Lyme disease is caused by Borrelia burgdorferi. The most common symptom is erythema migrans. Other symptoms include fever, headache and fatigue. Presentation as isolated cranial nerve palsy is rare.

Case report

A 66 year-old female presented with two weeks of headache and diplopia. Previously, a tick bite was found and she received Penicillin G. Double vision occurred while looking far and to the left. Vital signs were normal. She had no meningeal signs. Bilateral mild ptosis was associated with right eye esotropia and limited abduction of the left eye. Routine blood tests and Lyme serology were negative. Migraine treatment was provided at discharge. She returned two days later with worsening symptoms and chest pain which was described as sharp, in the mid-thoracic area, radiating anteriorly, aggravated by breathing and in the supine position. Intravenous methylprednisolone and muscle relaxant improved the chest pain. A new suspended pinprick deficit at T8-T10 was found.

MRI orbits, brain, spine with and without contrast, MRV, MRA of head and neck, were normal. Serum Lyme ELISA OD was 0.55. Lumbar puncture revealed normal CSF opening pressure, 23 cells, lymphocyte predominant, protein of 49.8 mg/dl, and glucose of 66 mg/dl. Lyme CSF to Serum pair index was 0.78. Serum VLSE antigen was 4.79, confirming Lyme diagnosis. Viral and bacterial testing was negative. ACE level was normal. The paraneoplastic serum and CSF, flow cytometry, IgG index, myelin basic protein, oligoclonal bands and cytopathology were negative. She received IV ceftriaxone for 21 days. One month later, her symptoms subsided.

Presentation of Lyme disease as isolated sixth cranial nerve palsy and negative testing is very rare. This highlights the importance of considering Lyme disease in cranial nerves palsy, especially in endemic areas.