A 58-year-old man came to the emergency room for a subacute binocular diplopia of at least 3 months onset initially attributed to the side effects of chemotherapy.
The patient had been treated with cycles of oxyplatinum/taxol and concomitant radiotherapy for large cell lung carcinoma in stage T2N3M0 diagnosed 7 months ago.
In the exploration, the best corrected VA was 0.9 in right eye (OD) and 0.8 in left eye (LE).
Both pupils were in middle mydriasis with little reactivity to light and convergence.
Regarding ocular motility, exotropia of -50 dp ( prismatic diopters) was observed with OD dominance but with alternating fixation capacity.
In the right eye, there was a limitation of supradue (++) and adduction (++) but with preservation of consciousness.
The OI showed a quasi-total palpebral ptosis and a severe limitation of the supradu (+++), adduction (++) and the infradu (+++) layers.
The anterior segment biomycosis was normal as well as ocular tension in both eyes (AO).
No pathological alterations were found in the eye fundus.
Neurological examination showed no clinical abnormalities.
Magnetic resonance imaging (MRI) of the brain revealed a solitary lesion in the posterior region of the floor of the third ventricle.
This lesion had a hyperintense annular aspect, with a hypointense central portion suggestive of necrosis, and affected bilaterally the nuclei and fascicles of the III central cranial nerve in the mesencephalon.
