A patient presents with diplopia. O/E adduction deficit is seen in one eye and abducting saccades in the other eye. Convergence is preserved. What is the likely diagnosis?
Internuclear ophthalmoplegia (INO): defect of horizontal gaze, caused due to lesion in medial longitudinal fasciculus (MLF). MLF connects 6th nerve nucleus to 3rd nerve nucleus of the opposite side. Thus, in INO, during lateral gaze these features are seen:* The adducting eye fails to move because 3rd nerve nucleus does not receive any input* The abducting eye moves laterally but suffers from abducting saccades* Convergence is normal as the pathway for convergence is completely different. The pathway for horizontal gaze may be summarized as: PPRF | 6th nerve nucleus of same side |MLF 3rd nerve nucleus of opposite side. Duane retraction syndrome (DRS): restrictive type of strabismus, co-contraction of medial and lateral rectus muscles due to anomalous innervation of one of extra ocular muscle antagonists during embryo-genesis
Paial third nerve palsy
Internuclear ophthalmoplegia
Duane's retraction syndrome
Absence of medial rectus muscle
Neuro Ophthalmology