• People with spinal muscular atrophy (SMA) often have spine deformities that make it difficult to administer Spinraza (nusinersen) directly to the spinal canal.
• Researchers have found that using an implanted catheter may ease drug delivery for those with SMA and complex spine anatomy.
• Using the implanted catheter also comes with some risks, researchers found, including a chance of mechanical malfunction and possible infection.

The drug Spinraza has proven effective in treating SMA by increasing the low levels of SMN protein associated with the condition. To work effectively, Spinraza is delivered directly to the central nervous system via an injection into the spinal canal. However, many people with SMA develop scoliosis, which causes deformities in the spine and can make the injection challenging to perform.

In a recent study — published in Muscle & Nerve — researchers explored an alternative approach to administering Spinraza: using a device called a subcutaneous intrathecal catheter (SIC). This system, implanted beneath the skin, bypasses spine deformities and allows administration of drugs directly into the spinal canal. The procedure to implant an intrathecal catheter is considered minimally invasive.

To determine efficacy of the SIC delivery system, researchers enrolled a group of 11 people with SMA and complex spine anatomy. They also assessed the safety of the SIC with a separate cohort of 17 individuals with SMA.

Using the SIC proved effective: The motor skills and coordination of the efficacy group — as measured by grip strength and the nine-hole peg test — improved as a result of treatment with nusinersen. (Spinraza is the branded name for nusinersen.)

“For SMA patients with complex spine anatomy, the SIC allows for reliable outpatient administration of nusinersen that results in meaningful improvements in upper limb function,” concluded the authors of the study, titled Nusinersen by Subcutaneous Intrathecal Catheter for Symptomatic Spinal Muscular Atrophy Patients With Complex Spine Anatomy.

However, 12 out of 17 people in the safety cohort experienced adverse events related to the SIC delivery system. Most resulted from mechanical malfunction or leakage of cerebrospinal fluid.

Although the potential risks must be taken into account, this approach may benefit those with SMA, according to the researchers. “For SMA patients with advanced disease, these various risks can be balanced against an expectation of small but functionally meaningful improvements of upper limb and hand function,” they wrote.