Age and Gender Specific Patterns of the Neuroleptic Malignant Syndrome

Background: Investigations of clinical correlates of the Neuroleptic Malignant Syndrome (NMS) may help to understand this phenomenon. This study examined age and gender related differences in NMS symptom patterns.

Method: Archival data from medical journals and medical professionals were obtained on 233 patients with suspected NMS: 80 of these patients met the criteria for NMS according to DSM5. The sample contained more men (70.1%) than women (29.9%). The age ranged from 15 to 83 years, with the mean at 41.2 years (SD=16.9).

The medication was known for 63 of the 80 patients: all were on the old antipsychotic medications, mostly on haloperidol (49.2%) and chlorpromazine (15.9 %).The frequent diagnoses were schizophrenia (30.3%), bipolar mood disorder (19.7%), and major depression (11.8%). The data file included frequencies of various clinical symptoms, vital signs, and results of laboratory tests.

Results: The following symptoms were recorded more often than in 12% of the 80 patients diagnosed with NMS by DSM5: decrease in level of consciousness (100% of patients), elevated creatine kinase (96.9%), tachycardia (94.0%), elevated WBC (93.8%), diastolic blood pressure above 89 (77.5%), systolic blood pressure above 139 (75.6%), autonomic dysregulation (77.5%), mutism (42.5%), tremor (33.8%), sialorrhea (21.2%), dysphagia (18.8%), stupor (17.5%), and urinary incontinence (16.2%). The patients’ gender and age were not statistically related to any of these variables, except for a significant but weak correlation of gender with mutism (phi=.26, p=.025, 2-tailed): 60.9% of women, but only 33.3% of men displayed mutism.

Numerous other symptoms and variables were evaluated, but were noted too infrequently, less often than in 12% in this sample, to be of relevance for the concept of NMS.

Discussion and Conclusions: Age and gender did not have a clinically important impact on the NMS symptom profiles. The high frequencies of lowered level of consciousness, elevated creatine kinase, tachycardia, elevated WBC, elevated blood pressure, autonomic dysregulation, mutism, tremor, sialorrhea, dysphagia, stupor, and incontinence are consistent with the existing clinical studies on the concept of NMS.

Keywords: neuroleptic malignant syndrome, antipsychotic medication, creatine kinase, sialorrhea, dysphagia, WBC, autonomic dysregulation.