March 28, 2017
6 min read
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Woman presents with spontaneous visual field loss

Dilated fundus exam demonstrated pallid disc edema and whitening of the nasal macula in the left eye.

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The New England Eye Center was consulted on a 61-year-old woman with a history of recently diagnosed left-sided greater than right-sided internal carotid artery aneurysms when she presented urgently to the Tufts Medical Center Emergency Department with spontaneous inferotemporal visual field loss noticed upon awakening. At the time of consultation, she additionally described a 3- to 4-week history of transient “black spots and flashes” that occurred in both eyes during coughing episodes that lasted roughly 1 minute. Otherwise, she reported neither pain nor diplopia and believed her remaining visual acuity to be at baseline.

A CT of the head and MRI/MRA of the head and neck were performed with concern for enlargement of or embolization from the previously identified aneurysms. The imaging showed stability of the lesions bilaterally. Of note, the patient had recently been started on aspirin and clopidogrel after identification of these aneurysms and was fully compliant with this regimen.

Examination

On examination, best corrected visual acuity was 20/20 in both eyes. There were full extraocular movements with a 1-mm anisocoria (left greater than right). The left pupil was sluggish in reaction to light with a 1+ afferent pupillary defect. Color plates were full, although visual fields by confrontation revealed an inferotemporal constriction from 3 to 6 o’clock in the left eye. Applanation IOP was within normal limits in both eyes. Slit lamp exam revealed an unremarkable anterior segment in both eyes. Dilated fundus exam, while unremarkable in the right eye, demonstrated pallid disc edema and whitening of the nasal macula in the left eye (Figure 1).

Figure 1. Pallid disc edema in the left eye with adjacent retinal nasal macular edema.

Images: Constans J, Hedges TR

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Further history

Further discussion with the patient illuminated the fact that she had been experiencing intermittent headaches and true jaw claudication over the preceding 2 to 3 months alongside a 14 lb unintentional weight loss. Attributing this to sinus disease, her primary care physician had prescribed intermittent pulse dose steroids and antibiotics throughout the duration of the time leading to her presentation at Tufts Medical Center. Additional workup in the ophthalmology clinic included OCT (Figure 2), confirming left-sided optic disc edema with adjacent inner retinal thickening within the area of nasal macular whitening seen on dilated fundus examination. A fluorescein angiogram showed patchy choroidal filling and delayed perfusion of the nasal macula, indicating insufficiency of the posterior ciliary and retinal arterial systems (Figure 3).

Serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were ordered, and she was immediately started on intravenous steroids overnight. By the next morning her lab work had been processed, revealing CRP 63.28 and ESR 70. Her visual acuity in the left eye had diminished slightly to 20/25 (eccentric) alongside 360° constriction of her visual field confirmed by automated perimetry. Repeat fundus exam revealed worsened optic disc edema with new disc hemorrhage in the left eye. She then underwent temporal artery biopsy that ultimately confirmed the diagnosis of giant cell arteritis.

Throughout the remainder of the patient’s hospitalization, her visual acuity and visual field constriction remained stable. Repeat OCT performed at time of discharge revealed an edematous optic disc. By the time of discharge, she had completed a 3-day course of high-dose IV steroids with conversion to an oral taper of prednisone. She was most recently seen for follow-up at 6 weeks, at which point her prednisone had been successfully tapered to 30 mg daily without recurrence of symptoms. Exam at that time revealed improvement in BCVA to 20/20 with resolution of disc edema and resultant superior/inferior thinning of the retinal nerve fiber layer to 62 µm by OCT. Repeated automated perimetry demonstrated stable visual fields, and she was continued on her oral steroid taper. Neurosurgery continues to follow with plans for further surgical management of her carotid aneurysms upon reaching maintenance dosing levels of steroid.

Figure 2. OCT analysis revealing retinal nerve fiber layer thickening in the left eye (a) and corresponding inner retinal thickening of the nasal macula seen on cross-section (b).
Figure 3. Fluorescein angiography of the affected fundus revealing patchy choroidal filling, edematous blocking of the nasal macula and late staining of the optic nerve.

Discussion

Largely a clinical diagnosis, giant cell arteritis (GCA) is a systemic vasculitis affecting both medium and large caliber arteries. It is most commonly seen after age 50 years in women, with a two to four times greater risk than men, of Scandinavian descent and remains a serious condition with often permanent and potentially devastating visual implications. The gravity of these sequelae necessitates timely diagnosis and treatment. A patient’s clinical picture, an elevated ESR of more than 50 and CRP aid in forming the diagnosis, although formal temporal artery biopsy remains the gold standard diagnostic modality.

False negative results on biopsy, although rare, have been described at rates of 3% to 9% and are often attributed to skip lesions within the arteries themselves. Oh and colleagues described a retrospective case control study involving 538 biopsies, 126 of which were positive (23.4%), investigating the value of temporal artery biopsy length in the diagnosis of GCA. Their analysis revealed a difference of 3 mm between mean length of positive and negative biopsy results with an overall mean length of 19.9 mm among positive biopsies. Furthermore, they demonstrated that a minimum length of 15 mm increased the odds of a positive result by an odds ratio of 2.25 and described a 3.4% increase in likelihood of a positive result with each successive 1 mm increase in biopsy size.

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Given its systemic nature, the clinical presentation of GCA is often varied with the additional potential for normal serology in up to 16% of cases. These findings alongside the rare, albeit clinically significant, false negative biopsy rate represent a diagnostic challenge, resulting in possible delay in treatment. The potential consequences therein necessitate investigation into alternative diagnostic modalities to either improve systemic recognition or enhance the diagnostic accuracy of the temporal artery biopsy.

In a prospective study, Lariviere and colleagues compared the role of PET scans vs. CTA scans in the diagnosis of GCA. Twenty-four patients were enrolled, 15 (62.5%) of whom were confirmed to have GCA by the American College of Rheumatology criteria and/or positive temporal artery biopsy. These patients then underwent PET and CTA imaging protocols. Pertinent findings between the groups included strong large vessel FDG uptake on PET in 10 of 15 patients (66.7%) and demonstrable mural thickening of the aorta or branch vessels on CTA in 11 of 15 patients (73.3%). Further analysis of the imaging results revealed higher sensitivity for GCA in the CTA group (66.7% vs. 73.3%) and superior specificity and positive predictive value in the PET group (100% vs. 84.6%; 100% vs. 84.6%, respectively). The negative predictive value was equivocal between the two groups (64.3% vs. 64.3%).

D’Souza and colleagues performed a retrospective case series investigating potential radiographic manifestations of GCA on MRI among biopsy-proven cases and found chiasmal involvement in GCA.

Jianu and colleagues advocated the use of sonography in the workup for GCA, focusing on both the orbital vessels, including the ophthalmic arteries, central retinal arteries and posterior ciliary arteries, as well as the branches of the external carotid artery. They describe using sonography in a case to identify signs of reduced flow to the retrobulbar arteries of the left eye suggested by increased vascular resistance and reduced end-diastolic velocity.

Mollan and colleagues investigated the use of transdermal OCT as an adjunct noninvasive imaging modality in the evaluation of the superficial temporal arteries of suspected GCA patients, citing a 10 times higher image resolution than either ultrasound or MRI/MRA, in addition to requiring less experience for image interpretation compared with the former and an overall greatly reduced cost when compared with the latter.

Summary

In the case above, we describe a patient with known bilateral carotid artery aneurysms who had been having characteristic GCA symptoms for 3 to 4 weeks before developing a new visual field deficit. The pallid appearance of her left optic nerve seen on fundus examination suggested that the arteritis had actually had a chronic, subclinical effect on the nerve throughout this duration. The pulse dosed steroids prescribed by her primary care physician for sinusitis were likely protective and fortunately aided in ensuring a good visual outcome.

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Giant cell arteritis remains a visually threatening disease entity with the potential to progress to blindness without prompt diagnosis and treatment. Its presentation is variable, often leading to a delay in initiation of the necessary corticosteroid regimen with direct effect on clinical outcomes. For this reason, more research is being performed on investigating additional imaging modalities that may enhance the ability for clinicians to recognize GCA and improve the diagnostic yield of definitive temporal artery biopsy.