MRI of the eye muscles in a case of ophthalmoplegia caused by common carotid artery occlusion suggests ischemic myopathy

Ocular muscle palsies following carotid artery disease is thought to be caused by ischemia of the cranial oculomotor nerves but it may also be due to ischemia of the extraocular muscles (EOM). We studied a patient with common carotid artery occlusion syndrome (CCAOS) to elucidate the two competing hypotheses. MRI and sonography of the orbita showed oedematous swelling of all left EOM. MRI short-tau inversion recovery (STIR) sequences showed hyperintensities and a prolonged T2-relaxation time in EOM indicating muscle oedema. It decreased within two weeks as ophthalmoplegia improved. For several reasons ischemic EOM myopathy rather than ischemic neuropathy seems to be the morphological correlate of ophthalmoplegia after ipsilateral CCAOS in this patient.