ABOUT SMA / HOW SMA AFFECTS NERVES AND MUSCLES

Motor neuron loss leading to muscle weakness in SMA

SMN protein is essential for motor neuron survival1

Muscles are controlled by motor neurons that send signals from the CNS.2 Motor neurons require SMN protein to survive. SMN protein plays an important role in the development and health of motor neurons, which control skeletal muscles.1

Motor neuron degeneration

Patients with SMA are born with a genetic defect that results in insufficient production of SMN protein.1 This results in motor neuron degeneration, muscle weakness, and muscle atrophy. Muscle weakness progresses over time, with a wide range of severity, from mid-proximal limb weakness to severe generalized weakness and respiratory failure.3

CNS, central nervous system; SMA, spinal muscular atrophy; SMN, survivor motor neuron.

Treatment of SMA involves many different types of healthcare specialists

LEARN ABOUT MULTIDISCIPLINARY CARE
LEARN ABOUT AN SMA TREATMENT

INDICATION

SPINRAZA® (nusinersen) is indicated for the treatment of spinal muscular atrophy (SMA) in pediatric and adult patients.

IMPORTANT SAFETY INFORMATION

Coagulation abnormalities and thrombocytopenia, including acute severe thrombocytopenia, have been observed after administration of some antisense oligonucleotides. Patients may be at increased risk of bleeding complications.

In the sham-controlled studies for patients with infantile-onset and later-onset SMA, 24 of 146 SPINRAZA-treated patients (16%) with high, normal, or unknown platelet count at baseline developed a platelet level below the lower limit of normal, compared to 10 of 72 sham-controlled patients (14%). Two SPINRAZA-treated patients developed platelet counts <50,000 cells per microliter, with the lowest level of 10,000 cells per microliter recorded on study day 28.

Renal toxicity, including potentially fatal glomerulonephritis, has been observed after administration of some antisense oligonucleotides. SPINRAZA is present in and excreted by the kidney. In the sham-controlled studies for patients with infantile-onset and later-onset SMA, 71 of 123 SPINRAZA-treated patients (58%) had elevated urine protein, compared to 22 of 65 sham-controlled patients (34%).

Laboratory testing and monitoring to assess safety should be conducted. Perform a platelet count, coagulation laboratory testing, and quantitative spot urine protein testing at baseline and prior to each dose of SPINRAZA and as clinically needed.

Severe hyponatremia was reported in an infant treated with SPINRAZA requiring salt supplementation for 14 months.

Cases of rash were reported in patients treated with SPINRAZA.

SPINRAZA may cause a reduction in growth as measured by height when administered to infants, as suggested by observations from the controlled study. It is unknown whether any effect of SPINRAZA on growth would be reversible with cessation of treatment.

The most common adverse reactions (≥20% of SPINRAZA-treated patients and ≥5% more frequently than in control patients) that occurred in the infantile-onset controlled study were lower respiratory infection and constipation. Serious adverse reactions of atelectasis were more frequent in SPINRAZA-treated patients (18%) than in control patients (10%). Because patients in this controlled study were infants, adverse reactions that are verbally reported could not be assessed. The most common adverse reactions that occurred in the later-onset controlled study were pyrexia, headache, vomiting, and back pain. Post-lumbar puncture syndrome has also been observed after the administration of SPINRAZA.

Please see full Prescribing Information.

As a courtesy, our full Prescribing Information is also available en Español. For prescribing decisions, please refer to official approved labeling.

References

1. National Institute of Neurological Disorders and Stroke. Spinal muscular atrophy fact sheet. https://www.ninds.nih.gov/health-information/disorders/spinal-muscular-atrophy. Reviewed July 30, 2024. Accessed June 24, 2025. 2. Stifani N. Motor neurons and the generation of spinal motor neuron diversity. Front Cell Neurosci. 2014;8:293. doi:10.3389/fncel.2014.00293 3. Arnold WD, Kassar D, Kissel JT. Spinal muscular atrophy: diagnosis and management in the new therapeutic era. Muscle Nerve. 2015;51(2):157-167. doi:10.1002/mus.24497 4. Hensel N, Kubinski S, Claus P. The need for SMN-independent treatments of spinal muscular atrophy (SMA) to complement SMN-enhancing drugs. Front Neurol. 2020;11:45. doi:10.3389/fneur.2020.00045

Stay Connected
Sign up with us to receive news and support information and hear about upcoming events.

ABOUT SMA
What Is SMA? How SMA Affects Nerves
and Muscles Multidisciplinary Care
Why SPINRAZA?
About SPINRAZA How SPINRAZA Works Presymptomatic Efficacy Early-Onset Efficacy Later-Onset Efficacy Real-World Evidence Safety
Starting SPINRAZA
How to Start Dosing & Administration
Patients on Therapy
Patients on Therapy
RESOURCE LIBRARY
Access & Reimbursement SMA360°™ Patient Support Events Video Hub

©2025 Biogen. All rights reserved.
This site is intended for US Healthcare Professionals only.
07/25 SPZ-US-3383 v12