Case Report: Ultra-early nusinersen initiation with pre-procedural spinal ultrasound-assisted intrathecal access in a symptomatic neonate with spinal muscular atrophy.

A full-term neonate presented at birth with generalized hypotonia, markedly reduced spontaneous movement, and tongue fasciculations. These findings raised early suspicion of an underlying severe neuromuscular disorder. Genetic testing confirmed homozygous deletion of SMN1 with two copies of SMN2 on day 5 of life, and intrathecal nusinersen was started on the same day. Because repeated lumbar puncture was required, spinal ultrasound was used before the first three intrathecal administrations during the neonatal period to evaluate lumbar anatomy and plan the puncture level and trajectory. This approach facilitated successful first-attempt intrathecal access during the early neonatal procedures. By day 68 of life, the infant had completed four loading doses without procedure-related complications. Motor function, assessed using the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), increased from 6 before treatment to 21 before the third dose and 30 before the fourth dose. Given the short follow-up period, these early changes should be interpreted cautiously. They are more likely to reflect early disease stabilization and preservation of residual motor function than reversal of established motor neuron loss. This case provides an individual-level real-world description of symptomatic neonatal spinal muscular atrophy treated within the first days of life after postnatal diagnosis. It also supports the feasibility of a structured ultrasound-assisted approach for early repeated intrathecal administration during the neonatal period.