Internuclear Ophthalmoplegia as the Presenting Sign of Giant Cell Arteritis.

Abstract

CASE REPORT A 62-year-old man presented with the acute onset of diplopia. His medical history included well-controlled hypertension, hypercholesterolemia, and polymyalgia rheumatica (PMR) that was treated 2 years previously with steroids. The PMR was in remission at the time of presentation. The patient presented to an outside ophthalmologist with binocular vertical diplopia and moderate-to-severe headache of 1-week duration. On examination, he was found to have a 10-prism diopter exotropia with reduced adduction of the left eye and horizontal dissociated abduction nystagmus of the right eye on right gaze, suggestive of an internuclear ophthalmoplegia (INO). He also had a left hypertropia in right gaze (Fig. 1). The patient was referred to an outside hospital for a full evaluation to rule out the possibility of stroke. MRI scan of the brain and MR angiography revealed only mild nonspecific white matter ischemic changes. The erythrocyte sedimentation rate (ESR) was normal for his age at 21 mm per hour, and his C-reactive protein (CRP) was mildly elevated at 2.7 mg/dL (normal <1 mg/dL).FIG. 1.: Ocular motility examination. Ocular motility examination demonstrating evidence of adduction deficit of the left eye on right gaze.The patient was subsequently referred to our neuro-ophthalmology unit, where his examination was unchanged from that previously noted. A temporal artery biopsy, performed due to persistent headache, demonstrated transmural lymphocytic infiltration that was also present at the adventitia, vasa vasorum, and vasa nervorum. Multiple giant cells at the level of the media with significant disruption of the internal elastic lamina were found; all of these findings were consistent with active giant cell arteritis (GCA). The patient was started on prednisone 80 mg per day and experienced complete resolution of symptoms and normalization of his CRP after 8 weeks of therapy. INO can occur in the setting of a lesion to the medial longitudinal fasciculus (MLF), which includes interneurons connecting the sixth nerve nucleus and the contralateral nucleus of the third nerve. Injury to the MLF occurs from a variety of etiologies and results in characteristic signs of adduction deficit on the side of the lesion with an abducting nystagmus of the contralateral eye. INO is often accompanied by skew deviation. It is most commonly caused by vertebrobasilar insufficiency or inflammatory demyelination (1,2). Pseudo–internuclear ophthalmoplegia (pseudo-INO) presents similarly to INO but occurs secondary to myasthenia gravis or can occur with medial rectus ischemia (3). Although we believe our patient experienced a pseudo-INO due to GCA-mediated ocular muscle ischemia, it is possible that he had a true INO with brainstem ischemia despite an apparently normal brain MRI. In addition, abducting nystagmus is classically associated with an INO but has been reported in patients with pseudo-INO (3–5). In GCA, T-cell–mediated chronic inflammation results in myofibroblast migration and intimal hyperplasia, leading to arterial occlusion and ischemia. Special stains may demonstrate histiocytic infiltrates at the level of the elastic lamina, a finding that can impact prognosis. Ischemia of the central retinal artery leads to vision loss, whereas ischemia due to disease of the basilar and ophthalmic arteries can cause INO and pseudo-INO, respectively (6–9). Diplopia is an uncommon finding in GCA, occurring in only 6% of patients, and may be caused by ischemia of the cranial nerves, extraocular musculature, or brainstem (8–12). An INO or pseudo-INO (from extraocular muscle involvement) as a cause of diplopia is an extremely rare finding in GCA. Our search revealed only 6 previous publications that report 8 cases of INO in patients with GCA. These are summarized in Table 1 (13–18). Our patient had a history of PMR and had a normal ESR at the time of presentation. A normal ESR is not unusual and may be seen in almost 20% patients with GCA cases. It is estimated that up to 10% of patients with a history PMR will develop GCA. We mention these findings to highlight the lack of typical symptoms in this patient and to illustrate the importance of the medical history in determining the etiology of an INO (19,20). This case reveals the importance of considering GCA in the differential diagnosis of INO (or pseudo-INO) in elderly patients.TABLE 1.: Summary of the literatureSTATEMENT OF AUTHORSHIP Category 1: a. Conception and design: G. L. Jensen; b. Acquisition of data: B. Al Othman; c. Analysis and interpretation of data: A. Kini. Category 2: a. Drafting the manuscript: B. Al Othman; b. Revising it for intellectual content: A. Lee. Category 3: a. Final approval of the completed manuscript: A. Lee.