Efgartigimod for Stiff Person Syndrome (ESPS)

Inclusion Criteria

• •1. Age 18-80, men and women, capable of giving informed consent.
• •2. Must have unexplained stiffness of limb and axial (trunk) muscles and involuntary striated muscle spasms.
• •3. DSI and HHS must be \>=2 (to allow for detection of improvement).
• •4. Presence of serum (or CSF) anti-GAD antibodies regardless of titers.
• •5. Stable dosage for at least two months before screening visit with antispasmodics (muscle relaxants, benzodiazepines, baclofen).
• •6. Women with children bearing potential must be willing to use highly effective contraception method during and for a minimum of 90 days after the last dose of IP.