One and a half syndrome
| Classification according to ICD-10 | |
|---|---|
| H51.0 | Conjugated eye paralysis |
| H51.2 | Internuclear ophthalmoplegia |
| ICD-10 online (WHO version 2019) | |
The one and a half syndrome is a neuro-ophthalmological clinical picture, which is caused by the combination of two different disorders of eye movement . These are:
- a conjugated, horizontal paralysis (a " complete paralysis")
- an internuclear ophthalmoplegia (INO) (a " half eye paralysis").
Symptoms
There is conjugate horizontal paralysis when looking towards the side of the injury. Both eyes cannot be moved beyond the center line in this direction.
In addition, the INO does not allow adduction of the eye on the same side when looking in the opposite direction. That is, the eye on the same side cannot be moved horizontally at all. On the contralateral eye, only an abduction movement is possible when looking in the direction of this eye. However, adduction of both eyes is possible with convergence movements .
Secondary findings sometimes there is an outward squint ( exotropia ) of the contralateral eye.
root cause
A one-and-a-half syndrome is the result of unilateral damage to the pons , in which both the core area of the abducens nerve or the paramedian pontine reticular formation (PPRF) (→ horizontal gaze palsy ) and the medial longitudinal fasciculus (MLF) on the same side (→ internuclear ophthalmoplegia) ) is affected.
The MLF contains fibers from internuclear neurons of the contralateral nucleus of the abdomen, which run to the ipslateral nucleus of the oculomotor nerve .
The cause of the damage in the pons area is usually a lacunar cerebral infarction , a demyelinating focus in multiple sclerosis , a cerebral hemorrhage or a tumor in the area of the pons.
literature
- Frank Thömke: Eye movement disorders. A Clinical Guide for Neurologists 2nd updated and expanded edition. Thieme, Stuttgart et al. 2008, ISBN 978-3-13-128742-7 .
