Definitions

Multiple Sclerosis (MS):

A chronic, immune-mediated disease of the central nervous system characterized by inflammation, demyelination, and neurodegeneration.

Disease-Modifying Therapies (DMTs):

Treatments designed to reduce disease activity and limit disability accumulation in MS.

High-Efficacy Therapies (HETs):

DMTs with a strong demonstrated effect on reducing inflammatory disease activity, generally including treatments such as monoclonal antibodies.

Early High-Efficacy Treatment (EHT):

A therapeutic strategy involving the initiation of high-efficacy DMTs early in the disease course, rather than following a gradual escalation approach.

Escalation Strategy:

A treatment approach that begins with a moderate-efficacy DMT and switches to a more effective therapy if disease activity persists or increases.

Progression Independent of Relapse Activity (PIRA):

Disability accumulation occurring independently of clinical relapses, reflecting progression that is not directly associated with acute relapse events.

Smouldering MS:

Chronic, ongoing disease processes involving compartmentalized inflammation and neurodegeneration that may contribute to disability progression despite limited overt inflammatory activity.

Secondary Progressive Multiple Sclerosis (SPMS):

A stage of MS characterized by gradual disability progression following an initial relapsing-remitting disease course.

Therapeutic Window of Opportunity:

An early period in the disease course during which effective treatment may have a greater impact on preventing irreversible neurological damage.

Biomarkers:

Measurable biological indicators, such as neurofilament light chain (NfL), that may help assess disease activity, neuroaxonal injury, and prognosis.

Neurological Reserve:

The capacity of the central nervous system to compensate for damage and maintain neurological function despite disease-related injury.