Multiple Sclerosis — Causes, Symptoms, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease affecting the central nervous system (brain, spinal cord, and optic nerves), in which the immune system attacks the myelin sheath — the protective covering of nerve fibres — causing demyelination, axonal damage, and neurological dysfunction. It is the most common non-traumatic cause of neurological disability in young adults and affects approximately 2.8 million people worldwide. MS is classified by disease course: relapsing-remitting MS (RRMS — 85-90% at onset, characterized by episodes of neurological worsening followed by full or partial recovery), secondary progressive MS (SPMS — RRMS that transitions to steady neurological decline), primary progressive MS (PPMS — 10-15%, progressive from onset with no discrete relapses), and progressive-relapsing MS. Diagnosis and treatment initiation early in the disease course significantly improves long-term outcomes.

MS results from a complex interplay of genetic predisposition and environmental triggers that activate autoreactive T-cells targeting myelin antigens. Genetic risk: HLA-DRB1*15:01 is the strongest genetic risk factor, increasing MS risk 3-fold; over 200 non-HLA genetic variants contribute. Environmental factors: vitamin D deficiency (lower sunlight exposure — MS is more prevalent at higher latitudes, with risk declining near the equator), Epstein-Barr virus (EBV) infection — virtually all MS patients have been infected with EBV, and a military cohort study showed 32-fold increased MS risk after EBV seroconversion; cigarette smoking doubles MS risk and accelerates progression; obesity in adolescence. Female predominance (3:1 female to male ratio). Peak age of onset is 20-40 years.

MS symptoms depend on the location of demyelinating lesions. Common presentations include: optic neuritis (painful visual loss in one eye — often the first presentation), internuclear ophthalmoplegia, diplopia, limb weakness or spasticity, sensory disturbances (numbness, tingling, the Lhermitte sign — electric shock sensation radiating down the spine on neck flexion), cerebellar ataxia (imbalance, coordination difficulties), bladder dysfunction (urgency, frequency, incontinence — affects 75% of patients), cognitive impairment ('cog fog' — affecting 50%), fatigue (most common and disabling symptom — affects 80%), depression, and sexual dysfunction. Uhthoff's phenomenon — temporary worsening of symptoms with heat (hot bath or exercise) — is characteristic. Relapses last more than 24 hours and are separated by 30 days or more.

Diagnosis applies the McDonald Criteria (2017 revision) requiring demonstration of lesions disseminated in space (DIS) and time (DIT) in the CNS, with no better alternative explanation. MRI brain and spinal cord is the cornerstone — T2/FLAIR hyperintense lesions in periventricular, juxtacortical, infratentorial, and spinal cord regions are characteristic; gadolinium-enhancing lesions indicate active inflammation. Cerebrospinal fluid (CSF) analysis via lumbar puncture: oligoclonal IgG bands (OCBs) are present in over 90% of MS patients (not seen in serum — CSF-specific), elevated IgG index. Visual evoked potentials (VEPs) detect subclinical optic pathway lesions. Blood tests exclude alternative diagnoses: AQP4-IgG (neuromyelitis optica), MOG-IgG, B12, syphilis serology, HIV, ANA. Differential diagnosis includes neuromyelitis optica spectrum disorder (NMOSD), CNS vasculitis, and vitamin B12 deficiency.

Acute relapse treatment: high-dose intravenous methylprednisolone 1g daily for 3-5 days shortens relapse duration but does not change long-term outcome. Disease-modifying therapies (DMTs) reduce relapse rate and slow disability accumulation. Platform therapies (moderate efficacy): beta-interferons (interferon beta-1a, 1b), glatiramer acetate, dimethyl fumarate, teriflunomide — reduce relapse rate by 30-50%. High-efficacy therapies: natalizumab (anti-VLA-4, reduces relapses 68%; risk of PML brain infection with JC virus seropositivity), ocrelizumab (anti-CD20, approved for RRMS and PPMS — first disease-modifying therapy for primary progressive MS), alemtuzumab (anti-CD52, 50% efficacy but risk of secondary autoimmune complications — thyroid disease, immune thrombocytopenia), cladribine. Symptom management: baclofen/tizanidine for spasticity; anticholinergics for bladder urgency; amantadine/fampridine for fatigue; pregabalin/amitriptyline for neuropathic pain; physiotherapy, occupational therapy, speech therapy. Stem cell therapy (autologous haematopoietic stem cell transplantation — aHSCT) is increasingly used for highly active MS.

Untreated or inadequately treated MS leads to progressive and largely irreversible neurological disability. Each clinical relapse causes axonal loss — without disease-modifying therapy, approximately 50% of patients develop secondary progressive MS within 10-15 years, with continuous disability accumulation. Severe spasticity from upper motor neurone dysfunction causes contractures, pressure sores, and respiratory compromise. Bladder dysfunction — urinary retention or incontinence — significantly increases the risk of recurrent urinary tract infections, ascending pyelonephritis, and urosepsis; urological complications are a major cause of hospitalisation in MS. Dysphagia from brainstem involvement causes aspiration pneumonia. Cognitive impairment affects 50% of MS patients and can progress to significant dementia in advanced disease. Depression and anxiety affect 50-60% of patients with MS — with a suicide rate 2-7 times higher than the general population — particularly in those with untreated disease. Severe fatigue, untreated, is the most common reason for employment loss. Falls and fractures from ataxia and weakness result in orthopaedic complications. Acute severe relapses (transverse myelitis, severe optic neuritis causing complete visual loss) may cause permanent disability if not treated promptly with IV methylprednisolone.

No definitive prevention exists, but vitamin D supplementation (1000-4000 IU daily) is recommended for all MS patients and may reduce relapse risk. Quit smoking — smoking worsens MS progression significantly and doubles relapse risk. Regular aerobic exercise (swimming, cycling) improves fatigue, spasticity, mood, and quality of life without worsening MS. Maintain healthy weight. Manage heat exposure — air conditioning, cooling vests for heat-sensitive patients. Treat depression and anxiety (highly prevalent). Avoid infections (vaccination with inactivated vaccines is safe; live vaccines require specialist advice with some DMTs). Regular MRI surveillance (6-12 monthly) detects disease activity enabling timely treatment escalation. Comprehensive neurorehabilitation maximises function.

Seek urgent neurological assessment for any first episode of neurological symptoms such as vision loss in one eye (optic neuritis), sudden weakness or numbness in a limb, difficulty walking, or coordination problems — these may represent a first MS relapse (clinically isolated syndrome/CIS). Early diagnosis and treatment initiation significantly improves prognosis. Contact your MS nurse or neurologist promptly for any new relapse symptoms lasting more than 24 hours. Attend emergency care for sudden severe symptoms (e.g., complete vision loss, inability to walk) which may need IV steroids urgently. Seek immediate neurological assessment if you are an established MS patient experiencing a relapse that is significantly worse than prior episodes, as severe relapses may require IV methylprednisolone to shorten duration and maximise neurological recovery. Patients with MS should routinely report any new symptom lasting more than 24 hours to their MS nurse or neurologist to enable appropriate assessment and treatment planning.