THE PATHOPHYSIOLOGY OF MULTIPLE SCLEROSIS

The Pathophysiology of Multiple Sclerosis

The Pathophysiology of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, often disabling disease of the central nervous system (CNS) affecting approximately 350,000 people in the United States. Prevalence among women is about twice of that found in men. It is believed that the immune system attacks the myelin sheath around the axons of the CNS, resulting in lesions. Potential symptoms include, but not are limited to, loss of function or feeling in limbs, loss of bowel or bladder control, sexual dysfunction, debilitating fatigue, blindness due to optic neuritis, loss of balance, pain, cognitive dysfunction, and emotional changes. MS remains one of the most disabling illnesses in the United States. (Abhijeet, 2007)

There are several possible courses. Between 65% and 70% begin with a relapsing-remitting course marked by periodic disease exacerbations, which remit partially or fully over the course of weeks or months. Most relapsing-remitting courses eventually give way to a secondary-progressive course in which there is also worsening between exacerbations. Approximately 10% to 15% have a primary-progressive course in which there is a steady worsening of symptoms with no exacerbations. Small percentages of patients have other courses, including a benign course with few symptoms, or in rare cases, a malignant course characterized by rapid deterioration resulting in death. (Claudia, 1999)

Neuropsychological Symptoms

Point prevalence for neuropsychological impairment ranges from 40% to 60% while lifetime prevalence is likely considerably higher. Problems with processing speed, attention, and concentration; verbal fluency; and verbal memory are among the most common problems. However, visual-spatial learning, construction, and organization, as well as executive functions, can also be affected. Memory deficits are commonly thought to be due to retrieval problems, yet some studies have also documented problems in encoding and storage of information. More cognitively impaired patients may also show euphoria or pathological laughing and crying, a state characterized by bouts of uncontrollable laughing, crying, or both in response to nonspecific stimuli in the absence of a matching mood state. The neuropsychological symptom profile in MS is heterogeneous. Severity of deficits can vary too. For some MS patients, neuropsychological symptoms may be the first symptoms to appear, while other patients may show preserved cognitive functioning decades after diagnosis. (Abhijeet, 2007)

Neuropsychological evaluation is recommended for patients reporting cognitive deficits. This can identify the source of problems, which can facilitate the development of adaptive strategies. For example, most patients refer to cognitive symptoms as “memory problems.” However, deficits in other areas such as attention and concentration or executive functioning can often masquerade as memory problems. Nevertheless, development of compensatory strategies may improve adaptation. Neuropsychological evaluation may also assist employers and family members in adjusting the environment to optimize performance and developing realistic expectations about the patient's abilities. (Fillipi, 2003)

Psychological Symptoms

Patients with MS frequently present with a variety of psychological difficulties. It is widely believed that depression is the most common and most debilitating psychological problem associated with MS. Cumulative lifetime prevalence of major depressive disorder following MS diagnosis is approximately 50%, which ...