Amyotrophic Lateral Sclerosis (ALS) is a relentlessly progressive neurodegenerative disorder characterized by the loss of motor neurons, the nerve cells that control voluntary muscles. This loss leads to muscle weakness, atrophy, and eventual paralysis, profoundly impacting mobility and function. While ALS is classically defined by these motor symptoms, the disease is recognized as a multi-system condition that affects various other parts of the body, including the skin. These dermatological changes range from direct consequences of the underlying disease pathology to indirect results of prolonged immobility and muscle wasting.
Distinguishing Pathological and Secondary Skin Changes
Skin changes in ALS can be categorized into those stemming directly from the disease process and those that are secondary consequences of motor impairment. Direct pathological changes involve the skin’s structural integrity, which shares a common embryonic origin with the nervous system. A significant finding is the abnormal aggregation of the protein TDP-43, a hallmark of ALS in the central nervous system, which has also been detected in the epidermis of patients.
The presence of TDP-43 inclusions in non-neuronal skin cells suggests that the misfolding process is systemic. Structural abnormalities in the dermis include a disorganized arrangement and reduced number of collagen bundles, the primary support proteins of the skin. This disruption reduces the skin’s natural resilience and elasticity. This loss of elasticity is sometimes observed clinically as a “delayed return phenomenon” (DRP), where pinched skin takes longer to return to its original shape.
Secondary changes, conversely, are indirect results of the loss of muscle function and subsequent physical decline. These include skin thinning, nutritional deficiencies impacting skin health, and the formation of pressure injuries due to confinement. The overall effect of both primary and secondary changes is a compromise to the skin’s ability to maintain its barrier function and heal effectively.
Dermatological Issues Stemming from Immobility and Atrophy
The most common skin issues arise from restricted mobility, which subjects the skin to sustained pressure, friction, and shear forces. Pressure injuries, historically called bedsores or pressure ulcers, develop when external pressure on a bony prominence compresses the underlying tissue and blood vessels. This sustained compression restricts blood flow, leading to localized tissue ischemia and death.
Muscle atrophy, a defining feature of ALS, reduces the protective padding over bony areas like the sacrum, heels, and hips, increasing the risk of pressure injury formation. The overall risk remains high due to the inability to shift weight independently. Friction and shear, caused by sliding down in a bed or chair, also contribute to these injuries, often tearing or separating skin layers.
Pressure injuries are classified by depth:
- A Stage 1 injury presents as non-blanchable redness on intact skin.
- A Stage 2 injury involves partial-thickness skin loss with an exposed dermis, often appearing as a shallow open ulcer or a blister.
- Stage 3 injuries show full-thickness skin loss where subcutaneous fat is visible, though bone or muscle is not yet exposed.
- The most severe is a Stage 4 injury, which involves full-thickness tissue loss with exposed bone, tendon, or muscle, posing a severe risk for systemic infection.
Autonomic Dysfunction and Skin Regulation
Beyond mechanical issues, the skin’s function can be impaired by the autonomic nervous system (ANS), the involuntary control system. The ANS regulates functions like heart rate, blood pressure, and specific skin functions, including sweating and blood flow. Damage to the sympathetic nervous system, often involving small nerve fibers in the skin, can lead to sudomotor dysfunction, or abnormal sweating.
Many ALS patients experience decreased sweat output, known as hypohidrosis, particularly in the lower extremities. This reduced sweating impacts the body’s ability to cool itself effectively through evaporation, leading to difficulties with thermoregulation. The body struggles to maintain a stable internal temperature, making patients susceptible to overheating or feeling cold.
Changes in peripheral vascular control can also manifest as skin mottling or temperature fluctuations in the extremities. This neurological disruption of skin regulation is independent of muscle weakness, reflecting the broader systemic nature of the disease. Consequently, managing the patient’s environmental temperature becomes important for comfort and safety.
Targeted Skin Care and Prevention Protocols
Proactive skin care focuses on preventing pressure injuries and managing the effects of autonomic dysfunction. The most effective strategy is frequent repositioning, which involves turning a patient every few hours, even throughout the night, to relieve sustained pressure on bony prominences. Specialized pressure-redistribution support surfaces, such as alternating pressure mattresses and gel cushions, are employed to minimize localized pressure.
For areas susceptible to friction and shear, like the elbows and heels, protective devices such as soft booties or padding can reduce mechanical injury. Meticulous hygiene and moisture management are also necessary, requiring daily skin checks for early signs of redness or discoloration. Skin that is too dry can crack and break down, while excessive moisture from sweat or incontinence encourages maceration and vulnerability to infection.
Nutritional status plays a substantial role in skin health and wound healing, especially given the catabolic state and swallowing difficulties common in ALS. Adequate intake of protein is necessary for tissue repair, and micronutrients like Vitamin C and Zinc are required for collagen synthesis and immune function. Nutritional support, often facilitated by a feeding tube in later stages, ensures the body has the resources to maintain tissue integrity and heal any wounds that may occur.