Multiple Sclerosis
A chronic disease, multiple sclerosis (MS) is characterized by exacerbations and remissions caused by progressive demyelination of the white matter of the brain and spinal cord. Sporadic patches of demyelination in various parts of the long conduction pathways of the central nervous system (CNS) cause widespread and varied neurologic dysfunction.
MS is a major cause of chronic disability in young adults ages 20 to 40. The prognosis varies. MS may progress rapidly, disabling the patient by early adulthood or causing death within months of onset. However, about 70% of patients lead active, productive lives with prolonged remissions.
The incidence of MS is highest in females and among people in higher socioeconomic groups as well as those living in northern climates and in urban areas. A family history of MS also increases the risk.
Causes
The exact cause of MS is unknown, but theories suggest a slow-acting viral infection, an autoimmune response of the nervous system, or an allergic response to an infectious agent. Other possible causes include trauma, anoxia, toxins, nutritional deficiencies, vascular lesions, and anorexia, all of which may contribute to destruction of axons and the myelin sheath.
Emotional stress, overwork, fatigue, pregnancy, and acute respiratory tract infections all have been known to precede the onset of this illness. Genetic factors may also be involved.
Complications
In MS, complications include injuries from falls, urinary tract infections (UTIs), constipation, joint contractures, pressure ulcers, rectal distention, and pneumonia.
Assessment
Clinical findings in MS correspond to the extent and site of myelin destruction, the extent of remyelination, and the adequacy of subsequent restored synaptic transmission. Symptoms may be transient or may last for hours or weeks. They may vary from day to day, with no predictable pattern, and be bizarre and difficult for the patient to describe.
The patient history commonly reveals initial visual problems and sensory impairment, such as numbness and tingling sensations (paresthesia).
After the initial episode, signs and symptoms may vary widely. Patient history may reveal blurred vision or diplopia; urinary problems, such as incontinence, frequency, urgency, and UTIs; emotional lability, such as mood swings, irritability, euphoria, and depression; and possibly dysphagia.
As the patient speaks, you may notice scanning or poorly articulated speech. Neurologic examination and muscle function testing may discover muscle weakness of the involved area, such as an arm or leg, and spasticity, hyperreflexia, intention tremor, gait ataxia, and paralysis that ranges from monoplegia to quadriplegia. Visual examination may reveal nystagmus, scotoma, optic neuritis, or ophthalmoplegia.
Diagnostic tests
Because diagnosis is difficult, some patients may undergo years of periodic testing and close observation. The following tests are helpful in diagnosing the disease.
Electroencephalography shows abnormalities in one-third of patients.
Cerebrospinal fluid (CSF) analysis reveals elevated immunoglobulin G (IgG) levels but normal total protein levels. Such elevated IgG levels are significant only when serum gamma globulin levels are normal, and they reflect hyperactivity of the immune system due to chronic demyelination. The white blood cell count may be slightly increased.
Evoked potential studies demonstrate slowed conduction of nerve impulses in 80% of MS patients.
Computed tomography scan may disclose lesions within the brain’s white matter.
Magnetic resonance imaging is the most sensitive method of detecting MS lesions. More than 90% of patients with MS show multifocal white matter lesions when this test is performed. It’s also used to evaluate disease progression.
Electrophoresis can be used to detect oligoctonal bands of immunoglobulin in CSF. They’re present in most patients and can be found even when the percentage of gamma globulin in CSF is normal.
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