How "malignant" is the neuroleptic malignant syndrome?

How "malignant" is the neuroleptic malignant syndrome? In early mild cases it may not be malignant at all Although cases of acute fatal psychoses associated with fever and neuromuscular disturbance have been reported sporadically since the nineteenth century' and the propensity for neuroleptic drugs to disrupt neuromuscular function has been described as their use has grown, the entity of the "neuroleptic malignant syndrome" is a comparatively recent phenomenon, mentioned in standard British psychiatric textbooks only for the past decade. In its brief lifespan it has generated considerable controversy with regard to its prevalence, diagnostic criteria, and management. A recent review estimated that the prevalence of the syndrome varied from 0.02% to 2% of admissions to acute psychiatric wards.2 Acute psychiatry is not the only domain of this disorder; cases have been described in patients with other conditions treated with neuroleptics and patients whose treatment with dopamine precursors has been stopped. All neuroleptics that are currently used have been incriminated. The mortality, estimated at 20% in the early 1 980s, seems to be falling,3 which may be ascribed to greater awareness of the condition and its earlier detection. Other explanations may exist for the falling mortality and the 100-fold variation in prevalence mentioned above. Although the neuroleptic malignant syndrome is described as having four classic signs (fever, rigidity, autonomic instability, and altered consciousness), no agreed criteria exist for the diagnosis of the syndrome in terms of severity or combination of these signs, and, as systematic searches for the syndrome have increased, milder or incomplete varieties (forrmes frustes) have been detected and included with the full blown cases. The neuroleptic malignant syndrome does not now seem quite as malignant as originally thought. Some authors believe that it is at one end of a range of effects induced by neuroleptics, such as parkinsonism or dystonia4; others that the term should be reserved for the full blown syndrome,5 which has the features of an idiosyncratic reaction more akin to malignant hyperpyrexia. The relation between the neuro-leptic malignant syndrome and catatonia is also unclear.6 This debate has crucial implications for management. Consensus exists about managing the full blown condition: immediate cessation of neuroleptics, rehydration, and correction of fever and acidosis are vital. Electroconvulsive therapy and benzodiazepines during an episode are considered to be safe. Rechallenge with neuroleptics, the mainstay of treatment for psychosis, is probably safe,7 provided that a gap of two weeks is left …