Elevated creatine kinase does not necessarily correspond temporally with onset of muscle rigidity in neuroleptic malignant syndrome: a report of two cases

Abstract

Neuroleptic malignant syndrome is an uncommon but dangerous complication of antipsychotic drugs, characterized by clinical symptoms that include hyperthermia, severe muscle rigidity, autonomic dysfunction, and altered mental state. Serum creatine kinase (CK) elevation occurs in over 90% of cases. Many diagnostic criteria sets for neuroleptic malignant syndrome have been proposed, all of which include hyperthermia and muscle rigidity as major symptoms, and serum CK elevation as either a major or minor symptom. In general, elevated CK occurs in the initial stage of neuroleptic malignant syndrome and corresponds temporally with the onset of muscle rigidity. However, in some exceptional cases, CK elevation and emergence of muscle rigidity do not appear in the same stage, making early diagnosis of neuroleptic malignant syndrome more difficult. Two rare cases of neuroleptic malignant syndrome are presented in which elevated serum CK and emergence of muscle rigidity did not occur in the same stage of neuroleptic malignant syndrome. An elevated CK level is common in the early stage of neuroleptic malignant syndrome, suggesting that serum CK elevation is a useful indicator for early detection of neuroleptic malignant syndrome. However, a definitive diagnosis of neuroleptic malignant syndrome must be determined from the presence of specific clinical symptoms.

Temporal changes in serum creatine kinase concentration and degree of muscle rigidity in 24 patients with neuroleptic malignant syndrome

“…By contrast, mild muscle rigidity is present at the onset of NMS in 71% of cases and peaks on day 4. On the other hand, we reported exceptional cases of NMS with regard to temporal changes in serum CK and muscle rigidity 13. As muscle rigidity first appeared after serum CK had normalized in cases 1 and 24, physicians should be aware of the existence of these uncommon findings.…”

Neuroleptic malignant-like syndrome with a slight elevation of creatine-kinase levels and respiratory failure in a patient with Parkinson's disease

“…In some exceptional cases of NMS, CK elevation and emergence of muscle rigidity do not appear at the same time. The former is common in the early stage, which may be a useful indicator for early detection of NMS 10. In addition, some NMLS cases without fever or altered consciousness have also been reported 8.…”

“…The former is common in the early stage, which may be a useful indicator for early detection of NMS. 10 In addition, some NMLS cases without fever or altered consciousness have also been reported. 8 During the course of our patient’s treatment, her maximum temperature was extremely high (above 41°C).…”

Neuroleptic malignant syndrome as part of an akinetic crisis associated with sepsis in a patient with Lewy body disease

“…A case of NMS with CK elevation to <1000 U/L such as in our patient is not uncommon. It has also been shown that CK elevation does not necessarily parallel the degree of muscle rigidity 11…”