Internuclear ophthalmoplegia as a presenting sign of Lyme disease: a case report

Aim: To describe an unusual case presentation of INO associated with possible Lyme disease. Methods: This is a case report of a 30 year old man who presented to the emergency department complaining of right orbital pain, double vision and an inability to look to the left. He was seen by the ophthalmologist and neurologist and reported worsening symptoms of a frontal headache and difficulties in walking. He had a history of tick bites and a consequent rash 2 months earlier. There was no vomiting, limb weakness or fever and also no significant history of trauma. Results: On examination visual acuity was 6/9 in the eye; pupils, fundus and discs were normal. Orthoptic assessment revealed a right/alternating exotropia with diplopia and right INO was confirmed on ocular movement testing. Vertical nystagmus was also noted on upgaze. Convergence was normal. He was diagnosed with a right internuclear ophthalmoplegia with intact convergence. CT scan and MRI were normal and so he was commenced on ceftriaxone 2 mg IV once daily for probable neuroborreliosis which after 3 days was switched to oral doxycycline 100 mg for 2 weeks. Tests for Lyme disease proved inconclusive. Four weeks later the patient was reassessed and his INO had resolved. Conclusion: Diagnosis of Lyme disease should be considered for sudden onset internuclear ophthalmoplegia. Internuclear ophthalmoplegia (INO) as the first sign of neuroborreliosis is extremely rare. To our knowledge there is only one other documented case of an adult patient with an isolated INO.