Neuro-Ophthalmic
Internuclear Ophthalmoplegia
Also known as: internuclear ophthalmoplegia, INO, adduction deficit, abduction nystagmus, MLF lesion, MS INO, brainstem diplopia
Filed as: Urgent
Source-cited from the record's own evidence list. Clinical content programme led by Dr Ankit Mathur, PhD, Grad Cert Ocu Thera, B.S. Optom. How the clinical content is governed
Clinical decision support only
Overview
A lesion of the medial longitudinal fasciculus in the brainstem, producing limited adduction on horizontal gaze with nystagmus of the abducting fellow eye. Convergence may be preserved depending on where the lesion sits. The association is demyelination in younger adults and brainstem stroke in older ones, so it is a brainstem localisation rather than a motility problem and warrants urgent neurological assessment.
Recognition
Symptoms: what patients report
- Binocular diplopia with a gaze-dependent horizontal pattern.
- Possible blurred vision, oscillopsia, dizziness, imbalance, or other neurologic symptoms.
- May occur in young adults with demyelination or older adults with brainstem stroke.
Signs: what the examination shows
- Adduction deficit in one eye on horizontal gaze.
- Abducting nystagmus of the fellow eye may be present.
- Convergence may be relatively spared depending on lesion location.
- Other brainstem signs may coexist.
What OptoGuide™ covers for internuclear ophthalmoplegia
- Pattern reasoning: what this combination of findings points to, and its differentiators
- Don't-miss risks and escalation triggers
- Management tiers with linked Australian therapeutics
- Referral urgency, specialty, and letter drafting
Sources
- Internuclear Ophthalmoplegia — EyeWiki
- The Neuro-Ophthalmology Survival Guide (Pane, Miller & Burdon) — standard reference text
Standard texts: Kanski's Clinical Ophthalmology: A Systematic Approach, Oxford Handbook of Ophthalmology, Oxford American Handbook of Ophthalmology, Signs in Ophthalmology: Causes & Differential Diagnosis.