Background: Vasculitis caused by neuroborreliosis is one of many rare described causes of stroke.
Case presentation: A female smoker in her fifties presented with dizziness due to a left cerebellar infarction, and after general stroke workup atherosclerosis was considered the probable cause. In the preceding months she had experienced nonspecific intermittent headache, neck pain and dizziness initially attributed to prior head trauma. Over the following months she presented with relapsing and additional symptoms from the posterior circulation and a new right cerebellar infarction was diagnosed. Contrast-enhanced MRI showed signs of myelitis and meningeal enhancement. CSF examination revealed leukocytes 230 · 106/L (0-4 · 106/L) with 98 % mononuclear cells, protein 3.12 g/L (0.00-0.45 g/L). Borrelia IgG and IgM antibodies were positive in serum and CSF, with ratio examinations consistent with intrathecal synthesis. She had a history of multiple tick bites, but not of erythema migrans. She had satisfactory clinical, biochemical and radiological response to antibiotic treatment with ceftriaxone.
Interpretation: Neuroborreliosis was considered the aetiology of her cerebellar infarctions although no definite signs of cerebral vasculitis were evident from CT angiography. Rare causes of stroke, including neuroborreliosis, should be considered in stroke patients without risk factors for cerebrovascular disease and negative primary workup, and in recurrent stroke despite secondary preventive treatment.