A person having limitation of adduction in left eye. In right eye saccadic movement on abduction and normal convergence. What is the most probably diagnosis? (AIIMS May 2009)
|B||Congenital absence of MR|
|C||Partial third nerve palsy|
|D||Duane's retraction syndrome|
Medial longitudinal fasciculus (MLF), carries fibres for conjugate horizontal eye movement from abducens internuclear neurons in the pons to the medial rectus subdivision of the contralateral oculomotor nuclear complex in the midbrain.
1. Lesions of the MLF produce internuclear ophthalmoplegia.
2. When the lesion is unilateral, the INO is characterized by weakness of adduction ipsilateral to the side of the lesion.
3. This weakness may vary from a complete loss of adduction beyond the midline to a mild decrease in the velocity of adduction without any limitation in the range of motion.
4. The fibers sub serving horizontal gaze in the MLF, each carry commands for all types of conjugate eye movements.
5. The second cardinal sign of an INO is nystagmus in contralatiral eye on abduction in the contra lateral eye.