This study provides Class IV evidence that for patients with SMA1 who are older than 7 months, nusinersen is beneficial.

Aim To determine factors associated with acquisition of a sitting position in patients with spinal muscular atrophy type 1 (SMA1) treated with nusinersen. Method Using data from the registry of patients with SMA1 treated with nusinersen, we compared the subgroups of sitters and non‐sitters after 14 months of therapy as a function of baseline level, SMN2 copy number, age at treatment initiation, and improvement at 2 and 6 months post‐treatment initiation. We used Hammersmith Infant Neurological Examination, Section 2 (HINE‐2) and Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders for motor evaluation. Results Fifty children (22 females, 28 males), mean age 22 months (SD 20.7; range 2.5–102.8mo) were treated. Data on sitting position acquisition were collected for 47 patients at month 14. Fifteen patients were able to sit unassisted; 11 of 15 had a baseline HINE‐2 score of at least 2 points and 11 of 14 had an improvement over baseline of at least 2 points at month 6. Patients who improved by 2 or more points at month 6 were three times more likely to be sitters at month 14 than those who did not. Interpretation High baseline motor function and improvement in HINE‐2 score after 6 months of treatment are associated with the probability of acquiring a sitting position in patients with SMA1 treated with nusinersen. What this paper adds Fifteen of 47 patients with spinal muscular atrophy could sit unaided 14 months after treatment with nusinersen. The number of SMN2 copies were not predictive of acquisition of a sitting position. Baseline condition and clinical response after 6 months of treatment were most predictive of sitting position acquisition.

Background: In spinal muscular atrophy, clinical trial results indicated that disease-modifying treatments are highly effective when given prior to symptom onset, which has prompted newborn screening programs in growing number of countries. However, prognosis of those patients cannot be inferred from clinical trials conducted in presymptomatic individuals, as in some cases disease presents very early. Methods: we conducted a systematic review of articles published up to January 2023. Results: Among 35 patients with three SMN2 copies treated before 42 days of age and followed-up for at least 18 months, all but one achieved autonomous ambulation. Of 41 patients with two SMN2 copies, who were non-symptomatic at treatment initiation, all achieved a sitting position independently and 31 were able to walk. Of 16 patients with two SMN2 copies followed-up for at least 18 months who presented with symptoms at treatment onset, 3 achieved the walking milestone and all but one were able to sit without support. Conclusions: evaluation of data from 18 publications indicates that the results of early treatment depend on the number of SMN2 copies and the initial neurological status of the patient.

Childhood chronic inflammatory demyelinating polyneuropathy (CIDP) needs to be differentiated from hereditary neuropathy. We aimed to validate existing CIDP nerve conduction study (NCS) criteria in a group of children with demyelinating neuropathies of chronic or subacute onset. Retrospective analysis of clinical and NCS results in 18 children with CIDP, 7 with hereditary neuropathy with pressure palsy (HNPP), and 24 with Charcot-Marie-Tooth 1a (CMT1a). AAN and EFNS electrodiagnostic CIDP criteria were fulfilled in 17 of 18 CIDP, 3 of 7 HNPP, and 23 of 24 CMT1a patients. A distal compound muscle action potential (dCMAP) of >9 ms was observed in 14 of 18 CIDP patients but not in any patients with HNPP. Abnormal median/normal sural SNAP (AMNS) and a 10 m/s difference between conduction velocities (CV) of two corresponding nerves were not observed in any CMT1a patients. NCS in CMT1a, HNPP, and CIDP reflect demyelination. dCMAP duration, sensory AMNS, and a 10 m/s CV difference parameter are most useful in the differential diagnosis of pediatric CIDP.

Objective Spinal muscular atrophy (SMA) is a common genetic cause of infant mortality. Nusinersen treatment ameliorates the clinical outcome of SMA, however, some patients respond well, while others have limited response. We investigated microRNAs in blood samples from SMA patients and their response to nusinersen treatment evaluating the potential of circulating microRNAs as biomarkers for SMA. Methods In a discovery cohort study, microRNA next‐generation sequencing was performed in blood samples from SMA patients (SMA type 2, n = 10; SMA type 3, n = 10) and controls (n = 7). The dysregulated microRNAs were further analysed in the therapeutic response cohort comprised of SMA type 1 patients (n = 22) who had received nusinersen treatment, at three time points along the treatment course (baseline, 2 and 6 months of treatment). The levels of the studied microRNAs were correlated to the SMA clinical outcome measures. Results In the discovery cohort, 69 microRNAs were dysregulated between SMA patients and controls. In the therapeutic response cohort, the baseline plasma levels of miR‐107, miR‐142‐5p, miR‐335‐5p, miR‐423‐3p, miR‐660‐5p, miR‐378a‐3p and miR‐23a‐3p were associated with the 2 and 6 months response to nusinersen treatment. Furthermore, the levels of miR‐107, miR‐142‐5p, miR‐335‐5p, miR‐423‐3p, miR‐660‐5p and miR‐378‐3p at 2 months of treatment were associated with the response after 6 months of nusinersen treatment. Interpretation Blood microRNAs could be used as biomarkers to indicate SMA patients’ response to nusinersen and to monitor the efficacy of the therapeutic intervention. In addition, some of these microRNAs provide insight into processes involved in SMA that could be exploited as novel therapeutic targets.

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