|
Internuclear ophthalmoplegia (INO) is a
specific
abnormality characterized by impaired
horizontal eye movement with weak adduction
of the affected eye and abduction nystagmus
of the contralateral eye. It is one of the
most localizing brainstem syndromes,
resulting from a lesion in the medial
longitudinal fasciculus (MLF) in the
dorsomedial brainstem tegmentum of either
the pons or the midbrain.
Internuclear
ophthalmoplegia
must be considered
in
the differential diagnosis of isolated medial
rectus paralysis. The nystagmus in these
patients is a secondary response to the weakness
of adduction and not caused directly by the
central defect.
Disseminated sclerosis
is the most common
cause of bilateral internuclear ophthalmoplegia,
and the unilateral type nearly always is caused
by an infarct of a small branch of the basilar
artery.
|
.jpg)
