Brain MRI abnormalities in neuromyelitis optica

doi:10.1016/j.ejrad.2010.06.024

European Journal of Radiology

Volume 80, Issue 2, November 2011, Pages 445-449

https://doi.org/10.1016/j.ejrad.2010.06.024 Get rights and content

Abstract

Objective

The purpose of this study was to explore brain MRI findings in neuromyelitis optica (NMO) and to investigate specific brain lesions with respect to the localization of aquaporin-4 (AQP-4).

Materials and methods

Forty admitted patients (36 women) who satisfied the 2006 criteria of Wingerchuk et al. for NMO were included in this study. All patients received a neurological examination and MRI scanning including brain and spinal cord. MRIs were classified as normal, nonspecific, multiple sclerosis-like, typical abnormalities. MS-like lesions were too few to satisfy the Barkhof et al. criteria for MS. Confluent lesions involving high AQP-4 regions were considered typical. Non-enhancing deep white matter lesions other than MS-like lesions or typical lesions were classified as nonspecific.

Results

Brain MRI lesions were delineated in 12 patients (25%). Four patients (10%) had hypothalamus, brainstem or periventricle lesions. Six (15%) patients were nonspecific, and 2 (5%) patients had multiple sclerosis-like lesions.

Conclusion

Brain MRIs are negative in most NMO, and brain lesions do not exclude the diagnosis of NMO. Hypothalamus, brainstem or periventricle lesions, corresponding to high sites of AQP-4 in the brain, are indicative of lesions of NMO.

Introduction

Neuromyelitis optica (NMO, also known as Devic's disease) is an inflammatory, demyelinating syndrome of the central nervous system that is characterized by severe attacks of optic neuritis and myelitis [1]. Evidence from several sources (clinical, imaging, immunologic, and immunopathologic) demonstrates that NMO is almost certainly a distinct disease, with a pathogenesis very different than that of MS [2]. The distinction has therapeutic implication [3], [4].

The serum autoantibody NMO-IgG was reported as a biomarker of NMO in 2004, which is 91% specific and 73% sensitive [5]. NMO-IgG has expanded the clinical spectrum of NMO. Based on recent findings [6], [7], [8], [9], Wingerchuk et al. proposed a revised diagnostic criteria for NMO. NMO-IgG was integrated into new NMO diagnostic criteria. The central nervous system (CNS) involvement beyond the optic nerves and spinal cord was relaxed [10].

It is widely held that brain involvement does not occur in NMO, and neurologists are reluctant to diagnose NMO and treat accordingly when brain MRI abnormalities are revealed. The target antigen of NMO-IgG is aquaporin-4 (AQP-4). The hypothalamus and regions adjacent to the third and fourth ventricles are enriched in AQP-4 [11], [12]. In this study, we describe the brain abnormalities in patients with NMO and investigate specific brain lesions with respect to the localization of AQP-4.

Section snippets

Subjects

The institutional review board in Xuanwu Hospital approved the study, and written informed consent was obtained from each participant. Forty patients with NMO (4 men, 36 women; mean age, 41.6 years; age range, 16–69 years) were included. The diagnosis of NMO was based on the criteria proposed by Wingerchuk et al. [10]. MRIs were classified as normal, nonspecific, multiple sclerosis-like, typical abnormalities. MS-like lesions were too few to satisfy the Barkhof et al. criteria for MS. Barkhof

Results

The main clinical, typical brain MRI and laboratory results of 4 patients are summarized in Table 1, Table 2.

Discussion

We describe brain lesions of NMO in 10 patients of 40 cases, typical brain lesions in 4 patients corresponding to the localization of AQP-4. We firstly describe brain abnormality in temporal lobe medially and in regions adjacent to right occipital horn. We detected NMO-IgG in almost 50% (2/4) patients with typical abnormality in NMO, however, our sample was small.

Devic and Gault first described the clinical and pathological characteristics of NMO [14]. The pathogenesis remains confusing.

AQP-4 and brain involvement

In the CNS, NMO-IgG binds selectively to the abluminal face of microvessels, pia, subpia, and Virchow-Robin sheaths [5], paralleling the sites of immune complex deposition in the spinal cord lesions of NMO [27]. AQP-4, the target antigen of NMO-IgG, is the most abundant CNS water channel that maintains water homoeostasis. Although it is in the dark how the NMO-IgG immune response leads to demyelination, it allowed confirmation that brain lesions may occur in NMO, occasionally in a rather

Conclusions

Brain MRI is negative in most patients with NMO, however, brain lesions do not exclude the diagnosis of NMO. MRI brain lesions, hypothalamus, brainstem or per-ventricle lesions localize at sites of high AQP-4 concentration. Advanced MRI techniques, such as MRS, MT and fMRI have a great potential to promote understanding brain lesion and brain plasticity.

A longitudinally extensive lesion may “break up” into noncontiguous segments over months or years. If cord lesions fail to meet the 3-segment

Acknowledgment

The authors thank PhD Stalder for his helpful manuscript revision and Prof. Ye as well as her group for their assistance in performing NMO-IgG tests. This work was supported by the State Key Program of National Nature Science of China (No. 30930029).

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