What Is Multiple Sclerosis: The Basics

Overview

Multiple Sclerosis or M.S., is a chronic autoimmune disease.

MS is known to affect the nervous system, which results in problems with vision, balance and muscle control. Since the nervous system affects the whole body, we also see symptoms of fatigue, digestive changes and more.

Epidemiology (Statistics)

  • Top disabling condition of young adults (U.S.)
  • Prevalence
    • Northern U.S.: 110 cases per 100,000 persons
    • Southern U.S.: 47 cases per 100,000 persons
    • S. Total: 250,000-350,000 patients affected

Types

  • Relapsing remitting (90% of cases)
    • Discrete attacks evolve over days to weeks
    • Recovery for weeks to months in which there is no neurologic worsening between attacks
  • Secondary progressive (50% of relapsing remitting cases)
    • Starts as relapsing remitting disease
    • Progresses to gradual neurologic deterioration outside of discrete, acute attacks
  • Primary progressive (PPMS) and progressive relapsing (10% of cases)
    • Steady functional decline from Multiple Sclerosis onset
    • Termed primary progressive if no attacks occur
    • Termed progressive relapsing if attacks occur

Pathophysiology

  • Acute attacks (relapsing remitting MS) are a result of inflammatory reaction
    • Inflammatory cells (T Cells, B Cells and¬†Macrophages) cross the blood-brain barrier at weakened vessel surfaces
    • Immunoglobulins (CD4 TH1 and TH17) target the myelin sheath
    • Macrophages damage the axons by releasing free radica
  • Results
    • Focal regions of demyelination of white matter
    • Particularly periventricular and subpial white matter

Risk Factors

  • Race: White > Black
  • Gender: Female > Male (2:1)
  • High socioeconomic status
  • Northern latitudes
  • Environmental factors (toxins, viruses)
  • Tobacco abuse
  • HLA histocompatible antigens
  • Vitamin D Deficiency (or less sunlight exposure)

Prognosis

  1. Relapse and remission cycles after first episode: 90%
  2. Benign course (1-2 relapses, then recovery): 20%
  3. Progressive course after 5 years of MS: 60-90%
  4. Progressive course from onset (10%)
  5. Rapidly progressive course from onset (very rare); also known as Marburg Type

Clinical Findings

  • Episodic course with acute relapses and remissions (80-90% of cases
  • Sensory Dysfunction
    • Sensory loss (37%)
      • loss of pain/temperature sensation
      • loss of vibratory sensation
    • Paresthesias (24%)
  • Upper motor neuron (UMN) dysfunction
    • spasticity
    • increased deep tendon reflexes
    • muscle spasms
    • extensor plantar response (Babinski)
    • Weakness (35%) (shoulder abduction, finger extension, foot dorsiflexion, hip/knee flexion)
  • Optic Neuritis (36%)
    • inflammation of the optic nerve; MS is the most common cause of optic neuritis
  • Autonomic dysfunction
    • urge incontinence (4%), due to hyperactive detrusor muscle
    • sexual dysfunction
    • bowel motility problems
  • Diplopia (15%)
  • Ataxia (11%)
  • Vertigo (6%)
  • Paroxysmal symptoms (4%)
  • Urinary Incontinence (4%)
  • Lhermitte Sign (3%)
  • Electrical sensation down spine on neck flexion
  • Dementia (2%)
  • Visual Loss (2%)
  • Facial palsy (1%)
  • Impotence (1%)
  • Myokymia (1%)
  • Seizures (1%)
  • Depressed mood
  • Fatigue
  • Hearing Loss and Tinnitus
  • Heat intolerance

Signs the Doctor May Find on Physical Examination

  • Dysarthria
  • Decreased pain, vibration and position sense
  • Decreased coordination and balance
    • Ataxia
    • Difficult tandem walking
  • Eye Exam
    • Visual field defects
    • Decreased Visual Acuity
    • Red color perception
    • Afferent Pupillary Defect
    • Optic Nerve pallor (Optic Neuritis)
    • Nystagmus (most commonly Horizontal Nystagmus)
    • Bilateral Internuclear Ophthalmoplegia
      • Nystagmus of abducting eye on lateral gaze
      • Other eye with slow adduction
    • Reflexes
      • Deep Tendon Reflexes hyperactive
      • Spasticity
      • Abdominal reflexes lost
      • Ankle Clonus present
      • Babinski Reflex with up-going toes
    • Charcot's Triad
      • Intention Tremor
      • Nystagmus
      • Scanning speech
    • Hot Bath Test
      • Hot bath exacerbates visual signs

References

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