A Systematic Review of Procedural Complications from Transforaminal Lumbar Puncture for Intrathecal Nusinersen Administration in Patients with Spinal Muscular Atrophy

Unilateral interlaminar fenestration on the convex side provides a reliable access for intrathecal administration of nusinersen in spinal muscular atrophy: a retrospective study

BACKGROUND

As the first gene therapy for spinal muscular atrophy (SMA), nusinersen is supposed to be administrated via intrathecal injection regularly for a lifetime. However, for SMA patients with severe spinal deformities, bony fusion following posterior spinal instrumentation sets great obstacles for the application of nusinersen. Therefore, efforts have been devoted to the exploration of appropriate approach for nusinersen administration. This study aims to evaluate the safety and reliability of unilateral interlaminar fenestration on the convex side during spinal fusion surgery for intrathecal nusinersen injection in SMA.

RESULTS

SMA patients receiving posterior spinal fusion and interlaminar fenestration in Peking Union Medical College Hospital from January 2020 to October 2021 were retrospectively analyzed. 13 patients were included. Of the 13 patients, 10 were classified into SMA type II and 3 into SMA type III. Distal fusion to pelvis was undertaken in 11 patients; while L5 was selected as the lowest instrumented vertebra in the other 2 patients. All patients received interlaminar fenestration on the convex side only with an area of about 15 mm × 20 mm. Fenestration at L2-L3 level was performed in 6 patients; while L3-L4 level was selected for windowing in the remaining 7 patients. 9 of the 13 patients received lumbar puncture and intrathecal nusinersen administration during the 1-year follow-up, with an accumulative total of 50 times. All injections were performed successfully under ultrasound guidance, with no one transferred to radiographic assistance. No severe complications occurred after injection.

CONCLUSIONS

In SMA with severe scoliosis planning to receive posterior spinal fusion, unilateral lumbar interlaminar fenestration on the convex side provides a feasible and reliable access for intrathecal nusinersen administration after surgery.

Nusinersen for spinal muscular atrophy types II and III: a retrospective single-center study in South Korea

BACKGROUND

This study investigated the efficacy and safety of nusinersen, an antisense oligonucleotide, in patients with spinal muscular atrophy (SMA) types II (OMIM: 253,550) or III (OMIM: 253,400), including those with severe scoliosis or requiring respiratory support via mechanical ventilation.

METHODS

Data from 40 patients with genetically confirmed SMA who were treated with nusinersen at our institute from March 2019 to April 2022 were retrospectively analyzed. Of these, 30 patients with an age of onset < 3 years and not on permanent ventilation were selected. Clinical and genetic characteristics were investigated, and motor function was evaluated based on the Hammersmith Functional Motor Scale-Expanded (HFMSE) score.

RESULTS

The mean age of symptom onset was 1.2 years. Most patients were diagnosed with SMA type II (27/30, 90%). Nusinersen was administered via computed tomography-guided or direct intrathecal injection in 87% (26/30) and 13% (4/30) of the patients, respectively. At the 6-, 14-, 22-, and 26-month follow-ups, 72%, 71%, 88%, and 86% of patients showed motor improvement, respectively, with mean changes in HFMSE scores of 2.10, 2.88, 4.21, and 5.29, respectively. Multivariable analysis showed that the use of noninvasive ventilation was associated with poorer outcomes of motor function.

CONCLUSIONS

Patients with SMA type II or III who received nusinersen treatment showed significant improvement in motor function. A longer treatment duration led to a higher number of patients with improved motor function. No significant side effects of nusinersen were observed. Patients with SMA, even those with severe scoliosis or on respiratory support, can be safely treated using nusinersen.

An Overview of the Therapeutic Strategies for the Treatment of Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a recessive, neurodegenerative disorder. It is one of the most common genetic causes of infant mortality and is characterized by muscle weakness, loss of ambulation, and respiratory failure. SMA is primarily caused by a homozygous deletion or mutation of the survival motor neuron 1 (SMN1) gene. Humans possess a second, nearly identical copy of SMN, known as the SMN2 gene. Although the disease severity correlates inversely with the number of SMN2 copies present, it can never completely compensate for the loss of SMN1 in patients with SMA; SMN2 expresses only a fraction of the functional SMN transcript. The SMN protein is ubiquitous in human cells and plays several roles, ranging from assembling the spliceosome machinery to autophagy, RNA metabolism, signal transduction, cellular homeostasis, DNA repair, and recombination. Although the underlying mechanism remains unclear, anterior horn cells of the spinal cord gray matter are highly vulnerable to decreased SMN protein levels. To harness SMN2's ability to provide SMN function, two treatment strategies have been approved by the Food and Drug Administration (FDA), including an antisense oligonucleotide, nusinersen (Spinraza), and a small molecule, risdiplam (Evrysdi). Onasemnogene abeparvovec (Zolgensma) is an FDA-approved adeno-associated virus 9-mediated gene replacement therapy that creates a copy of the human SMN1 gene. In this review, we summarize the SMA etiology and FDA-approved therapies, and discuss the development of SMA therapeutic strategies and the challenges we faced.

Current treatments of spinal muscular atrophy in adults

Spinal muscular atrophy (SMA) is a rare autosomal recessive neuromuscular disorder related to motor neuron degeneration. SMA patients present generally severe muscular weakness and atrophy, which can reduce life expectancy and lead to severe functional disability. In recent years, the management of this condition has been revolutionized by the development of innovative therapies that target alternative splicing of pre-messenger SMN2 RNA by antisense oligonucleotides or small molecules and by the approval of the first vector-based SMN1 gene therapy. The high significance of the trials in children led to fast-tracking of these therapies to all SMA patients despite the absence of data in adults. Real-life data are progressively providing a better understanding of the expected benefits and tolerability. They also highlight the difficulties of evaluating these patients and the need to take into account the patients' reported expectations and outcome. A review of the main data in adult patients is presented. The mechanisms of action of these innovative therapies are discussed as well as the limits of evaluations of these therapies in adults with longstanding severe amyotrophy.

Advances and limitations for the treatment of spinal muscular atrophy

Spinal muscular atrophy (5q-SMA; SMA), a genetic neuromuscular condition affecting spinal motor neurons, is caused by defects in both copies of the SMN1 gene that produces survival motor neuron (SMN) protein. The highly homologous SMN2 gene primarily expresses a rapidly degraded isoform of SMN protein that causes anterior horn cell degeneration, progressive motor neuron loss, skeletal muscle atrophy and weakness. Severe cases result in limited mobility and ventilatory insufficiency. Untreated SMA is the leading genetic cause of death in young children. Recently, three therapeutics that increase SMN protein levels in patients with SMA have provided incremental improvements in motor function and developmental milestones and prevented the worsening of SMA symptoms. While the therapeutic approaches with Spinraza^®, Zolgensma^®, and Evrysdi^® have a clinically significant impact, they are not curative. For many patients, there remains a significant disease burden. A potential combination therapy under development for SMA targets myostatin, a negative regulator of muscle mass and strength. Myostatin inhibition in animal models increases muscle mass and function. Apitegromab is an investigational, fully human, monoclonal antibody that specifically binds to proforms of myostatin, promyostatin and latent myostatin, thereby inhibiting myostatin activation. A recently completed phase 2 trial demonstrated the potential clinical benefit of apitegromab by improving or stabilizing motor function in patients with Type 2 and Type 3 SMA and providing positive proof-of-concept for myostatin inhibition as a target for managing SMA. The primary goal of this manuscript is to orient physicians to the evolving landscape of SMA treatment.    

Scoliosis Orthopedic Surgery Combined With Nusinersen Intrathecal Injection Significantly Improved the Outcome of Spinal Muscular Atrophy Patient: A Case Report

Background

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by pathogenic variation of the survival motor neuron (SMN) 1 gene. Symptoms of SMA include progressive limb muscle weakness, atrophy, and severe scoliosis. Nusinersen is an antisense oligonucleotide that can enhance the production of the SMN protein. Here, we report a case with scoliosis who received orthopedic surgery combined with Nusinersen intrathecal injections.

Case Presentation

Scoliosis orthopedic surgery followed by Nusinersen intrathecal injections was given to a 16-year-old girl who had thoracic and lumbar scoliosis and type 3 SMA. Surgery was performed for T3-S2 posterolateral fusion (PLF), with a channel left on the vertebral laminae of L3-L4. The balance of the spine and pelvis was significantly improved and the height increased by 9 cm. Lumbar puncture was conducted with local anesthesia under ultrasound and CT guidance through the laminae channel and Nusinersen was successfully injected. Comparing the two approaches, real-time ultrasound guidance for intrathecal Nusinersen injections after spinal surgery is preferred, however, CT guidance is an alternative if the initial puncture procedure is difficult. After the aforementioned multidisciplinary treatment, a good outcome was achieved, as demonstrated by a 2-point increase in RULM and MFM32 scores 2 months later.

Conclusion

Scoliosis orthopedic surgery combined with Nusinersen intrathecal injection is an effective treatment for SMA patients with scoliosis.

CNS endothelial derived extracellular vesicles are biomarkers of active disease in multiple sclerosis

Background

Multiple sclerosis (MS) is a complex, heterogenous disease characterized by inflammation, demyelination, and blood–brain barrier (BBB) permeability. Currently, active disease is determined by physician confirmed relapse or detection of contrast enhancing lesions via MRI indicative of BBB permeability. However, clinical confirmation of active disease can be cumbersome. As such, disease monitoring in MS could benefit from identification of an easily accessible biomarker of active disease. We believe extracellular vesicles (EV) isolated from plasma are excellent candidates to fulfill this need. Because of the critical role BBB permeability plays in MS pathogenesis and identification of active disease, we sought to identify EV originating from central nervous system (CNS) endothelial as biomarkers of active MS. Because endothelial cells secrete more EV when stimulated or injured, we hypothesized that circulating concentrations of CNS endothelial derived EV will be increased in MS patients with active disease.

Methods

To test this, we developed a novel method to identify EV originating from CNS endothelial cells isolated from patient plasma using flow cytometry. Endothelial derived EV were identified by the absence of lymphocyte or platelet markers CD3 and CD41, respectively, and positive expression of pan-endothelial markers CD31, CD105, or CD144. To determine if endothelial derived EV originated from CNS endothelial cells, EV expressing CD31, CD105, or CD144 were evaluated for expression of the myelin and lymphocyte protein MAL, a protein specifically expressed by CNS endothelial cells compared to endothelial cells of peripheral organs.

Results

Quality control experiments indicate that EV detected using our flow cytometry method are 0.2 to 1 micron in size. Flow cytometry analysis of EV isolated from 20 healthy controls, 16 relapsing–remitting MS (RRMS) patients with active disease not receiving disease modifying therapy, 14 RRMS patients with stable disease not receiving disease modifying therapy, 17 relapsing-RRMS patients with stable disease receiving natalizumab, and 14 RRMS patients with stable disease receiving ocrelizumab revealed a significant increase in the plasma concentration of CNS endothelial derived EV in patients with active disease compared to all other groups (p = 0.001). Conclusions: For the first time, we have identified a method to identify CNS endothelial derived EV in circulation from human blood samples. Results from our pilot study indicate that increased levels of CNS endothelial derived EV may be a biomarker of BBB permeability and active disease in MS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00299-4.