Posttreatment Lyme Disease Syndrome-What It Might Be and What It Is Not.

Lyme disease is a multisystem disease caused by Borrelia burgdorferi infection and accounts for well-defined manifestations, appearing either at an early or late stage. Appropriate antibiotic therapy generally leads to a favorable outcome. Still, unspecific persisting symptoms such as fatigue, myalgia, arthralgia or cognitive dysfunction are reported by several patients months to years after adequate treatment. Their underlying pathophysiologic mechanism is unclear. However, there is no evidence for microbiological persistence in these cases and attempts to resolve the symptoms by repeated or prolonged antibiotic treatment have not been convincingly successful, but they may rather be harmful. To narrow down the controversially handled entity of posttreatment Lyme disease syndrome (PTLDS) and to avoid overdiagnosis and overtreatment, case definitions have been proposed, acknowledging PTLDS as a complex of nonspecific, subjective symptoms, which are neither caused by ongoing infection nor by any other identifiable disease. PTLDS is mainly a diagnosis of exclusion and requires careful evaluation of differential diagnosis followed by counseling about optimal management in light of missing specific therapeutic options.