Neuroscience · Year 2 · from Neuroscience
Case 3: Internuclear Ophthalmoplegia
Patient Presentation
Demographics: 32-year-old female
Chief Complaint: Double vision when looking to the right
History of Present Illness: A 32-year-old woman presents with horizontal double vision that is worse when looking to the right. She noticed it 3 days ago when driving and had difficulty changing lanes because of the visual disturbance. She recalls having an episode of visual blurring in her right eye that lasted 2 weeks about 18 months ago, which she attributed to stress and did not seek evaluation. She also mentions occasional tingling in her feet over the past year. She has no other medical history.
Physical Examination:
- Vital signs: Normal
- General: Healthy-appearing young woman
- Neurological:
- Mental status: Normal
- Cranial nerves:
- Pupils: Equal, reactive
- Eye movements: On RIGHT gaze - failure of LEFT eye adduction with nystagmus of abducting right eye; convergence intact; LEFT gaze normal
- Motor: 5/5 throughout; no weakness
- Sensory: Mildly decreased vibration sense at ankles bilaterally
- Reflexes: 3+ bilateral lower extremities; bilateral Babinski responses
- Coordination: Mild intention tremor on finger-to-nose
- Gait: Mildly ataxic
Workup:
- MRI brain: Multiple periventricular, juxtacortical, and callosal white matter lesions; T2 hyperintense lesion in left medial longitudinal fasciculus (MLF); several lesions enhance with gadolinium, others do not (dissemination in time)
- MRI cervical spine: Two short-segment T2 hyperintense lesions
- Lumbar puncture: 3 WBC; protein 55 mg/dL; glucose normal; positive oligoclonal bands (present in CSF, not serum)
- Visual evoked potentials: Prolonged P100 latency right eye (evidence of prior optic neuritis)
Diagnosis: Multiple sclerosis with internuclear ophthalmoplegia
Treatment:
- IV methylprednisolone 1 g daily for 5 days for acute relapse
- Initiation of disease-modifying therapy (ocrelizumab) after discussion of options
- Neuro-ophthalmology follow-up
- INO improved significantly after steroids
- Long-term MS monitoring plan established
Clinical Pearl: Internuclear ophthalmoplegia (INO) results from a lesion of the medial longitudinal fasciculus (MLF), which connects the CN VI nucleus to the contralateral CN III nucleus, coordinating lateral gaze. The syndrome consists of impaired adduction of the ipsilateral eye (the eye on the side of the MLF lesion) with nystagmus of the contralateral abducting eye on lateral gaze. Convergence is typically preserved because it uses a different pathway. In young patients, bilateral INO is highly suggestive of multiple sclerosis. In older patients, brainstem stroke is more common. The adducting eye fails because the MLF normally carries the command from the contralateral CN VI nucleus to the CN III nucleus controlling medial rectus function.
Clinical Image
Image Description: Cross-sectional diagram of the medulla showing the structures affected in lateral medullary syndrome (Wallenberg syndrome), including the vestibular nuclei, nucleus ambiguus, spinal trigeminal nucleus and tract, spinothalamic tract, sympathetic fibers, and inferior cerebellar peduncle, with the lateral territory supplied by PICA highlighted.
Attribution: Image from Wikimedia Commons (https://commons.wikimedia.org/), Creative Commons Attribution-ShareAlike license.