Objective:

Background:

Stiff person syndrome (SPS) is a disabling, immune-mediated disorder causing progressive rigidity and painful spasms. Botulinum toxin (BoNT) anecdotally improves symptoms in people with SPS. Evidence for safety and efficacy of repeated BoNT injections longitudinally is lacking.

Design/Methods:

We conducted a retrospective cohort study of 22 seropositive SPS patients who received at least 3 BoNT treatments by a single injector (EM) at Johns Hopkins between August 2018 and January 2023, approximately every 3 months. Muscles were selected based on patient-specific phenomenological presentation.  Between visits 1 and 3, we compared: muscles injected, units per muscle, patient-reported response (Likert scale 1-5; higher=better response), time to effect, side effects, systemic therapies used, and timed 25-foot walk. These data points will also be collected for patients who have 8 or more visits, when applicable. 

Results:

 Twenty-two SPS patients (21 anti-GAD-65, 1 amphiphysin) were included. The majority were female (68.2%), white (68.2%), had classic features (90.1%), with a median age 53.1 years and median Modified Rankin Score of 2. 86.4% were on immune therapies and all were on additional symptomatic treatments at the time of BoNT treatments. Common muscle groups injected included cranio-cervical, upper trunk/shoulders, lower trunk/hips, and distal legs. Supramaximal doses (up to 795 units) were used without adverse effects. Between the first and third injections, the number of patients reporting improvement increased from 64% to 81%, and the mean Likert rating increased from 3.78 to 4.53. Additional analyses will be done to compare outcomes at later visits for patients with 8 or more visits (n=10).

Conclusions:

BoNT may be an effective adjunctive symptomatic therapy for people with SPS with targeted muscle selection based on specific phenomenology. Moreover, there  may be a durable treatment effect with repeat injections over time.