Time-Efficacy in SMA Type 1 and 2 Cases Treated with Nusinersen

Spinal muscular atrophy is a neuromuscular degenerative disorder characterized by progressive apoptosis of motor neurons, with severe weakness and bulbar dysfunction. The aim of the study was to analyze the correlations between the moment of initiation of treatment (nusinersen) and clinical evolution, and also the change of electrophysiological parameters and motor scales, fol-lowed up for 2 years. This study was carried out between 2018 and 2022 on 60 SMA children (29 girls, 31 boys), (29 type 1 and 31 type 2; 29 with 2 copies of SMN2, 29 with 3 copies, and 2 with 4 copies), aged between 3 weeks and 196 months, divided into 2 groups according type of SMA. For both types of SMA, statistically significant negative correlations were found between the elapsed interval from the onset of the disease to the initiation of treatment and upper motor acquisitions (type 1: p < 0.0001, r = -0.713, type 2: p<0.001, r = -0.560) and between age at the beginning of treatment and improvement in motor function (type 1: p <0.0001, r =-0.726, type 2: p<0.001, r=-0.553). For patients with type 2 SMA, a negative correlation was also identified between age at the time of onset and motor evolution (p<0.05, r = -0.378). Electrophysiological parameters were strongly positive correlated with motor improvement (p<0.0001, r=0.600). Our study established the necessity of early SMA diagnosis and therapy beginning, and demonstrated that Compound Motor Action Potential can be a predictive factor in the disease's progression. Keywords: Compound Motor Action Potential; motor scales; Spinal Muscular Atrophy