Introduction
Multiple sclerosis (MS) is a chronic disease affecting the central nervous system (CNS), which includes the brain, spinal cord, and optic nerves. Unlike peripheral nerves, the CNS is the primary target of MS. Typically, MS manifests between the ages of 15 and 50, although cases outside this range have been documented. [1] It stands as the most prevalent non-traumatic cause of neurological disability in young adults. [2] The incidence of MS is on the rise, with a significantly higher occurrence in women compared to men. MS lesions are characterized by inflammation, demyelination, and axonal damage. The onset of MS is generally subacute, developing over hours to days. Symptoms vary widely, depending on the lesion’s location within the CNS. While some symptoms are non-specific, others, such as bilateral internuclear ophthalmoplegia, strongly suggest MS. Diagnosing MS can range from straightforward to highly complex. [3] Advances in diagnostic tools, including MRI, evoked potential studies, and cerebrospinal fluid (CSF) analysis, have significantly improved the accuracy and speed of MS diagnosis. [4]
The Diagnosis of MS
The majority of individuals with MS (around 85%) initially experience relapses or attacks, marked by CNS-related symptoms. [5] These relapses are followed by periods of remission, either complete or partial, before subsequent relapses occur, often in different CNS locations. This pattern is known as relapsing-remitting MS (RRMS). The first such episode is termed a clinically isolated syndrome (CIS). Conversely, about 15% of patients exhibit a gradual progression of the disease from onset, without distinct initial attacks, which is classified as primary progressive MS (PPMS). PPMS often presents with spinal cord syndrome characteristics.
Current diagnostic criteria for MS mandate:
- Objective evidence of at least two separate CNS lesions consistent with MS, dispersed in both space and time.
- Exclusion of other potential causes for these CNS lesions.
These principles were initially outlined in the Schumacher criteria of 1965, when MS diagnosis was purely clinical. [6] The Poser criteria in 1983 succeeded the Schumacher criteria, incorporating paraclinical evidence from diagnostic advancements in the 1970s. These criteria, informed by a comprehensive literature review and expert consensus, [7] were initially for clinical trials but later adopted clinically. The Poser criteria introduced the term ‘laboratory-supported definite multiple sclerosis.’ In 2000, an international panel developed the McDonald criteria, [8] refined in 2001 and 2005, which enabled earlier and more accurate MS diagnosis. These criteria utilize MRI, evoked potentials, and CSF analysis to confirm dissemination in space and time, as detailed in Tables 1, 2, and 3. [8,9] The McDonald criteria also facilitated earlier PPMS diagnosis compared to previous standards, as shown in Table 1.
Table 1. The Diagnosis of MS: McDonald Criteria – 2005
| Clinical presentation | Additional data needed for MS diagnosis
