Amyotrophic lateral sclerosis (ALS), formerly known as Lou Gehrig disease, is a neurodegenerative disease with upper and lower motor neuron dysfunction. The disease most commonly manifests between fifty and seventy years of age, often beginning with asymmetric weakness in the hands or feet. However, initial presentation is highly variable and some patients present with atypical/non-specific symptoms such as subtle vocal changes. As the disease progresses, most patients eventually develop one or both of the life-threatening symptoms: respiratory impairment and dysphagia. Riluzole and edaravone are currently the only drugs approved for the treatment of ALS. Multidisciplinary care is extremely important and includes nursing care, physiotherapy, and eventually assisted ventilation and enteral feeding. Most patients will die within 3–5 years, although approx. 30% have a chance of living longer.
- Prevalence: 5/100,000 population in the US 
- Incidence: 2–3 cases/100,000 population per year worldwide 
- Sex: ♂ > ♀
- Mean age of onset is 65 years.
- Can be sporadic (90%) or familial (10%).
Epidemiological data refers to the US, unless otherwise specified.
The definitive cause of ALS is still unknown, studies have suggested an interaction between genetic predisposition and environmental factors. 
Genetics: Mutations of the following genes have been found in approx. 70% of familial clusters and some sporadic cases. 
- SOD1: codes for ; mutations are associated with either a very agressive or very slow disease progression 
- FUS: Mutations are associated with a young-onset rapidly-progressing ALS. 
- Environmental risk factors 
- Classically affects the entire motor neuron system at two or more levels (both upper and lower motor neuron degeneration).
- Potential underlying mechanisms include abnormal RNA processing and protein aggregation, excitotoxicity, mitochondrial dysfunction, and defective neurofilaments.
General disease characteristics
- Both upper motor neuron (UMN) and lower motor neuron (LMN) signs are present (see )
- Constant disease progression: it usually starts in one arm and/or leg then progresses to the contralateral side and eventually, after months or years, affects the respiratory system.
- Symptoms are highly variable and potentially non-specific (e.g., subtle vocal changes or difficulties grasping objects)
- Asymmetric limb weakness, often beginning with weakness in the hands and feet
- Bulbar symptoms such as dysarthria, dysphagia, and tongue atrophy (20% of cases at disease onset)
- Pseudobulbar palsy with pseudobulbar affect may develop.
- Fasciculations, cramps, and muscle stiffness
- Weight loss
- Cognitive impairment (approx. 15% of ALS patients meet the criteria for
- Autonomic symptoms (e.g., constipation, bladder dysfunction) may develop; the mechanism of development is unclear. 
- Respiratory failure due to paralysis of respiratory muscles
- Dysphagia due to bulbar weakness
- Physical examination (including testing reflexes, Babinski's sign, etc.)
- Denervation: indicated, e.g., by fibrillations, positive sharp waves, and large amplitudes
- Nerve conduction studies: usually normal
- MRI and laboratory tests to exclude other potential diagnoses (see “Differential diagnosis” below)
- Increased creatine kinase
The differential diagnoses listed here are not exhaustive.
- Riluzole: a glutamate antagonist
- Edaravone (free radical scavenger): has been shown to slow functional decline in some patients with ALS
- Multidisciplinary and symptomatic therapy
Rilouzole rilly helps treating Lou Gehrig disease
- Most patients die within 3–5 years
- 5-year-survival: 30%
- 10-year-survival: 10–20%
- Early bulbar and/or respiratory symptoms are associated with a worse prognosis