The neuroleptic malignant syndrome—a systematic case series analysis focusing on therapy regimes and outcome

Introduction Neuroleptic malignant syndrome (NMS) is a rare, potentially life-threatening antipsychotic-associated disorder that requires an efficient and timely therapy. The aim of the study was to compare the effectiveness of different NMS therapies and to analyze its outcome depending on NMS severity. Method Systematic search for NMS cases in biomedical databases. The focus of the analysis was on therapy with dantrolene, bromocriptine, and electroconvulsive therapy (ECT) when each was compared with symptomatic therapy. Primary outcomes were the survival rate and the duration of treatment. Result 405 case reports were included. Overall, no statistically significant differences regarding mortality rate or duration of treatment were found between dantrolene, bromocriptine, or ECT compared to supportive care. A subgroup analysis regarding NMS severity showed that the mortality under specific NMS pharmacotherapy (dantrolene, bromocriptine) and under ECT was significantly lower than under purely symptomatic therapy in severe NMS (P = 0.018). The difference was not significant in mild and moderate cases. Discussion An overall superiority of the specific NMS therapy (dantrolene, bromocriptine, and ECT) was not found in this study. When regarding severity classification, specific therapies were superior but only in severe cases, and ECT showed the lowest mortality rate. In previous case series, an effect on survival or the duration of the disease could only be observed in part for specific therapies, but the evidence available is inconsistent. The results of this study support our hypothesis that NMS treatment with dantrolene, bromocriptine, and ECT is advantageous over purely symptomatic therapy in severe NMS cases.