Multiple Sclerosis and Related Disorders (2014) 3, 284–293

Available online at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/msard

REVIEW

The role of imaging in diagnosing neuromyelitis optica spectrum disorder Lucy A. Matthewsa,b,n, Jacqueline A. Palacea,b a

Oxford University Hospitals NHS Trust, United Kingdom Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom

b

Received 13 May 2013; received in revised form 31 October 2013; accepted 14 November 2013

KEYWORDS

Abstract

Neuromyelitis optica; Multiple sclerosis; MRI; Imaging

Early identification of neuromyelitis optica allows aggressive acute and prophylactic relapse management aimed at preventing disability. Since the discovery of pathogenic aquaporin-4 antibodies the neuromyelitis optica spectrum has widened significantly: brain lesions no longer preclude the diagnosis and there are reports of symptoms of cerebral origin presenting as the first manifestation of the condition, prior to optic nerve or spinal cord disease. Defining antibody negative neuromyelitis optica, and distinguishing it from other inflammatory disorders such as multiple sclerosis can therefore be a challenge. In this review we discuss the role of conventional imaging in the diagnosis of neuromyelitis optica, and the scope of quantitative MRI modalities to identify more specific pathophysiological features to aid in the differentiation from other conditions and assess treatment response. & 2013 Elsevier B.V. All rights reserved.

Contents 1. 2.

3.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 Conventional MRI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 2.1. Spinal cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 2.2. Optic nerves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 2.3. Brain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 Non-conventional MRI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 3.1. Diffusion tensor and Magnetisation Transfer Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 3.1.1. Spinal cord DTI and MTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 3.2. Magnetic resonance spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 3.3. Volumetric imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 3.4. Functional MRI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

n

Correspondence to: Department of Neurology, Level 3 West Wing, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom. Tel.: +44 1865 222799. E-mail address: [email protected] (L.A. Matthews). 2211-0348/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msard.2013.11.003

Role of imaging in diagnosis of neuromyelitis optica 4. Future challenges . . . . . . . . . . . . . . . . . . . . . . . . . 5. Summary: useful imaging discriminators that favour NMO Conflicts of interest and funding statements. . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.

Introduction

Neuromyelitis optica (NMO) is an autoimmune demyelinating condition with a specific biomarker—serum antibodies against the aquaporin-4 water channel, which are present in up to 77% with the diagnosis (Lennon et al., 2004, 2005; Waters et al., 2012). There is an overlap in the early clinical features of NMO and MS (optic neuritis, myelitis, cerebral symptoms) but follow-up of patients with NMO has revealed a high morbidity and mortality linked to its relapse related disability and progressive deterioration between relapses is exceedingly rare (Wingerchuk et al., 2007, 2006; Merle et al., 2007). Therefore unlike MS rapid treatment of relapses is vital (Sellner et al., 2010), and aggressive immunosuppression to prevent relapses should be initiated at the time of diagnosis (Wingerchuk, 2007). Additionally β-interferon, a disease modifying therapy commonly used in MS, can worsen NMO (Palace et al., 2010). Early and accurate diagnosis is therefore very important. There are recent reports of patients with AQP4 antibodies who present atypically with brain symptoms prior to any optic nerve or spinal cord involvement (Kim et al., 2011; Apiwattanakul et al., 2010; McKeon et al., 2008), and limited forms of the disease such as recurrent severe optic neuritis and transverse myelitis (Matthews et al., 2009; Waters et al., 2008). We therefore commonly use the term NMO spectrum disorder (NMOSD) to encompass all of these phenotypes. Clearly it can be difficult to define the boundaries of antibody negative NMOSD and in particular to differentiate it from MS. There is clinical need for other differentiating biomarkers, not only to identify seronegative NMOSD but also to assess the sensitivity of aquaporin-4 antibody assays and to enable us to monitor the effectiveness of treatments in clinical practice and trials. The following review discusses the role of conventional MRI and the potential of quantitative measures in the diagnosis of NMOSD.

2.

Conventional MRI

The conventional imaging features of NMOSD are summarised in Table 1, and Figs. 1 and 2.

2.1.

Spinal cord

The conventional MRI appearances for a patient presenting with an MS-like illness provide a strong clue that they may have NMOSD. Longitudinally extensive (i.e., greater than three vertebral segments in length) spinal cord lesions, which can be visualised as high signal on T2 weighted spinecho MRI, form part of the 2006 revised diagnostic criteria for NMO (Fig. 1a) (Wingerchuk et al., 2006). They have high sensitivity and specificity, and are currently the most important MRI marker of NMOSD and should prompt testing for aquaporin-4 antibodies. In the acute stage these lesions

285 ...... over MS. ...... ......

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

. . . .

290 290 290 291

may be associated with gadolinium contrast enhancement and probable cord swelling (Wingerchuk et al., 1999; de Seze et al., 2002). Shorter lesions can be seen either early in a relapse (in the first days) or in patients who have had other attacks with longitudinally extensive lesions (Krampla et al., 2009). Consequently imaging during the established relapse phase is important. MS is characterised by short and often multiple spinal cord lesions or diffuse changes particularly in the later stages (Bot et al., 2004). In large cross-sectional Dutch and Australian studies of multiple sclerosis spinal cord imaging the prevalence of longitudinally extensive T2 signal change is estimated at 2.9% and 2.3% respectively (Bot et al., 2004; Qiu et al., 2010), and is very exceptionally a presenting feature (4/574 patients in the Qiu et al., 2010 study). T1 hypointensity has been reported during the acute phase of NMO transverse myelitis but is not usually seen in MS (Miller et al., 2008; Downer et al., 2012). Asymptomatic spinal lesions are a feature of MS but not recognised in NMO (O'Riordan et al., 1998). NMOSD spinal lesions, like those found in MS, are most often located in the cervical cord (Wingerchuk et al., 2006, 1999; de Seze et al., 2002). Extension of these lesions superiorly into the medulla is a feature of NMOSD (Wingerchuk et al., 2006; de Seze et al., 2002), and has been found to be highly predictive (Lu et al., 2010). Axial T2 weighted MRI commonly, but not invariably, reveals NMOSD lesions to be centrally located (Fig. 1b) (Krampla et al., 2009; Nakamura et al., 2008). This is in contrast to MS where lesions are more often found in the lateral white matter (Nakamura et al., 2008). The central location of NMOSD lesions corresponds to sites of high aquaporin-4 water channel concentration i.e., in the spinal grey matter (as shown in immunopathological studies) (Roemer et al., 2007). Nakamura et al. (2008) demonstrated that over 60% of NMO spinal lesions occupied the central grey matter in the acute stage, compared to less than 20% of MS lesions on conventional cervical and thoracic spinal imaging. The important message is that the length of the spinal cord lesion on clinical MRI can be a very useful diagnostic aid. It helps distinguish between MS and NMOSD but it is not absolute, because in addition to the rare appearance of long lesions in MS, short lesions have been described in seropositive NMO (Krampla et al., 2009). LETM has also been reported in systemic lupus erythematous (SLE), Sjogren's syndrome and related to infectious myelitis and parainfectious idiopathic transverse myelitis (Kitley et al., 2012) However the observed coexistence of other autoantibodies and antibody mediated conditions in patients with NMO may explain LETM in Sjogrens syndrome and SLE (Pittock et al., 2008)) Hence all patients with LETM should be tested for serum AQP-4 antibodies; where negative the differential becomes wider, and without biopsy and pathological examination differentiating an MS phenotype with LETM from AQP4ab negative NMOSD presents a dilemma because there are no other specific diagnostic tools.

286

Table 1

L.A. Matthews, J.A. Palace

Conventional MRI Findings in NMO. Imaging sequence

Spinal Sagittal T2 spin echo cord

Common features

 Longitudinally extensive (greater than three

  Sagittal T1 spin echo

  

Axial T2

 

Post gadolinium T1

Orbits Fat suppressed T2 spin echo

Post gadolinium T1

Brain

T2 weighted spin echo/proton density/fluid attenuated T2



vertebral segments) increased signal indicative of lesion (majority located in cervical or thoracic cord; Fig. 1a) (Wingerchuk et al., 2006, 1999) Cervical spinal lesions extending into medulla (Wingerchuk et al., 1999; Lu et al., 2010) Cord swelling ( 50%; Fig. 1a) (Wingerchuk  Lesions that extend over less than et al., 1999; de Seze et al., 2002) 3 vertebral segments (Krampla et al., Spinal lesions are symptomatic 2009) T1 hypointensity within acute lesions (Miller et al., 2008) T1 hypointensity and atrophy at site of chronic lesions (Fig. 1c) (Wingerchuk et al., 1999; de Seze et al., 2002; Krampla et al., 2009) Lesions centred on grey matter ( 60%, Fig. 1b) (Krampla et al., 2009; Nakamura et al., 2008) White matter lesions (Nakamura et al., 2008) Contrast enhancing lesions during/shortly after relapse (up to 64%) (Wingerchuk et al., 1999; de Seze et al., 2002)

 Hyperintensity within optic nerve, which can extend to chiasm, during optic neuritis (Wingerchuk et al., 1999; Li et al., 2008)  Chronic optic nerve atrophy  Chronic optic nerve sheath thickening (Li et al., 2008)  Gadolinium enhancement of optic nerves and chiasm during and shortly following optic neuritis ( 83%) (Wingerchuk et al., 1999; Li et al., 2008)

 Non-specific deep white matter/subcortical



   

T1 weighted

Uncommon features

hyperintensities (prevalence  55–82%; Fig. 2d) (Pittock et al., 2006a; CabreraGomez et al., 2008; Matthews et al., 2013) Typical for NMO i.e., distributed in areas of high AQP4 expression e.g., periventricular grey matter ( 7%; Fig. 2a–c) (Pittock et al., 2006a, 2006b; Kim et al., 2011) Medullary lesions contiguous with spinal cord lesions (Wingerchuk et al., 1999; de Seze et al., 2002) Confluent/hemispheric (Pittock et al., 2006a; Kim et al., 2011) Odematous/tumefactive (particularly in children) (McKeon et al., 2008; Ikeda et al., 2011)  Lesions which satisfy MS diagnostic criteria Linear or round periventricular/corpus callosum signal abnormality, but not ovoid, at onset ( 5%) (Pittock et al., 2006a)  Cortical lesions (Pittock et al., 2006a; and not in Dawson finger configuration Isose et al., 2011) (Miller et al., 2008; Matthews et al., 2013)

Role of imaging in diagnosis of neuromyelitis optica

287

Table 1 (continued ) Imaging sequence

Post gadolinium T1

Common features

Uncommon features

T1 hypointensity and atrophy in chronic lesions (Kim et al., 2011) Symptomatic contrast enhancing lesions (Pittock et al., 2006a) Contrast enhancement can be “cloud like” in appearance (Ito et al., 2009)

Case reports of asymptomatic contrast enhancing lesions at the time of an optic nerve/spinal cord relapse (Kim et al., 2011; Cabrera-Gomez et al., 2008)

Fig. 1 (a) Acute longitudinally extensive transverse myelitis in an AQP-4 antibody positive patient visualised on a sagittal T2 MRI. Note the cord swelling. (b) Axial gradient echo showing a centrally located NMO lesion at C3 vertebral level involving both grey and white matter. MS lesions can also be found to involve the grey matter, an example is shown (C5 vertebral level). (c) T1 hypointensities (black holes) in a seropositive NMO patient, at the site of a residual myelitic lesion seen on T2.

2.2.

Optic nerves

Optic neuritis is a common feature of NMO and compared to that seen in MS has a poorer prognosis in terms of functional recovery (Merle et al., 2007; Wingerchuk et al., 1999; Pirko et al., 2004). It is also more commonly bilateral (Wingerchuk et al., 1999). The literature on optic nerve MRI features specific to NMOSD is lacking: during an inflammatory optic neuritis of any cause there can be high signal within the optic nerve on a fat-suppressed T2 weighted scan, gadolinium contrast enhancement and in the longterm atrophy of the affected optic nerve occurs (Kidd et al., 2003; Rizzo III et al., 2002; Wang et al., 2011). Contrast enhancement post optic neuritis can last for at least 30 days (Hickman et al., 2004)). Bilateral optic nerve enhancement with extension to the optic chiasm should alert the clinician to the possibility of NMOSD (Li et al., 2008). Li et al. (2008) reported optic nerve sheath thickening in NMOSD patients with previous recurrent optic neuritis. There is a growing body of evidence that NMOSD is restricted to lesions and does not feature the widespread neurodegeneration associated with MS. Interestingly MR signal abnormalities have been found in the optic nerve of patients with MS who have not been affected by optic neuritis (Miller et al., 1988); this has not been reported in NMOSD.

2.3.

Brain

NMOSD is defined by the presence of serum AQP4 antibodies, and the discovery of this biomarker has revealed the true frequency and nature of brain lesions associated with the condition. It has now been widely published that over time the prevalence of NMO patients (who fulfil the Mayo clinic 2006 criteria) with lesions on brain MRI is greater than 50% (McKeon et al., 2008; Downer et al., 2012; Li et al., 2008; Pittock et al., 2006a; Kim et al., 2011). A normal brain MRI at onset is unusual for MS (Miller et al., 2008; Polman et al., 2011). In NMO, brain MRI is more likely to be normal the closer it is performed to the initial symptoms (Wingerchuk et al., 1999; Pittock et al., 2006a). Pittock et al. (2006a) documented that 52% of 27 patients with NMO who were imaged within 6 months of their first symptoms had an abnormal brain MRI. NMO typical lesions have been described in approximately 7% of patients (Pittock et al., 2006b). These include signal change in areas of high aquaporin-4 expression, namely the brainstem, hypothalamus and in the periependymal tissue bordering the lateral, third and fourth ventricles, and the Sylvian aqueduct (Fig. 2a–c) (Downer et al., 2012; Pittock et al., 2006a, 2006b; O’Riordan et al., 1996; Poppe et al., 2005). Lesions in the area postrema are indicative of NMO (Downer et al., 2012; Popescu et al., 2011). T2 hyperintensities within the corpus callosum are also frequent (Pittock et al.,

288

L.A. Matthews, J.A. Palace

Fig. 2 (a) “Typical” NMO brain lesions, shown as hyperintensities on T2 FLAIR, bordering the Sylvian aqueduct, 4th ventricle and lateral ventricles. There are also lesions within the medulla oblongata and corpus callosum, and a large hemispheric white matter lesion that has been biopsied. The patient is AQP-4 antibody positive. (b) Lesion adjacent to the 4th ventricle visualised on axial FLAIR in an AQP4-ab positive patient. (c) Large periventricular lesion extending into the white matter in a seropositive NMO patient. There is a corresponding area of T1 hypointensity. Note also the non-specific deep white matter lesions. (d) Atypical deep white matter/subcortical brain lesions in two seropositive NMO patients. (e) MS-like brain lesions in a seropositive NMO patient who fulfils Barkhof's MRI criteria for MS.

2006a; Nakamura et al., 2009). The commonest brain abnormality however is non-specific deep or subcortical white matter lesions, which are found in approximately 55–82% of patients on long-term follow-up (Fig. 2d) (Pittock et al., 2006a; CabreraGomez et al., 2008; Matthews et al., 2013). MS-like lesions have been reported in 5–6% on initial imaging (Downer et al., 2012; Pittock et al., 2006a), and 10–16% on the last available scan (Pittock et al., 2006a; Matthews et al., 2013). Several studies have investigated whether brain lesion distribution can distinguish NMO from MS (Downer et al., 2012; Li et al., 2008; Pittock et al., 2006a; Matthews et al., 2013; Matsushita et al., 2010). Pittock found that 66% of NMO patients (4 of 6 patients) with MS-like brain lesions fulfilled Barkhof's MRI criteria for MS (an example is shown in Fig. 2e) (Pittock et al., 2006a; Barkhof et al., 1997).

However Dawson's fingers (ovoid lesions perpendicular to the lateral ventricles) and s-shaped U-fibre lesions have been found to be very unusual in seropositive NMO (Downer et al., 2012; Matthews et al., 2013). Particular caution should be observed with antibody negative patients, as the current NMO diagnostic criteria would favour against the diagnosis if they fulfil MS MRI criteria at onset (Downer et al., 2012). As in MS, NMO lesions can show gadolinium contrast enhancement especially during relapse (Kim et al., 2011; Cabrera-Gomez et al., 2008; Ito et al., 2009). A particular “cloud-like” pattern of enhancement has been described as well as accompanying oedema (Ito et al., 2009). Tumefactive, enhancing and symptomatic brain lesions are particularly prevalent in the paediatric population (McKeon et al., 2008).

Role of imaging in diagnosis of neuromyelitis optica

3.

Non-conventional MRI

Clinical or conventional MRI sequences (i.e., T1 weighted imaging, spin echo T2 and gadolinium enhanced T1) are sensitive means of screening for inflammatory demyelinating central nervous system disease. However signal change abnormalities on T2 imaging are non-specific and give little information about the underlying pathophysiology. For example T2 signal reflects water content, which may be altered with oedema, demyelination or axonal damage. In the challenge of finding a consistent diagnostic imaging marker for NMOSD and a method of measuring disease activity to monitor therapies, conventional MRI falls short. Non-conventional approaches to MRI, where the signal is harnessed quantitatively, are able to give information more specific to pathological processes and to assess change over time. Such techniques have been extensively applied to MS and have demonstrated that even in areas of the MS brain that appear normal on conventional imaging there are diffuse abnormalities (Tortorella et al., 2006; Larsson et al., 1992; Griffin et al., 2001). In contrast to MS, NMO tends to cause severe symptomatic inflammatory damage (usually of the optic nerve or spinal cord) and is not associated clinically with a progressive phase Wingerchuk et al., 2007. It is hence anticipated that NMO should not be associated with either diffuse normal appearing white matter damage (away from tracts affected by lesions) or progressive changes outside of relapses. Therefore characterising the normal appearing brain tissue and assessing change over time could provide a useful method of diagnostic distinction. The next section of this review discusses a selection of studies that have applied these techniques to NMO.

3.1. Diffusion tensor and Magnetisation Transfer Imaging Diffusion MRI and Magnetisation Transfer Imaging (MTI) provide in-vivo quantitative measurements of tissue structure not detected on standard imaging. The underlying principles of DTI and MTI are discussed elsewhere. Two indices used to describe the diffusion properties of tissue are fractional anisotropy (FA), where a reduction in FA represents a reduction in the directionality of white matter tracts often interpreted as a reduction in tissue integrity, and mean diffusivity (MD), where an increase in MD represents less restriction to the diffusion of water molecules and therefore is also interpreted as a reduction in tissue integrity. Magnetisation transfer ratio (MTR) is the commonly used measure in MTI. MRI research investigating whether there are occult abnormalities in the normal appearing brain tissue of NMO patients, using DTI and MTI, has shown variable results. The first quantitative imaging study by Filippi et al. (1999) demonstrated no group differences in the normal appearing brain tissue MTR between eight NMO patients compared to healthy controls, whereas they did find a difference when comparing MS patients to controls. Later the same research group were able to identify reduced MTR and increased MD within the grey matter when compared to controls, but no significant difference in the white matter (Rocca et al., 2004a). Yu et al. (2006) also found abnormalities within the normal appearing brain tissue, but in

289 contrast reported changes in the white matter with low FA, and elevated MD within the region of the optic and corticospinal tracts. Conversely in the region of the corpus callosum they showed no significant difference between NMO and control DTI indices, and in a subsequent publication suggested that NMO and relapsing remitting MS (RRMS) could be differentiated using these corpus callosum values, as they were significantly lower in the RRMS group (Yu et al., 2007). Further work showed correlation between disability scores measuring visual and pyramidal function, and the optic and corticospinal tract diffusion measures respectively (Yu et al., 2008). The authors postulated this was due to Wallerian degeneration secondary to a lack of sensory input. Consistent with these findings are those of a more recent study by Pichiecchio et al. (2012) that utilised a method known as Tract-Based Spatial Statistics (TBSS) (Smith et al., 2006), aimed at improving the sensitivity and reliability of multi-subject DTI studies, and found localised reductions in FA in the optic radiations. In this study 4 of 7 patients were aquaporin-4 antibody seropositive. Using the same method of DTI analysis (TBSS) Liu et al. published a study in the same year (2012) that reported a widespread significant increase in the diffusion indices MD, λ1 and λ23 in the white matter of patients with clinically defined NMO when compared to controls (Liu et al., 2012). Although a relatively large group of NMO patients was recruited (n=27), neither aquaporin-4 antibody nor NMO-Ig testing was available to the authors. It is not clear whether lesioned tissue was excluded from this latter study. Although more comparative data between NMO and MS is required, the results of the majority of these studies may indicate that a lack of diffuse white matter DTI abnormalities suggests a diagnosis of NMO rather than MS. 3.1.1. Spinal cord DTI and MTR The spinal cord has to date been relatively poorly studied with quantitative imaging techniques due to the challenges presented by its size and acute sensitivity to motion such as cardiac pulsation and respiration. In one of the few existing studies fractional anisotropy was reduced in the dorsal and lateral white matter of the NMO cervical spinal cord in 10 antibody positive patients, which correlated with disability (Qian et al., 2011). Filippi et al. (1999) also studied the MTR of the upper cervical cord in their 1999 study, and found reduction within lesioned spinal cord that was indistinguishable from the changes found in lesioned MS spinal cord.

3.2.

Magnetic resonance spectroscopy

Proton or magnetic resonance spectroscopy (MRS) measures the MR signal from hydrogen-bound neural metabolites and quantifies the biochemical constitution of tissues. In support of the hypothesis that NMOSD is lesion focused and spares the normal appearing brain tissue, the metabolite n-acetyl aspartate (NAA; a surrogate marker of neural integrity) as a ratio to creatine was at normal levels when measured over multiple voxels positioned in the deep white matter in a group of 8 seropositive NMOSD patients (Aboul-Enein et al., 2010). The research also demonstrated normal choline: creatine ratios. This result was reproduced in a larger study of 24 patient showing, as well, normal myoinositol:creatine ratio (de Seze et al., 2010). Conversely NAA has been found

290

L.A. Matthews, J.A. Palace

to be consistently low in the normal appearing brain tissue of MS patients (Chard et al., 2002; Davie et al., 1997)). Thus normal NAA levels in the normal appearing white matter may be in favour of NMO versus MS. Ciccarelli et al. (2013) have recently reported that in five NMO patients with LETM lower myo-inositol/creatine values were found within NMO spinal cord lesions, when compared to healthy control spinal cord tissue and MS spinal cord lesions. Myo-inositol is thought to be a surrogate marker of astrocyte density, therefore a relatively lower concentration in NMO lesions may be expected due to the autoimmune attack of aquaporin-4 water channels, which are situated on astrocytic foot processes.

3.3.

Volumetric imaging

Structural MRI, particularly if acquired with a three dimensional sequence, can be analysed in such a way to quantify and compare the volumes of whole brains, sub-cortical structures and tissue types. Filippi et al. (1999) reported in his MTI paper that there was no significant difference between the whole brain volumes of NMO patients when compared to the healthy control group. In contrast to this significant atrophy of MS brains and subcortical structures has been widely reported, even at the earliest stage (e.g., Dalton et al., 2004). A voxel-based morphometry study looking at differences in grey matter volume between NMO patients, RRMS patients and controls showed no significant differences between NMO patients when compared to the healthy volunteers, when corrected for multiple comparisons (Duan et al., 2012), but widespread significant reductions in grey matter volume in RRMS compared with both controls and NMO patients. An analysis of cortical thickness in NMO using the Freesurfer tool found mild thinning in some cortical areas (the postcentral, precentral and calcarine gyri) and the thalamus when compared to controls Calabrese et al., 2012).

3.4.

Functional MRI

Two studies from the same research group in Beijing have found disruption in the amplitude and homogeneity in the resting state functional networks of NMO patients with normal brain MRIs, when compared to controls (Liang et al., 2011; Liu et al., 2011). The abnormalities were localised to areas of the frontal, cingulate and temporal cortex as well as the thalamus and caudate. The serological status of these patients is not known. Disruption to the resting state networks of MS patients has also been demonstrated (e.g., Bonavita et al., 2011). Rocca et al. (2004b) measured the hand movement related activation of the cortex in NMO patients with spinal cord lesions, finding increased recruitment of sensorimotor, temporal and occipital cortical areas when compared to controls. The increased activation in these regions correlated with MTR measures of spinal cord damage. Functional cortical reorganisation in MS patients with spinal cord disease has also been reported (Filippi et al., 2002).

4.

Future challenges

With our newly found appreciation for the expanded features of AQP4 antibody disease, the future potential for imaging is threefold: (1) To clarify the features that differentiate AQP4 antibody disease from the more prevalent mimic relapsing remitting MS in order to apply this to AQP4 antibody negative NMOSD.

Longitudinally extensive spinal lesions and T2 hyperintensities in the area postrema and periaqueductal regions of the brainstem are indicative of NMO and atypical for MS. Panel 2 summarises useful differentiating features on conventional imaging and some potential discriminators from preliminary studies of quantitative measures. (2) To provide a means of measuring disease activity and treatment response (in the clinic and in treatment trials). (3) To study in-vivo the pathophysiological mechanisms of this recently characterised inflammatory demyelinating condition.

Quantitative measures of the integrity of normal appearing tissue in NMO suggest that neurodegeneration is limited to lesions and the white matter tracts affected by those lesions, in contrast to the diffuse and global changes found in MS. This finding could provide the basis of the development of more specific biomarkers of NMO.

5. Summary: useful imaging discriminators that favour NMO over MS

 Longitudinally extensive (greater than three vertebral        

segments) spinal cord lesions, which may be contiguous with lesions of the brainstem. Spinal lesions centred on the grey matter. The absence of asymptomatic spinal lesions. Increase of T2 signal and/or contrast enhancement within the optic nerve that extends to the chiasm. Brain lesions in the area postrema of the brainstem. Periventricular brain lesions can be found in both conditions, but the absence of perpendicular ovoid morphology and Dawson's fingers is in favour of NMO. Absence of cortical lesions. Absence of s-shaped U-fibre juxtacortical lesions. Initial quantitative studies suggest a lack of normal appearing white matter abnormalities is in favour of NMO over MS.

Conflicts of interest and funding statements Dr. Lucy Matthews has no conflicts of interest relevant to this submission. She has previously received funding from the Medical Research Council, UK (G0901996) and currently

Role of imaging in diagnosis of neuromyelitis optica receives funding from the Guthy–Jackson Charitable Foundation. Dr. Jacqueline Palace is on the advisory boards of Biogen Idec, Merck Serono, Teva Aventis, Bayer Schering and Novartis. She has received funding from the MS Society UK, Medical Research Council, UK and currently the Guthy– Jackson Charitable Foundation. She has a patent pending with ISIS Innovation (Oxford University). She has received conference support from Merck Serono and Novartis.

References Apiwattanakul M, Popescu BF, Matiello M, Weinshenker BG, Lucchinetti CF, Lennon VA, et al. Intractable vomiting as the initial presentation of neuromyelitis optica. Ann Neurol 2010;68 (5):757–61. Aboul-Enein F, Krssak M, Hoftberger R, Prayer D, Kristoferitsch W. Diffuse white matter damage is absent in neuromyelitis optica. AJNR: Am J Neuroradiol 2010;31(1):76–9. Bot JC, Barkhof F, Polman CH, Lycklama a Nijeholt GJ, de Groot V, Bergers E, et al. Spinal cord abnormalities in recently diagnosed MS patients: added value of spinal MRI examination. Neurology 2004;62(2):226–33. Barkhof F, Filippi M, Miller DH, Scheltens P, Campi A, Polman CH, et al. Comparison of MRI criteria at first presentation to predict conversion to clinically definite multiple sclerosis. Brain 1997;120(Pt 11):2059–69. Bonavita S, Gallo A, Sacco R, Corte MD, Bisecco A, Docimo R, et al. Distributed changes in default-mode resting-state connectivity in multiple sclerosis. Mult Scler 2011;17(4):411–22. Cabrera-Gomez J, Saiz-Hinarejos A, Graus F, Gonzalez-Quevedo A, Rodriguez-Rojas R, Quevedo-Sotolongo L, et al. Brain magnetic resonance imaging findings in acute relapses of neuromyelitis optica spectrum disorders. Mult Scler 2008;14(2):248–51. Chard DT, Griffin CM, McLean MA, Kapeller P, Kapoor R, Thompson AJ, et al. Brain metabolite changes in cortical grey and normalappearing white matter in clinically early relapsing-remitting multiple sclerosis. Brain 2002;125(Pt 10):2342–52. Ciccarelli O, Thomas D, De Vita E, Wheeler-Kingshott C, Kachramanoglou C, Kapoor R, et al. Low myo-inositol indicating astrocytic damage in a case series of NMO. Ann Neurol 2013. Apr 3. Calabrese M, Oh MS, Favaretto A, Rinaldi F, Poretto V, Alessio S, et al. No MRI evidence of cortical lesions in neuromyelitis optica. Neurology 2012;79(16):1671–6. Downer JJ, Leite MI, Carter R, Palace J, Kuker W, Quaghebeur G. Diagnosis of neuromyelitis optica (NMO) spectrum disorders: is MRI obsolete? Neuroradiology 2012 Apr;54(4):79–85. Davie CA, Barker GJ, Thompson AJ, Tofts PS, McDonald WI, Miller DH. 1H magnetic resonance spectroscopy of chronic cerebral white matter lesions and normal appearing white matter in multiple sclerosis. J Neurol Neurosurg Psychiatry 1997;63 (6):736–42. Dalton CM, Chard DT, Davies GR, Miszkiel KA, Altmann DR, Fernando K, et al. Early development of multiple sclerosis is associated with progressive grey matter atrophy in patients presenting with clinically isolated syndromes. Brain 2004;127(Pt 5):1101–7. Duan Y, Liu Y, Liang P, Jia X, Yu C, Qin W, et al. Comparison of grey matter atrophy between patients with neuromyelitis optica and multiple sclerosis: a voxel-based morphometry study. Eur J Radiol 2012 Feb;81(2):e110–4. de Seze J, Stojkovic T, Ferriby D, Gauvrit JY, Montagne C, MounierVehier F, et al. Devic's neuromyelitis optica: clinical, laboratory, MRI and outcome profile. J Neurol Sci 2002;197(1–2):57–61. de Seze J, Blanc F, Kremer S, Collongues N, Fleury M, Marcel C, et al. Magnetic resonance spectroscopy evaluation in patients

291 with neuromyelitis optica. J Neurol Neurosurg Psychiatry 2010;81(4):409–11. Filippi M, Rocca MA, Moiola L, Martinelli V, Ghezzi A, Capra R, et al. MRI and magnetization transfer imaging changes in the brain and cervical cord of patients with Devic's neuromyelitis optica. Neurology 1999;53(8):1705–10. Filippi M, Rocca MA, Falini A, Caputo D, Ghezzi A, Colombo B, et al. Correlations between structural CNS damage and functional MRI changes in primary progressive MS. Neuroimage 2002;15 (3):537–46. Griffin CM, Chard DT, Ciccarelli O, Kapoor B, Barker GJ, Thompson AI, et al. Diffusion tensor imaging in early relapsing-remitting multiple sclerosis. Mult Scler 2001;7(5):290–7. Hickman SJ, Toosy AT, Miszkiel KA, Jones SJ, Altmann DR, MacManus DG, et al. Visual recovery following acute optic neuritis—a clinical, electrophysiological and magnetic resonance imaging study. J Neurol 2004;251(8):996–1005. Ito S, Mori M, Makino T, Hayakawa S, Kuwabara S. “Cloud-like enhancement” is a magnetic resonance imaging abnormality specific to neuromyelitis optica. Ann Neurol 2009;66(3):425–8. Ikeda K, Ito H, Hidaka T, Takazawa T, Sekine T, Yoshii Y, et al. Repeated non-enhancing tumefactive lesions in a patient with a neuromyelitis optica spectrum disorder. Intern Med 2011;50 (9):1061–4. Isose S, Mori M, Takahashi N, Ito S, Kuwabara S. Neurological pictures. Clumsy hand syndrome due to a localised cortical lesion in the primary sensory cortex in neuromyelitis optica. J Neurol Neurosurg Psychiatry 2011;82(5):559–60. Kim W, Kim SH, Lee SH, Li XF, Kim HJ. Brain abnormalities as an initial manifestation of neuromyelitis optica spectrum disorder. Mult Scler 2011 Sep;17(9):1107–12. Krampla W, Aboul-Enein F, Jecel J, Lang W, Fertl E, Hruby W, et al. Spinal cord lesions in patients with neuromyelitis optica: a retrospective long-term MRI follow-up study. Eur Radiol 2009;19(10):2535–43. Kitley JL, Leite MI, George JS, Palace JA. The differential diagnosis of longitudinally extensive transverse myelitis. Mult Scler 2012 Mar;18(3):271–85. Kidd D, Burton B, Plant GT, Graham EM. Chronic relapsing inflammatory optic neuropathy (CRION). Brain 2003;126(Pt 2):276–84. Kim JE, Kim SM, Ahn SW, Lim BC, Chae JH, Hong YH, et al. Brain abnormalities in neuromyelitis optica. J Neurol Sci 2011;302(1–2):43–8. Lennon VA, Wingerchuk DM, Kryzer TJ, Pittock SJ, Lucchinetti CF, Fujihara K, et al. A serum autoantibody marker of neuromyelitis optica: distinction from multiple sclerosis. Lancet 2004;364 (9451):2106–12. Lennon VA, Kryzer TJ, Pittock SJ, Verkman AS, Hinson SR. IgG marker of optic-spinal multiple sclerosis binds to the aquaporin4 water channel. J Exp Med 2005;202(4):473–7. Lu Z, Qiu W, Zou Y, Lv K, Long Y, You W, et al. Characteristic linear lesions and longitudinally extensive spinal cord lesions in Chinese patients with neuromyelitis optica. J Neurol Sci 2010;293(1–2):92–6. Li Y, Xie P, Lv F, Mu J, Li Q, Yang Q, et al. Brain magnetic resonance imaging abnormalities in neuromyelitis optica. Acta Neurol Scand 2008;118(4):218–25. Larsson HB, Thomsen C, Frederiksen J, Stubgaard M, Henriksen O. In vivo magnetic resonance diffusion measurement in the brain of patients with multiple sclerosis. Magn Reson Imaging 1992;10 (1):7–12. Liu Y, Duan Y, He Y, Yu C, Wang J, Huang J, et al. A tract-based diffusion study of cerebral white matter in neuromyelitis optica reveals widespread pathological alterations. Mult Scler 2012;18 (7):1013–21. Liang P, Liu Y, Jia X, Duan Y, Yu C, Qin W, et al. Regional homogeneity changes in patients with neuromyelitis optica

292 revealed by resting-state functional MRI. Clin Neurophysiol 2011;122(1):121–7. Liu Y, Liang P, Duan Y, Jia X, Wang F, Yu C, et al. Abnormal baseline brain activity in patients with neuromyelitis optica: a restingstate fMRI study. Eur J Radiol 2011;80(2):407–11. Merle H, Olindo S, Bonnan M, Donnio A, Richer R, Smadja D, et al. Natural history of the visual impairment of relapsing neuromyelitis optica. Ophthalmology 2007;114(4):810–5. McKeon A, Lennon VA, Lotze T, Tenenbaum S, Ness JM, Rensel M, et al. CNS aquaporin-4 autoimmunity in children. Neurology 2008;71(2):93–100. Matthews LA, Baig F, Palace J, Turner MR. The borderland of neuromyelitis optica. Pract Neurol 2009;9(6):335–40. Miller DH, Weinshenker BG, Filippi M, Banwell BL, Cohen JA, Freedman MS, et al. Differential diagnosis of suspected multiple sclerosis: a consensus approach. Mult Scler 2008;14 (9):1157–74. Miller DH, Newton MR, van der Poel JC, du Boulay EP, Halliday AM, Kendall BE, et al. Magnetic resonance imaging of the optic nerve in optic neuritis. Neurology 1988;38(2):175–9. Matthews L, Marasco R, Jenkinson M, Kuker W, Luppe S, Leite MI, et al. Distinction of seropositive NMO spectrum disorder and MS brain lesion distribution. Neurology 2013;80(14):1330–7. Matsushita T, Isobe N, Piao H, Matsuoka T, Ishizu T, Doi H, et al. Reappraisal of brain MRI features in patients with multiple sclerosis and neuromyelitis optica according to anti-aquaporin4 antibody status. J Neurol Sci 2010;291(1–2):37–43. Nakamura M, Miyazawa I, Fujihara K, Nakashima I, Misu T, Watanabe S, et al. Preferential spinal central gray matter involvement in neuromyelitis optica. an MRI study. J Neurol 2008;255(2):163–70. Nakamura M, Misu T, Fujihara K, Miyazawa I, Nakashima I, Takahashi T, et al. Occurrence of acute large and edematous callosal lesions in neuromyelitis optica. Mult Scler 2009;15 (6):695–700. O’Riordan JI, Losseff NA, Phatouros C, Thompson AJ, Moseley IF, MacManus DG, et al. Asymptomatic spinal cord lesions in clinically isolated optic nerve, brain stem, and spinal cord syndromes suggestive of demyelination. J Neurol Neurosurg Psychiatry 1998;64(3):353–7. O’Riordan JI, Gallagher HL, Thompson AJ, Howard RS, Kingsley DP, Thompson EJ, et al. Clinical, CSF, and MRI findings in Devic's neuromyelitis optica. J Neurol Neurosurg Psychiatry 1996;60 (4):382–7. Palace J, Leite MI, Nairne A, Vincent A. Interferon Beta treatment in neuromyelitis optica: increase in relapses and aquaporin 4 antibody titers. Arch Neurol 2010;67(8):1016–7. Pittock SJ, Lennon VA, de Seze J, Vermersch P, Homburger HA, Wingerchuk DM, et al. Neuromyelitis optica and non organspecific autoimmunity. Arch Neurol 2008;65(1):78–83. Pirko I, Blauwet LA, Lesnick TG, Weinshenker BG. The natural history of recurrent optic neuritis. Arch Neurol 2004;61 (9):1401–5. Pittock SJ, Lennon VA, Krecke K, Wingerchuk DM, Lucchinetti CF, Weinshenker BG. Brain abnormalities in neuromyelitis optica. Arch Neurol 2006a;63(3):390–6. Polman CH, Reingold SC, Banwell B, Clanet M, Cohen JA, Filippi M, et al. Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald criteria. Ann Neurol. 2011;69(2):292–302. Pittock SJ, Weinshenker BG, Lucchinetti CF, Wingerchuk DM, Corboy JR, Lennon VA. Neuromyelitis optica brain lesions localized at sites of high aquaporin 4 expression. Arch Neurol 2006b;63 (7):964–8. Poppe AY, Lapierre Y, Melancon D, Lowden D, Wardell L, Fullerton LM, et al. Neuromyelitis optica with hypothalamic involvement. Mult Scler 2005;11(5):617–21. Popescu BF, Lennon VA, Parisi JE, Howe CL, Weigand SD, CabreraGomez JA, et al. Neuromyelitis optica unique area postrema

L.A. Matthews, J.A. Palace lesions: nausea, vomiting, and pathogenic implications. Neurology 2011;76(14):1229–37. Pichiecchio A, Tavazzi E, Poloni G, Ponzio M, Palesi F, Pasin M, et al. Advanced magnetic resonance imaging of neuromyelitis optica: a multiparametric approach. Mult Scler 2012;18 (6):817–24. Qiu W, Wu JS, Zhang MN, Matsushita T, Kira JI, Carroll WM, et al. Longitudinally extensive myelopathy in Caucasians: a West Australian study of 26 cases from the Perth Demyelinating Diseases Database. J Neurol Neurosurg Psychiatry 2010;81 (2):209–12. Qian W, Chan Q, Mak H, Zhang Z, Anthony MP, Yau KK, et al. Quantitative assessment of the cervical spinal cord damage in neuromyelitis optica using diffusion tensor imaging at 3 T. J Magn Reson Imaging 2011;33(6):1312–20. Roemer SF, Parisi JE, Lennon VA, Benarroch EE, Lassmann H, Bruck W, et al. Pattern-specific loss of aquaporin-4 immunoreactivity distinguishes neuromyelitis optica from multiple sclerosis. Brain 2007;130(Pt 5):1194–205. Rizzo III JF, Andreoli CM, Rabinov JD. Use of magnetic resonance imaging to differentiate optic neuritis and nonarteritic anterior ischemic optic neuropathy. Ophthalmology 2002;109 (9):1679–84. Rocca MA, Agosta F, Mezzapesa DM, Martinelli V, Salvi F, Ghezzi A, et al. Magnetization transfer and diffusion tensor MRI show gray matter damage in neuromyelitis optica. Neurology 2004a;62 (3):476–8. Rocca MA, Agosta F, Mezzapesa DM, Falini A, Martinelli V, Salvi F, et al. A functional MRI study of movement-associated cortical changes in patients with Devic's neuromyelitis optica. NeuroImage 2004b;21(3):1061–8. Sellner J, Boggild M, Clanet M, Hintzen RQ, Illes Z, Montalban X, et al. EFNS guidelines on diagnosis and management of neuromyelitis optica. Eur J Neurol 2010;17(8):1019–32. Smith SM, Jenkinson M, Johansen-Berg H, Rueckert D, Nichols TE, Mackay CE, et al. Tract-based spatial statistics: voxelwise analysis of multi-subject diffusion data. NeuroImage 2006;31 (4):1487–505. Tortorella P, Rocca MA, Mezzapesa DM, Ghezzi A, Lamantia L, Comi G, et al. MRI quantification of gray and white matter damage in patients with early-onset multiple sclerosis. J Neurol 2006;253 (7):903–7. Waters PJ, McKeon A, Leite MI, Rajasekharan S, Lennon VA, Villalobos A, et al. Serologic diagnosis of NMO: a multicenter comparison of aquaporin-4-IgG assays. Neurology 2012;78 (9):665–71. (discussion 9). Wingerchuk DM, Pittock SJ, Lucchinetti CF, Lennon VA, Weinshenker BG. A secondary progressive clinical course is uncommon in neuromyelitis optica. Neurology 2007;68(8):603–5. Wingerchuk DM, Lennon VA, Pittock SJ, Lucchinetti CF, Weinshenker BG. Revised diagnostic criteria for neuromyelitis optica. Neurology 2006;66(10):1485–9. Wingerchuk DM. Diagnosis and treatment of neuromyelitis optica. Neurologist 2007;13(1):2–11. Waters P, Jarius S, Littleton E, Leite MI, Jacob S, Gray B, et al. Aquaporin-4 antibodies in neuromyelitis optica and longitudinally extensive transverse myelitis. Arch Neurol 2008;65 (7):913–9. Wingerchuk DM, Hogancamp WF, O'Brien PC, Weinshenker BG. The clinical course of neuromyelitis optica (Devic's syndrome). Neurology 1999;53(5):1107–14. Wang F, Liu Y, Duan Y, Li K, Brain MRI. abnormalities in neuromyelitis optica. Eur J Radiol 2011;80(2):445–9. Yu CS, Lin FC, Li KC, Jiang TZ, Zhu CZ, Qin W, et al. Diffusion tensor imaging in the assessment of normal-appearing brain tissue damage in relapsing neuromyelitis optica. AJNR: Am J Neuroradiol 2006;27(5):1009–15.

Role of imaging in diagnosis of neuromyelitis optica Yu CS, Zhu CZ, Li KC, Xuan Y, Qin W, Sun H, et al. Relapsing neuromyelitis optica and relapsing-remitting multiple sclerosis: differentiation at diffusion-tensor MR imaging of corpus callosum. Radiology 2007;244(1):249–56.

293 Yu C, Lin F, Li K, Jiang T, Qin W, Sun H, et al. Pathogenesis of normal-appearing white matter damage in neuromyelitis optica: diffusion-tensor MR imaging. Radiology 2008;246(1):222–8.

The role of imaging in diagnosing neuromyelitis optica spectrum disorder.

Early identification of neuromyelitis optica allows aggressive acute and prophylactic relapse management aimed at preventing disability. Since the dis...
915KB Sizes 3 Downloads 21 Views

Recommend Documents


Three cases of neuromyelitis optica spectrum disorder.
Neuromyelitis optica (NMO) is characterized by attacks of optic neuritis and longitudinally extensive transverse myelitis. Cases positive for aquaporin 4 antibodies are classified to NMO spectrum disorder (NMOSD) which includes cases with optic neuri

Mycophenolate mofetil in the treatment of neuromyelitis optica spectrum disorder.
Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disorder of the central nervous system. Recently, various immunosuppressant medications were introduced as therapeutic options for preventing relapse of NMOSD. However, our

Immunoadsorption in patients with neuromyelitis optica spectrum disorder.
Neuromyelitis optica spectrum disorder (NMOSD) is a neuroinflammatory disorder of the central nervous system, distinct from multiple sclerosis by affecting predominantly the optic nerve and the spinal cord, and mediated by antibodies directed against

Insufficient treatment of severe depression in neuromyelitis optica spectrum disorder.
To investigate depression frequency, severity, current treatment, and interactions with somatic symptoms among patients with neuromyelitis optica spectrum disorder (NMOSD).

Cerebral Cortex Involvement in Neuromyelitis Optica Spectrum Disorder.
Brain lesions involving the cerebral cortex are rarely described in patients with neuromyelitis optica spectrum disorder (NMOSD), in contrast to multiple sclerosis. We investigated cerebral cortex involvement using conventional brain magnetic resonan

MRI characteristics of neuromyelitis optica spectrum disorder: an international update.
Since its initial reports in the 19th century, neuromyelitis optica (NMO) had been thought to involve only the optic nerves and spinal cord. However, the discovery of highly specific anti-aquaporin-4 antibody diagnostic biomarker for NMO enabled reco

Treatment of Neuromyelitis Optica Spectrum Disorder: Acute, Preventive, and Symptomatic.
Neuromyelitis optica spectrum disorder (NMOSD) is a rare, autoimmune disease of the central nervous system that primarily attacks the optic nerves and spinal cord leading to blindness and paralysis. The spectrum of the disease has expanded based on t

neuromyelitis optica spectrum disorders with methotrexate.
To review our experience using methotrexate as a single long-term immunosuppressant (IS) therapy in neuromyelitis optica/neuromyelitis optica spectrum disorders (NMO/NMOSD).

Muscle damage in patients with neuromyelitis optica spectrum disorder.
Increasing evidence has shown that skeletal muscle damage plays a role in neuromyelitis optica spectrum disorder (NMOSD). The objective of this study was to compare the serum creatine kinase (sCK) levels in NMOSD patients with different clinical stat

Longitudinally extensive optic neuritis in neuromyelitis optica spectrum disorder.
Neuomyelitis optica, sarcoid, and multiple sclerosis can all cause optic neuritis. Further means of distinguishing the causes of optic neuritis among these etiologies would be valuable for the clinician.