Nusinersen, an antisense oligonucleotide enhancing the production of the survival motor neuron protein, is approved for the treatment of spinal muscular atrophy (SMA) but requires repetitive lumbar punctures. Application via a subcutaneous port connected to a permanent intrathecal catheter has been proposed as an alternative for patients with severe scoliosis, spinal fusion, or comorbidities, rendering serial interlaminar punctures complicated and risky. Since experience with this technique is sparse and follow-up data are lacking, we assessed feasibility, safety, and tolerability of this approach in eight patients with SMA II/SMA III receiving Nusinersen in a multicenter study. Median age at port implantation was 21 years (range: 10-30 years), and median follow-up time thereafter was 19 months (range: 7-24 months). Leakage of the port catheter occurred in two patients, promptly resolving after resuturing. No further complications such as infection, dislocation, kinking, or obstruction of the port were noted in any of the patients. These findings suggest that application via an intrathecal port and catheter system represents a safe and feasible option for Nusinersen treatment in subjects with SMA. However, to detect rare adverse events longer term follow-up in a larger study cohort is warranted.