TY - CHAP M1 - Book, Section TI - Internuclear Ophthalmoplegia (INO) A1 - Singh, Manpreet A1 - Whitfield, Denise A2 - Knoop, Kevin J. A2 - Stack, Lawrence B. A2 - Storrow, Alan B. A2 - Thurman, R. Jason PY - 2021 T2 - The Atlas of Emergency Medicine, 5e AB - Internuclear ophthalmoplegia (INO) is a specific gaze deficit caused by lesions to the medial longitudinal fasciculus (MLF) of the dorsomedial brain stem. It presents with horizontal eye movement deficits characterized by poor adduction in the affected eye and abduction nystagmus in the contralateral eye. Occasionally INO can be present bilaterally. Smooth binocular vision and the ability to visually track require synchronized ocular movements. The MLF coordinates neuronal signaling between cranial nerves III, IV, and VI to achieve synchronous eye movements. The majority of INO cases are associated with multiple sclerosis, although mass lesions, trauma, and cerebrovascular disease are potential causes as well. The diagnosis of INO is made by neurologic examination, specifically assessing horizontal eye movement. Findings can be subtle and may require specialized neurologic testing. SN - PB - McGraw-Hill CY - New York, NY Y2 - 2024/03/29 UR - accessemergencymedicine.mhmedical.com/content.aspx?aid=1198097682 ER -