Abstract
Ophthalmoplegia/ophthalmoparesis (internal, external, or both) has been reported in dogs secondary to neoplasia affecting the oculomotor nerve and is usually given a poor prognosis. The purpose of this retrospective study was to describe the clinical findings, magnetic resonance imaging (MRI) findings, management, outcome, and follow-up in a group of canine cases with idiopathic oculomotor neuropathy. Inclusion criteria included cases with ophthalmoplegia/ophthalmoparesis (internal, external or both) as sole neuroophthalmologic signs, complete ophthalmic and neurologic examination, head MRI, and a minimum follow-up period of 1 year. Dogs with progressive neurological signs not related to oculomotor neuropathy were excluded. Fourteen cases met the inclusion criteria. All cases were unilaterally affected. Magnetic resonance imaging showed equivocal enlargement of the oculomotor nerve in three cases, mild enlargement in five, and marked enlargement in six. Contrast enhancement was present in 12 cases, being marked in six. When present, the contrast enhancement was focal in eight cases and diffuse in four. The median follow-up time was 25 months. External ophthalmoparesis improved in seven cases, five cases under no treatment and two under systemic corticosteroid therapy. The clinical signs in the other seven cases remained unchanged. Idiopathic oculomotor neuropathy should be included as a differential diagnosis in dogs presenting with unilateral ophthalmoplegia/ophthalmoparesis (internal, external, or both) with the absence of other neurologic and ophthalmic signs, and with the MRI findings restricted to the oculomotor nerve. Idiopathic oculomotor neuropathy has a good prognosis as the clinical signs do not deteriorate and they can improve without treatment.
Highlights
The oculomotor nerve innervates the ipsilateral extraocular muscles and the ipsilateral levator palpebrae superioris muscle.[1]
The aims of this study were to describe the clinical findings, magnetic resonance imaging (MRI) features, management, outcome, and long-term follow-up of canine cases diagnosed with idiopathic oculomotor neuropathy
A putative association between cranial neuropathy and hypothyroidism has been stated in the veterinary literature,[18,19] this is not borne out by other studies.[17,20]
Summary
The oculomotor nerve (cranial nerve III or CN III) innervates the ipsilateral extraocular muscles (dorsal, ventral, and medial rectus and ventral oblique muscle) and the ipsilateral levator palpebrae superioris muscle.[1]. The aims of this study were to describe the clinical findings, magnetic resonance imaging (MRI) features, management, outcome, and long-term follow-up of canine cases diagnosed with idiopathic oculomotor neuropathy
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