Lyme neuroborreliosis-associated cerebrovascular events in the Finnish endemic area

Objectives: Neuroborreliosis is a rare cause of cerebral vasculitis and stroke. The incidence of Lyme borreliosis in Finland has been increasing in the last 20 years, so we expect that Lyme neuroborreliosis-associated vasculitis can be a more common cause of stroke in the future. Materials & methods: We have retrospectively identified all adult patients (>16 years old) diagnosed with borreliosis (A69.2 Lyme borreliosis), transient ischemic attack (TIA, G45), and ischemic stroke (I63) at Helsinki University Hospital during 1.1.2014-31.10.2019 at our neurological emergency department. Medical data and follow-up data were retrospectively collected from medical records. Neuroborreliosis was diagnosed according to the European Federation of Neurological Societies guidelines. Results: We have identified 10 cases of neuroborreliosis-associated stroke or TIA and/or vasculitis. Vasculitis as a manifestation of borreliosis was diagnosed in six patients of 1454 (0.4%) and stroke or TIA in nine (0.6%) of all borreliosis patients at Helsinki University Hospital. Clinical outcomes for all our patients were good with a modified Rankin scale (mRS) 0-2. Conclusions: Lyme neuroborreliosis-associated vasculopathy and cerebrovascular events still remain rare but should be considered especially in Lyme borreliosis endemic areas. Prognosis is good with appropriate antibiotic treatment, but additional immunosupressive treatment is sometimes needed.