Clinically isolated syndromes suggestive of multiple sclerosis, part 2: non-conventional MRI, recovery processes, and management

The onset of multiple sclerosis (MS) in 85% of young adults is with a subacute clinically isolated syndrome (CIS) of the optic nerves, brainstem, or spinal cord. Whereas multifocal brain lesions are present on MRI in many patients with a CIS, some patients have additional abnormalities on quantitative MRI in otherwise normal-appearing white and grey matter that suggest an extensive pathological process. Functional outcome for patients with symptomatic CIS lesions is determined by the interplay of inflammation, demyelination, axonal damage, remyelination, and cortical adaptation. Recovery of function may be accelerated by high dose corticosteroids, and although interferon beta delays the development of a second relapse, its long-term effect is unknown. A better understanding of pathological and pathogenetic processes in patients with a CIS will facilitate the development of disease-modifying treatments for patients with MS before they become disabled. Continued clinical and laboratory investigation of patients with a CIS should be encouraged.     

Clinically isolated syndromes and the relationship to multiple sclerosis

The most common presentation of multiple sclerosis (MS) is with a clinically isolated syndrome (CIS) affecting the optic nerves, brainstem or spinal cord. Two thirds of patients with CIS will have further episodes of neurological dysfunction and convert to relapsing-remitting MS, while the remaining patients have a monophasic illness, at least clinically. Abnormalities on a baseline MRI scan predict the subsequent development of MS in patients with CIS. In the long term, about 80% of patients with an abnormal MRI convert to MS compared with 20% with a normal MRI. For patients who develop MS the long term prognosis is varied. After 20 years, almost half will have developed secondary progressive MS, while around one third have a benign disease course with little physical disability. Disease-modifying treatments delay conversion to MS in selected CIS patients with abnormal MRI but an effect on long term disability has not been demonstrated. In this review we discuss recent advances in the diagnosis, management and prognostication of patients with CIS.     

Clinically isolated syndromes

Clinically isolated syndrome (CIS) is a term that describes a first clinical episode with features suggestive of multiple sclerosis (MS). It usually occurs in young adults and affects optic nerves, the brainstem, or the spinal cord. Although patients usually recover from their presenting episode, CIS is often the first manifestation of MS. The most notable risk factors for MS are clinically silent MRI lesions and CSF oligoclonal bands; weak or uncertain risk factors include vitamin D deficiency, Epstein-Barr virus infection, smoking, HLA genes, and miscellaneous immunological abnormalities. Diagnostic investigations including MRI aim to exclude alternative causes and to define the risk for MS. MRI findings incorporated into diagnostic criteria in the past decade enable MS to be diagnosed at or soon after CIS presentation. The course of MS after CIS is variable: after 15-20 years, a third of patients have a benign course with minimal or no disability and a half will have developed secondary progressive MS with increasing disability. Prediction of the long-term course at disease onset is unreliable. Disease-modifying treatments delay the development from CIS to MS. Their use in CIS is limited by uncertain long-term clinical prognosis and treatment benefits and adverse effects, although they have the potential to prevent or delay future tissue damage, including demyelination and axonal loss. Targets for future therapeutic progress are to achieve safe and effective long-term immunomodulation with neuroprotection and repair.     

Monthly brain magnetic resonance imaging scans in patients with clinically isolated syndrome

We investigated if monthly gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) can assist the clinician in anticipating the diagnosis of multiple sclerosis (MS) in the very first few months following a clinically isolated syndrome (CIS). A consecutive series of CIS patients with > or = 3 T2-weighted (T2W) hyperintense brain MRI lesions suggestive of MS were followed up for the first six consecutive months after enrollment with monthly triple-dose Gd-enhanced brain MRI scan. MRI conversion to MS was defined by the presence of either > or = 1 new Gd-enhancing lesion or > or = 1 new T2W lesions in the subsequent MRI scan. Sixty patients were included. Of them, 30 (50%) had at least one Gd-enhancing lesion on the baseline MRI scan. After three months, MRI conversion to MS was observed in 80% and 62% of patients based on the appearance of > or = 1 new T2 lesion and > or = 1 new Gd-enhancing lesions, respectively. The presence of > or = 1 new T2W lesion was observed in 90% and 82% of patients who had, at baseline, a Gd-positive MRI scan and dissemination in space based on the new McDonald's criteria, respectively The rate of MRI conversion remained almost stable in the last two MRI scans. Our study suggests that the majority of CIS patients with an abnormal baseline scan showed an MRI conversion to MS after three months. The model of six months as the optimal interval for repeating MRI exam is not supported by the present data.     

Polyregional and hemispheric syndromes: a study of these uncommon first attacks in a CIS cohort

Clinically isolated syndromes (CIS) classically refer to optic neuritis (ON), brainstem or spinal cord syndromes. Less common first episodes suggestive of central nervous system (CNS) demyelination, such as hemispheric or clinically polyregional syndromes, have been only slightly studied. The aim of this study was to describe these CIS topographies in our cohort of patient with a CIS. We evaluated 320 patients with a CIS, and classified the topographies of the attacks according to clinical symptoms only into CIS of the optic nerve (123), brainstem (78), spinal cord (89), hemispheric (6), polyregional (12) or undetermined (12) topographies. Patients underwent brain MRI within three months of their first attack, and again 12 months later. Conversion to multiple sclerosis (MS), determined either clinically or by magnetic resonance imaging (MRI), was evaluated according to topography. Hemispheric and polyregional syndromes were closer to brainstem or spinal cord syndromes than ON in clinical and MRI conversion terms, although a statistical analysis was not performed because of the small number of patients. There are differences between several studies in the definition, and, therefore, the prevalence of these so-called atypical CIS. Consensus on the denomination and definition of these syndromes must be reached.     

Correlation of clinical,magnetic resonance imaging,and cerebrospinal fluid findings in optic neuritis

We found 42 of 74 patients (57%) with isolated monosymptomatic optic neuritis to have 1 to 20 brain lesions, by magnetic resonance imaging (MRI). All of the brain lesions were clinically silent and had characteristics consistent with multiple sclerosis (MS). None of the patients had ever experienced neurologic symptoms prior to the episode of optic neuritis. During 5.6 years of follow-up, 21 patients (28%) developed definite MS on clinical grounds. Sixteen of the 21 converting patients (76%) had abnormal MRIs; the other 5 (24%) had MRIs that were normal initially (when they had optic neuritis only) and when repeated after they had developed clinical MS in 4 of the 5. Of the 53 patients who have not developed clinically definite MS, 26 (49%) have abnormal MRIs and 27 (51%) have normal MRIs. The finding of an abnormal MRI at the time of optic neuritis was significantly related to the subsequent development of MS on clinical grounds, but interpretation of the strength of that relationship must be tempered by the fact that some of the converting patients had normal MRIs and approximately half of the patients who did not develop clinical MS had abnormal MRIs. We found that abnormal IgG levels in the cerebrospinal fluid correlated more strongly than abnormal MRIs with the subsequent development of clinically definite MS.     

Assessing the value of spinal cord lesions in predicting development of multiple sclerosis in patients with clinically isolated syndromes

The purpose of this study was to determine the value of spinal cord lesions as a predictive factor for conversion in clinically isolated syndrome (CIS) patients. Patients with CIS and without immunomodulatory treatment were prospectively included. Age at onset, sex, clinical syndrome at onset, oligoclonal bands, and presence, number and location of lesions on brain and spinal MRI were analyzed. Conversion to multiple sclerosis (MS) was the primary endpoint. Cox regression was used to compare outcomes between groups. A total of 75 patients were included: 53 (71%) women, mean age at onset 32.7 years (SD ± 7.5), mean follow-up time 72.5 months (SD ± 9; range 17-104 months). There were 11 (14.6%) patients with one focal spinal cord lesion, while 13 (17%) patients had two or more spinal cord lesions at the first scan during the onset of the disease. Of the 23 patients (30.6%) who converted to clinically definite MS (CDMS), 2 had a normal spinal cord MRI, 8 patients had one spinal cord lesion, and 13 had more than one lesion on MRI (p < 0.001). In multivariable analyses, one focal spinal cord lesion was significantly associated with increased risk of conversion to MS (p = 0.01, HR 3.5, CI 95% 2.1-6.9), while the presence of two or more focal spinal cord lesions was independently associated with a higher risk of conversion to MS (p < 0.001, HR 5.9, CI 95% 3.2-10.8). CIS patients with an abnormal baseline spinal cord MRI have a higher risk for developing clinically definite MS, independent of brain lesions as well as the presence of cerebrospinal fluid oligoclonal banding (OSF-OB) .     

Magnetic resonance imaging findings predicting subsequent disease course in patients at presentation with clinically isolated syndromes suggestive of multiple sclerosis

. This review summarizes the main contributions given by magnetic resonance imaging (MRI) to predict disease evolution in patients at presentation with clinically isolated syndromes (CIS) suggestive of multiple sclerosis (MS). In these patients, the extent of lesions on T2-weighted scans of the brain is a robust predictor of the subsequent development of clinically definite MS (CDMS), moderate to severe disability and new MRI lesions. The risk of developing CDMS in patients with CIS is further increased when some of these lesions are enhancing or when additional lesions are seen on T2-weighted scans of the spinal cord. Recent studies using new MRI techniques have shown that irreversible tissue disruption is an early event in the course of MS and that subtle normal-appearing white matter changes occur in patients with CIS and are associated with an increased risk of developing CDMS. These findings are changing our views of how to monitor early MS evolution and of early MS treatment strategy.     

Is optic neuritis more benign than other first attacks in multiple sclerosis?

Optic neuritis presentations are thought to have a better prognosis. The aim of our study was to compare conversion to multiple sclerosis on the different topographies of CISs. We prospectively evaluated 320 patients with CISs (123 with optic neuritis, 78 with brainstem syndromes, 89 with spinal cord syndromes, and 30 with other topographies) who were observed for a median of 39 months. Patients underwent brain MRI within 3 months of their first attack and again 12 months later. Conversion to multiple sclerosis determined either clinically or by MRI was evaluated according to topography. Baseline MRI was normal in 49.2% of patients with optic neuritis compared with 24% in brainstem syndromes, 24% in spinal cord syndromes, and 18.5% in other syndromes. Optic neuritis behaved differently from the other CISs for lower conversion to clinically definite multiple sclerosis and smaller proportion of patients fulfilling MRI dissemination in space, time, or both. Nevertheless, when only patients with abnormal cranial MRI results at baseline were selected, no differences for clinical or MRI conversion were found. Optic neuritis has a smaller risk for conversion to multiple sclerosis. Nevertheless, MRI at baseline, not CIS topography, appears to be the crucial issue at multiple sclerosis presentation.     

The utility of MRI in suspected MS: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

Advancements in imaging technologies and newly evolving treatments offer the promise of more effective management strategies for MS. Until recently, confirmation of the diagnosis of MS has generally required the demonstration of clinical activity that is disseminated in both time and space. Nevertheless, with the advent of MRI techniques, occult disease activity can be demonstrated in 50 to 80% of patients at the time of the first clinical presentation. Prospective studies have shown that the presence of such lesions predicts future conversion to clinically definite (CD) MS. Indeed, in a young to middle-aged adult with a clinically isolated syndrome (CIS), once alternative diagnoses are excluded at baseline, the finding of three or more white matter lesions on a T2-weighted MRI scan (especially if one of these lesions is located in the periventricular region) is a very sensitive predictor (>80%) of the subsequent development of CDMS within the next 7 to 10 years. Moreover, the presence of two or more gadolinium (Gd)-enhancing lesions at baseline and the appearance of either new T2 lesions or new Gd enhancement on follow-up scans are also highly predictive of the subsequent development of CDMS in the near term. By contrast, normal results on MRI at the time of clinical presentation makes the future development of CDMS considerably less likely.     

Prospective combined brain and spinal cord MRI in clinically isolated syndromes and possible early multiple sclerosis: impact on dissemination in space and time

Background: The diagnosis of multiple sclerosis (MS) is based on dissemination in space (DIS) and time (DIT). The aim of the study was to assess the impact of spinal cord (SC) imaging on the evidence of DIS and DIT. Methods: Thirty‐five treatment‐naive patients with a first clinical symptom suggestive of MS were examined in a 2‐year prospective longitudinal follow‐up assessment. Brain and SC magnetic resonance imaging (MRI), Expanded Disability Status Scale and multiple sclerosis functional composite were analysed at baseline and after 1 and 2 years. Results: At study entry, 21 patients were classified as clinically isolated syndrome suggestive of MS (CIS) and 14 patients as possible early MS. SC lesions were detected at baseline in 14 CIS patients (67%, median: 1.0, enhancing 29%) and in 11 patients with possible early MS (79%, median: 2.0, enhancing 29%). DIS as depicted by additive SC imaging was detected in two additional individuals according to the revised versus the 2001 McDonald criteria. All patients with emerging cord lesions showed new brain lesions. Five individuals developed clinically asymptomatic cord lesions. Conclusions: Spinal cord abnormalities are frequent in CIS patients and in patients with possible early MS. SC imaging slightly improved the establishment of DIS, but had no impact on the evidence of DIT.     

Cognitive dysfunction 24-31 years after isolated optic neuritis

OBJECTIVE: Cognitive dysfunction is common in multiple sclerosis (MS), but long-term data on cognition in patients with clinically isolated syndromes are sparse. METHODS: We determined cognitive functions in 22 patients 44-75 years old diagnosed with optic neuritis 24-31 years earlier but had no further clinical bouts and had not progressed clinically to MS. We used a neuropsychological test battery covering nine cognitive domains. Magnetic resonance imaging (MRI) of the brain had been performed earlier and was normal in six patients and showed two or more white matter abnormalities compatible with demyelinating lesions in 16 patients. RESULTS: On neuropsychological testing, one patient was within normal range on all tests, six subjects showed borderline results, and 15 patients (68%) showed significantly impaired performance in at least one cognitive domain. Seven patients showed significant impairment in two or more domains. Executive function, visuo-spatial ability, and information processing speed were the most frequently affected domains. There was no apparent correlation between MRI findings and cognitive function. CONCLUSIONS: We conclude that cognitive dysfunction is common in patients many years after clinically isolated optic neuritis. Cognitive dysfunction was found even in patients who had no apparent demyelinating lesions on follow-up MRI.     

Spinal cord MRI in clinically isolated optic neuritis

BACKGROUND/METHODS: One hundred and fifteen patients with clinically isolated optic neuritis underwent magnetic resonance imaging (MRI) of the brain and spinal cord within 3 months of the onset of symptoms. RESULTS: Eighty one (70%) patients had brain lesions and 31 (27%) had cord lesions. Cord lesions were seen in 12% with a normal brain MRI, 21% with between one and eight brain lesions, and 45% with nine or more brain lesions. When the new diagnostic criteria for MS were applied, MRI cord imaging used for evidence of dissemination in time and space allowed a diagnosis of MS in only one additional asymptomatic patient at 1 year, two additional asymptomatic patients at 3 years. CONCLUSIONS: Using existing criteria, spinal cord imaging rarely contributes to the diagnosis in patients with clinically isolated optic neuritis.     

Symptomatic retrochiasmal lesions in multiple sclerosis: clinical features, visual evoked potentials, and magnetic resonance imaging.

We have studied 18 patients with relapsing-remitting multiple sclerosis (MS) who had symptomatic visual field defects due to retrochiasmal lesions. In 17, the lesion responsible was identified by magnetic resonance imaging (MRI), computed x-ray tomography (CT), or both. The lesion responsible involved the posterior optic radiations in eight cases, the optic tract and lateral geniculate nucleus in six, and the posterior limb of the internal capsule in three. The prognosis for recovery of the field defect was good; complete recovery occurred in 14 patients, and only two showed no recovery at all. The striking characteristic of the lesions was that most were unusually large; indeed, many were detectable on CT as well as MRI. Half-field asymmetries of either amplitude or latency of the visual evoked potentials (VEPs), consistent with a postchiasmal lesion, were present in only five out of 13 patients acutely. In only three of these did the abnormality persist at follow-up. We conclude that only large postchiasmal lesions are likely to cause symptomatic homonymous field defects in MS, usually characterized by rapid recovery. Hemifield VEPs have a low sensitivity for the detection of postchiasmal as compared with prechiasmal abnormalities.     

Clinical, MRI, CSF and electrophysiological findings in different stages of multiple sclerosis

Effective therapy in the earliest stages of multiple sclerosis (MS) demands early correct diagnosis. Retrospective analysis included 130 patients (90 women) with a median age of 35.5 years, median duration of the disease of 2 years and median EDSS score of 3.0. Twenty-seven patients had clinically isolated syndrome (CIS) suggestive of MS, 66 relapsing-remitting (RR) MS, 19 secondary progressive (SP) MS and 18 primary progressive (PP) MS. The predominant symptoms were sensory in 52% of the patients with CIS compared to 27% in patients with RRMS, whereas they were more often motor in patients with PPMS. Patients with CIS had higher CSF cell counts than patients diagnosed in later stages of the disease and oligoclonal bands were found in 89% of all patients without statistically significant differences between the subgroups. Prolonged latencies of visual evoked potentials (VEP) were found in only 29% of patients with CIS compared to 66% in RRMS, 75% in SPMS and 65% of PPMS patients. Fifty-six percent of patients with CIS, 88% with RRMS, 74% with SPMS and 78% of patients with PPMS fulfilled modified the Barkhof et al. MRI criteria at the time of diagnosis. Patients in early MS often present with sensory symptoms. Brain MRI can be inconclusive in over 40% of patients with CIS but the elevated CSF cell count and positive oligoclonal bands are helpful in establishing the diagnosis of CIS suggestive of MS. In later stages of the disease the combination of clinical features, MRI, prolonged VEP latencies and positive CSF oligoclonal bands secures the correct diagnosis.     

临床孤立综合征转归为视神经脊髓炎的相关因素分析

目的探讨临床孤立综合征(CIS)转归为视神经脊髓炎(NMO)的影响因素。方法收集2004-09-2011-09就诊于作者医院神经内科CIS患者109例。回顾性分析所有患者首次发病时头颅和脊髓MRI特点及临床表现。采用酶联免疫吸附法(ELISA)检测血清水通道蛋白4抗体(AQP4-Ab)水平,另备30份健康者血清作为健康对照组,以高于健康对照组血清AQP4-Ab浓度的均值+3倍标准差者为阳性。结果 (1)随访0.5～7年,中位数为3.0年,四分位数间距为4.6年,转归为NMO 46例,转归为多发性硬化(MS)29例,其余仍是CIS,包括24例脊髓炎,10例视神经炎(ON)。(2)转归为NMO组血清AQP4-Ab水平明显高于MS组、脊髓炎组、ON组和健康对照组(P<0.05)。(3)转归为NMO组AQP4-Ab阳性率为63.03%(29/46),高于转归为MS组的13.79%(4/29)、脊髓炎组的29.17%(7/24)、ON组的20.00%(2/10),差异均有统计学意义(P<0.05)。(4)多因素分析结果提示:AQP4-Ab阳性、NMO颅内典型病灶、脊髓损伤>3个节段、扩展残疾状态量表(EDSS)与CIS转归为NMO有关。结论 AQP4-Ab阳性、NMO颅内典型病灶或者脊髓损伤>3个节段、EDSS评分对预测CIS转归为NMO有临床价值。     

Clinical isolated syndrome: a 3-year follow-up study in China

Objective

To summarize the characteristics of Chinese clinically isolated syndrome (CIS) patients and their 3-year follow-up results. Investigate the relationship between CIS features and clinical outcomes.

Methods

Forty-nine CIS patients were recruited and 42 of them were able to be followed up for a mean of 38 months (range 26-48 months). We recorded baseline features including patient demographics, site of CIS, presence or absence of cerebrospinal fluid (CSF) oligoclonal bands (OCB) and MRI lesions in brain and spinal cord. The incidence of conversion to clinically definite MS (CDMS) or neuromyelitis optica (NMO) after CIS was calculated, and the relationship between baseline features and CDMS was explored. All data were statistically processed with SPSS for Windows Version 11.5.

Results

After a mean follow-up of 38 months, 10/42 patients had converted to CDMS (24%), and one patient had developed definite NMO. The other 31 patients remained in CIS status. A spinal cord syndrome was the initial CIS manifestation in 57% of patients. The conversion rates to MS were 22% (5/23) for patients presenting with a spinal cord syndrome and 27% (3/11) for multi-focal manifestations. The three-year CDMS conversion rates were 70% (7/10) for patients who fulfilled the MRI dissemination in space criteria (2005 revised McDonald) at onset of CIS, while only 9% (3/32) of patients who did not fulfill these criteria converted to CDMS. Females had significantly higher conversion rate than males.

Conclusion

A spinal cord syndrome was the most common initial presentation of our Chinese CIS group. After a mean follow-up of 38 months, the conversion rate to MS was approximately 25%. The 2005 revised McDonald MRI criteria for dissemination in space is a key prognostic factor for conversion to MS in CIS in Chinese patients.     

Longitudinal MRI and neuropsychological assessment of patients with clinically isolated syndrome

Cognitive impairment (CI) may occur in clinically isolated syndrome (CIS) patients. While the relationship between CI and magnetic resonance imaging (MRI) has been investigated extensively in multiple sclerosis (MS), MRI correlates of CI in CIS patients are unknown. To investigate the evolution of CI and to determine brain MRI structural correlates associated with CI in CIS patients. This prospective 24-month observational study examined 81 CIS patients treated with 30 µg of intramuscular interferon beta 1a once a week. MRI acquisition and neuropsychological (NP) assessment were performed at baseline, 6, 12 and 24 months. Participants were tested with Czech-validated version of Minimal Assessment of Cognitive Function in MS battery and MRI measures of lesion activity and burden, and global, tissue-specific and regional brain atrophy were performed. Over 24 months, 36 CIS patients developed clinically definite MS (CDMS). CI was observed in 10 (12.3 %) CIS patients at baseline and at the 24 months follow-up. Eight CIS patients changed their CI status over the follow-up (four improved and four worsened). No significant difference in development of CI was detected between stable CIS patients and those who developed CDMS. In multivariate regression and mixed-effect model analyses, no significant relationship was found between NP and MRI parameters. The lack of significant relationship between MRI metrics and cognition in this group of CIS patients could be attributed to several factors including the cognitive reserve, effect of disease-modifying therapy and relatively short follow-up period.     

A three-year, multi-parametric MRI study in patients at presentation with CIS

OBJECTIVES: To define the extent of overall brain damage in patients with clinically isolated syndromes (CIS) suggestive of multiple sclerosis (MS) and to identify non-conventional magnetic resonance (MR) metrics predictive of evolution to definite MS. METHODS: Brain conventional and magnetization transfer (MT) MRI scans were obtained from 208 CIS patients and 55 matched healthy controls, recruited in four centres. Patients were assessed clinically at the time of MRI acquisition and after a median period of 3.1 years from disease onset. The following measures were derived: T2, T1 and gadolinium (Gd)- enhancing lesion volumes (LV), normalized brain volume (NBV), MTR histogram-derived quantities of the normal-appearing white matter (NAWM) and grey matter (GM). RESULTS: During the follow-up, 43 % of the patients converted to definite MS. At baseline, a significant inter-centre heterogeneity was detected for T2 LV (p = 0.003), T1 LV (p = 0.006), NBV (p < 0.001) and MTR histogram-derived metrics (p < 0.001). Pooled average MTR values differed between CIS patients and controls for NAWM (p = 0.003) and GM (p = 0.01). Gdactivity and positivity of International Panel (IP) criteria for disease dissemination in space (DIS), but not NAWM and GM MTR and NBV, were associated with evolution to definite MS. The final multivariable model retained only MRI IP criteria for DIS (p = 0.05; HR = 1.66, 95 % CI = 1.00-2.77) as an independent predictor of evolution to definite MS. CONCLUSIONS: Although irreversible tissue injury is present from the earliest clinical stages of MS, macroscopic focal lesions but not "diffuse" brain damage measured by MTR are associated to an increased risk of subsequent development of definite MS in CIS patients.     

Evaluation of the 2005 McDonald MRI criteria for dissemination in space in Afro-Caribbean patients with clinically isolated syndromes

Background:  In 2005, the McDonald MRI criteria for dissemination in space were revised to improve diagnosis of multiple sclerosis (MS) in non-Caucasians.
Methods:  We included patients with a first clinically isolated syndrome (CIS) to assess their performance in the Afro-Caribbean population. Baseline brain and spine MRI examinations were available within 3 months after onset of CIS. The development of a second clinical event was used as the main outcome indicating clinically definite MS.
Results:  A total of 66 patients (52F/14M) were included between January 1998 and January 2008 (mean age: 34.7; median follow-up: 34 months). CIS was classified as spinal cord (30.3%), optic neuritis (28.8%), brainstem (24.2%), multiregional (10.6%), hemispheric (4.5%), or undetermined (1.5%). Overall conversion rate was 42.4% (median: 11 months). The McDonald criteria revised for dissemination in space were fulfilled in 33.3% (sensitivity: 0.39 (±0.18); specificity: 0.66 (±0.15), positive predictive value: 0.46 (±0.20), negative predictive value: 0.60 (±0.15).
Conclusion:  The Afro-Caribbean population is characterized by a strong proportion of CIS in the spinal cord and a lower burden of disease on the baseline brain MRI. This may explain the low sensitivity of the 2005 McDonald criteria for dissemination in space. Further prospective studies emphasizing MRI spinal cord features are needed to improve diagnostic criteria in a population of African descent.