ALS Beyond Motor Neurons: How Amyotrophic Lateral Sclerosis Affects Multiple Organ Systems

Amyotrophic Lateral Sclerosis (ALS) is defined by progressive degeneration of upper and lower motor neurons, but its impact cascades across virtually every organ system. Understanding these secondary effects is essential for comprehensive care.

1. Respiratory System (Most Critical)

• Diaphragm & intercostal weakness → restrictive lung disease.
• Reduced vital capacity, ineffective cough → atelectasis, pneumonia risk.
• Nocturnal hypoventilation → morning headaches, fatigue, cognitive fog.
• Management: NIV (BiPAP), mechanical insufflation-exsufflation (cough assist), tracheostomy ventilation in advanced disease.

2. Cardiovascular & Autonomic

• Autonomic dysfunction: orthostatic hypotension, arrhythmias, heart rate variability loss.
• Direct myocardial involvement debated; some show subclinical cardiomyopathy.
• Immobility → DVT/PE risk; prophylactic anticoagulation often needed.

3. Gastrointestinal & Nutrition

• Dysphagia (bulbar + limb) → malnutrition, dehydration, aspiration pneumonia.
• Gastroparesis, constipation (autonomic + immobility + opioids).
• Early PEG tube placement improves survival and quality of life.
• High-calorie, high-protein, texture-modified diets.

4. Genitourinary

• Neurogenic bladder: urgency, retention, incontinence.
• UTI risk from incomplete emptying, catheterization.
• Bowel: neurogenic bowel → constipation, impaction, incontinence.
• Scheduled voiding, anticholinergics, intermittent catheterization, bowel regimen.

5. Skin & Musculoskeletal

• Pressure injuries from immobility + sensory loss + malnutrition.
• Osteoporosis: disuse + vitamin D deficiency + glucocorticoids (if used) → fracture risk.
• Contractures, joint pain from spasticity + weakness.
• Prevention: specialized surfaces, turning schedule, range-of-motion, bisphosphonates if indicated.

6. Cognitive & Behavioral (ALS-FTD Spectrum)

• ~15% meet criteria for frontotemporal dementia (FTD).
• Up to 50% have milder executive/language deficits.
• Features: apathy, disinhibition, loss of empathy, perseveration, executive dysfunction.
• Impacts decision-making, compliance, caregiver burden.
• Screening: ALS-CBS, ECAS.

7. Pain

• Nociceptive: spasticity, contractures, immobility, pressure sores.
• Neuropathic: less common but possible.
• Management: baclofen/tizanidine for spasticity, gabapentinoids, NSAIDs/acetaminophen, opioids cautiously, positioning, PT.

Multidisciplinary Care Model

ALS clinics integrate neurology, pulmonology, gastroenterology, nutrition, PT/OT/SLP, respiratory therapy, palliative care, social work, and neuropsychology. This coordinated approach extends survival and preserves quality of life.