Diagnosing subtypes of neuroleptic malignant syndrome: an introduction to the Lee-Carroll Scale

Neuroleptic malignant syndrome (NMS) shares common features with catatonia and serotonin syndrome (SS). For instance, catatonia is a risk factor for the development of NMS.

We performed a pilot study to examine if the Lee-Carroll Scale is able to differentiate the proposed NMS subtypes and explore possible relationship between NMS and SS. A consecutive series of cases reported to the Neuroleptic Malignant Syndrome Information Service (NMSIS) were reviewed with 29 cases of "definite NMS." The Hynes-Vickar Scale (an NMS scale), Hegerl Scale (a SS scale), and Lee-Carroll Scale (an NMS subtype scale) were applied to these case report forms.

Although the groups were too small for statistical analysis, the 2 catatonic NMS subtypes appear to have higher NMS scores on the Hynes-Vickar Scale, and lower SS scores on the Hegerl Scale than the non-catatonic NMS subtype. The scores on the Lee-Carroll Scale were highest for non-catatonic NMS subtype. This pilot study suggests that the Lee-Carroll scale may help differentiate the subtypes of NMS, and provides some support that non-catatonic NMS may be a form of SS. NMS subtypes may be important in the early detection and treatment of NMS.