Neuroleptic Malignant Syndrome: Two Cases without Muscle Rigidity

OBJECTIVE: Two patients with neuroleptic malignant syndrome without muscle rigidity are described. CLINICAL PICTURE: Both patients developed fever and altered consciousness while taking neuroleptic but did not develop muscle rigidity; the symptoms subsided when the neuroleptic was stopped but recurred when it was given again. TREATMENT: The neuroleptic was stopped; one patient received supportive treatment and the other received bromocriptine. OUTCOME: One patient died while the other survived. CONCLUSION: The pathophysiology is proposed as a combination of involvement of the central thermoregulatory, neuroregulatory and autonomic nervous systems, and the peripheral skeletal muscle. It supports the concept of a spectrum of clinical severity of neuroleptic malignant syndrome.