An autopsy case of neuroleptic malignant syndrome (NMS) and its immunohistochemical findings of muscle-associated proteins and mitochondria

Neuroleptic malignant syndrome (NMS) is a rare but potentially fatal disorder. In forensic cases, post-mortem diagnosis of NMS is sometimes difficult if ante-mortem information, such as neuroleptic ingestion or signs and symptoms, cannot be obtained. A 39-year-old Japanese male on a neuroleptic treatment regimen suddenly became agitated and died. Autopsy revealed muscle rigidity and hyperthermia. Post-mortem examination of blood revealed elevation of creatine phosphokinase-MM (CK-MM) and lactate dehydrogenase-4 and dehydrogenase-5 (LDH-4 and LDH-5). In renal glomeruli and tubules, myoglobin was stained immunohistochemically. From these findings, the cause of death was considered to be NMS. To support the diagnosis of NMS, both skeletal and cardiac muscles were stained with actin, myoglobin, desmin and mitochondria antibodies immunohistochemically. Actin, myoglobin, desmin, and mitochondria had been lost from skeletal, but not from the cardiac muscle, which suggested that only the skeletal muscle was damaged. Moreover, because mitochondria had disappeared only from the skeletal muscle, it was considered that skeletal muscle degeneration was caused by mitochondrial damage. Therefore, it is suggested that immunostaining of skeletal muscle by antibodies for muscle-associated proteins and mitochondria is useful to corroborate a diagnosis of NMS.