Nusinersen is a medication used to treat spinal muscular atrophy (SMA), a genetic disorder that affects muscle strength and movement. It works by increasing the production of a protein called survival motor neuron (SMN), which is essential for the health of motor neurons. By enhancing SMN levels, nusinersen helps improve muscle function and slows the progression of the disease. Administered through an injection into the spinal canal, nusinersen is typically given in a series of doses over time. It is approved for use in patients of all ages with SMA, making it a significant advancement in the treatment of this condition.