[Are catatonia and neuroleptic malignant syndrome related conditions?].

Introduction: Catatonia and neuroleptic malignant syndrome are both conditions that can compromise survival and whose successful treatment depends on early diagnosis.

Objective: Distinguishing between these two conditions is difficult in a clinical setting and is further complicated by diagnostic criteria overlap. Are they both variations of a single disorder or two distinct conditions that happen to share certain characteristics? The goal of this paper is to review the available published data concerning the existence of a link between these two conditions and to specify the nature of the link between them.

Method: We identified relevant articles from the PubMed registry by cross-referencing "catatonia" and "neuroleptic malignant syndrome". The articles returned were selected according to language (English and French) and publication date (before November 2007).

Results: Opinions are clearly divided concerning the existence of a link between these two conditions. The most commonly held opinion is that catatonia and neuroleptic malignant syndrome are two entities on the same spectrum. There are, however, no less than five different hypotheses concerning the nature of the link between them: first hypothesis: neuroleptic malignant syndrome is a drug-induced form of catatonia; second hypothesis: neuroleptic malignant syndrome is a drug-induced form of malignant catatonia; third hypothesis: neuroleptic malignant syndrome and malignant catatonia are one and the same; fourth hypothesis: catatonia is a risk factor for neuroleptic malignant syndrome; fifth hypothesis: neuroleptic malignant syndrome is a heterogeneous syndrome that includes both catatonic and non-catatonic responses to antipsychotic drugs. Other research maintains that catatonia and neuroleptic malignant syndrome are two distinct conditions. This point of view has fewer proponents, but benefits from historical, clinical and neurobiological studies that comfort this hypothesis. A careful clinical examination should in theory enable the distinction between these two entities and various neurobiological hypotheses are put forward to explain the differences between them. ANALYSIS AND DISCUSSION: The analysis of the data does not enable the elaboration of a single consensus on the existence of a link between catatonia and neuroleptic malignant syndrome. Additionally, the different hypotheses' level of scientific proof is insufficient to confirm or reject them. We only have at our disposal isolated case studies or studies with varying diagnostic criteria.

Conclusion: A review of the literature does not enable us to confirm or invalidate a link between catatonia and neuroleptic malignant syndrome. However, answering this question would have direct consequences, since the suggestion of a link has led to the contraindication of neuroleptics for the treatment of catatonia, which contraindication has been extended on principle to the use of all newer antipsychotic medication. But since the link between catatonia and neuroleptic malignant syndrome has not been established according to scientific criteria, should the contraindication of atypical antipsychotic drugs be maintained in the treatment of catatonia?