Because the effects of nerve injury are widespread, the many complications can be very severe and affect all parts of the body. Although not all individuals with multiple sclerosis (MS) experience all of the following complications, any of them can negatively affect the individual's quality of life.
Fatigue: Fatigue is one of the most common and debilitating MS symptoms and affects at least two thirds of patients with MS. Fatigue causes a general lack of energy that significantly limits daily functioning regardless of any neurologic symptoms or specific muscle weaknesses. Up to 40% of patients describe it as the most disabling MS symptom, which is higher than weakness, spasticity, motor control, or bowel or urinary problems. Many conditions that are common in MS, including sleep disorders, depression, hypersensitivity to sensation, hypothyroidism, medications, and heat, may contribute to fatigue. None fully explain the consistent presence or severity of this problem in MS. Researchers using imaging techniques have identified possible changes in part of the brain in MS that may play a role in the fatigue of MS.
Loss of mobility and spasticity: Nearly every individual with MS loses some mobility, which may take the form of impaired motor control, muscle weakness, impaired balance, tremor, and, importantly, spasticity. Spasticity is one of the primary symptoms of MS. It is characterized by weakness, loss of dexterity, and the inability to control specific movements. Spasticity is usually more severe in the legs and torso. Mobility can also be affected by many non-physical factors, including mental well-being, fatigue, and even the weather.
Pain: About two-thirds of MS patients experience pain at some point during the course of the disease and 40% are never pain free. MS causes many pain syndromes - some are acute (short-term) while others are chronic (long-term). Some worsen with age and disease progression. Pain syndromes associated with MS are trigeminal (facial) pain, powerful spasms and cramps, optic neuritis (pain in the eye), stiffened joints, and a variety of sensations including feelings of itching, burning, and shooting pain.
Bowel dysfunction: Bowel dysfunction, which can include constipation or fecal incontinence, is a serious problem for many MS patients. Constipation may be caused by the disorder itself or by medications used to treat spasms or other symptoms. Diarrhea may also occur.
Sexual dysfunction: Sexual dysfunction is a common problem in those with MS, occurring in over 70% of patients. Men are likely to have impotence and women have problems with vaginal lubrication, both leading to sexual dysfunction. It appears to be highly associated with urinary dysfunction.
Urinary urgency: Individuals with urinary urgency feel the need to urinate frequently and urgently. When urinary urgency takes place, the signals that coordinate urination are disrupted and the individual experiences an uncontrollable urge to urinate that can cause incontinence.
Incontinence: Incontinence is the loss of bladder control. Sometimes MS will disrupt the nerve signals sent to the body parts that control urine movement allowing urine to be expelled involuntarily.
Nocturia: Individuals with nocturia must awake frequently during the night to go to the bathroom. There are a number of causes for this type of incontinence, but those with MS may experience nocturia due to the interruption of brain impulses that travel up and down the spine to coordinate urination.
Urinary hesitancy: Urinary hesitancy refers to difficulty initiating urination. With MS, this problem may be caused by interruption of brain impulses that control that part of the urination process.
Visual problems: Vision problems that can occur with MS include: blurred or dimmed vision; pain with eye movement; blind spots, particularly involving central vision; color blindness; double vision; and nystagmus, or vision that jumps uncontrollably.
Difficulty swallowing: One-third to one-half of MS patients experience difficulty in chewing or swallowing, problems that may be caused or made worse by many MS medications.
Speech and hearing problems: Problems in speech may occur because of difficulty in controlling the quality of the voice and articulating words. Problems with language itself, however, are very rare in MS. Hearing problems also occur in MS and may affect speech.
Lung problems: As the muscles that control breathing weaken, the ability to cough is impaired and the individual with MS is at higher risk for pneumonia and other complications in the lungs. Breathing may become difficult, and may eventually require the use of a respirator to aid in breathing.
Osteoporosis: Osteoporosis, or the loss of bone density, and subsequent fractures are a common problem among individuals with MS. Osteoporosis is caused and worsened by immobility and by some MS medications. Fractures caused by falls can be far more serious in MS patients than in the normal population, leading to problems including deconditioning (loss of physical fitness) or even inability to walk, constipation (from pain-relieving medications such as opiates), and respiratory complications.
Cognitive problems: Cognitive problems, such as having trouble concentrating and solving problems, affect about half of MS patients. It has been found that more people with MS leave work because of such difficulties than because of physical problems. In about 10% of cases, mental dysfunction may be severe and resemble dementia. The severity of such mental changes appears to be associated with the degree of loss of brain tissue.
Depression: Between 40-60% of MS patients suffer from depression at some point over the course of the illness, and studies have reported risks for suicide ranging from 3-15%. There is some evidence that depression in multiple sclerosis is not only due to the social and psychological impact of MS but to the disease process itself. Furthermore, in one study, depression had biologic effects, such as increasing production of inflammatory cytokines (including interleukins) that could exacerbate the disease itself. Treating depression then may even help reduce the disease process. Doctors should assess patients for depression, even though there may be no obvious signs of it. It should be noted that the risk for suicide may be present even in patients who are not obviously depressed. Individuals at highest risk for suicide are those who live alone, those with a history of an emotional disorder (such as those with depression, anxiety, or alcohol abuse), a family history of mental illness, and people with high social stress.