Aberrant Regeneration of Cranial Nerve 3 Following Schwannoma Resection.

Abstract

A 21-year-old female presented with a complete, pupil-involving third nerve palsy after resection of a schwannoma located in the left cavernous sinus 7 years prior. On examination, the patient had complete ptosis of the left upper lid, which was present in primary, up, and lateral gazes and improved in downgaze (Fig. 1). With manual elevation of the left lid, the patient experienced diplopia in all gazes and was noted to have hypertropia and exotropia. Extraocular movements revealed intact incyclotorsion and paralysis of supraduction, adduction, and infraduction. With attempted downgaze she had improvement of the left upper lid ptosis (Fig. 2; Supplemental Digital Content 1, available at https://links.lww.com/IOP/A259). This paradoxical eyelid opening with attempted downgaze is the result of the third cranial nerve associated with the inferior rectus subnucleus being misdirected to the levator palpebrae. This phenomenon is also known as pseudo-Von Graefe’s sign. The patient reported that 2 years after the tumor resection, the lid started to elevate in attempted downgaze. Examination of the left eye was unremarkable. Upon genetic testing, the patient was found to have Neurofibromatosis type 2 without any evidence of a posterior subcapsular cataract, wedge cortical cataract, or hamartomas of the retina or retinal pigment epithelium.FIG. 1.: Top: upgaze, Middle: primary gaze, Bottom: left gaze.FIG. 2.: Top: primary gaze, Middle: primary gaze with left upper lid manually elevated, Bottom: downgaze with elevation of left upper lid.