多発性硬化症 L:はじめに

Multiple sclerosis is a chronic autoimmune condition that damages myelin, the protective sheath around nerve fibers in the central nervous system. Over time, MS also damages the underlying axons, contributing to irreversible neurological disability. The disease typically begins between ages 20 and 40 and is twice as common in women as in men.

Optic neuritis is a frequent MS symptom causing unilateral vision loss in one eye along with pain during eye movement. Patients may also experience reduced color vision. Additionally, internuclear ophthalmoplegia can impair coordination of horizontal eye movements, affecting overall visual function and eye coordination.

MS commonly presents with paresthesias—numbness, tingling, or electric-shock sensations affecting limbs, face, or trunk. Motor features include muscle weakness, spasticity, and gait difficulty. Cerebellar signs such as ataxia, tremor, and instability are also typical. These alterations in muscle tone and coordination significantly impact patient mobility and function.

Autonomic dysfunction in MS causes neurogenic bladder symptoms such as urgency and incontinence. Cognitive changes and mood disturbances, including depression, commonly occur. These non-motor symptoms significantly impact quality of life and require comprehensive management alongside physical symptoms affecting daily activities.

MS typically follows a relapsing-remitting pattern characterized by relapses and remissions. During relapses, new or worsening neurological symptoms develop over days to weeks. These are followed by remissions—periods when symptoms partially or fully improve. This cyclical pattern of flare-ups and recovery defines the most common form of MS.

MS risk involves both genetic susceptibility and environmental factors. First-degree relatives and identical twins show higher disease risk. Greater prevalence in northern latitudes suggests environmental contributors like vitamin D deficiency increase susceptibility. The exact cause remains unclear, but these combined factors determine individual disease risk.

Fatigue is a common MS symptom that often occurs independently of physical activity level or disease severity. This persistent exhaustion affects many patients and significantly impacts daily functioning and quality of life. Unlike activity-related fatigue, MS-related fatigue may persist despite adequate rest and recovery periods.