An Open-label Study to Assess the Safety and Tolerability of ISIS 396443 in Patients With Spinal Muscular Atrophy Who Previously Participated in 396443-CS2 or 396443-CS10

The primary objective of this study is to examine the safety and tolerability of nusinersen (ISIS 396443) administered intrathecally to participants with Spinal Muscular Atrophy (SMA) who previously participated in ISIS 396443-CS2 (NCT01703988) or ISIS 396443-CS10 (NCT01780246). The secondary objective is to examine the plasma and cerebrospinal fluid (CSF) pharmacokinetic(s) (PK) of nusinersen administered intrathecally to participants with SMA who previously participated in ISIS 396443-CS2 or ISIS 396443-CS10.