French clinicians report their experience with measuring compound muscle action potentials (CMAP) in infants with symptomatic SMA who have received gene therapy (onasemnogene abeparvovec):
- 19 infants with SMA, including 12 with two copies of the SMN2 gene, were included in the study,
- their CMAPs were measured at several nerves (median, ulnar, peroneal and tibial) at several points in time,
- a cumulative motor index (CMI) was constructed from the values obtained,
- after administration of gene therapy, this index improved significantly and then stabilised at relatively low values after 24 months,
- the baseline CMI (before therapy) proved to be fairly predictive of the benefit of treatment.
This minimally invasive technique is a very useful aid in initiating treatment and for prognosis.
