Multiple Sclerosis: Early Signs, Diagnosis, and Modern Disease-Modifying Therapies

What Is Multiple Sclerosis?

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system (CNS) in which the immune system attacks the myelin sheath — the fatty insulating layer around nerve fibres — and, over time, the nerve fibres themselves. "Multiple sclerosis" literally means "multiple scars" — referring to the plaques of demyelination visible on MRI scattered throughout the brain, spinal cord, and optic nerves.

MS affects approximately 2.9 million people worldwide. It is the most common cause of non-traumatic neurological disability in young adults, with onset typically between ages 20 and 40. Women are affected 2–3× more often than men.

Types of MS

• Relapsing-remitting MS (RRMS) — 85% of initial diagnoses. Discrete episodes of neurological dysfunction (relapses) followed by partial or complete recovery (remission). May transition to secondary progressive MS over time.
• Secondary progressive MS (SPMS) — Follows RRMS; disability accumulates steadily between or instead of relapses.
• Primary progressive MS (PPMS) — 15% of diagnoses. Steady disability accumulation from onset without relapses. Older age of onset, slight male predominance; historically harder to treat.
• Clinically isolated syndrome (CIS) — A first demyelinating episode. With characteristic MRI lesions, risk of conversion to MS is high; early DMT reduces this risk.

Early Warning Signs

Symptoms depend on the location of demyelinating lesions in the CNS. Common early presentations include:

• Optic neuritis — painful loss of vision or blurred vision in one eye; often the first MS symptom. Vision usually recovers over weeks to months.
• Sensory symptoms — numbness, tingling, or a "band-like" tightness around the torso or limbs ("MS hug")
• Uhthoff's phenomenon — temporary worsening of existing symptoms with heat or exercise (not a relapse; a useful diagnostic clue)
• Motor weakness — usually one limb; may present as foot drop or clumsiness
• Lhermitte's sign — electric shock sensation down the spine when flexing the neck; indicates cervical cord involvement
• Balance and coordination problems — unsteady gait, dizziness
• Fatigue — the most common MS symptom; disproportionate, often worst in the afternoon ("MS fatigue" differs from tiredness)
• Bladder dysfunction — urgency, frequency, difficulty emptying
• Cognitive symptoms — slowed processing speed, memory and word-finding difficulties ("cog fog")

Diagnosis: McDonald Criteria

MS is diagnosed using the 2017 McDonald criteria, which require evidence of dissemination in space (lesions in at least two different CNS regions) and dissemination in time (episodes at different time points). MRI is central to diagnosis:

• MRI brain and spinal cord — characteristic lesions in periventricular, juxtacortical, infratentorial, and spinal cord locations. Gadolinium-enhancing lesions indicate active inflammation.
• Cerebrospinal fluid (CSF) — oligoclonal bands (IgG) present in >90% of MS patients; normal in healthy individuals
• Visual evoked potentials — slowed conduction reflects optic nerve demyelination; useful when MRI is inconclusive

Key differentials include neuromyelitis optica spectrum disorder (NMOSD) — now distinguishable by AQP4 and MOG antibodies — migraine with white matter changes, and small vessel disease.

Relapse Management

Relapses (attacks lasting >24 hours, separated from prior relapse by >30 days) are treated with high-dose IV methylprednisolone (500–1,000 mg/day for 3–5 days). Steroids shorten relapse duration but do not alter long-term disability trajectory.

Disease-Modifying Therapies (DMTs)

DMTs reduce relapse frequency and slow disability accumulation. The field has expanded dramatically — there are now over 20 approved agents. Patients and neurologists choose between lower- and higher-efficacy agents:

Moderate-Efficacy (Platform) Therapies

• Interferon beta-1a/1b (Avonex, Betaferon, Rebif) — injectable; reduce relapses by ~30%
• Glatiramer acetate (Copaxone) — injectable; similar efficacy to interferons; no flu-like side effects
• Dimethyl fumarate (Tecfidera) — oral; ~50% relapse reduction; requires lymphocyte monitoring
• Teriflunomide (Aubagio) — oral; ~30% relapse reduction; teratogenic

High-Efficacy Therapies

• Natalizumab (Tysabri) — monthly IV infusion; blocks lymphocyte trafficking into the CNS; ~68% relapse reduction; risk of PML (rare brain infection) in JC-antibody positive patients
• Ocrelizumab (Ocrevus) — 6-monthly IV infusion; anti-CD20, depletes B-cells; ~46% relative reduction in disability progression in PPMS — the first approved DMT for primary progressive MS
• Ofatumumab (Kesimpta) — monthly subcutaneous anti-CD20; similar efficacy to ocrelizumab; self-administered
• Alemtuzumab (Lemtrada) — two annual treatment courses; very high efficacy; significant autoimmune side effects requiring monthly monitoring for 4 years
• Cladribine (Mavenclad) — oral; two short treatment courses in two years; ~50% disability progression reduction
• Autologous haematopoietic stem cell transplantation (aHSCT) — intensive immune reset; used in young patients with aggressive RRMS; can achieve sustained remission ("MIST trial")

Symptomatic Management

• Fatigue: amantadine, modafinil, energy conservation strategies, graded exercise
• Spasticity: baclofen, tizanidine, physiotherapy, cannabinoids (nabiximols/Sativex)
• Bladder: anticholinergics, intermittent self-catheterisation for incomplete emptying
• Neuropathic pain: gabapentin, pregabalin, duloxetine
• Depression: very common in MS; SSRIs and psychological support are effective