Stiff Person Syndrome When IVIg Has Not Achieved Adequate Response
This protocol addresses patients with Stiff Person Syndrome who have completed an initial immunotherapy course with intravenous immunoglobulin (IVIg) and have not met expected clinical targets — or who could not tolerate IVIg — and require a defined next step in management.
Prior Treatment Line — Inadequate Response
Following a full initial course of intravenous immunoglobulin (IVIg), the following goals were not adequately reached:
- Reduced stiffness, particularly in the paraspinal muscles
- Fewer falls
- Improved gait and ability to walk without assistive devices
- Reduction of anxiety-triggered spasms
Failure to achieve these targets after the initial IVIg course — or poor tolerability — is the indication for escalation to this protocol.
Next-Line Approach (Partial Overview)
This protocol involves a targeted monoclonal antibody-based immunotherapy administered as a short intravenous course. The complete regimen — including sequence, timing, and administration plan — is available in the full protocol.
Clinical Goals
Response is assessed at 6 months. The primary target is meaningful clinical improvement, with restoration of independent walking ability as the key functional marker of treatment success.
References
DOI: 10.1212/NXI.0000000000200109
- If the benefit of IVIg is not sufficient after 3 months or it is poorly tolerated, one may consider to proceed to rituximab which anecdotally had been promising.
- 2 g divided in 15 d
- He was randomized to rituximab and started to improve after 3 months; by the 6th month after the infusion, he had become independent in his walking abilities to the point of even went skiing (D).
- On this basis, rituximab is a very liable option for a subset of patients with significant symptoms (benefiting close to half of them in the large controlled study), who do not sufficiently respond to IVIg and the GABA-enhancing drugs.
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