The diagnosis of MS is most often based on the identification of neurological symptoms associated with demyelination lesions identified on MRI scans.
- The incidence rate of MS measured in France is 181.1 cases per 100,000 inhabitants in 2021.
- It is an immune disease with neurological consequences. “It is based on the activation of inflammatory pathways, B lymphocytes and T lymphocytes, leading to immune activation and having, on the lesion level, iterative demyelination,” explains Professor Pierre Labauge.
- MRI is the tool that makes it possible to visualize MS lesions formed in the central nervous system, and also makes it possible to “detect the appearance of new multiple sclerosis lesions, even when there is no necessarily new symptoms”, indicates Professor Louapre.
In France, 122,810 cases of multiple sclerosis were identified in 2021, which corresponds to 181.1 cases per 100,000 inhabitants with a ratio of 2.4 women affected for 1 man. This prevalence has continued to increase worldwide since the 1990s, notably thanks to better diagnosis.
MS: “a disease with neurological consequences whose origin is immune”
“Multiple sclerosis is a disease with neurological consequences whose origin is immune, explains Professor Pierre Labauge, neurologist at Montpellier University Hospital and member of the FCRIN4MS network. It is based on the activation of inflammatory pathways, B lymphocytes and T lymphocytes, leading to immune activation and having, on the lesion level, iterative demyelination.” This demyelination leads clinically to a loss of function, and thus, to neurological signs of focus, motor deficit, sensitivity disorders, urinary disorders and balance disorders.
The presence of these symptoms, which can occur in the form of a flare-up, generally leads to a quick consultation with a treating physician who can then refer the patient to a specialist in order to carry out magnetic resonance imaging (MRI) examinations.
Multiple sclerosis lesions are visualized using MRI
“MRI can visualize multiple sclerosis lesions that have formed in the central nervous systemtells us Professor Céline Louapre, neurologist at Pitié Salpêtrière and co-coordinator of the FCRIN4MS network. Their appearance and distribution are generally quite typical, which allows in a large proportion of cases to confirm the diagnosis only with the history of symptoms, clinical examination and MRI of the brain and spinal cord.”
This diagnostic assessment is often completed by a lumbar puncture. “It makes it possible to analyze the cerebrospinal fluid which circulates around the brain and spinal cord, because the presence of immunoglobulin peaks can support the diagnosis, and its analysis also makes it possible to eliminate alternative diagnoses.”, adds the specialist.
“During follow-up, brain and spinal cord MRI can detect the appearance of new multiple sclerosis lesions, even though there are not necessarily new symptoms. This allows the basic treatment to be adapted to best control the disease. However, in patients with progressive multiple sclerosis, the neurological handicap can worsen without any new visible lesion, because the mechanisms of neurodegeneration are microscopic mechanisms, not visible on the scale of standard MRI.”
