Letters to the Editor

To the Editor: We noted with interest the report by Sachdev et al. This retrospective study identified agitation, increased neuroleptic dosage, and history of ECT as risk factors for neuroleptic malignant syndrome. The clinical overlap of neuroleptic malignant syndrome and catatonia (1–3) prompts us to seek clarification related to catatonia.

The authors used catatonia as one of the possible subcriteria for diagnosis of neuroleptic malignant syndrome but did not report how many of the 25 patients or 50 comparison subjects showed catatonic signs. This is especially relevant since their definition of agitation as “excessive and purposeless motor activity” (p. 1156), which they found to be a risk factor for neuroleptic malignant syndrome, matches the published definitions for catatonic excitement (4, 5). DSM-IV and other diagnostic criteria (4) accept a single motor sign as sufficient to diagnose catatonia. The increased risk of neuroleptic malignant syndrome reported after administration of neuroleptics to patients with catatonia (1) may be confirmed if Sachdev et al. have data on catatonic signs in their neuroleptic malignant syndrome cases.

The authors also found prior history of ECT as a risk factor for neuroleptic malignant syndrome. Perhaps this also relates to catatonia, since this syndrome may be recurrent (6) and the patients with neuroleptic malignant syndrome may have had prior ECT, a common treatment for catatonia (7).