[A case of neurosyphilis presenting with acute right hemiparesis improved by adjunctive steroid therapy].

A 57-year-old man was rushed to our hospital with acute right hemiplegia. Head MRI revealed high signals in the left motor cortex that did not correspond to vascular control, mainly in the cortex, on DWI. However, serum and cerebrospinal fluid were positive for syphilis antibodies, cerebrospinal fluid protein was elevated, and there was no atrial fibrillation. Head MRA and MRV were normal, so the patient was diagnosed with neurosyphilis and antisyphilis therapy was administered. However, the right hemiplegia did not improve much, so an additional steroid was administered, which resulted in a marked improvement in clinical symptoms. It is thought that the steroid contributed to the improvement of symptoms in this case due to vasculitis caused by Treponema pallidum, an excessive immunological response to the destruction of the bacteria, and cytokine release due to inflammation. Additional administration of steroids may be considered in addition to antisyphilis therapy.