Spinal cord lesions in patients with neuromyelitis optica: a retrospective long-term MRI follow-up study

A comprehensive review of the advances in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is a rare relapsing neuroinflammatory autoimmune astrocytopathy, with a predilection for the optic nerves and spinal cord. Most cases are characterised by aquaporin-4-antibody positivity and have a relapsing disease course, which is associated with accrual of disability. Although the prognosis in NMOSD has improved markedly over the past few years owing to advances in diagnosis and therapeutics, it remains a severe disease. In this article, we review the evolution of our understanding of NMOSD, its pathogenesis, clinical features, disease course, treatment options and associated symptoms. We also address the gaps in knowledge and areas for future research focus.

Cervical myelitis: a practical approach to its differential diagnosis on MR imaging

BACKGROUND

 Differential diagnosis of non-compressive cervical myelopathy encompasses a broad spectrum of inflammatory, infectious, vascular, neoplastic, neurodegenerative, and metabolic etiologies. Although the speed of symptom onset and clinical course seem to be specific for certain neurological diseases, lesion pattern on MR imaging is a key player to confirm diagnostic considerations.

METHODS

 The differentiation between acute complete transverse myelitis and acute partial transverse myelitis makes it possible to distinguish between certain entities, with the latter often being the onset of multiple sclerosis. Typical medullary MRI lesion patterns include a) longitudinal extensive transverse myelitis, b) short-range ovoid and peripheral lesions, c) polio-like appearance with involvement of the anterior horns, and d) granulomatous nodular enhancement prototypes.

RESULTS AND CONCLUSION

 Cerebrospinal fluid analysis, blood culture tests, and autoimmune antibody testing are crucial for the correct interpretation of imaging findings. The combination of neuroradiological features and neurological and laboratory findings including cerebrospinal fluid analysis improves diagnostic accuracy.

KEY POINTS

  · The differentiation of medullary lesion patterns, i. e., longitudinal extensive transverse, short ovoid and peripheral, polio-like, and granulomatous nodular, facilitates the diagnosis of myelitis.. · Discrimination of acute complete and acute partial transverse myelitis makes it possible to categorize different entities, with the latter frequently being the overture of multiple sclerosis (MS).. · Neuromyelitis optica spectrum disorders (NMOSD) may start as short transverse myelitis and should not be mistaken for MS.. · The combination of imaging features and neurological and laboratory findings including cerebrospinal fluid analysis improves diagnostic accuracy.. · Additional brain imaging is mandatory in suspected demyelinating, systemic autoimmune, infectious, paraneoplastic, and metabolic diseases..

The utility of diffusion-weighted imaging in patients with spinal cord infarction: difference from the findings of neuromyelitis optica spectrum disorder

Background

Magnetic resonance imaging (MRI) plays a crucial role in diagnosing spinal cord infarction (SCI). However, the findings are often indistinguishable from those of other intramedullary diseases, such as neuromyelitis optica spectrum disorder (NMOSD). Although diffusion-weighted imaging (DWI) is a promising technique, the utility for discriminating SCI from NMOSD remains unclear because the DWI findings of acute NMOSD lesions have not been investigated in detail.

Methods

Clinical and MRI findings were retrospectively evaluated in 15 and 12 patients with acute SCI and NMOSD, respectively. First, clinical characteristics were compared between the SCI and NMOSD groups. Second, MRI abnormalities were examined to find differences between these groups. Third, in the SCI group, factors influencing T2 and DWI abnormalities were analyzed using the mixed-effects logistic regression analysis.

Results

The proportion of female patients was higher in the NMOSD group (92%) than in the SCI (40%). The time from symptom onset to nadir was smaller in the SCI group (median [interquartile range]; 4 [0.1–8.3] hours) than in the NMOSD (252 [162–576]). On T2-weighted images, SCI lesions had smaller length than NMOSD (2 [1–2] and 5 [2–7] vertebral segments, respectively). Focal lesions within the T9–L2 level were found only in patients with SCI. DWI hyperintensity was observed both in the SCI (frequency, 100%) and NMOSD (60%) groups. On apparent diffusion coefficient (ADC) maps, the hyperintensities of SCI had corresponding hypointensities, whereas those of NMOSD were isointense and a large portion of NMOSD lesions had hyperintense signals. Owl’s eyes sign and pencil-like hyperintensity, typically reported as T2 findings suggestive of SCI, were also found on DWI. Posterior linear hyperintensity was frequently detected on DWI in patients with posterior spinal artery infarction. The presence of MRI abnormality revealing SCI was modeled with the time from symptom onset, imaging sequence and plane, and affected vascular territory.

Conclusions

DWI and ADC maps help distinguish SCI from NMOSD. The time from symptom onset, imaging sequence, and imaging plane should be considered when MRI findings are interpreted in patients with suspected SCI.

MRI Patterns Distinguish AQP4 Antibody Positive Neuromyelitis Optica Spectrum Disorder From Multiple Sclerosis

Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are inflammatory diseases of the CNS. Overlap in the clinical and MRI features of NMOSD and MS means that distinguishing these conditions can be difficult. With the aim of evaluating the diagnostic utility of MRI features in distinguishing NMOSD from MS, we have conducted a cross-sectional analysis of imaging data and developed predictive models to distinguish the two conditions. NMOSD and MS MRI lesions were identified and defined through a literature search. Aquaporin-4 (AQP4) antibody positive NMOSD cases and age- and sex-matched MS cases were collected. MRI of orbits, brain and spine were reported by at least two blinded reviewers. MRI brain or spine was available for 166/168 (99%) of cases. Longitudinally extensive (OR = 203), "bright spotty" (OR = 93.8), whole (axial; OR = 57.8) or gadolinium (Gd) enhancing (OR = 28.6) spinal cord lesions, bilateral (OR = 31.3) or Gd-enhancing (OR = 15.4) optic nerve lesions, and nucleus tractus solitarius (OR = 19.2), periaqueductal (OR = 16.8) or hypothalamic (OR = 7.2) brain lesions were associated with NMOSD. Ovoid (OR = 0.029), Dawson's fingers (OR = 0.031), pyramidal corpus callosum (OR = 0.058), periventricular (OR = 0.136), temporal lobe (OR = 0.137) and T1 black holes (OR = 0.154) brain lesions were associated with MS. A score-based algorithm and a decision tree determined by machine learning accurately predicted more than 85% of both diagnoses using first available imaging alone. We have confirmed NMOSD and MS specific MRI features and combined these in predictive models that can accurately identify more than 85% of cases as either AQP4 seropositive NMOSD or MS.

Retinal optical coherence tomography and magnetic resonance imaging in neuromyelitis optica spectrum disorders and MOG-antibody associated disorders: an updated review

INTRODUCTION

Neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein IgG antibody-associated disorders (MOGAD) comprise two groups of rare neuroinflammatory diseases that cause attack-related damage to the central nervous system (CNS). Clinical attacks are often characterized by optic neuritis, transverse myelitis, and to a lesser extent, brainstem encephalitis/area postrema syndrome. Retinal optical coherence tomography (OCT) is a non-invasive technique that allows for in vivo thickness quantification of the retinal layers. Apart from OCT, magnetic resonance imaging (MRI) plays an increasingly important role in NMOSD and MOGAD diagnosis based on the current international diagnostic criteria. Retinal OCT and brain/spinal cord/optic nerve MRI can help to distinguish NMOSD and MOGAD from other neuroinflammatory diseases, particularly from multiple sclerosis, and to monitor disease-associated CNS-damage.

AREAS COVERED

This article summarizes the current status of imaging research in NMOSD and MOGAD, and reviews the clinical relevance of OCT, MRI and other relevant imaging techniques for differential diagnosis, screening and monitoring of the disease course.

EXPERT OPINION

Retinal OCT and MRI can visualize and quantify CNS damage in vivo, improving our understanding of NMOSD and MOGAD pathology. Further efforts on the standardization of these imaging techniques are essential for implementation into clinical practice and as outcome parameters in clinical trials.

A window into the future? MRI for evaluation of neuromyelitis optica spectrum disorder throughout the disease course

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, inflammatory disease of the central nervous system marked by relapses often associated with poor recovery and long-term disability. Magnetic resonance imaging (MRI) is recognized as an important tool for timely diagnosis of NMOSD as, in combination with serologic testing, it aids in distinguishing NMOSD from possible mimics. Although the role of MRI for disease monitoring after diagnosis is not as well established, MRI may provide important prognostic information and help differentiate between relapses and pseudorelapses. Increasing evidence of subclinical disease activity and the emergence of newly approved, highly effective immunotherapies for NMOSD adjure us to re-evaluate MRI as a tool to guide optimal treatment selection and escalation throughout the disease course. In this article we review the role of MRI in NMOSD diagnosis, prognostication, disease monitoring, and treatment selection.

Pain in NMOSD and MOGAD: A Systematic Literature Review of Pathophysiology, Symptoms, and Current Treatment Strategies

Neuromyelitis optica spectrum disorders (NMOSDs) and myelin oligodendrocyte glycoprotein-antibody-associated disease (MOGAD) are autoimmune inflammatory disorders of the central nervous system (CNS). Pain is highly prevalent and debilitating in NMOSD and MOGAD with a severe impact on quality of life, and there is a critical need for further studies to successfully treat and manage pain in these rare disorders. In NMOSD, pain has a prevalence of over 80%, and pain syndromes include neuropathic, nociceptive, and mixed pain, which can emerge in acute relapse or become chronic during the disease course. The impact of pain in MOGAD has only recently received increased attention, with an estimated prevalence of over 70%. These patients typically experience not only severe headache, retrobulbar pain, and/or pain on eye movement in optic neuritis but also neuropathic and nociceptive pain. Given the high relevance of pain in MOGAD and NMOSD, this article provides a systematic review of the current literature pertaining to pain in both disorders, focusing on the etiology of their respective pain syndromes and their pathophysiological background. Acknowledging the challenge and complexity of diagnosing pain, we also provide a mechanism-based classification of NMOSD- and MOGAD-related pain syndromes and summarize current treatment strategies.

Radiological characteristics of neuromyelitis optica spectrum disorder in Kuwait

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disorder of the central nervous system that predominantly targets optic nerves and spinal cord. Studies of NMOSD are scarce in the Middle East.

OBJECTIVE

To evaluate the MRI characteristics of NMOSD patients in Kuwait.

PATIENT AND METHODS

This is an observational, retrospective study on NMOSD patients who attended the MS clinic. Patients who fulfilled the 2015 diagnostic criteria of NMOSD were included. Patients` clinical, radiological and serological data were extracted from the medical records. The radiological variables were compared according to gender and AQP4 serostatus.

RESULTS

Forty-two patients fulfilling the NMOSD diagnostic criteria. The mean age and mean age of onset were 32.6 ± 11.4 and 28.9 ± 9.8 years respectively. Females represented 83.3 % of the cohort with female-to-male ratio of 5:1. Thirty-one patients (73.8 %) tested positive for AQP4 antibody. Nineteen patients (45.2 %) had bilateral optic nerve involvement, while chiasmal involvement was seen in 8 (19.0 %) patients. Spinal cord was involved in 36 (85.7 %) patients; of whom 27 (64.3 %) had LETM. The most common spinal segment involved was the cervical (72.2 %) followed by the dorsal (25.0 %) regions. The brain was involved in 39 (92.8 %) patients and the periventricular region around fourth and lateral ventricles was the most commonly involved site (n = 35; 83.3 %), along with periaqueductal (n = 25; 61.9 %) and corpus callosal (n = 24; 57.1 %) regions. Isolated area postrema involvement was observed in 9 (21.4 %) patients.

CONCLUSION

This is the first study describing the radiological characteristics of NMOSD in Kuwait. Although our data is comparable with the previous international studies, a higher percentage of bilateral optic nerve, brain, and callosal involvement was observed. Further multicenter studies with a larger cohort are needed to confirm our results.

Short segment myelitis as the initial and only manifestation of aquaporin-4 immunoglobulin G-positive neuromyelitis optica spectrum disorders

Background:

Short segment myelitis (SSM, < 3 vertebral segments) is an under-recognized initial manifestation of neuromyelitis optica spectrum disorders (NMOSD). Though infrequent, failure to recognize SSM in patients with NMOSD would lead to incorrect diagnosis and treatment. Therefore, delineation of features of NMOSD-associated SSM is of paramount importance.

Objective:

Our study aimed to determine the demographic, clinical and radiological features of NMOSD-associated SSM, and compare those with NMOSD-associated longitudinally extensive transverse myelitis (LETM) and multiple sclerosis (MS)-associated SSM, respectively.

Methods:

Chinese patients presenting initially only with acute myelitis and diagnosed with NMOSD (n = 46) and MS (n = 11) were included. Clinical, serological, imaging and disability data were collected. Mann–Whitney U test or two-tailed Fisher’s exact tests were used to analyse the data.

Results:

Of the 46 enrolled NMOSD patients, 34 (74%) collectively had 38 LETM lesions, while 12 (26%) had 14 SSM lesions. When compared with LETM, NMOSD presenting with SSM were more likely to have a delayed diagnosis and a lower level of disability at nadir during the first attack. T1-weighted imaging hypointensity was more prominent in NMOSD-associated LETM lesions than NMOSD-associated SSM lesions. When compared with MS-associated SSM, NMOSD-associated SSM lesions were more likely to be centrally located, grey matter involving and transversally extensive on axial imaging and spanned no less than 2 vertebral segments on sagittal imaging.

Conclusion:

These findings suggest that SSM does not preclude the possibility of a NMOSD diagnosis. Testing for serum aquaporin-4 immunoglobulin G (AQP4-IgG) and careful study of lesions on spinal cord magnetic resonance imaging could aid in an earlier and correct diagnosis.

Rapid myelin water imaging for the assessment of cervical spinal cord myelin damage

Background

Rapid myelin water imaging (MWI) using a combined gradient and spin echo (GRASE) sequence can produce myelin specific metrics for the human brain. Spinal cord MWI could be similarly useful, but technical challenges have hindered routine application. GRASE rapid MWI was recently successfully implemented for imaging of healthy cervical spinal cord and may complement other advanced imaging methods, such as diffusion tensor imaging (DTI) and quantitative T₁ (qT₁).

Objective

To demonstrate the feasibility of cervical cord GRASE rapid MWI in multiple sclerosis (MS), primary lateral sclerosis (PLS) and neuromyelitis optica spectrum disorder (NMO), with comparison to DTI and qT₁ metrics.

Methods

GRASE MWI, DTI and qT₁ data were acquired in 2 PLS, 1 relapsing-remitting MS (RRMS), 1 primary-progressive MS (PPMS) and 2 NMO subjects, as well as 6 age (±3 yrs) and sex matched healthy controls (HC). Internal cord structure guided template registrations, used for region of interest (ROI) analysis. Z score maps were calculated for the difference between disease subject and mean HC metric values.

Results

PLS subjects had low myelin water fraction (MWF) in the lateral funiculi compared to HC. RRMS subject MWF was heterogeneous within the cord. The PPMS subject showed no trends in ROI results but had a region of low MWF Z score corresponding to a focal lesion. The NMO subject with a longitudinally extensive transverse myelitis lesion had low values for whole cord mean MWF of 12.8% compared to 24.3% (standard deviation 2.2%) for HC. The NMO subject without lesions also had low MWF compared to HC. DTI and qT₁ metrics showed similar trends, corroborating the MWF results and providing complementary information.

Conclusion

GRASE is sufficiently sensitive to detect decreased myelin within MS spinal cord plaques, NMO lesions, and PLS diffuse spinal cord injury. Decreased MWF in PLS is consistent with demyelination secondary to motor neuron degeneration. GRASE MWI is a feasible method for rapid assessment of myelin content in the cervical spinal cord and provides complementary information to that of DTI and qT₁ measures.

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Downstream myelin changes in motor tracts of primary lateral sclerosis spinal cord.

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Low myelin water fraction in multiple sclerosis and neuromyelitis optica cord lesions.

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Diffuse demyelination evidence in neuromyelitis optica normal-appearing white matter.

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Myelin water imaging provides complementary information to diffusion and T₁ metrics.

Short transverse myelitis in Chinese patients with neuromyelitis optica spectrum disorders

BACKGROUND

Short transverse myelitis (STM) is considered uncommon in neuromyelitis optica spectrum disorders (NMOSD). Poor recognition of STM occurring in NMOSD may lead to increased delay in diagnosis and appropriate treatment.

OBJECTIVES

The aim of this study was to assess the frequency and characteristics of STM in Chinese patients with NMOSD.

METHODS

We enrolled 91 patients with NMOSD based on the 2015 International Consensus Diagnostic Criteria for NMOSD. The patients were divided into STM group and longitudinally extensive transverse myelitis (LETM) group according to the length of initial spinal cord lesions at the initial myelitis manifestation of NMOSD.

RESULTS

Initial STM was observed in 18 patients (18/91, 19.8%). The STM episode was the first manifestation of NMOSD in 9 patients (50%) and preceded by optic neuritis in 3 patients (16.7%), area postrema syndrome in 5(27.8%) and brainstem syndrome in 1(5.6%). Compared to the NMOSD patients with an initial LETM, patients with STM suffered less motor and bowel or bladder disability, had minor EDSS at clinical onset, but suffered earlier relapse (P＜.05). Thirteen patients had single short spinal lesion (13/18, 72.2%) and 5 patients had two short lesions. Of the 23 STM lesions, 4 lesions spanned 2.5 vertebral segments, 12 showed a length of continuous 2 vertebral segments, 7 were confined to single vertebral segment. The lesions on axial imaging involved the central grey matter in 61.1% (11/18) patients with STM and in 95.9%（70/73）patients with LETM (P＜.05). Both the patients with STM（50%）and LETM (34.2%) had brain lesions.

CONCLUSIONS

Initial STM does not exclude consideration of NMOSD diagnosis.

Neuromyelitis Optica

Neuromyelitis optica (NMO), formerly known as Devic disease, is an autoimmune astrocytopathic disease characterized by transverse myelitis and optic neuritis. Most patients demonstrate a relapsing course with incomplete recovery between attacks, resulting in progressive disability. The pathogenesis involves production of aquaporin-4 antibodies (AQP4-IgG) by plasmablasts in peripheral circulation, disruption of the blood-brain barrier, complement-mediated astrocyte injury, and secondary demyelination. The diagnosis relies on characteristic clinical manifestations in the presence of serum AQP4-IgG positivity or specific neuroimaging findings, and exclusion of alternative etiologies. Current treatment involves aggressive immunosuppression with pulse-dose steroids during acute attacks and long-term immunosuppression for attack prevention.

Magnetic Resonance Imaging and Clinical Features in Acute and Subacute Myelopathies

Differential diagnosis of acute and subacute transverse myelopathy includes inflammatory, infectious, vascular, metabolic and paraneoplastic etiologies. Information on the diagnostic approach to transverse myelopathy with regard to daily clinical practice is provided. The differentiation between five lesion patterns on magnetic resonance imaging (MRI) in myelitis may be helpful: (1) longitudinal extensive transverse myelitis, (2) short segment ovoid or peripherally located, (3) "polio-like", (4) granulomatous and (5) segmental with rash. A correlation with these imaging features is supported if the clinical course and neurological symptoms are known. Although the mean interval from onset to nadir of symptoms in spinal cord infarction is 1 h, an overlap with a fulminant course of myelitis is possible, and impaired diffusion may also occur in acute inflammatory processes. As a result, laboratory testing, including aquaporin-4 antibodies and cerebrospinal fluid analysis, is crucial for the correct interpretation of imaging findings. Moreover, the discrimination of acute complete and acute partial transverse myelitis is advantageous in order to identify diverse entities, the latter often being a precursor to multiple sclerosis. Additional brain imaging is mandatory in suspected demyelinating, infectious, neoplastic and systemic autoimmune disease. A symmetrical lesion pattern restricted to individual tracts or dorsal columns indicates subacute combined degeneration of the spinal cord and, in addition to deficiency syndromes, a paraneoplastic etiology should be considered.

Cervical cord myelin water imaging shows degenerative changes over one year in multiple sclerosis but not neuromyelitis optica spectrum disorder

Spinal cord pathology is a feature of both neuromyelitis optica spectrum disorder (NMOSD) and relapsing-remitting multiple sclerosis (MS). While subclinical disease activity has been described in MS using quantitative magnetic resonance imaging measures, current evidence suggests that neurodegeneration is absent between relapses in NMOSD, although most evidence comes from brain studies. We aimed to assess cross-sectional differences and longitudinal changes in myelin integrity in relapse-free MS and NMOSD subjects over one year. 15 NMOSD, 15 MS subjects, and 17 healthy controls were scanned at 3 T using a cervical cord mcDESPOT protocol. A subset of 8 NMOSD, 11 MS subjects and 14 controls completed follow-up. Measures of the myelin water fraction (f_M) within lesioned and non-lesioned cord segments were collected. At baseline, f_M in lesioned and non-lesioned segments was significantly reduced in MS (lesioned: p = 0.002; non-lesioned: p = 0.03) and NMOSD (lesioned: p = 0.0007; non-lesioned: p = 0.002) compared to controls. Longitudinally, f_M decreased within non-lesioned cord segments in the MS group (− 7.3%, p = 0.02), but not in NMOSD (+ 5.8%, p = 0.1), while change in lesioned segments f_M did not differ from controls' in either patient group. These results suggest that degenerative changes outside of lesioned areas can be observed over a short time frame in MS, but not NMOSD, and support the use of longitudinal myelin water imaging for the assessment of pathological changes in the cervical cord in demyelinating diseases.

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MS and NMOSD subjects underwent longitudinal cervical cord myelin water imaging.

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Reduced myelin water fraction in MS and NMOSD normal-appearing and lesioned areas

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Decrease in myelin in normal-appearing tissue over 1 year in MS, but not NMOSD

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Further evidence that disease progression is absent between relapses in NMOSD.

Comparative molecular dynamics study of neuromyelitis optica-immunoglobulin G binding to aquaporin-4 extracellular domains

Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system in which most patients have serum autoantibodies (called NMO-IgG) that bind to astrocyte water channel aquaporin-4 (AQP4). A potential therapeutic strategy in NMO is to block the interaction of NMO-IgG with AQP4. Building on recent observation that some single-point and compound mutations of the AQP4 extracellular loop C prevent NMO-IgG binding, we carried out comparative Molecular Dynamics (MD) investigations on three AQP4 mutants, TP^137-138AA, N¹⁵³Q and V¹⁵⁰G, whose 295-ns long trajectories were compared to that of wild type human AQP4. A robust conclusion of our modeling is that loop C mutations affect the conformation of neighboring extracellular loop A, thereby interfering with NMO-IgG binding. Analysis of individual mutations suggested specific hydrogen bonding and other molecular interactions involved in AQP4-IgG binding to AQP4.

Ring-enhancing spinal cord lesions in neuromyelitis optica spectrum disorders

OBJECTIVE

We assessed the frequency and characteristics of ring-enhancing spinal cord lesions in neuromyelitis optica spectrum disorder (NMOSD) myelitis and myelitis of other cause.

METHODS

We reviewed spinal cord MRIs for ring-enhancing lesions from 284 aquaporin-4 (AQP4)-IgG seropositive patients at Mayo Clinic from 1996 to 2014. Inclusion criteria were as follows: (1) AQP4-IgG seropositivity, (2) myelitis attack and (3) MRI spinal cord demonstrating ring-enhancement. We identified two groups of control patients with: (1) longitudinally extensive myelopathy of other cause (n=66) and (2) myelitis in the context of a concurrent or subsequent diagnosis of multiple sclerosis (MS) from a population-based cohort (n=30).

RESULTS

Ring-enhancement was detected in 50 of 156 (32%) myelitis episodes in 41 patients (83% single; 17% multiple attacks). Ring-enhancement was noted on sagittal and axial images in 36 of 43 (84%) ring enhancing myelitis episodes and extended a median of two vertebral segments (range, 1-12); in 21 of 48 (44%) ring enhancing myelitis episodes, the ring extended greater than or equal to three vertebrae. Ring-enhancement was accompanied by longitudinally extensive (greater than or equal to three vertebral segments) T2-hyperintensity in 44 of 50 (88%) ring enhancing myelitis episodes. One case of a spinal cord biopsy during ring-enhancing myelitis revealed tissue vacuolation and loss of AQP4 immunoreactivity with preserved axons. The clinical characteristics of ring-enhancing myelitis episodes did not differ from non-ring-enhancing episodes. Ring-enhancing spinal cord lesions were more common in NMOSD than other causes of longitudinally extensive myelopathy (50/156 (32%) vs 0/66 (0%); p≤0.001) but did not differ between NMOSD and MS (50/156 (32%) vs 6/30 (20%); p=0.20).

CONCLUSIONS

Spinal cord ring-enhancement accompanies one-third of NMOSD myelitis episodes and distinguishes NMOSD from other causes of longitudinally extensive myelopathies but not from MS.

Human Aquaporin-4 and Molecular Modeling: Historical Perspective and View to the Future

Among the different aquaporins (AQPs), human aquaporin-4 (hAQP4) has attracted the greatest interest in recent years as a new promising therapeutic target. Such a membrane protein is, in fact, involved in a multiple sclerosis-like immunopathology called Neuromyelitis Optica (NMO) and in several disorders resulting from imbalanced water homeostasis such as deafness and cerebral edema. The gap of knowledge in its functioning and dynamics at the atomistic level of detail has hindered the development of rational strategies for designing hAQP4 modulators. The application, lately, of molecular modeling has proved able to fill this gap providing a breeding ground to rationally address compounds targeting hAQP4. In this review, we give an overview of the important advances obtained in this field through the application of Molecular Dynamics (MD) and other complementary modeling techniques. The case studies presented herein are discussed with the aim of providing important clues for computational chemists and biophysicists interested in this field and looking for new challenges.

Early and extensive spinal white matter involvement in neuromyelitis optica

OBJECTIVES

Studies of longitudinally extensive spinal cord lesions (LESCLs) in neuromyelitis optica (NMO) have focused on gray matter, where the relevant antigen, aquaporin-4 (AQP4), is abundant. Because spinal white matter pathology in NMO is not well characterized, we aimed to clarify spinal white matter pathology of LESCLs in NMO.

METHODS

We analyzed 50 spinal cord lesions from eleven autopsied NMO/NMO spectrum disorder (NMOSD) cases. We also evaluated LESCLs with three or fewer spinal cord attacks by 3-tesla MRI in 15 AQP4 antibody-positive NMO/NMOSD patients and in 15 AQP4 antibody-negative multiple sclerosis (MS) patients.

RESULTS

Pathological analysis revealed seven cases of AQP4 loss and four predominantly demyelinating cases. Forty-four lesions from AQP4 loss cases involved significantly more frequently posterior columns (PC) and lateral columns (LC) than anterior columns (AC) (59.1%, 63.6%, and 34.1%, respectively). The posterior horn (PH), central portion (CP), and anterior horn (AH) were similarly affected (38.6%, 36.4% and 31.8%, respectively). Isolated perivascular inflammatory lesions with selective loss of astrocyte endfoot proteins, AQP4 and connexin 43, were present only in white matter and were more frequent in PC and LC than in AC (22.7%, 29.5% and 2.3%, P^corr  = 0.020, and P^corr  = 0.004, respectively). MRI indicated LESCLs more frequently affected PC and LC than AC in anti-AQP4 antibody-seropositive NMO/NMOSD (86.7%, 60.0% and 20.0%, P^corr  = 0.005, and P^corr  = 0.043, respectively) and AQP4 antibody-seronegative MS patients (86.7%, 73.3% and 33.3%, P^corr  = 0.063, and P^corr  = 0.043, respectively). PH, CP and AH were involved in 93.3%, 86.7% and 73.3% of seropositive patients, respectively, and in 53.3%, 60.0% and 40.0% of seronegative patients, respectively.

CONCLUSIONS

NMO frequently and extensively affects spinal white matter in addition to central gray matter, especially in PC and LC, where isolated perivascular lesions with astrocyte endfoot protein loss may emerge. Spinal white matter involvement may also appear in early NMO, similar to cerebral white matter lesions.

Acute Respiratory Failure due to Neuromyelitis Optica Treated Successfully with Plasmapheresis

Neuromyelitis Optica (NMO) is a demyelinating autoimmune disease involving the central nervous system. Acute respiratory failure from cervical myelitis due to NMO is known to occur but is uncommon in monophasic disease and is treated with high dose steroids. We report a case of a patient with NMO who developed acute respiratory failure related to cervical spinal cord involvement, refractory to pulse dose steroid therapy, which resolved with plasmapheresis.

Differentiating neuromyelitis optica from other causes of longitudinally extensive transverse myelitis on spinal magnetic resonance imaging

BACKGROUND

Although spinal magnetic resonance imaging (MRI) findings of neuromyelitis optica (NMO) have been described, there is limited data available that help differentiate NMO from other causes of longitudinally extensive transverse myelitis (LETM).

OBJECTIVE

To investigate the spinal MRI findings of LETM that help differentiate NMO at the acute stage from multiple sclerosis (MS) and other causes of LETM.

METHODS

We enrolled 94 patients with LETM into our study. Bright spotty lesions (BSL), the lesion distribution and location were evaluated on axial T2-weighted images. Brainstem extension, cord expansion, T1 darkness and lesion enhancement were noted. We also reviewed the brain MRI of the patients during LETM.

RESULTS

Patients with NMO had a greater amount of BSL and T1 dark lesions (p < 0.001 and 0.003, respectively). The lesions in NMO patients were more likely to involve greater than one-half of the spinal cord's cross-sectional area; to enhance and be centrally-located, or both centrally- and peripherally-located in the cord. Of the 62 available brain MRIs, 14 of the 27 whom were NMO patients had findings that may be specific to NMO.

CONCLUSIONS

Certain spinal cord MRI features are more commonly seen in NMO patients and so obtaining brain MRI during LETM may support diagnosis.

Differential Diagnosis of Acute Myelopathies: An Update

Appropriate description may lead to adequate diagnostic and therapeutic measures, and therefore, a simple scheme to categorize and term the imaging findings of acute myelopathy is suggested based on current literature. Assigning imaging findings to five groups, that is (a) "segmental with rash," (b) "poliolike," (c) "granulomatous-nodular," (d) "longitudinally extensive transverse myelitis," (e) "short-segment ovoid or peripherally located," provides a rationale to lessen differential diagnoses. The key for understanding, proper description and differential diagnosis is the correlation of two time points: When did the first symptoms appear and when did imaging take place? Early infarction within the first 24 h will show neither swelling nor enhancement.

Predictive value of MRI parameters in severity and recovery of first-episode myelitis in aquaporin-4 antibody disease

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) associated with aquaporin-4 antibodies (AQP4-Ab) typically causes longitudinally-extensive transverse myelitis (LETM). Few data exist about the association of MRI features with LETM attack severity and recovery.

METHODS

AQP4-Ab positive NMOSD patients with a first myelitis attack were retrospectively identified and spinal MRI scans reviewed. Association of MRI features with EDSS scores at attack nadir and recovery was evaluated.

RESULTS

22 patients were included. Median nadir EDSS score was 8 (range 1 to 8.5). Nadir EDSS scores correlated with total MRI lesion length (r=0.48, p=0.025), higher scores were seen in those with gadolinium enhancement (p=0.025) and there was a trend towards higher scores with central cord involvement. The median recovery EDSS was 6 (range 0 to 10). Total lesion length correlated with poor recovery (r=0.48, p=0.027) but this was confounded by correlation between nadir and recovery EDSS scores.

CONCLUSION

We confirm that myelitis in AQP4-Ab disease is severe and show that the severity correlates with lesion length and residual disability. Spinal cord lesions in first myelitis attacks are similar to appearances reported later in the disease course, with propensity to involve the central grey matter and high frequency of cord oedema and T1 hypointensity.

Reduction in serum aquaporin-4 antibody titers during development of a tumor-like brain lesion in a patient with neuromyelitis optica: a serum antibody-consuming effect?

Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the CNS with severe involvement of the optic nerve and spinal cord. Highly specific serum IgG autoantibodies (NMO-IgG) that react with aquaporin-4 (AQP4), the most abundant CNS water channel protein, are found in patients with NMO. However, in vivo evidence combining the results of AQP4 antibody serum levels and brain pathology is lacking. We report a patient with NMO whose AQP4 antibody levels decreased simultaneously with clinical deterioration caused by the development of a tumor-like brain lesion. In the seminecrotic biopsied brain lesion, there was activated complement complex, whereas only very scattered immunoreactivity to AQP4 protein was detectable. The decrease in serum AQP4 antibody levels and the loss of AQP4 in the tumor-like lesion could represent a "serum antibody-consuming effect" during lesion formation.

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 recognition of more diverse clinical spectrum of manifestations. Brain MRI abnormalities in patients seropositive for anti-aquaporin-4 antibody are common and some may be relatively unique by virtue of localization and configuration. Some seropositive patients present with brain involvement during their first attack and/or continue to relapse in the same location without optic nerve and spinal cord involvement. Thus, characteristics of brain abnormalities in such patients have become of increased interest. In this regard, MRI has an increasingly important role in the differential diagnosis of NMO and its spectrum disorder (NMOSD), particularly from multiple sclerosis. Differentiating these conditions is of prime importance because early initiation of effective immunosuppressive therapy is the key to preventing attack-related disability in NMOSD, whereas some disease-modifying drugs for multiple sclerosis may exacerbate the disease. Therefore, identifying the MRI features suggestive of NMOSD has diagnostic and prognostic implications. We herein review the brain, optic nerve, and spinal cord MRI findings of NMOSD.

Overlapping CNS inflammatory diseases: differentiating features of NMO and MS

Neuromyelitis optica (NMO) has long been considered as a variant of multiple sclerosis (MS) rather than a distinct disease. This concept changed with the discovery of serum antibodies (Ab) against aquaporin-4 (AQP4), which unequivocally differentiate NMO from MS. Patients who test positive for AQP4-Abs and present with optic neuritis (ON) and transverse myelitis (TM) are diagnosed with NMO and those who show an incomplete phenotype with isolated ON or longitudinally extensive TM (LETM) or less commonly brain/brainstem disease are referred to as NMO spectrum disorders (NMOSD). However, many patients, who have overlapping features of both NMO and MS, test negative for AQP4-Abs and may be difficult to definitively diagnose. This raises important practical issues, since NMO and MS respond differently to immunomodulatory treatment and have different prognoses. Here we review distinct features of AQP4-positive NMO and MS, which might then be useful in the diagnosis of antibody-negative overlap syndromes. We identify discriminators, which are related to demographic data (non-white origin, very late onset), clinical features (limited recovery from ON, bilateral ON, intractable nausea, progressive course of disability), laboratory results (cerebrospinal fluid (CSF) pleocytosis with eosinophils and/or neutrophils, oligoclonal bands, glial fibrillary acidic protein in the CSF) and imaging (LETM, LETM with T1 hypointensity, periependymal brainstem lesions, perivenous white matter lesions, Dawson's fingers, curved or S-shaped U-fibre juxtacortical lesions). We review the value of these discriminators and discuss the compelling need for new diagnostic markers in these two autoimmune demyelinating diseases of the central nervous system.

High-Resolution Spectral Domain-Optical Coherence Tomography in Multiple Sclerosis, Part II - the Total Macular Volume. The First Follow-Up Study over 2 Years

Background: Recent studies investigating the use of optical coherence tomography (OCT) in multiple sclerosis (MS) patients have resulted in wide-ranging and often contradictory outcomes. This is mainly due to the complex etiology and heterogeneity of MS, physiological variations in the retinal nerve fiber layer (RNFL) and/or total macular volume (TMV), and limitations in methodology. It remains to be discovered whether any retinal changes in MS develop continuously or in a stepwise fashion, and whether these changes occur in all or a subset of patients. High-resolution spectral domain-OCT devices (SD-OCT) would be required to detect subtle retinal changes and longitudinal studies would have to be carried out to investigate retinal changes over time. In addition, if the hypothesis is correct, then retinal and global brain tissue changes should be detected in a substantial majority of MS patients and detection should be possible with a high degree of disease activity and/or long disease course.

Methodology: In order to address the factors above, 37 MS patients (relapsing–remitting, n = 27; secondary progressive, n = 10) were examined prospectively on two occasions with a median interval of 22.4 ± 0.5 months [range 19–27]. SD-OCT was utilized with the Spectralis 3.5 mm circle scan protocol (with locked reference images and eye-tracking mode). None of the patients had optic neuritis 12 months prior to study entry or during the observation period.

Principal Findings: The initial TMV pattern differed between study participants, but remained relatively unchanged over the 2-year observation period despite high disease activity or long disease course. The TMV correlated well with the RNFL.

Conclusion: The significance of differences in TMV (and RNFL) between study participants remains unclear. Until these differences have been explored further, OCT data in MS patients should be interpreted with caution.

Differentiation of neuromyelitis optica from multiple sclerosis on spinal magnetic resonance imaging

In order to examine the accuracy of magnetic resonance imaging (MRI)-based diagnosis of neuromyelitis optica (NMO) versus multiple sclerosis (MS), we performed a retrospective, rater-blinded review of 29 cases of NMO and 30 cases of MS using the criteria of long (more than three vertebral levels), continuous lesions with a central cord location for NMO and more peripheral and patchy lesions for MS. Using these criteria, two raters were able to distinguish the two conditions with a good degree of confidence, particularly when the imaging was performed at the time of an acute cord attack. The sensitivity and specificity for diagnosis of NMO were 86.2% and 93.3%, respectively, for Rater A and 96.4% and 78.6%, respectively, for Rater B, with a kappa value of 0.72. Thus there are significant differences in lesion characteristics that allow the distinction on spinal cord imaging between MS and NMO with a moderately high degree of confidence. The location of the lesion as evident on MRI of the spine can be regarded as a distinguishing diagnostic feature between MS and NMO.

Update on the diagnosis and treatment of neuromyelitis optica: recommendations of the Neuromyelitis Optica Study Group (NEMOS)

Neuromyelitis optica (NMO, Devic’s syndrome), long considered a clinical variant of multiple sclerosis, is now regarded as a distinct disease entity. Major progress has been made in the diagnosis and treatment of NMO since aquaporin-4 antibodies (AQP4-Ab; also termed NMO-IgG) were first described in 2004. In this review, the Neuromyelitis Optica Study Group (NEMOS) summarizes recently obtained knowledge on NMO and highlights new developments in its diagnosis and treatment, based on current guidelines, the published literature and expert discussion at regular NEMOS meetings. Testing of AQP4-Ab is essential and is the most important test in the diagnostic work-up of suspected NMO, and helps to distinguish NMO from other autoimmune diseases. Furthermore, AQP4-Ab testing has expanded our knowledge of the clinical presentation of NMO spectrum disorders (NMOSD). In addition, imaging techniques, particularly magnetic resonance imaging of the brain and spinal cord, are obligatory in the diagnostic workup. It is important to note that brain lesions in NMO and NMOSD are not uncommon, do not rule out the diagnosis, and show characteristic patterns. Other imaging modalities such as optical coherence tomography are proposed as useful tools in the assessment of retinal damage. Therapy of NMO should be initiated early. Azathioprine and rituximab are suggested as first-line treatments, the latter being increasingly regarded as an established therapy with long-term efficacy and an acceptable safety profile in NMO patients. Other immunosuppressive drugs, such as methotrexate, mycophenolate mofetil and mitoxantrone, are recommended as second-line treatments. Promising new therapies are emerging in the form of anti-IL6 receptor, anti-complement or anti-AQP4-Ab biologicals.

Neuromyelitis optica in Austria in 2011: to bridge the gap between neuroepidemiological research and practice in a study population of 8.4 million people

BACKGROUND

In 2008 the Austrian Task Force for Neuromyelitis Optica (NMO) started a nation-wide network for information exchange and multi-centre collaboration. Their aim was to detect all patients with NMO or NMO spectrum disorders (NMO-SD) in Austria and to analyse their disease courses and response to treatment.

METHODS

(1) As of March 2008, 1957 serum samples (of 1557 patients) have been tested with an established cell based immunofluorescence aquaporin-4 antibody (AQP4-ab) assay with a high sensitivity and specificity (both >95%). All tests were performed in a single reference laboratory (Clinical Dept. of Neurology of the Innsbruck Medical University). (2) A nation-wide survey with several calls for participation (via email newsletters, articles in the official journal of the Austrian Society of Neurology, and workshops) was initiated in 2008. All collected data will be presented in a way that allows that every individual patient can be traced back in order to ensure transparency and to avoid any data distortion in future meta-analyses. The careful and detailed presentation allows the visualization and comparison of the different disease courses in real time span. Failure and response to treatment are made visible at one glance. Database closure was 31 December 2011. All co-operators were offered co-authorship.

RESULTS

All 71 NMO- or NMO-SD patients with AQP4-ab positivity (age range 12.3 to 79.6 years) were analysed in detail. Sex ratio (m:f = 1:7) and the proportion of patients without oligoclonal bands in cerebrospinal fluid (86.6%) were in line with previously published results. All identified patients were Caucasians.

CONCLUSIONS

A nationwide collaboration amongst Austrian neurologists with good network communications made it possible to establish a database of 71 AQP4-ab positive patients with NMO/NMO-SD. This database is presented in detail and provides the basis for further studies and international cooperation in order to investigate this rare disease.

Relapsing Devic's disease in a child

Neuromyelitis optica (NMO) also named Devic's disease is an acute demyelinating disorder that primarily affects the spinal cord and optic nerves. NMO can occur rarely in children but pediatric NMO cases need specific consideration owing to possible poor visual and motor outcome. In this case report, a NMO case of a 10-year-old girl with bilateral optic neuritis, cerebral, and spinal cord involvement is presented.

Monitoring neuromyelitis optica activity

Neuromyelitis optica (NMO) is a demyelinating and inflammatory disease essentially restricted to the spinal cord and the optic nerves. Emerging evidence indicates that serum antiaquaporin-4 (AQP4) antibodies have a critical role in its pathogenesis. NMO courses with multiple relapses, often leading to severe disability. Management of NMO focuses on the effective treatment of acute attacks and the prevention of relapses. The latter is currently attempted with immunosuppressive drugs. Although several factors have been associated with disease activity, especially serum levels of anti-AQP4 IgG, no single one of them has been proved clinically useful for guiding treatment. New drugs that target specifically AQP4 antibodies and complement activation are being developed; they may prove to be more efficient with fewer side effects.

“Bright spotty lesions” on spinal magnetic resonance imaging differentiate neuromyelitis optica from multiple sclerosis

Background:

Spinal magnetic resonance imaging (MRI) finding of longitudinally extensive spinal cord lesions (LESCL) extending over three vertebral segments and involvements of spinal central gray matter have been reported in patients with neuromyelitis optica (NMO).

Objectives:

We aimed to review spinal MRI findings in NMO and multiple sclerosis (MS), and to determine whether the “bright spotty lesions” (BSLs) are a discriminative finding of NMO.

Methods:

For this study, 24 consecutive patients with NMO and 34 patients with MS were enrolled. BSLs were defined as very hyperintense spotty lesions on axial T2WI. We also studied the length, distribution, signal homogeneity, size, and presence of contrast-enhanced lesions.

Results:

BSLs were more frequently found in patients with NMO (54%) than in those with MS (3%; p < 0.01). LESCL were found in 67% of the NMO patients. BSLs were seen in 63% of the patients without LESCL. BSLs or LESCL were found in 88% of the NMO patients. Inhomogeneous lesions, transversally extensive lesions, and central lesions were more frequently seen in NMO than in MS.

Conclusions:

BSLs are a newly defined spinal MRI finding specifically seen in NMO. In combination with LESCL, BSLs can help differentiate patients with NMO from those with MS with higher sensitivity than LESCL alone.

Neuromyelitis optica mimicking intramedullary tumor

Neuromyelitis optica (NMO) is considered to be a rarer autoimmune disease than multiple sclerosis. It is very difficult to make a diagnosis of MNO for doctors who are not familiar with its clinical features and diagnostic criteria. We report a case of a young female patient who had been suffering motor weakness and radiating pain in both upper extremities. Cervical MRI showed tumorous lesion in spinal cord and performed surgery to remove lesion. We could not find a tumor mass in operation field and final diagnosis was NMO. NMO must be included in the differential diagnosis of lesions to rescue the patient from invasive surgical interventions. More specific diagnostic tools may be necessary for early diagnosis and proper treatment.

Modifications of longitudinally extensive transverse myelitis and brainstem lesions in the course of neuromyelitis optica (NMO): a population-based, descriptive study

BACKGROUND

Neuromyelitis optica (NMO) includes transverse myelitis, optic neuritis and brain lesions. Recent studies have indicated that the brainstem is an important site of attack in NMO. Longitudinally extensive transverse myelitis (LETM) is an important component of the clinical diagnosis of NMO. The frequency of brainstem and LETM lesions, changes over time of LETM and the clinical consequences in the course of NMO have only been sparsely studied.

METHODS

The study was a population-based retrospective case series with clinical and magnetic resonance imaging (MRI) follow-up of 35 patients with definite NMO and a relapsing-remitting course.

RESULTS

Brainstem lesions were observed in 25 patients, 18 in medulla oblongata (11 in area postrema). Lesions in the pons, mesencephalon and diencephalon occurred in 10, 7 and 7 patients, respectively. Lesions were symptomatic in medulla oblongata and pons, asymptomatic in mesencephalon and diencephalon. Brainstem lesions were observed significantly more often in anti-aquaporin-4 (AQP-4) antibody positive than in seronegative patients (p < 0.002).LETM was demonstrated by MRI of the spinal cord in 30/36 patients, 23/30 of whom had follow-up MRI of the spinal cord. Recurrent LETM was observed in five patients. In nine patients the LETM changed into multiple lesions during remission or treatment. Spinal cord atrophy was observed in 12/23 (52%) patients, correlating to Expanded Disability Status Scale (r = 0.88, p < 0.001).

CONCLUSIONS

NMO patients had frequent occurrence of brainstem lesions and LETM. Brainstem lesions were associated with anti-AQP4 antibody positivity. LETM lesions differentiated over time and the outcome included relapses, fragmentation and atrophy. Correlation was observed between spinal cord atrophy and neurological disability.