CASE REPORT: Isolated unilateral pitosis; involvement of partial fasiculer due to midbrain infarction

Ptosis could be caused by oculomotor nerve palsy in the midbrain infarction. Isolated midbrain infarction is rare. We report a patient with isolated unilateral ptosis caused by partial fascicular oculomotor paresis due to midbrain infarction. A 59-year-old woman was unable to open her right eye on waking up the morning and was admitted to our hospital. Ptosis was found in the right eye. The other examination findings were normal. In radiological imaging showed an acute infarction in the right paramedian midbrain and the lesion was compatible with localization of the right oculomotor fascicle. She was diagnosed with partial fascicular oculomotor paresis due to paramedian midbrain infarction. By administration of anti-platelet agents, ptosis was resolved within 1.5 months. The anatomy of the third cranial nerve fascicle and its courses through the midbrain is a topic of debate. Previous reports of oculomotor fascicular infarction have elucidated the human oculomotor fascicular arrangement and from these material topographical models have been proposed. Compared to proposed models for arrangement of oculomotor fascicle, this case demonstrates that the fibers to levator palpebrae may be located in the most caudal portion of the oculomotor fascicles. The case is interesting in that the isolated ptosis due to the oculomotor fascicular palsy only involved the levator palpebrae fibers and is intended to contribute to the literature by being discussed with the oculomotor fascicles models