Internuclear opthalmoplegia due to pontine infarction


  • 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


  • 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




Author: radhianahassan