Expanded Access Program (EAP) for Nusinersen in Participants With Infantile-onset (Consistent With Type 1) Spinal Muscular Atrophy (SMA)

Key Inclusion Criteria: * Genetic documentation of 5q SMA homozygous gene deletion, homozygous mutation, or compound heterozygote. * Onset of clinical signs and symptoms at ≤ 6 months (180 days) of age, consistent with infantile onset, Type I SMA * Patient whose care in the opinion of the treating physician meets, and is expected to continue to meet, the guidelines set out in the 2007 Consensus Statement for Standard of Care in SMA Key Exclusion Criteria: * Patient is qualified to participate in an ongoing clinical trial with nusinersen * Participation in a prior nusinersen study * Previous exposure to nusinersen * History of brain or spinal cord disease that would interfere with the LP procedures or CSF circulation * Presence of implanted shunt for the drainage of CSF or implanted CNS catheter * Previous or current participation in a clinical trial with an investigational gene therapy for SMA * Participation in a study with an investigational therapy for SMA within 6 months or five half-lives of the investigational drug, whichever is the longer, prior to the first dose of nusinersen. NOTE: Other protocol defined Inclusion/Exclusion criteria may apply