One and a half syndrome

A half - syndrome is a neuroophthalmologisches disease which is caused by the combination of two different kinds of disturbances of the eye movement. These are:

• A conjugate horizontal gaze palsy (a " whole gaze palsy " )
• A Internuclear ophthalmoplegia ( INO ) ( "half gaze palsy ").

Symptoms

There is a conjugate horizontal gaze palsy, looking in the direction of the side of the injury. Both eyes can not be moved through the mid-line in this direction.

Moreover, by the INO, looking in the opposite direction, the adduction of the equilateral eye not possible. That is, the equilateral eye can not be moved horizontally. On the contralateral eye only an abduction movement is possible, looking in the direction of this eye. However, an adduction of both eyes is possible with convergence movements.

Nebenbefundl. sometimes there is a divergent strabismus ( exotropia ) of the contralateral eye.

Cause

One and a half syndrome is a result of a unilateral damage in the area of the pons, in which both the core area of ​​the nervus abducens or the paramedian pontine reticular formation ( PPRF ) (→ horizontal gaze palsy ) and the ipsilateral medial longitudinal fasciculus (MLF ) (→ internuclear ophthalmoplegia ) is affected.

The MLF contains fibers internukleärer neurons of the contralateral Abduzenskerns which drag to ipslateralen core of the oculomotor nerve.

The cause of the injury Ponsbereich is mostly a lacunar infarction, a Entmarkungsherd in multiple sclerosis, cerebral hemorrhage or a tumor in the region of the pons.