One-and-a-half-syndrome.

Hi, 

These rare syndromes are seen due to lesions of unilateral PPRF and ipsilateral MLF. According to affected CN, the lesion is called one-and-a-half or Eight-and-a-half, Foville's syndrome or Syndrome of the pontine tegmentum or Inferior Medial Pontine Syndrome.... 

Best wishes

one and a half syndrome is due to MLF and PPRF lesion

here i am describing a patient

when looking right , right eye cant abduct and left eye can adduct

when looking left left eye cant adduct and right eye get an abducting nystagmus

this is not one and a half syndrome

here the lesion is in the right MLF and right 6th nucleus

in one and half syndrome its MLF and PPRF

Hi, 

Check this chapter

A Textbook of Neuroanatomy (2e), M. Patestas. 

In Chapter of Cranial Nerves: Figure 17.15 (INO)

i read that article

it describe one and  half syndrome. there The eye affected by the lesion cannot move horizontally to either side, but the eye on the side opposite the lesion can abduct; convergence is unaffected.

but in this case 

when looking right , right eye cant abduct and left eye can adduct

when looking left left eye cant adduct and right eye get an abducting nystagmus