Delays in diagnosing multiple sclerosis (MS) persist – even in the very systems designed to prevent them [1]. The third edition of the Atlas of MS by the Multiple Sclerosis International Federation (MSIF) examined healthcare system barriers to MS diagnosis in 107 countries [1]. It found that 80% reported at least one barrier to diagnosis, and 60% reported at least one obstacle to adopting the 2017 McDonald Criteria [1].
Limited resources are a key factor contributing to delays in MS diagnosis across many countries [1]. However, resource limitations are not the only reason for the delayed adoption of the McDonald Criteria [1]. In fact, nearly half of World Bank high/upper middle-income countries reported at least one barrier to adopting the 2017 McDonald Criteria [1]. This suggests that the proposed 2024 revisions should be accompanied by enhanced dissemination and education efforts [1].
Recognising country-specific challenges in MS diagnosis: Thailand´s case
Each country faces its own unique challenges in MS diagnosis, which must be considered when addressing the issue at a global level. In our recent webinar, Dr. Shanthi Viswanathan presented a cross-sectional study conducted in Southeast Asia [2]. All countries in the region reported barriers to early diagnosis and access to treatment. The reasons range from limited epidemiological data and unique disease presentations to shortages in human and technological resources, insufficient education and research capacity, and broader socio-economic factors [2].
To further explore these topics, we spoke with Adjunct Associate Professor Sasitorn Siritho, from Siriraj Hospital, Mahidol University in Thailand. According to the World Bank, Thailand became an upper-middle-income economy in 2011. Professor Siritho specifies, “Thailand is generally classified as an upper-middle-income country, but in rural areas, limited awareness of MS and a shortage of healthcare professionals remain significant challenges.” According to the MSIF Atlas, in Thailand there is a total of 0.01 MS specialist neurologists per 100,000 people.
“Across the country, we have about 865 neurologists serving nearly 72 million people and only less than 10 MS specialist neurologists,” says Prof. Siritho. “Five are based in Bangkok, while the others are spread across all other provinces. Although there are around 15 university-based hospitals in Bangkok, we currently lack access to kappa free light chains (KFLC) and rely solely on testing for oligoclonal bands (OCBs). However, we expect kappa assays to become available in the near future.”
As Professor Ontaneda noted, in the proposed revisions to the McDonald criteria, KFLC index will be considered interchangeable with OCBs, and may be used as a substitute for OCBs in the diagnosis of MS.
In the proposed 2024 McDonald criteria, the optic nerve is the fifth topographic region for demonstrating dissemination in space. “This is great for us,” Says Prof Siritho, “as we have strong collaborations with the ophthalmologists, and access to visual evoked potentials and optical coherence tomography (OCT) will not be an issue – at least in research centres. I am less certain about access in rural areas. Also, the proposed introduction of central vein signs (CVS) is good news.”
The Central Vein Sign (CVS) can improve the specificity of MS diagnosis and can be visualised using susceptibility-weighted imaging (SWI). While it will not be required for the diagnosis of MS – given that SWI may not be universally available – the Select6 approach can support diagnostic confidence. This method involves identifying at least six CVS-positive lesions, or, in cases with fewer than ten lesions, confirming that the majority contain a central vein [3]. CVS may be a very useful tool to facilitate the diagnosis.
“CVS will be relatively easy to capture on magnetic resonance imaging (MRI) as SWI sequences are already included in our protocols,” says Prof Siritho, “In Bangkok, 3 Tesla MRI are available. Again, I am less certain about access in rural areas, but most university-based hospitals across Thailand have access at least to 1.5 Tesla scanners.”
She continues, “There is another important consideration: in the Thai population, neuromyelitis optica spectrum disorders (NMOSD) is the most prevalent inflammatory demyelinating disease of the central nervous system, with a prevalence of 3.33 per 100,000 people. MS follows at 0.77, and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) at 0.51 per 100,000 adults [4]. That is why we must be extremely cautious to avoid misdiagnosis. We need to raise awareness among both the general population and healthcare professionals and increase the number of neurologists – particularly those trained in neuroimmunology – to ensure early and accurate diagnosis of NMOSD and MS.”
Chile: MS diagnosis across a diverse latitudinal and demographic landscape
The prevalence of multiple sclerosis (MS) is still higher in countries farther from the equator – and this trend appears to be getting stronger [5]. In this respect, Chile offers a particularly interesting case, as its 4,270 km length spans a wide range of latitudes.
Professor Ethel Ciampi, from the Pontifical Catholic University of Chile, also serves as a member of the Ministry of Health’s expert committee on MS in Santiago since 2015. She tells us, “In the far south of Chile, there is a significant population of immigrants from Croatia. This group not only experiences lower exposure to vitamin D, but also shows a higher incidence and prevalence of MS.” According to the MSIF Atlas of MS, the prevalence of multiple sclerosis is 144 per 100,000 people in Croatia, compared to 16 per 100,000 in Chile.
“As we move closer to the equator, MS becomes less prevalent,” Prof. Ciampi explains. “As a result, we tend to suspect MS less frequently. Under the proposed 2024 McDonald criteria, MRI will play a more central and supportive role than ever in diagnosing MS. A group of 14 neurologists from 16 centres – 10 in the public sector and 6 in the private sector – across Latin America observed that only 40% of public health centres and 67% of private centres have access to a neuroradiologist specialised in MS and other demyelinating diseases, a resource considered crucial for accurate diagnosis and monitoring [6]. Moreover, significant disparities exist between private and public healthcare systems. Patients in private centres typically have quicker access to MRI, while in the public system, even individuals with acute symptoms may face waiting times of six months to a year.”
Furthermore, a panel of MS neurologists from 19 centres across 9 Latin American countries identified disparities in access to OCT, with availability in 80% of private healthcare settings compared to just 44% in public institutions [7]. The panel recommended making OCT universally accessible in MS centres and highlighted the importance of consistent protocols and better clinical understanding to support its effective use in everyday care [7]. Prof. Ciampi adds, “This approach could help reduce inequities between public and private centres, and consequently, between patients of different socioeconomic backgrounds. I believe that the proposed inclusion of the optic nerve as a fifth topographic region in the 2024 MS diagnostic criteria, along with the KFLC index, has strong potential to address these disparities.”
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Written by Stefania de Vito
Special thanks to Professor Sasitorn Siritho (Siriraj Hospital, Mahidol University, Thailand) and to Professor Ethel Ciampi (Pontifical Catholic University of Chile) for their insights.
References
[1] Solomon AJ et al. Neurol. 2023; 101.6: e624-e635.
[2] Viswanathan S et al. Mult. Scler. Relat. Disord. 2024; 85: 105555.
[3] Ontaneda D et al. NeuroImage Clin. 2021; 32: 102834.
[4] Tisavipat N et al. Mult. Scler. Relat. Disord. 2023; 70: 104511.
[5] Simpson S et al. JNNP 2019; 90(11): 1193-1200.
[6] Ciampi E et al Mult. Scler. Relat. Disord. 2022; 59: 103649.
[7] Ciampi E et al. Mult. Scler. J. 2024; 13524585251329159.