Characteristic linear lesions and longitudinally extensive spinal cord lesions in Chinese patients with neuromyelitis optica

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Abstract

Objective

To investigate the characteristics of the linear lesions and longitudinally extensive spinal cord (LESC) lesions in Chinese patients with neuromyelitis optica (NMO).

Methods

The medical records and magnetic resonance imaging (MRI) scans of 29 patients with NMO were reviewed. The frequencies and distributions of linear and LESC lesions were compared against those displayed by 22 multiple sclerosis (MS) patients. Furthermore, the association of lesions with aquaporin-4 IgG (AQP4-IgG) antibody was investigated.

Results

The NMO patients had significantly more linear lesions than MS patients (48.3 vs 0%, p < 0.001). In the NMO group, linear lesions were found in the medulla in 34.5% (10/29) of patients, across the medullospinal region in 10.3% (3/29) and in the spinal cord in 13.8% (4/29). LESC lesions can be seen more frequently in NMO than MS (72.4 vs 22.7%, p < 0.001). In 93.1% (27/29) of the NMO cases, the axial section of the spinal MRI showed lesions on the central gray matter only, whilst the spinal lesions in MS were usually located in the peripheral white matter (72.7%, 16/22). The AQP4-IgG antibody was found to be associated with both linear and LESC lesions in NMO cases.

Conclusions

High frequency of linear lesions and LESC lesions were found in Chinese patients with NMO and linear lesions were correlated with AQP4-IgG antibody.

Introduction

Neuromyelitis optica (NMO) is an idiopathic inflammatory demyelinating disorder preferentially involving the optic nerves and spinal cord in the early stages of the disease process. Despite various similarities, NMO is distinguishable from multiple sclerosis (MS) by both clinical and laboratory features [1], [2]. One recently discovered distinction is the presence of the IgG antibody against the aquaporin-4 channel protein (AQP4-IgG) at the astrocytes on the blood–brain barrier (BBB) [3], [4], [5]. AQP4-IgG has been shown to be highly specific and moderately sensitive to NMO in Caucasian and Asian populations [3], [6], [7], [8].

Previous reports indicate that magnetic resonance imaging (MRI) scans of Caucasian NMO patients will often show distinctive longitudinally extensive spinal cord (LESC) lesions [2]. In Asia however, it remains unclear, as LESC lesions were also frequently encountered in Asian patients with classical MS as well as optic-spinal MS (OSMS) [7]. Linear lesions were initially reported in 2.8% (6/47) of Japanese patients with NMO, and were suggested to be a unique feature distinguishing NMO from MS in Japanese patients [10]. However, this characteristic lesion in NMO was not confirmed by other studies in different populations, and its relationship with the AQP4-IgG antibody is yet to be investigated.

This study aims to investigate the characteristics of linear lesions and LESC lesions in Chinese patients with NMO.

Section snippets

Patients

Clinical data and MRI scans of twenty-nine consecutive Chinese (Han ethnicity) NMO patients from our MS database [11] between 2004 and 2009 were reviewed. All NMO patients fulfilled the 2006 Wingerchuk diagnostic criteria [12]. From the same time period, twenty-two consecutive MS patients, diagnosed based on the 2005 McDonald criteria [13] and showing both brain and spinal lesions on MRI, were enrolled as controls. Four of these controls were diagnosed as OSMS based on the criteria by Kira et

Clinical features

The clinical features of the patients with NMO and MS are summarised in Table 1. NMO patients were on average, older at onset (36.9 ± 14.2 vs 29.6 ± 9.9 yrs, p = 0.044) and displayed a greater EDSS score at their last visit than MS patients (5.3 ± 2.3 vs 3.1 ± 1.8, p = 0.001). There were no statistical differences in any other clinical features between NMO and MS. Brain and spinal MRI scans were taken on 18.4 ± 16.1 days (range 2–63) after the initiation of bouts in NMO and 24.4 ± 17.6 days days (range 4–60) in MS

Discussion

It remains unclear as to whether NMO and MS are distinct diseases or that they exist within a spectrum of the same disease. Typically, studies involving NMO focus on Westerners [2] and Japanese [17], whilst clinical data from Chinese NMO patients is rare [6]. To our knowledge, this is the first report on NMO patients from China mainland.

Our study showed linear lesions occurred in 48.3% of our NMO patients. Traditionally, LESC lesions have been regarded as characteristic of the NMO disease

Conflict of interest

No conflict of interest.

Sources of funding

This study is funded by Sun yat-sen University Clinical Research 5010 program and Science and Technology program of Guangdong (2008B030301047).

Acknowledgments

We acknowledge Dr Liam Johnson from the Centre for Neuromuscular and Neurological Disorders, University of Western Australia, for editing assistance.

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Zhengqi LU, Wei QIU, Yan ZOU and Kefeng LV, contributed equally to this work.

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