Pathogenesis of neurologic manifestations of Mycoplasma pneumoniae infection

Mycoplasma pneumoniae has been associated with various neurologic manifestations, but exactly how the organism can cause such a wide variety of diseases is a long-standing mystery. In this respect, although pneumonia has been considered the hallmark of Mycoplasma pneumoniae infection, emerging accumulations of data have revealed that the infection can cause a number of extrapulmonary manifestations even in the absence of pneumonia. The importance of host immune response in the pathomechanism of pneumonia has been established, but the pathomechanisms of extrapulmonary manifestations remain largely unknown. For this review, extrapulmonary manifestations due to M. pneumoniae infection were classified into three categories: a direct type, in which locally induced cytokines must play a role; an indirect type, in which immune modulation such as autoimmunity must play a role; and a vascular occlusion type, in which vasculitis or thrombosis (either or both, and with or without systemic hypercoagulable state) must play a role. This classification was then applied within a literature review for neurologic manifestations. Most neurologic manifestations due to M. pneumoniae infection could be reasonably classified into and explained by one of the three types of pathomechanisms.