relapsing-remitting multiple sclerosis

relapsing-remitting multiple sclerosis is the most common initial disease course of the autoimmune disorder multiple sclerosis. It is characterized by clearly defined attacks of new or increasing neurological symptoms, known as relapses or exacerbations, followed by periods of partial or complete recovery, termed remissions. This pattern is distinct from the progressive forms of the disease, such as primary progressive multiple sclerosis, where neurological decline occurs steadily from onset without distinct relapses.

Signs and symptoms

Symptoms during a relapse result from acute inflammation and demyelination within the central nervous system and can affect any neurological pathway. Common manifestations include optic neuritis, causing visual loss and pain with eye movement, and Lhermitte's sign, an electric shock sensation down the spine upon neck flexion. Motor symptoms may involve weakness or spasticity, often in the limbs, while sensory disturbances include numbness, tingling, or neuropathic pain. Brainstem involvement can lead to diplopia, vertigo, or dysarthria, and cerebellar damage may cause ataxia or intention tremor. Symptoms of bladder dysfunction and profound fatigue are also highly prevalent. Between attacks, during remission, symptoms may resolve completely or leave residual deficits.

Diagnosis

Diagnosis follows the internationally recognized McDonald criteria, which integrate clinical history with paraclinical evidence to demonstrate dissemination of lesions in both time and space within the central nervous system. Magnetic resonance imaging of the brain and spinal cord is the cornerstone, revealing characteristic T2 hyperintense lesions in regions such as the periventricular white matter, corpus callosum, or infratentorial areas. The detection of oligoclonal bands in the cerebrospinal fluid via a lumbar puncture provides supportive evidence of intrathecal immunoglobulin synthesis. Differential diagnoses that must be excluded include neuromyelitis optica spectrum disorder, associated with aquaporin-4 antibodies, and other inflammatory conditions like sarcoidosis or Lyme disease.

Pathophysiology

The pathophysiology involves an autoimmune attack directed against the myelin sheath and, to a lesser extent, axons within the central nervous system. This process is mediated by T cells, particularly CD4+ T helper cells and CD8+ cytotoxic T cells, which become activated against myelin antigens such as myelin basic protein and myelin oligodendrocyte glycoprotein. These cells cross the blood–brain barrier, initiating a cascade that recruits B cells and macrophages, leading to inflammatory demyelination and axonal transection. The episodic nature of relapses is thought to reflect periodic breaches in immunoregulation, possibly triggered by environmental factors like infection with the Epstein–Barr virus. The underlying genetic susceptibility is strongly linked to alleles within the major histocompatibility complex, particularly HLA-DRB1*15:01.

Treatment

The primary goal of treatment is to reduce the frequency and severity of relapses and delay long-term disability through disease-modifying therapies. First-line injectable agents include interferon beta-1a, interferon beta-1b, and glatiramer acetate. For more active disease, higher-efficacy therapies are used, such as the monoclonal antibodies natalizumab, which targets alpha-4 integrin, and ocrelizumab, an anti-CD20 agent that depletes B cells. Other options include fingolimod, siponimod, and cladribine. Acute relapses are typically treated with short courses of high-dose corticosteroids, such as methylprednisolone, to hasten recovery. Comprehensive management also addresses symptoms with medications for spasticity like baclofen, neuropathic pain agents such as pregabalin, and rehabilitation through physical therapy.

Prognosis

The long-term prognosis is highly variable and unpredictable for any individual. A significant proportion of individuals with relapsing-remitting multiple sclerosis will eventually transition to secondary progressive multiple sclerosis, characterized by a steady accrual of disability independent of relapses. Factors associated with a worse prognosis include a high relapse rate early in the disease, significant residual disability from initial attacks, and a high burden of lesions on early MRI scans. The development of progressive disease is correlated with accumulated axonal loss and neurodegeneration. However, the advent of effective disease-modifying therapies has been shown to improve long-term outcomes, delaying the time to reach key disability milestones such as requiring a walking aid.

Category:Multiple sclerosis Category:Autoimmune diseases Category:Neurological disorders