SMA is a fatal neuromuscular disorder characterized by progressive muscle weakness, atrophy, respiratory compromise, and paralysis. Nusinersen, the first Food and Drug Administration approved treatment for SMA, is administered intrathecally. Nusinersen was effective in phase III randomized controlled trials in infants with SMA1 and children with later onset SMA in improving motor function. Recent phase 3 clinical trial of nusinersen in later onset SMA included patients up to 12 years of age at the time of screening. Data on efficacy and safety of intrathecal nusinersen in older children and adults with SMA is lacking.

To report our experience of treating spinal muscular atrophy (SMA) patients with intrathecal nusinersen who are of 12 years of age and older at the time of first injection.

Retrospective chart review

12 patients (6 males; 1 type 1, 4 type 2 and 7 type 3 SMA) between 12 and 52 years of age were treated with nusinersen. Mean Revised Upper Limb Module (RULM) score at baseline, after loading and first maintenance doses of nusinersen were 14.4±9.3, 17.3±10.5, and 19.8±9.9 respectively. Two type 3 patients were ambulatory at baseline and the ambulation was after loading and first maintenance doses. Improvements in endurance, hand movements, hand writing, and louder/clearer speech were reported. All patients had scoliosis and 10 had spinal fusion and instrumentation. 37 lumbar and 18 cervical punctures were performed with successful administration of intrathecal nusinersen. Post lumbar puncture site pain and headache were reported in 5 occurrences.

Improvements and stability in motor functions and ambulation was noted with nusinersen in our cohort of older children and adults with SMA. Our data also demonstrate feasibility and safety of intrathecal administration of nusinersen in such patients.