High-Reolution Magnetic Reonance Imaging of the Extraocular Mucle and Nerve Demontrate Variou Etiologie of Third Nerve Paly Original Reearch Article

Purpoe The etiology of third nerve paly i uually diagnoed by hitory, motility examination, and preence of lid and pupil involvement, a well a cranial and vacular imaging. We ued high-reolution magnetic reonance imaging (hrMRI) of the oculomotor nerve and affected extraocular mucle (EOM) to invetigate oculomotor paly. Deign Propective, noncomparative, obervational cae erie in an academic referral etting. Method Twelve patient with nonaneurymal oculomotor paly of 0.75 to 252 month’ duration were tudied. In the orbit and along the intracranial oculomotor nerve, hrMRI at 1- to 2-mm thickne wa performed. Coronal plane image of each orbit were obtained in multiple, controlled gaze poition. tructural abnormalitie of the oculomotor nerve and aociated change in EOM volume and contractility were evaluated. Reult Cae were categorized a tumor related, congenital, diabetic, traumatic, and idiopathic according to clinical characteritic and hrMRI finding. Reduction of volume and contractility of affected EOM were noted in ix patient; however, there wa no marked EOM atrophy in two cae of diabetic oculomotor paly, and there were four cae of aberrant regeneration. hrMRI demontrated the oculomotor nerve at the midbrain and at EOM in all cae, and in two cae with previou normal neuroimaging elewhere that demontrated contrat-enhancing tumor on the oculomotor nerve. One patient with apparently unilateral congenital inferior diviion oculomotor paly had no detectable ipilateral and a hypoplatic contralateral oculomotor nerve exiting the midbrain. Concluion hrMRI provide valuable information in patient with oculomotor paly, uch a tructural abnormalitie of the orbit and oculomotor nerve, and atrophy and diminihed contractility of innervated EOM. Thi information could be helpful in diagnoi and management of oculomotor paly.