Partial involvement of the upper division of the oculomotor nerve of microvascular etiology: a case report

Abstract

A 70-year-old woman with uncontrolled hypertension woke up with a vertical binocular diplopia worsened when looking upward, without pain during ocular movements. After two days, she presented with left eyelid ptosis. She denied any history of trauma. At admission in hospital, was ruled out macular and/or retinal pathologies. Upon neurologic examination, she had restricted upward gaze in the left eye and eyelid ptosis, without pupillary involvement or other cranial nerve deficits, consistent with involvement of the upper division (UD) of the left third cranial nerve (CN III). The patient underwent extensive investigation for cranial nerve syndrome, including magnetic resonance imaging (MRI), cerebrospinal fluid analysis, and laboratory tests. All of these exams had normal results, and microvascular (MV) etiology was then considered. Ischemic involvement of the CN III often presents with limitation of extrinsic eye movement of all muscles innervated by this nerve. When the limitation is restricted to the UD of the CN III, the most common etiologies are related to extrinsic mechanical compression of the orbit, mainly due to neoplastic and infiltrative processes, in addition to skull base trauma. MV etiology due to involvement of the vasa-nervorum should be considered a diagnosis of exclusion in patients with high cardiovascular risk. In these cases, structural causes should be initially investigated with Orbital MRI and the image should be carefully evaluated for mechanical compression. After ruling out such etiology, MV disease responsible for the irrigation of the CN III should be considered, actively searching for risk factors such as hypertension and diabetes mellitus, which, if present, should be promptly controlled with lifestyle changes and appropriate medication treatment.