Frequency and clinical significance of Lyme seropositivity in patients with isolated optic neuritis.

We evaluated antibody reactivity against Borrelia burgdorferi in 20 consecutive patients with newly diagnosed isolated optic neuritis who resided in a region endemic for Lyme disease. Four (20%) patients had positive serology. All three patients who had follow-up serologies showed rising convalescent levels of Borrelia-specific IgM. One patient refused lumbar puncture, one had normal CSF constituents except for an elevated Lyme antibody index, and two had CSF lymphocytic pleocytosis that remained unexplained after extensive evaluations for causes other than Lyme disease. We treated both patients who had CSF pleocytosis with intravenous ceftriaxone; the pleocytosis and optic nerve function improved. The other two patients received oral antibiotics and showed excellent recovery of visual acuity. We believe that serologic testing for Lyme disease is warranted for individuals with optic neuritis who reside in an endemic region, and patients with rising convalescent antibody levels or unexplained CSF pleocytosis should receive antibiotic treatment for Lyme disease.