Clinical:
- A 63 years old lady
- Day 8 post laparotomy for multiple liver abscess
- Developed sudden onset blurring of vision and diploplia
- Clinical examination showed isolated impaired adduction with nystagmus of right eye
- CT Brain done showed no abnormality
- MRI requested to rule out brain stem lesion with clinical diagnosis of right internuclear opthalmoplegia (INO)
Imaging findings:
- CT scan did not demonstrate any abnormality
- MRI shows a small focal hyperintense lesion in the right side of the rostral pons, anterior to the roof of the 4th ventricle. This lesion show fluid restriction on DWI . No significant enhancement post contrast. The lesion is not seen on other sequences.
Diagnosis: Acute infarction in the right rostral pons causing internuclear opthalmoplegia
Discussion:
- Internuclear ophthalmoplegia (INO) is a disorder of eye movement, classically
characterized by impaired adduction on the side of a lesion with dissociated nystagmus of the abducting eye. - INO in young patients is most commonly caused by multiple sclerosis
- INO in older age group is mostly caused by cerebrovascular disease
- Other rare causes of INO include brain stem tumour, haemorrhage, trauma, infection, Wernicke encephalopathy, drugs and degenerative disorder
- INO is caused by lesions involving the MLF (medial longitudinal fasciculus) which lies in the pontine tegmentum
