Study of an Intrathecal Port and Catheter System for Subjects With Spinal Muscular Atrophy

Inclusion Criteria:

1. Subject is 3 years or older

2. Subject diagnosed with SMA who are candidates for Spinraza treatment as indicated inits label

3. Subject resistant to lumbar puncture (LP), where resistance is defined as:

4. Subject with respiratory issues or other comorbidities who is at an increasedrisk for complications due to the need for repeat anesthesia and imagingradiation exposure to safely perform LP; or

5. Subjects for whom the treating physician determines implantation of theThecaFlex DRx™ System is otherwise in the subject's best interest

6. Subject has been prescribed nusinersen via chronic intrathecal bolus administrationin accordance with the drug labeling and first port access of the ThecaFlex DRxsystem is planned within 2 weeks of implantation

7. Subject, per Investigator discretion, is able to undergo a percutaneous or opensurgical procedure for index port and catheter implantation where at least 7 cm ofthe ThecaFlex DRx system catheter will be placed intrathecally

8. Subject (or subject's legally authorized representative) is willing and able toprovide written informed consent; and

9. Subject and parent/caregiver able and willing to complete all clinical investigationprocedures, measurements, and visits.

Exclusion Criteria:

1. Subject meets any of the contraindications for use of the ThecaFlex DRx™ System asoutlined in the ThecaFlex DRx™ System Instructions for Use

2. Presence or history of (< 6 months prior to the procedure): an implantedmicroinfusion pump, intrathecal catheter, or other intrathecal drug deliverydevices/component, or implanted shunt for drainage of cerebrospinal fluid (CSF), orreservoir in the CSF space (note: any ThecaFlex Port and Catheter System must not beplaced in the same location as a previous indwelling port and catheter)

3. Subject is pregnant or nursing or plans to become pregnant during the course of theclinical investigation

4. Any condition or event, which in the opinion of the Investigator may adverselyaffect the safety and effective implantation and use of the ThecaFlex DRx™ system orconfound the clinical investigation, including:

5. Severe structural impediment that may preclude safe implantation of thecatheter and port

6. Major medical events within 60 days prior to screening; or

7. Relevant surgeries (e.g., head and neck, back, etc.) within 60 days prior toscreening or planned during the duration of the clinical investigation

8. Space-occupying lesion with mass effect

9. Posterior fossa mass

10. Arnold-Chiari malformation

11. Coagulation abnormalities and/or thrombocytopenia

12. Insufficient or inadequate skin or underlying fat to adequately protect theport or enough surface area to allow the skin to close safely

13. Subject is contraindicated for administration of nusinersen per its approvedlabeling

14. History of intrathecal granuloma formation

15. History of bacterial meningitis or aseptic meningitis within 6 months of screening

16. History of tumors or other spinal abnormalities documented by magnetic resonanceimaging (MRI) or computed tomography (CT) that would interfere with the catheterimplantation procedures or CSF circulation

17. History of hydrocephalus

18. Diagnosed degenerative muscular disease other than SMA

19. History of depression, cognitive impairment, or another psycho-behavioral problemthat in the opinion of the Investigator may preclude safe participation in theclinical investigation and

20. Serious medical condition that, in the opinion of the investigator, may lead toreduced life expectancy beyond 12 months.

21. Subject is involved in another Investigation Device Exemption Study.