Multiple Sclerosis

Overview – Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, immune-mediated disease of the central nervous system that causes patchy demyelination in the brain and spinal cord. It typically presents in young adults and follows a relapsing-remitting or progressive course. Clinical features depend on the CNS regions affected but often include limb weakness, optic neuritis, and sensory changes. This article provides a concise overview of multiple sclerosis for final-year medical students, with a focus on pathology, diagnosis, and prognosis.

Definition

Multiple sclerosis is a chronic autoimmune demyelinating disorder of the central nervous system characterised by white matter lesions, which result in neurological deficits that relapse and remit or progressively worsen.

Aetiology

• Autoimmune inflammatory disorder of unknown trigger
• Genetic predisposition (e.g. HLA-DRB1 association)
• Environmental factors: Vitamin D deficiency, EBV infection, smoking

Pathophysiology

• T-cell mediated attack on oligodendrocytes and myelin
• Demyelination in the CNS → impaired nerve conduction
• Inflammation leads to:
  • Axonal damage
  • Gliosis (scar formation)
  • Plaque formation, especially periventricular white matter

Morphology

Macroscopic

• Multiple plaques of demyelination, especially around ventricles
• Plaques appear as pink-grey lesions in white matter

Microscopic

• Perivascular infiltrates (T-cells, macrophages, plasma cells)
• Loss of myelin with relative axonal preservation
• Reactive gliosis surrounding demyelinated zones

Clinical Features

• Typical onset: Age 20–40 years
• Relapsing-remitting course (most common), or progressive
• White matter symptoms:
  • Limb weakness
  • Ataxia
  • Paraesthesia
  • Optic neuritis (e.g. blurred vision, eye pain)
  • Internuclear ophthalmoplegia
  • Vertigo and nystagmus (without tinnitus or deafness)
• Late-stage: Spastic quadriparesis → respiratory failure → pneumonia

Investigations

• MRI brain and spine: Multiple white matter plaques, especially periventricular
• CSF analysis:
  • Oligoclonal IgG bands (indicative of intrathecal synthesis)
• Evoked potentials: delayed conduction time

Diagnosis

• Clinical + Radiological criteria
• Requires evidence of:
  • Dissemination in space (multiple CNS locations)
  • Dissemination in time (more than one episode)

Management

• Currently incurable
• Supportive care:
  • Physiotherapy, occupational therapy, psychosocial support
• Acute relapses:
  • High-dose corticosteroids
• Disease-modifying therapies:
  • Immunomodulators (e.g. interferon-beta, glatiramer acetate, natalizumab)
  • Aim to reduce relapse rate and delay progression

Complications

• Spasticity
• Urinary retention or incontinence
• Chronic fatigue
• Depression
• Pneumonia due to chest muscle paralysis (end-stage)

Differential Diagnosis

• Neuromyelitis optica
• Acute disseminated encephalomyelitis (ADEM)
• CNS vasculitis
• B12 deficiency
• HIV-related CNS disease

Summary – Multiple Sclerosis

Multiple sclerosis is a chronic autoimmune condition causing patchy CNS demyelination, most often in young adults. Its relapsing-remitting or progressive course leads to varied neurological symptoms, including limb weakness and optic neuropathy. Diagnosis is clinical, supported by MRI and CSF findings. For a broader context, see our Nervous System Overview page.