Microvascular decompression for a patient with oculomotor palsy caused by posterior cerebral artery compression: A case report and literature review

Abstract

Background: Aneurysm compression, diabetes, and traumatic brain injury are well-known causative factors of oculomotor nerve palsy (ONP), while cases of ONP induced by neurovascular conflicts have rarely been reported in the medical community. Here, we report a typical case of ONP caused by right posterior cerebral artery (PCA) compression to increase neurosurgeons' awareness of the disease and reduce misdiagnosis and recurrence.

Case summary: A 54-year-old man without a known medical history presented with right ONP for the past 5 years. The patient presented to the hospital with right ptosis, diplopia, anisocoria (rt 5 mm, lt 2.5 mm), loss of duction in all directions, abduction, and light impaired pupillary reflexes. Magnetic resonance angiography and computed tomography venography examinations showed no phlebangioma, aneurysm, or intracranial lesion. After conducting oral glucose tolerance and prostigmin tests, diabetes and myasthenia gravis were excluded. Cranial nerve magnetic resonance imaging showed that the right PCA loop was in direct contact with the cisternal segment of the right oculomotor nerve (ON). Microvascular decompression (MVD) of the culprit vessel from the ON through a right subtemporal craniotomy was carried out, and the ONP symptoms were significantly relieved after 3 mo.

Conclusion: Vascular compression of the ON is a rare pathogeny of ONP that may be refractory to drug therapy and ophthalmic strabismus surgery. MVD is an effective treatment for ONP induced by neurovascular compression.

Keywords: Case report; Magnetic resonance imaging; Microvascular decompression; Neurovascular conflict; Oculomotor nerve; Oculomotor nerve palsy; Posterior cerebral artery.

Figure 1

Right ocular motility in different directions of gaze is compared before and after surgery (3 months). A-F: Showing the deficits in primary position (A), adduction (B), medial-to-upper left (C), elevation (D), and medial-to-upper right (E) except abduction (F); G-L: Demonstrating a good recovery from the right oculomotor nerve palsy with mild deficits in elevation. The representative axial (right) and sagittal (left) T2-weighted image before surgery (M) showing that the right oculomotor nerve (ON) (yellow arrow) was in direct contact with the right posterior cerebral artery (PCA) (orange arrow). The representative axial (right) and sagittal (left) T2-weighted image at 3 mo after surgery (N) showing that there was no contact between PCA and ON.

Figure 2

Representative three-dimensional images. A-C: Demonstrated the right oculomotor nerve (ON) (yellow arrow) was compressed by the right posterior cerebral artery (PCA) (orange arrow) downwardly before surgery; D-F: Demonstrated the decompression of the right oculomotor nerve by the Telfon cottons (blue arrow) between the right PCA and the right oculomotor nerve 3 mo after surgery.

Figure 3

Intraoperative microsurgical view after separating the tense arachnoid membrane and coating of the right posterior cerebral artery. A: The right posterior cerebral artery (PCA) (orange arrow) compressing the oculomotor nerve (yellow arrow); B: Teflon cotton (yellow arrow) used to cushion the oculomotor nerve against the PCA.