Longitudinal overview of symptomatic and immunosuppressive drugs in LEMS.

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune neuromuscular junction disorder characterized by muscle weakness and autonomic dysfunction. While amifampridine is the established first-line symptomatic treatment, longitudinal data regarding the evolution of therapeutic regimens over time and the use of immunosuppressive therapies remain limited. This retrospective study analyzed 70 LEMS patients treated at the Leiden University Medical Center (LUMC) between 1992 and 2023. Treatment was evaluated and a four-point "leg score" was developed and used to retrospectively quantify functional impairment and response to amifampridine. Sixty-six percent of the cohort was female, the median age of diagnosis was 54 years and non-tumor LEMS was more prevalent (77%). All patients used amifampridine at some point, and 91% initiated it within six months of diagnosis. Amifampridine improved leg scores in 57% of patients. Although 58% of patients reported side effects (mostly paresthesia), discontinuation was rare (7%). Pyridostigmine was used in 81% of patients. Immunosuppressive drug use-predominantly prednisolone and azathioprine -increased over time, reaching 44% after five years. Conversely, azathioprine, prednisolone and pyridostigmine were discontinued by 50%, 38% and 32% of patients, respectively, often due to adverse effects. In conclusion, amifampridine provides significant clinical benefits and remains the cornerstone of LEMS therapy. Immunomodulatory therapies were introduced gradually and their use increased over time. Compared with autoimmune myasthenia gravis, immunomodulatory therapy was used less frequently during the early disease course of LEMS.