Spinraza is administered by injection directly into the fluid surrounding the spinal cord, a procedure called an intrathecal injection. Each dose is 12 mg (5 mL), delivered over one to three minutes using a spinal needle, similar to a lumbar puncture. The procedure must be performed by a healthcare professional experienced in lumbar punctures, typically at a hospital or specialized clinic.
What the Procedure Looks Like
Before the injection, a small amount of cerebrospinal fluid (5 mL) is withdrawn from the lower back. The medication is then injected into that same space. The actual injection takes between one and three minutes. For younger patients or those whose spine is harder to access, ultrasound or other imaging may be used to guide the needle into the correct position.
Sedation is sometimes used, depending on the patient’s age and condition. Infants and young children are the most common candidates for sedation, since staying still during a spinal needle procedure can be difficult. For older children and adults, local numbing of the skin is more typical, though the approach varies by center.
Lab Tests Before Each Dose
Before every Spinraza injection, three sets of lab work are required: a platelet count, clotting tests (prothrombin time and activated partial thromboplastin time), and a urine protein test. These same tests are done at baseline before the very first dose. The platelet and clotting tests help confirm it’s safe to perform the spinal injection without excessive bleeding risk, while the urine protein test monitors kidney function since the drug is cleared through the kidneys.
The Dosing Schedule
Treatment starts with a loading phase of four doses. The first three doses are given at two-week intervals, and the fourth dose comes 30 days after the third. After that, maintenance doses are given once every four months, indefinitely. The dose itself never changes: it’s always 12 mg regardless of the patient’s age or weight.
This means in the first year of treatment, you can expect roughly six injections. From year two onward, it drops to three per year. Each visit involves the lab work, the procedure, and a short observation period afterward.
Challenges With Scoliosis and Spinal Hardware
Many people with spinal muscular atrophy develop scoliosis or have spinal fusion rods, which can make a standard lumbar puncture difficult or impossible through the usual approach. In these cases, doctors rely on CT-guided or fluoroscopy-guided injections to navigate around hardware or curved vertebrae and find a safe path to the spinal fluid. Some centers use a cervical (neck-level) approach when the lower spine is inaccessible. These more complex procedures may take longer and sometimes require general anesthesia.
Common Side Effects From the Injection
The most frequent side effects are related to the lumbar puncture itself rather than the drug. These include:
- Headache: often called a post-lumbar-puncture headache, it typically worsens when sitting or standing and improves when lying flat
- Back pain: soreness at the injection site that usually resolves within a day or two
- Nausea or vomiting: most common in the hours immediately after the procedure
- Bruising or swelling: at the needle insertion site
Lying flat for 30 to 60 minutes after the injection can reduce the chance of a post-puncture headache. Many clinics build this rest period into the visit. Staying well hydrated before and after the procedure also helps.
Why It Can’t Be Given Another Way
Spinraza works by helping nerve cells in the spinal cord produce more of a protein that people with SMA are missing. The drug is a type of molecule that doesn’t cross the blood-brain barrier effectively when taken by mouth or injected into a vein. Delivering it directly into the cerebrospinal fluid puts it where it needs to act: right next to the motor neurons in the spinal cord. That’s why the intrathecal route is necessary despite being more involved than a typical injection.
Each vial is stored refrigerated and must be brought to room temperature naturally before use, without external heat sources. Once drawn into the syringe, the medication needs to be administered within four hours. The vials are single-use, meaning any leftover solution is discarded.