Magnetic Resonance Imaging Abnormalities of the Optic Nerve Sheath and Intracranial Internal Carotid Artery in Giant Cell Arteritis

Background: Giant cell arteritis (GCA) is an important diagnostic consideration in elderly patients with vision changes. Superficial temporal artery biopsy (TAB) has long been considered the gold standard diagnostic approach for GCA, but MRI has gained interest as an alternative diagnostic modality. Although most of the literature has focused on imaging abnormalities of branches of the external carotid artery, there have been a few reports of GCA-related inflammatory involvement of the orbit and internal carotid arteries (ICAs) on MRI.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Magnetic Resonance Imaging Abnormalities of the Optic Nerve Sheath and Intracranial Internal Carotid Artery in Giant Cell Arteritis Sidney M. Gospe III, MD, PhD, Timothy J. Amrhein, MD, Michael D. Malinzak, MD, PhD, M. Tariq Bhatti, MD, Pradeep Mettu, MD, Mays A. El-Dairi, MD Downloaded from http://journals.lww.com/jneuro-ophthalmology by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3i3D0OdRyi7TvSFl4Cf3VC4/OAVpDDa8K2+Ya6H515kE= on 05/04/2022 Background: Giant cell arteritis (GCA) is an important diagnostic consideration in elderly patients with vision changes. Superficial temporal artery biopsy (TAB) has long been considered the gold standard diagnostic approach for GCA, but MRI has gained interest as an alternative diagnostic modality. Although most of the literature has focused on imaging abnormalities of branches of the external carotid artery, there have been a few reports of GCA-related inflammatory involvement of the orbit and internal carotid arteries (ICAs) on MRI. Methods: This was a retrospective cross-sectional study of patients undergoing TAB at a single tertiary referral center over a 5-year period. Patients who had undergone contrast-enhanced MRI of the brain and orbits within 1 month of biopsy were included. Fifty-four TAB-positive and 78 TAB-negative patients were reviewed, with the MRI studies of 7 TAB-positive and 6 TAB-negative patients deemed adequate for interpretation. MRI studies were reviewed by 2 masked neuroradiologists, and the findings were correlated with biopsy results and clinical findings. Results: Intracranial ICA vessel wall enhancement was identified in 6 of 7 TAB-positive patients (sensitivity 86%), compared with 2 of 6 TAB-negative patients (specificity 67%). Optic nerve sheath enhancement was identified in 5 of 7 TAB-positive patients (sensitivity 71%) and in 2 of 6 TAB-negative patients (specificity 67%), bilateral in all such cases. The combination of both abnormal imaging findings was observed in 5 of 7 TAB-positive patients (sensitivity 71%) and in none of the 6 TAB-negative patients (specificity 100%). Conclusions: Intracranial ICA and optic nerve sheath enhancement were observed in a majority of patients with TAB-proven GCA, and the combination of these findings was Departments of Ophthalmology (SMG, MTB, PM, MAE-D), Radiology (TJA, MDM), Neurology (MTB), and Neurosurgery (MTB), Duke University Medical Center, Durham, North Carolina. Dr. Bhatti is now with the Departments of Ophthalmology and Neurology, Mayo Clinic, Rochester, MN; Dr. Mettu is now with the Raleigh Eye and Face Plastic Surgery, Raleigh, NC. The authors report no conflicts of interest. Address correspondence to Mays A. El-Dairi, MD, Duke Eye Center, 2351 Erwin Road, Durham, NC 27710; E-mail: [e-mail] 54 highly specific for GCA. Identification of these abnormalities on MRI should raise concern for GCA and prompt a thorough review of systems, laboratory testing, and consideration of TAB in patients with ocular complaints potentially consistent with ischemia. Journal of Neuro-Ophthalmology 2021;41:54–59 doi: 10.1097/WNO.0000000000000860 © 2019 by North American Neuro-Ophthalmology Society O cular manifestations of giant cell arteritis (GCA) are common (1), with at least 8% of patients suffering permanent vision loss due to infarction of the optic nerve, retina, or both (2). Because profound vision loss may develop in both eyes within days to weeks of one another (3), it is essential that GCA be diagnosed and treated expeditiously. Although the disease may be diagnosed on clinical observation (4), demonstration of granulomatous inflammation on a superficial temporal artery biopsy (TAB) has long been considered the gold standard diagnostic criterion for GCA. However, there is active investigation into the use of vascular imaging modalities such as color duplex sonography and MRI to evaluate for signs of inflammation of the superficial temporal and occipital arteries (5). Some have argued that these techniques may supplant TAB as a less invasive yet reliable means of diagnosing GCA (6). Although existing diagnostic procedures evaluate branches of the external carotid artery for signs of inflammation, most often it is pathology of the vasculature derived from the internal carotid artery (ICA) that leads directly to vision loss. It was recently reported in a small prospective study using high-resolution MRI that approximately 50% of patients with GCA exhibited vessel wall enhancement of one or both intradural ICAs (7), contradicting a previous understanding that vasculitic involvement of the intracranial arteries rarely occurs in GCA (8). In addition, there is a growing body of literature suggesting Gospe et al: J Neuro-Ophthalmol 2021; 41: 54-59 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution that enhancement of the optic nerve sheath may be observed in patients with GCA undergoing fat-suppressed orbital MRI (9–14), possibly reflecting arteritic involvement of the penetrating pial vessels, which supply the nerve sheath and derive from the ophthalmic artery and posterior ciliary arteries (14,15). The purpose of this study was to investigate the frequency of ICA and optic nerve sheath enhancement in patients who underwent TAB and to determine their specificity for GCA. METHODS Patient Cohort This retrospective cross-sectional study was approved by the Duke University Institutional Review Board and conducted in accordance with Health Insurance Portability and Accountability Act and the Declaration of Helsinki. A waiver of informed consent was granted owing to the retrospective nature of the study. Archival medical records and MRI studies were reviewed in consecutive patients undergoing TAB to evaluate for GCA at Duke University Medical Center from January 1, 2009, through October 31, 2014. The Cerner PathNet clinical database containing the results of pathologic examination of specimens evaluated at Duke University Medical Center was searched using the Systematized Nomenclature of Medicine code 309481000 for temporal artery sample. Biopsy reports were reviewed for all identified subjects, who were then divided into those with biopsy specimens positive for arteritis or negative for arteritis. Subjects with biopsy results deemed equivocal were excluded unless they underwent a subsequent TAB with a definitive result. Imaging Review Our institution’s picture archiving and communication system was used to determine which of the subjects with positive and negative temporal artery biopsies had undergone contrast-enhanced cranial MRI within 1 month before or after the initial TAB. Any study without fat-suppressed postcontrast T1 orbital sequences was excluded. All remaining MRI studies were independently reviewed by 2 neuroradiologists (T.J.A. and M.D.M.) who were masked to the biopsy results. The presence and laterality of optic nerve sheath and ICA enhancement was noted, and any studies that were not adequate for interpretation were excluded. equivocal for arteritis and were excluded from further analysis. The charts of the 54 TAB-proven GCA patients were reviewed, and 15 had undergone cranial MRI within 1 month of the TAB, with 8 of these studies including contrast and a fat-suppressed orbital protocol. Among the TAB-negative patients, 21 had undergone MRI and 7 of these included contrast and orbital fat suppression. In each of these groups, one MRI was deemed inadequate for interpretation by the radiologists (one because of the motion artifact and the other because of the failure of the ICAs to be captured on a coronal section), resulting in a final cohort of 7 biopsy-positive and 6 biopsy-negative patients. The demographics and clinical findings of the 13 patients are shown in Table 1. Among the 7 patients with TAB-proven GCA, the indication for biopsy was acute optic neuropathy with optic disc swelling in 3 patients, diplopia secondary to an ocular motor nerve palsy in 2 patients (including one also presenting with transient vision loss), unexplained visual field defect in 1 patient, and headache with subjective vision changes in 1 patient. Imaging Review Upon independent review by the 2 neuroradiologists, there was disagreement regarding ICA mural enhancement in one of the 13 patients (kappa = 0.84), and this discrepancy was resolved by consensus. Interobserver agreement for the presence of optic nerve sheath enhancement was 100% (kappa = 1.0). Among patients with TAB-proven GCA, 86% (6 of 7) demonstrated enhancement of the intracranial ICAs: 4 bilateral and 2 unilateral (Fig. 1A). Conversely, bilateral ICA enhancement was noted in 17% (1 of 6) of TABnegative patients, with the remaining 5 demonstrating no enhancement of either ICA (Fig. 1B). Optic nerve sheath enhancement (Fig. 1C) was noted in 71% (5 of 7) of TABpositive patients (bilateral in all 5). Two of the 6 (33%) TAB-negative patients exhibited bilateral optic nerve sheath enhancement, whereas the remaining 4 had normalappearing optic nerve sheaths bilaterally (Fig. 1D). The combination of ICA and optic nerve sheath enhancement was identified in 5 of the 7 (71%) TAB-positive patients and in none of the TAB-negative patients. Thus, the sensitivity of ICA enhancement, optic nerve sheath enhancement, and the combination of these findings for TABconfirmed GCA was 86%, 71%, and 71%, respectively. The specificity of these findings for GCA was 83%, 67%, and 100%, respectively. RESULTS Correlation of Imaging Findings With Clinical Presentation Patient Cohort Among the 2 TAB-negative individuals with ICA enhancement, 1 patient (#11) had suffered a unilateral sixth nerve palsy with headache. After the diplopia resolved within several months, the etiology was concluded to be microvascular ischemic; the ICA enhancement was not noted at the time, Our search for TAB performed between 2009 and 2014 identified 140 patients. Of these, 54 had a TAB of at least one artery that was positive for arteritis and 78 had negative TAB. The remaining 8 patients had TAB specimens read as Gospe et al: J Neuro-Ophthalmol 2021; 41: 54-59 55 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 1. Patient demographics and clinical and radiographic findings Patient Sex Age TAB Pre-MRI Steroid ICA ONS ESR CRP Duration (mm/hr)(mg/mL) (days) Enhancement Enhancement 1 F 79 Positive 57 5.30 21 Yes-bilateral Yes-bilateral 2 F 83 Positive 77 0.17 9 Yes-left No 3 F 87 Positive 77 ND 0 No No 4 M 75 Positive 21 6.29 0 Yes-bilateral Yes-bilateral 5 F 64 Positive 94 5.57 0 Yes-bilateral Yes-bilateral 6 F 67 Positive 45 1.09 7 Yes-bilateral Yes-bilateral 7 F 76 Positive 16 0.14 1 Yes-right Yes-bilateral 8 F 92 Negative 20 0.64 0 No Yes-bilateral 9 M 67 Negative 15 ND 11 No Yes-bilateral 10 11 F M 66 Negative 68 Negative 91 23 0.77 0.22 0 0 No Yes-bilateral No No 12 F 60 Negative 17 0.09 0 No No 13 M 75 Negative 5 0.12 0 Yes-bilateral No Clinical Presentation Sequential anterior ischemic optic neuropathy with NLP vision OU. The second eye was affected despite ongoing treatment with prednisone 60 mg daily. Eye pain and headaches. Visual field defect OD with normal fundus examination. Headache and subjective vision changes OU. Normal fundus examination. Sequential bilateral cranial nerve VI palsies. Anterior ischemic optic neuropathy OS (NLP). Unstable angina. Right cranial nerve IV palsy and transient vision loss OS. Anterior ischemic optic neuropathy OS. Acute vision loss with optic disc edema OS. Subjective vision changes with normal fundus OD. Vision loss with simultaneous optic disc edema and BRAO OS Cranial nerve VI palsy Cranial nerve VI palsy and headache Jaw pain with progressive bilateral optic neuropathy without disc edema (NLP OU). Presumed paraneoplastic optic neuropathy (history of glioblastoma multiforme with positive antiretinal and antioptic nerve antibodies) Tolosa–Hunt syndrome with cranial nerve III palsy CRP, C-reactive protein; ESE, erythrocyte sedimentation rate; ICA, internal carotid artery; NLP, no light perception; ND, not done; OD, right eye; ONS, optic nerve sheath; OS, left eye; OU both eyes; TAB, temporal artery biopsy. and the reason for this MRI finding is uncertain. The other patient (#13) suffered a left third nerve palsy and was noted to have enhancement of the nerve within the cavernous sinus. After extensive workup, a diagnosis of Tolosa–Hunt syndrome was made, and the ICA enhancement was presumably secondary to inflammation of the adjacent cavernous sinus. GCA-related optic nerve sheath enhancement was not invariably associated with ipsilateral optic neuropathy. In fact, patient #1 was the only representative of the TAB56 positive cohort with bilateral optic nerve sheath enhancement and visual loss in both eyes (the clinical presentation was consistent with anterior ischemic optic neuropathy in both eyes). By contrast, 1 patient (#4) developed sequential sixth nerve palsies but no decrease in visual acuity or visual field defects in either eye, whereas 2 patients (#5 and #7) developed anterior ischemic optic neuropathy in the left eye while the right eyes remained asymptomatic and retained normal visual function despite bilateral optic nerve sheath enhancement. Similarly, 1 patient (#6) exhibited bilateral Gospe et al: J Neuro-Ophthalmol 2021; 41: 54-59 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 1. Representative findings on fat-suppressed postcontrast T1-weighted MRI. Each panel has a representative coronal section (left) and axial section (right). A. Bilateral mural enhancement of the intracranial internal carotid arteries (arrowheads) of patient 5 with positive temporal artery biopsy. Note that optic nerve sheath enhancement is also apparent on the axial section. B. Normal-appearing intracranial internal carotid arteries of patient 10 with a negative temporal artery biopsy. No optic nerve sheath enhancement was identified (not shown). C. Bilateral optic nerve sheath enhancement and thickening (arrowheads) of patient 6 with a positive temporal artery biopsy. D. Normal-appearing optic nerve sheaths of patient 11 with a negative temporal artery biopsy. optic nerve sheath enhancement but experienced episodes of transient monocular vision loss limited to the left eye. Among the 2 TAB-negative patients (#8 and #9) with optic nerve sheath enhancement, both developed unilateral optic disc edema with vision loss despite bilateral optic nerve sheath enhancement. In patient #8, an extensive laboratory workup including lumbar puncture failed to identify an etiology for the bilateral optic nerve sheath enhancement, resulting in the final diagnosis of idiopathic orbital inflammation. Patient #9 presented with simultaneous optic disc edema and branch retinal artery occlusion in the left eye. In addition to bilateral mild optic nerve sheath enhancement, there was equivocal increased enhancement involving the bilateral cavernous sinuses and increased dural enhancement along the medial aspect of the middle cranial fossa on the left. Any further workup was performed outside our institution and is not available for our review, thus leaving the final diagnosis uncertain. CONCLUSIONS Our study is the first to systematically examine the MRI appearance of the intracranial ICAs and optic nerve sheaths of patients with histological confirmation of GCA in all cases. We have observed that the MRI findings of intracranial ICA enhancement and optic nerve sheath enhancement were present in a majority of patients with TAB-positive GCA who underwent contrast-enhanced Gospe et al: J Neuro-Ophthalmol 2021; 41: 54-59 MRI of the brain and orbits with fat suppression within 1 month of biopsy. These findings were observed at a much lower rate in patients whose TABs were negative for arteritis. Notably, the combination of these 2 MRI abnormalities was exclusively observed in patients with TAB-positive GCA. To date, there is scant additional literature available regarding the prevalence of these findings. Consistent with our results, one recent prospective study by Siemonsen et al (7) using high-resolution contrastenhanced MRI found that 10 of 20 patients with GCA demonstrated vessel wall enhancement of at least 1 ICA, whereas none of 8 patients without GCA exhibited this finding. Although optic nerve sheath enhancement in GCA has been described in several case reports (9,13,16– 20) and case series (10–12), the only existing data regarding the frequency of this finding come from a recent prospective study using high-resolution black-blood MRI to evaluate the orbital microvasculature in patients with suspected GCA (14). It identified abnormal enhancement aside the optic nerves in 14 of 18 patients with GCA (13 bilateral and 1 unilateral), whereas none of the 9 patients without GCA demonstrated optic nerve sheath enhancement. Although this is largely consistent with our findings, we should note that our study used a standard orbital MRI protocol; it is possible that overall sensitivity and specificity of these observations for GCA may be improved by using special vessel wall imaging such as the black-blood technique. Also of note, in contrast to our investigation, TABs were performed 57 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution in only a minority of subjects in either of these prospective studies, with most patients being assigned to GCA and nonGCA cohorts based on clinical criteria and, in some cases, temporal artery ultrasound. Although we believe that these MRI observations carry diagnostic utility, their pathophysiological significance is unclear. GCA is a systemic inflammatory condition with the potential to affect medium and large caliber arteries throughout the body, yet ischemia of the central nervous system from intracranial vasculitis is considered to be a rare manifestation of the disease (21,22). Despite 6 of 7 TABpositive GCA patients in our study demonstrating intracranial ICA enhancement, none exhibited clinical or radiographic signs of stroke. The prospective study by Siemonsen and colleagues (7) found evidence of subacute or chronic central nervous system infarcts in 15% of its cohort, higher than the previously reported 3%–4%. However, the ICA mural enhancement rarely corresponded to areas of observed vascular stenosis or occlusion noted in their study. It is uncertain, therefore, whether or not intracranial ICA enhancement truly heralds a higher risk of impending stroke. The nature of the optic nerve sheath enhancement in GCA patients is particularly intriguing. Our findings are similar to those of previous reports in that when present, the enhancement typically affects the optic nerve sheaths bilaterally, yet patients with this finding may not exhibit bilateral optic neuropathies (13,17). In fact, one of our patients with bilateral optic nerve sheath enhancement suffered bilateral sixth nerve palsies but did not develop an optic neuropathy or transient vision loss in either eye. As proposed by Liu and Miller (13), it therefore would seem most likely that optic nerve sheath enhancement in GCA reflects disruption of the blood–tissue barrier because of arteritic involvement of the small vessels intrinsic to the nerve sheaths and is not necessarily causally related to any optic neuropathy that may develop. However, the absence of any potential mechanistic link between optic nerve sheath enhancement and optic neuropathy certainly does not diminish the high risk of profound vision loss that may develop rapidly in unrecognized or untreated GCA. Our study is limited by its small sample size and retrospective nature. Because patients at our institution with typical presentations of ocular microvascular ischemia (e.g., anterior ischemic optic neuropathy, central or branch retinal artery occlusion, and isolated acute ocular motor cranial neuropathy) do not routinely undergo contrastenhanced MRI with fat suppression, only w10% of patients who underwent TAB also had neuroimaging studies appropriate for inclusion in our review. This naturally raises questions about the generalizability of our findings beyond those patients with atypical presentations of GCA who were believed to warrant neuroimaging at the time of presentation. Moreover, as a retrospective analysis, our study lacks standardization regarding which MRI units and specific 58 imaging protocols were used to evaluate the patients, as well as the duration of corticosteroid treatment before imaging. Certainly, a larger prospective study with standardized MRI protocols would be welcomed to confirm that our findings of high rates of intracranial ICA and optic nerve sheath enhancement are seen in a larger cohort of all patients with suspected GCA. In summary, we have observed that ICA vessel wall enhancement and optic nerve sheath enhancement were present in most patients with TAB-proven GCA. Although these MRI findings individually were both reasonably specific for GCA, the combination of ICA and optic nerve sheath enhancement demonstrated a 100% specificity for this disease. The observation of concurrent ICA and optic nerve sheath enhancement in clinical practice should raise suspicion for GCA in patients aged 60 years and older and, at the very least, prompt a thorough review of GCA symptoms to determine the appropriateness of empiric corticosteroid treatment and a TAB. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: S. M. Gospe, T. J. Amrhein, P. Mettu, M. T. Bhatti, and M. A. El-Dairi; b. Acquisition of data: S. M. Gospe and M. A. El-Dairi; c. Analysis and interpretation of data: S. M. Gospe, T. J. Amrhein, M. D. Malinzak, M. T. Bhatti, and M. A. ElDairi. Category 2: a. Drafting the manuscript: S. M. Gospe and M. A. El-Dairi; b. Revising it for intellectual content: S. M. Gospe, T. J. Amrhein, M. D. Malinzak, P. Mettu, M. T. Bhatti, and M. A. El-Dairi; Category 3: a. Final approval of the completed manuscript: S. M. Gospe, T. J. Amrhein, M. D. Malinzak, P. Mettu, M. T. Bhatti, and M. A. El-Dairi. REFERENCES 1. Singh AG, Kermani TA, Crowson CS, Weyand CM, Matteson EL, Warrington KJ. Visual manifestations in giant cell arteritis: trend over 5 decades in a population-based cohort. J Rheumatol. 2015;42:309–315. 2. Chen JJ, Leavitt JA, Fang C, Crowson CS, Matteson EL, Warrington KJ. Evaluating the incidence of arteritic ischemic optic neuropathy and other causes of vision loss from giant cell arteritis. Ophthalmology. 2016;123:1999–2003. 3. 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