Internuclear ophthalmoplegia, unspecified eye

This code describes a neurological condition characterized by impaired adduction (inward movement) of one eye during conjugate gaze, with nystagmus (involuntary eye movements) in the abducting (outward-moving) eye. It results from a lesion in the medial longitudinal fasciculus (MLF), typically in the brainstem. This specific code is used when the affected eye is not specified.

Use this code when documentation indicates internuclear ophthalmoplegia without specifying whether it affects the right or left eye, or if it is bilateral. This diagnosis is commonly associated with multiple sclerosis, stroke, or brainstem tumors. Supporting documentation should include neurological exam findings detailing the characteristic eye movement abnormalities.

• Avoid using this code if the laterality (right, left, or bilateral) is clearly documented; instead, use the more specific codes H51.21, H51.22, or H51.23.
• Always code the underlying cause of the internuclear ophthalmoplegia (e.g., multiple sclerosis, stroke) first, as this condition is a manifestation of another disease.
• Ensure the medical record clearly distinguishes internuclear ophthalmoplegia from other types of ophthalmoplegia or gaze palsies.