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Stiff person syndrome (SPS) is a rare neurological disease with features of an autoimmune disease. SPS is characterised by severe progressive muscle stiffness of the spine and lower extremities with superimposed muscle spasms triggered by external stimuli such as noise, touch and emotional distress.1 Patients with SPS respond to high doses of muscle relaxants, such as diazepam and baclofen, several anticonvulsants, and gabapentin. Previous studies have reported that several causal treatments with corticosteroids, plasmapheresis, intravenous immunoglobulin (Ig) and new immunomodulating agents can reduce stiffness and lower sensitivity to stimuli and stress in patients with SPS.2 ,3 Because SPS is a chronic disease, patients generally require long-term treatments, which may be effective but difficult to take for long periods.
Tacrolimus (Prograf, FK506) is a macrolide molecule belonging to the same immunosuppressant class as cyclosporine. Tacrolimus has a lower molecular weight and is 100-fold more potent in inhibiting T cell proliferation than cyclosporine. It acts through inhibition of the calcium-calcineurin (CaN) pathway and exerts its immunosuppressive effect by reducing the proliferation of activated T cells.4 We now report the successful treatment of patients with SPS using tacrolimus as the immunosuppressive agent.
We assigned two patients with SPS who had incomplete responses to conventional therapies and fulfilled the defined clinical criteria (online supplementary table 1).3
At baseline and each month thereafter, a neurologist used the distribution of stiffness index, the most consistent indicator of stiffness among patients and within patients, to evaluate the patients with SPS.3 Scores on this index range from 0 to 6 and reflect the extent of stiffness. The same neurologist also assessed the patients for changes in frequency of spasms with use of the heightened-sensitivity scale, which has been a reproducible and consistent means of assessing the number of factors triggering spasms.3 …
Contributors Conceived and designed the study: SN. Performed the treatments: KF, YS, NM, YN. Performed and assessed the tests: MH (MR spectroscopy), RU (transcranial magnetic stimulation) and YI. Analysed the data: SN, KF. Wrote the paper: SN, KF, RK.
Funding This work was supported in part by grants from the Neuroimmunological Disease Research Committee and the Ministry of Health, Labour and Welfare, Japan.
Competing interests None.
Patient consent Obtained.
Ethics approval The University of Tokushima Graduate School, Tokushima, Japan.
Provenance and peer review Not commissioned; externally peer reviewed.
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