Symptoms and Diagnosis
MS can affect people of all ages; however, the average age of disease onset is between 20 and 40 years.48 Fatigue, numbness in the limbs, impaired vision, muscle weakness, loss of balance, and bladder dysfunction are frequent symptoms.
Symptoms of multiple sclerosis vary widely, depending on the location of affected nerve fibers.48
- Symptoms affecting mobility tend to appear early in the course of MS and they may include weakness, clumsiness, leg dragging, stiffness, and a tendency to drop objects.
- Common sensory symptoms include numbness, sensations of heaviness, tingling, and electrical sensations.
- Visual symptoms are also common, affecting more than one-third of all people who have MS. The classic visual disturbances, such as blurred or foggy vision and eyeball pain, usually appear early in the course of the disease.
- MS can also interfere with the nerves that supply the vestibular apparatus in the inner ear, which is where balance is perceived. This can result in dizziness, nausea, and vomiting.
- In the later stages of the disease, involvement of the genitourinary tract may result in loss of bladder, sexual, and bowel function.56
- Over 40% of MS patients suffer from changes in memory, reasoning, spatial perception, and verbal fluency.57
- Symptoms of MS are often triggered or worsened by an increase in body temperature.
MS is a tremendously variable and unpredictable disease. Different patients will experience different symptoms, rates of disease progression, and responses to treatment.
Four Disease Courses Have Been Identified in MS
- Progressive relapsing (PR) MS, which is the least common disease course, shows progression of disability from onset but with clear acute relapses, with or without full recovery. Approximately 5% of people with MS appear to have PRMS at diagnosis.
- Secondary progressive (SP) MS begins with an initial relapsing-remitting disease course, followed by progression of disability. Typically, secondary-progressive disease is characterized by: less recovery following attacks, persistently worsening functioning during and between attacks, and accompanied by progressive disability. Many patients with RRMS do develop SPMS ultimately.
- Primary progressive (PP) MS is characterized by progression of disability from onset, without plateaus or remissions or with occasional plateaus and temporary minor improvements. A person with PPMS, by definition, does not experience acute attacks. Ten percent of diagnosed MS are PPMS.
- Relapsing remitting (RR) MS represents 85% of clinical diagnoses of the disease. It is characterized by clearly defined acute attacks with full recovery or with residual deficit upon recovery. Periods between disease relapses are characterized by a lack of disease progression.
No single test gives a definitive diagnosis for MS, and variable symptoms and disease course make early diagnosis a challenge. Most presumptive diagnoses of MS are based on the clinical symptoms seen in an acute attack. These presumptions are then supported by a combination of diagnostic imaging with magnetic resonance imaging (MRI), antibody testing of the fluid found in the CNS, measurements to evaluate how efficiently nerves conduct impulses (since demyelination slows nerve conduction) and evaluation of how the symptoms progress through time.58