Multiple Sclerosis and Related Disorders

CASE

A 34-year-old woman experiences a sudden loss of vision in the left eye that lasts for 2 months, with spontaneous resolution. Three years later, she notices numbness ascending to the waistline that partially resolves after 6 weeks. She is treated with intravenous (IV) methylprednisolone, and improves. Her magnetic resonance imaging (MRI) scan shows periventricular lesions, and her cerebrospinal fluid (CSF) shows oligoclonal bands.

Multiple sclerosis (MS) is a relapsing and sometimes progressive disorder that affects primarily the white matter of the central nervous system (CNS—brain and spinal cord). It is an inflammatory disease in which lymphocytes and macrophages damage the myelin sheath, and also may cause axonal damage. It is more common in women, and usually begins between ages 20 and 40 years, although it sometime starts outside this range. MS generally is considered a cell-mediated autoimmune disease directed against myelin components, triggered in some fashion, possibly by an infection. Despite many attempts, an infectious agent has not been identified in MS, and it is not considered an infectious disease.

MAJOR CATEGORIES IN THE CLASSIFICATION OF MULTIPLE SCLEROSIS

The relapsing-remitting type, in which patients have discrete attacks of new or worsened neurologic symptoms that come on over a few days. These may resolve over a 4- to 8-week period, with or without corticosteroid treatment. Patients in this category often return to their preattack baseline, but may have residual disability after an attack. They may transition to secondary progressive disease after some years of disease activity.

Attack = exacerbation = relapse = bout.

Note: An attack of MS is defined as a worsening of neurologic symptoms and or signs over days, not due to infection or increased temperature.
The secondary progressive type, in which the patients initially have relapsing-remitting disease, but after some years now have gradual worsening in between discrete attacks. They may have continued attacks, or stop having attacks.
The primary progressive type, where the patients are often older at onset, and have a progressive course from onset, without attacks. They tend to have fewer MRI lesions than relapsing-remitting or secondary progressive patients.

Rarer Categories of Multiple Sclerosis

The progressive relapsing type, where the patients have gradual neurologic deterioration from the onset, with subsequent superimposed exacerbations.
The fulminant type, in which patients have a rapid severe progression, with relapses over a period of months.

SIGNS AND SYMPTOMS

Signs and symptoms occur in multiple anatomic areas of brain and spinal cord affected by the disease.

Common symptoms include the following:

Sensory (numbness, tingling, heaviness in an extremity, sensory level).
Visual (visual loss, color vision change, field defects).
Brainstem (diplopia, dizziness, difficulty swallowing or speaking).
Motor (weakness, spasticity, cramping, ataxia).
Bowel and bladder dysfunction.
Cognitive complaints (fatigue, poor attention, altered memory).

Common signs include the following:

Corticospinal tract (weakness, spasticity, hyperreflexia, upgoing toes).
Sensory (vibration loss, decreased pin sense, sensory level).
Brainstem (nystagmus, internuclear ophthalmoplegia, facial weakness).
Optic nerve (loss of visual acuity, central scotomas, loss of color vision, optic nerve atrophy, afferent pupillary defect).
Tremor.

Note: Heat may worsen the symptoms by altering axonal conduction. Transient episodes of neurologic dysfunction (tonic spasms) may occur and last seconds or minutes (transient neurologic events).

DIAGNOSIS

The diagnosis of MS is based primarily on clinical findings reflecting involvement of multiple sites in the brain or spinal cord occurring at different times (i.e., “multiple lesions in time and space”), and an abnormal MRI scan. MRI is the most important laboratory test, and often shows multiple areas of white matter change in the periventricular white matter, corpus callosum, brainstem, and spinal cord. Active MS lesions enhance with gadolinium. Cerebrospinal fluid (CSF) may indicate an inflammatory process with mild pleocytosis and mild protein alteration, increased IgG/albumin ratio and IgG synthesis index, and oligoclonal banding. Evoked potentials (especially those that are visually evoked) are often abnormal, and reflect areas of white matter demyelination. Recently the diagnostic criteria for MS have been modified. In addition to the “two attacks, two clinical findings” criterion, MS also can be diagnosed in patients who have one attack, or progressive disease from the onset. The McDonald criteria allows the diagnosis of MS with a single clinical attack if there are new lesions on subsequent MRI scans.

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