This patient should undergo lumbar puncture. He has unilateral facial nerve palsy, headache, neck stiffness, and a circular rash with central clearing that is clinically consistent with erythema migrans. The presence of erythema migrans in a patient with risk factors for Lyme disease is diagnostic of infection. Neuroborreliosis occurs in 10% to 15% of patients with Lyme disease, and cranial nerve palsy, particularly of the facial nerve (cranial nerve VII), is the most common presentation. When unilateral or bilateral facial nerve palsy is present in isolation, oral doxycycline treatment for 14 to 28 days is sufficient for Lyme disease. However, when the central nervous system is involved, parenteral therapy with ceftriaxone, cefotaxime, or penicillin is recommended. In this patient, the presence of headache and nuchal rigidity raise concern for concomitant meningitis. Because confirmation of meningeal involvement would change therapy, a lumbar puncture is first necessary to determine appropriate therapy. Cerebrospinal fluid (CSF) findings in Lyme meningitis are indistinguishable from other forms of aseptic meningitis.
Testing for antibodies to Borrelia burgdorferi adds little to the diagnosis because the presence of erythema migrans with cranial neuropathy is sufficient for diagnosis of neuroborreliosis. Serum antibody testing for B. burgdorferi infection would be important in the absence of a compatible skin lesion or with inconsistent exposure history.
In neuroborreliosis, a delay in starting antimicrobial treatment is not associated with adverse outcomes as it is in bacterial meningitis, and empiric therapy can be deferred until CSF cell counts are available.
Performing a head CT is unnecessary because Lyme neuroborreliosis is rarely associated with intraparenchymal lesions, and thus the risk of lumbar puncture in this previously healthy, cognitively intact patient is low.
