What are the symptoms of Amyotrophic Lateral Sclerosis (ALS)?

Symptoms of Amyotrophic Lateral Sclerosis (ALS)

ALS presents with progressive motor weakness that can begin in either the limbs (spinal onset) or the muscles controlling speech and swallowing (bulbar onset), with nearly all patients eventually developing bulbar symptoms regardless of initial presentation. 1, 2

Motor Symptoms

Upper and Lower Motor Neuron Signs

• Muscle weakness that progresses to functional quadriplegia, affecting both upper and lower motor neurons 3
• Hyperreflexia and spasticity (upper motor neuron signs) 3
• Muscle fasciculations (visible twitching under the skin) 3
• Muscle atrophy (wasting) and progressive weakness 3

Pattern of Onset

• Limb onset (70% of cases): Weakness typically begins asymmetrically in one limb, which distinguishes it from other neuromuscular conditions 2
• Bulbar onset (30% of cases): Initial symptoms affect speech and swallowing muscles 3
• The disease eventually spreads to affect all motor functions regardless of initial presentation 2

Bulbar Symptoms

Dysphagia (Swallowing Difficulties)

• Occurs in 85.7% of patients with bulbar onset 2
• Develops in 42.9% of upper limb onset and 71.4% of lower limb onset cases as disease progresses 2
• Progresses through 5 stages: normal eating → early eating problems (difficulty chewing) → dietary consistency changes → need for tube feeding → nothing by mouth 4
• Increased meal time and fatigue during/after eating 4, 5
• Poor lip seal with drooling and food trapping in the mouth 4
• Reflux of food and liquid into the nose 4
• High risk of aspiration due to incomplete epiglottic closure 4

Dysarthria (Speech Difficulties)

• Almost 80% of patients with bulbar onset develop dysarthria 1
• Speech remains adequate on average for 18 months from the first bulbar symptom 6
• Progressive decline in articulation rate and intelligibility 6
• 60% of patients eventually require augmentative and alternative communication (AAC) methods 6

Other Bulbar Manifestations

• Sialorrhea (excessive drooling) 7
• Difficulty managing saliva 8

Respiratory Symptoms

• Dyspnea (shortness of breath) develops as respiratory muscles weaken 7
• Impaired cough due to weakness of expiratory muscles 7
• Respiratory complications are the most common cause of death, typically occurring within 3-5 years of diagnosis 3
• Progressive involvement of inspiratory, expiratory, and upper airway muscles 7

Disease Progression Timeline

• Mean survival is 3-5 years after symptom onset, with only 5-10% of patients living longer than 10 years 1, 2
• Nearly all patients manifest bulbar involvement in advanced disease, regardless of initial onset pattern 4, 2
• Bulbar onset has a shorter life expectancy compared to limb onset 5

Key Clinical Pitfalls

• Silent aspirations can occur without obvious choking symptoms, requiring videofluoroscopy for detection 4
• Dysphagia screening should be performed at diagnosis and every 3 months during follow-up, even in patients without obvious swallowing complaints 4
• Patients may have normal eating habits on screening scales yet show swallowing abnormalities on videofluoroscopy (66.7% in one study) 4
• Early recognition is critical because many patients already have severe dysarthria at the time of diagnosis 6