Oculomotor nerve palsy etiology
The most common cause of isolated oculomotor nerve palsy is microvascular infarction which is caused as a result of diseases, such as diabetes mellitus, hypertension, atherosclerosis, and collagen vascular disease and is pupil-sparing.
Another common cause of isolated oculomotor nerve palsy is direct compression by an intracranial aneurysm, usually an posterior communicating artery aneurysm and tumors that presents as oculomotor nerve palsy with pupillary involvement 1).
Unilateral oculomotor nerve palsy as an initial manifestation of chronic subdural hematoma (CSDH) is a rare clinical condition.
Oculomotor nerve palsy (ONP) usually occurs in chronic subdural hematoma (CSDH) as a common sign of brain herniation that typically is associated with a deterioration of consciousness.