Magnetic Resonance Imaging of Neuromyelitis Optica (Devic s Syndrome)

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1 J Radiol Sci 2012; 37: Magnetic Resonance Imaging of Neuromyelitis Optica (Devic s Syndrome) Chien-Chuan Huang Tai-Yuan Chen Tai-Ching Wu Yu-Kun Tsui Te-Chang Wu Wen-Sheng Tzeng Chien-Jen Lin Department of Medical Imaging, Chi-Mei Medical Center, Tainan, Taiwan Abstract Neuromyelitis optica (NMO, also known as Devic s syndrome) is a demyelinating disease of the central nervous system characterized by recurrent optic neuritis and acute transverse myelitis. The disease was initially considered a variant of multiple sclerosis (MS). However, recent literature had suggested that NMO is a distinct disease from MS, with poorer prognosis and different therapy. Therefore, it is important to distinguish NMO from MS as soon as possible. The presentations of optic neuritis and acute transverse myelitis in patients with NMO can be separate or simultaneous in clinical course, and the variations in clinical symptoms make early recognition and diagnosis of NMO difficult. We report two cases of NMO with their manifestations on magnetic resonance imaging (MRI) in our hospital. With the use of MRI and the specific autoantibody NMO-IgG, NMO can be diagnosed earlier and more accurately. Neuromyelitis optica (NMO, Devic s syndrome) is a demyelinating disease of the central nervous system (CNS) characterized by recurrent optic neuritis and myelitis [1]. The disease was initially considered a variant of multiple sclerosis (MS). However, recent literature had suggested that NMO is a distinct disease from MS with poorer prognosis and different therapeutic strategy (Table 1). The autoantibody NMO-IgG was reported in 2004 with 91% specificity and 73% sensitivity for NMO [2]. Revised diagnostic criteria were proposed in 2006 based on NMO-IgG (Table 2). The absolute restriction on CNS involvement beyond the optic nerve and spinal cord was removed [3]. We report two cases of NMO in our hospital with initial and follow-up MRI manifestations. Case 1 A 13-year-old girl had a history of idiopathic optic neuritis which resulted in bilateral blindness many years ago. Initially, the patient presented with unspecific back pain and constipation. One day, she was brought to the emergency department because of abdominal pain. Laboratory data including complete blood count (CBC) and biochemistry studies were within normal limit. She was admitted to the pediatric ward with an initial clinical impression of abdominal ileus. Progressive weakness of both lower extremities with acute urine retention was noted during her admission. Physical examination showed a significant decrease in muscle power of both lower extremities. Follow-up CBC revealed mild leukocytosis (white blood Correspondence Author to: Tai-Yuan Chen Department of Medical Imaging, Chi-Mei Medical Center No. 901, Zhong-Hua Road, Yongkang, Tainan 710, Taiwan J Radiol Sci March 2012 Vol.37 No.1 45

2 Table 1. The comparison between MS and NMO [2, 3, 8-12] MS NMO Demographic Median age of onset (years) Population All group, most common in Caucasian African, Asian, and Indian Pathogenesis Unclear, virus or autoimmune-mediated attack of myelinated axon by T-cell proposed Unclear, IgG and complement deposition with loss of AQP4 from spinal cord lesion observed Clinical Bilateral optic neuritis (% of patients) 41% absolute required criteria Transverse myelitis (% of patients) Less than 10% absolute required criteria MRI features Initial normal brain MRI (% of patients) 47% 77% Intracranial lesions Multiple perpendicular callososeptal lesions Hypothalamus, brainstem or periventricle lesion Longitudinally extensive spinal cord lesion (% of patients) 15% 98% Laboratory features NMO-IgG (% of patients) 9% 73%, with specificity 91% CSF analysis Oligoclonal band (% of patients) 85-90% 20-30% Therapeutic option Corticosteroid therapy for acute demyelination Immunomodulatory therapies Plasmapheresis and immunosuppressant Abbreviations: MS, multiple sclerosis; NMO, neuromyelitis optica; AQP4, aquaporin 4; MRI, magnetic resonance imaging; CSF, cerebrospinal fluid. Table 2. Revised criteria for neuromyelitis optica [3] Definite NMO Optic neuritis Acute myelitis At least two of three supportive criteria Contiguous spinal cord MRI lesion extending over 3 vertebral segments Brain MRI not meeting diagnostic criteria for multiple sclerosis NMO-IgG-seropositive status Abbreviations: MRI, magnetic resonance imaging; NMO, neuromyelitis optica. cell (WBC) count = 13600/uL), and anti-dsdna was within normal limit (anti-dsdna=1.8iu/ml). A nerve conduction velocity study revealed bilateral lumbosacral plexopathy. With a clinical suspicion of acute transverse myelitis, contrast-enhanced MRI of the whole spine was performed. Swelling of the spinal cord with contiguous high signal intensity on T2-weighted images was identified from level C6 to T6 (Fig. 1a, 1b). Entire cross section of the spinal cord was involved, and no obvious enhancement after intravenous gadolinium administration was observed (Fig. 1c). The findings were consistent with acute transverse myelitis, and no other intracranial abnormality was identified on the serial brain MR images. Cerebrospinal fluid (CSF) analysis showed negative oligoclonal band and no pleocytosis (WBC count = 0/mm3). Considering the patient s history of optic neuritis, NMO was strongly suspected. Therefore, we checked serum NMO-IgG and the result was positive. 46 J Radiol Sci March 2012 Vol.37 No.1

contiguous lesion from level C6 to T6 with high signal intensity. b.

3 Figure 1 1a 1c 1b Figure 1. a. Sagittal T2-weighted image (2750/103, repetition time/echo time [TR/TE]) shows contiguous lesion from level C6 to T6 with high signal intensity. b. Axial T2-weighted image (2550/88, TR/TE) demonstrates high signal lesion involving entire cross section of the spinal cord, suggesting acute transverse myelitis. c. Contrast-enhanced T1-weighted image with fat suppression (1977/12, TR/TE) shows no obvious enhancement after intravenous gadolinium administration. J Radiol Sci March 2012 Vol.37 No.1 47

2a 2b The patient received several cycles of immunosuppressive therapy (cyclophosphamide) in the past 4 years owing to relapsing NMO episodes.

4 Figure 2 Figure 2. a. Coronal T2-weighted image (2560/106, TR/TE) shows swelling of right optic nerve (white arrow). b. Coronal T1-weighted image with fat suppression (2000/7, TR/TE) shows strong enhancement of right optic nerve after intravenous gadolinium administration (white arrow). 2a 2b The patient received several cycles of immunosuppressive therapy (cyclophosphamide) in the past 4 years owing to relapsing NMO episodes. Follow-up MRI of cervical spine revealed myelomalacia with progressive spinal cord atrophy, which is consistent with the consequences of NMO. Case 2 A 36-year-old female had a history of recurrent vision loss in the past 2 years, and optic neuritis was diagnosed by visual evoked potential (VEP) study. In the preceding few days, the patient complained of progressive numbness of both extremities and blurred vision on the right side. Contrast-enhanced MRI of the orbit showed swelling of the right optic nerve with strong enhancement following intravenous gadolinium administration (Fig. 2a, 2b). No other intracranial abnormality or space-occupying lesion was identified. Furthermore, MRI of the cervical spine revealed high signal intensity from level C2 to C6 on T2-weighted image with patchy enhancement after intravenous gadolinium administration (Fig. 3). Although serum NMO-IgG was not checked for this patient, the clinical course and imaging findings were consistent with NMO diagnostic criteria. The patient received anti-inflammatory agent (methylprednisolone) to prevent acute demyelination and further immunomodulation therapy (interferon beta-1a) was arranged. As the patient s symptoms got improved gradually, she received regular follow-up in our hospital. MRI of cervical spine was performed one month later, the results demonstrated slight regression of the aforementioned lesions. 48 J Radiol Sci March 2012 Vol.37 No.1

5 Figure 3 Figure 3. Sagittal T2-weighted image (2583/114, TR/TE) reveals contiguous lesion with high signal intensity at level C2 to C6. Discussion The first diagnostic criteria for NMO were proposed in 1999 [3]. There were three absolute requirements in the criteria: optic neuritis, acute myelitis, and no symptoms implicating other CNS regions. In order to increase specificity, three supportive criteria were stated: 1) brain MRI at disease onset is normal or does not fulfill imaging criteria for MS; 2) spinal cord MRI shows a lesion extending over three vertebral segments; and 3) CSF reveals a WBC count of 50/mm3 or a neutrophil count of 5/mm 3. The aquaporin 4 (AQP4) is the most abundant water channel localized to the blood-brain barrier and is found in CNS microvessles, pia, subpia and Virchow-Robin space [2]. The serum autoantibody NMO-IgG selectively binds to AQP4 and has been reported to have sensitivity at 73% and specificity at 91% for NMO [2]. Wingerchuk et al. proposed the revised criteria for NMO in 2006 (Table 2). The revised diagnostic criteria emphasized the specificity of longitudinally extensive spinal cord lesions and NMO-IgG seropositivity. The absolute restriction on CNS involvement beyond the optic nerve and spinal cord was removed. The MRI features of NMO consist of the optic neuritis and myelitis. The optic neuritis manifested as swelling of optic nerve with high-signal intensity foci on T2-weighted images. Enhancement is also demonstrated following intravenous administration of gadolinium. Image patterns of acute transverse myelitis in patients with NMO usually appear as a longitudinally extensive cord lesion. The enhancement pattern can be variable but may also extend uninterrupted over a long segment of the cord. The longitudinally extensive lesion has been suggested to be the most reliable difference of NMO from MS on MRI [4], although longitudinally extensive lesion may break up and become noncontiguous lesion after many months or years [5]. Spinal cord lesions longer than two segments in patient with MS were also reported in Asians and Africans [6]. The typical intracranial MRI findings in patient with MS are characterized by multiple perpendicular callososeptal lesions with high T2 signal intensity, radiating from ventricles. Initially, it was thought that patients of NMO should have normal brain MRI. Further study indicated that some intracranial abnormalities can be observed on brain MRI, including hypothalamus, brainstem, or periventricle lesions localized at sites with high AQP4 concentration [5]. Although brain MRI is negative in most cases of J Radiol Sci March 2012 Vol.37 No.1 49

6 NMO, brain lesions do not exclude the diagnosis of NMO. In our first case, the lesion extended from level C6 to T6, and contrast-enhanced brain MRI showed no abnormal intracranial signal intensity or space-occupying lesions. Thus, MS was less likely. Based on the patient s past history of optic neuritis, NMO was initially considered, and the diagnosis was then confirmed by NMO-IgG seropositivity. In the second case, MRI revealed simultaneous findings of optic neuritis and acute myelitis. No other intracranial abnormal signal intensity or space-occupying lesion was identified. Both of our cases were consistent with the revised criteria of NMO. In contrast to conventional MS, clinical experience and case series suggest that NMO requires long-term immunosuppressive therapy [4]. Corticosteroid therapy may have little or no immediate effect on severe NMO exacerbations, so rescue therapy with plasmapheresis is indicated in these cases [7]. As attacks of optic neuritis and acute myelitis in NMO can result in permanent neurologic disability, immunosuppressive therapy for prevention of disease recurrence should be initiated as soon as possible [1]. Conclusion The presentations of optic neuritis and acute transverse myelitis in patient with NMO can be separate or simultaneous in clinical course. Distinguishing NMO from MS is important because NMO has a poorer prognosis and requires different therapy. However, the variations in clinical symptoms make the diagnosis of NMO difficult. It should be considered when recurrent optic neuritis, transverse myelitis, or both are present and brain MRI findings are normal or lesions fail to meet the criteria for MS. With MRI and the serum autoantibody NMO-IgG, NMO can be diagnosed earlier and more accurately. References 1. Wingerchuk DM, Hogancamp WF, O'Brien PC, Weinshenker BG. The clinical course of neuromyelitis optica (Devic's syndrome). Neurology 1999; 53: Lennon VA, Wingerchuk DM, Kryzer TJ, et al. A serum autoantibody marker of neuromyelitis optica: distinction from multiple sclerosis. Lancet 2004; 364: Wingerchuk DM, Lennon VA, Pittock SJ, et al. Revised diagnostic criteria for neuromyelitis optica. Neurology 2006; 66: Wingerchuk DM. Diagnosis and treatment of neuromyelitis optica. Neurologist 2007; 13: Wang F, Liu Y, Duan Y, Li K. Brain MRI abnormalities in neuromyelitis optica. Eur J Radiol 2011; 80: Chen SY, Lo CP, Hsu WL, et al. Modifications to the McDonald MRI dissemination in space criteria for use in Asians with classic multiple sclerosis: the Taiwanese experience. Mult Scler 2010; 16: Watanabe S, Nakashima I, Misu T, et al. Therapeutic efficacy of plasma exchange in NMO-IgG-positive patients with neuromyelitis optica. Mult Scler 2007; 13: Nakashima I, Fujihara K, Miyazawa I, et al. Clinical and MRI features of Japanese patients with multiple sclerosis positive for NMO-IgG. J Neurol Neurosurg Psychiatry 2006; 77: Jarius S, Paul F, Franciotta D, et al. Mechanisms of disease: aquaporin-4 antibodies in neuromyelitis optica. Nat Clin Pract Neurol 2008; 4: Ghezzi A, Bergamaschi R, Martinelli V, et al. Clinical characteristics, course and prognosis of relapsing Devic's Neuromyelitis Optica. J Neurol 2004; 251: Kira J. Multiple sclerosis in the Japanese population. Lancet Neurol 2003; 2: Banwell B, Ghezzi A, Bar-Or A, et al. Multiple sclerosis in children: clinical diagnosis, therapeutic strategies, and future directions. Lancet Neurol 2007; 6: J Radiol Sci March 2012 Vol.37 No.1

Neuromyelitis Optica: A Case Report

Pediatr Neonatol 2010;51(6):347 352 CASE REPORT Neuromyelitis Optica: A Case Report Wei-Chia Chia 1, Jian-Nan Wang 1, Ming-Chi Lai 2 * 1 Department of Family Medicine, Chi-Mei Medical Center, Yong Kang