with nusinersen (248.04 pg/ml prior to treatment, 197.10 pg/dl at 2 months, 104.43 pg/dl at 6 months, 131.03 pg/dl at 14 months).

CONCLUSIONS

We identified an increase of flSMN transcript in serum EVs of SMA 2 individuals treated with nusinersen that was more pronounced in the younger individuals. Our results indicate that flSMN transcript expression in serum EVs is a possible biomarker in SMA to predict or monitor the response to treatment.

Cone-beam computed tomography guided nusinersen administrations in adult spinal muscular atrophy patients with challenging access: a single- center experience

BACKGROUND

The challenging anatomic predispositions in adult patients with spinal muscular atrophy (SMA) preclude the conventional lumbar punctures. Consequently, an introduction of alternative method for intrathecal delivery of nusinersen is required. Cone-beam CT (CBCT) allows volumetric display of the area of interest, pre-procedural planning and real time needle guidance which results in accurate anatomic navigation. The aim of the study was to evaluate technical success, safety, and feasibility of CBCT lumbar intrathecal delivery of nusinersen in the adult SMA patients with challenging anatomical access.

PATIENTS AND METHODS

Thirty-eight adult SMA patients were treated in our institution. Patients with challenging access were selected by multidisciplinary board for image guided administration of nusinersen either due to implantation of the posterior fusion instrumentation, severe scoliosis defined as Cobb's angle > 40º or body mass index over 35. Technical success, radiation exposure and occurrence of adverse events were assessed.

RESULTS

Twenty patients were selected, and 108 CBCT-guided procedures were performed. Each patient underwent at least 4 administrations. Transforaminal approach was performed in 82% of patients. The technical success was 100%, with primary success of 93.5%. The median radiation effective dose of the administrations was 5 mSv, the mean value equalled 10 mSv. Only mild adverse events were reported in the study.

CONCLUSIONS

CBCT-guided lumbar intrathecal administrations of nusinersen in an adult SMA population with challenging access was feasible and safe image guided method.