A woman in her 60s presented with 2 years of slowly worsening binocular oblique diplopia. She underwent strabismus surgery 20 years prior to correct a hypotropic left globe, but had no imaging at the time. Examination revealed partial left ptosis, a nonreactive mydriatic left pupil, and limited adduction, elevation, and depression of the left globe, consistent with a left oculomotor nerve palsy. Magnetic resonance imaging (MRI) of the orbits revealed a presumed schwannoma of the proximal oculomotor nerve, with striking selective atrophy of the corresponding left medial, superior, and inferior recti, inferior oblique, and levator palpebrae superioris (Figure). The lateral rectus and superior oblique were normal in appearance. These MRI findings are consistent with chronic denervation caused by the oculomotor nerve lesion.1 The presumed schwannoma was treated with stereotactic radiotherapy. Fifteen months later, her left third nerve palsy remained clinically stable and her MRI results were unchanged. She has been referred for strabismus surgery.
Szigiato A, Lee DH, Fraser JA. Selective Extraocular Muscle Atrophy Secondary to Chronic Oculomotor Denervation. JAMA Ophthalmol. 2017;135(2):e164664. doi:10.1001/jamaophthalmol.2016.4664
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