Inferior rectus palsy as an isolated ocular motor sign: acquired etiologies and outcome

The aim of this work is to elucidate underlying etiologies, lesion locations, and outcomes of inferior rectus (IR) palsy of acquired origin. Retrospective search identified 44 patients with acquired IR palsy between April 2006 and May 2011 from four Neurology and two Ophthalmology Clinics in Korea. We analyzed clinical features, the results of radiological and laboratory evaluation, and prognosis. The most common causes were vascular (n = 16, 36 %) and trauma (n = 12, 27 %). Vascular disorders included microvascular ischemia (n = 10, 23 %), cerebral infarction (n = 5, 11 %), and dural arterio-venous fistula (n = 1, 2 %). Other causes were inflammation (n = 7, 16 %), myasthenia gravis (n = 5, 11 %), and thyroid ophthalmopathy (n = 1, 2 %). We were unable to determine the etiology in the remaining three patients (7 %). Most patients (95 %) showed a complete recovery with or without treatment. Acquired IR palsy mostly occurs with brainstem or orbital lesions, and has an excellent prognosis.