Presentations

Abstract

Introduction: Internuclear Ophthalmoplegia (INO) is a condition characterized by impaired lateral gaze. While various conditions can cause unilateral INO, bilateral INO is typically associated with multiple sclerosis. In this abstract, we present a case of bilateral INO caused by aseptic meningitis, which is an atypical manifestation.

Case Information: A 29-year-old female presented to the emergency department with double vision, frontal headache, and gait instability. Ophthalmic examination revealed asymmetric bilateral internuclear ophthalmoplegia. Laboratory tests showed mild leukocytosis and elevated inflammatory markers. MRI scans of the spine and head did not indicate any demyelinating illness. Further review of the patient's history revealed a recent upper respiratory tract illness followed by neck stiffness and cold sores. The patient was empirically given Acyclovir, leading to a significant improvement in symptoms. Subsequent cerebrospinal fluid (CSF) analysis showed lymphocytic pleocytosis, suggesting aseptic meningitis. However, CSF and serum PCR tests were negative for common viral pathogens. Multiple sclerosis workup was negative, and the patient was discharged with oral valacyclovir.

Discussion/Clinical Findings: Internuclear Ophthalmoplegia (INO) is caused by damage to the Medial Longitudinal Fasciculus, a bundle of neurons connecting the nuclei of cranial nerves III and VI. It is characterized by impaired eye adduction on the affected side and impaired abduction of the contralateral eye.1 Typical symptoms include nystagmus, horizontal diplopia, dizziness, gait instability, and headaches. While imaging can help visualize lesions, INO is primarily diagnosed clinically.2 CSF analysis is reserved for cases where infection or multiple sclerosis is suspected. Treatment involves managing the underlying cause. Multiple sclerosis is the most common cause of INO, but other causes include brainstem infarctions, trauma, vasculitis, and infections.3 Bilateral INO is highly suggestive of multiple sclerosis and requires a complete workup. However, aseptic meningitis should also be considered, as preceding infections can be subtle.4 Aseptic meningitis is diagnosed through CSF analysis, cultures, and PCR tests. It is important to note that CSF is sterile in most cases, especially if antimicrobials have been administered. References: 1- Feroze KB, Wang J. Internuclear Ophthalmoplegia. 2023 Jun 26. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. PMID: 28722999. 2- Tien CW, Donaldson L, Parra-Farinas C, Micieli JA, Margolin E. Sensitivity of Magnetic Resonance Imaging of the Medial Longitudinal Fasciculus in Internuclear Ophthalmoplegia. J Neuroophthalmol. 2024 Mar 1;44(1):107-111. doi: 10.1097/WNO.0000000000001783. Epub 2023 Jan 4. PMID: 36626595. 3- Keane JR. Internuclear ophthalmoplegia: unusual causes in 114 of 410 patients. Arch Neurol. 2005 May;62(5):714-7. doi: 10.1001/archneur.62.5.714. PMID: 15883257. 4- Bakker SL, Gan IM. Temporary divergence paralysis in viral meningitis. J Neuroophthalmol. 2008 Jun;28(2):111-3. doi: 10.1097/WNO.0b013e3181782561. PMID: 18562842.

Conclusion: Bilateral internuclear ophthalmoplegia is commonly associated with Multiple Sclerosis and requires a complete workup. However, it can also be a presenting sign of Aseptic Meningitis.