Describe general disease characteristics.
Both upper motor neuron (UMN) and lower motor neuron (LMN) signs are present (see Upper motor neuron injury vs. lower motor neuron injury)
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.
List early symptoms.
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
Split hand sign: a wasting pattern in which the muscles of the thenar eminence atrophy due to degeneration of the lateral portion of the anterior horn of the spinal cord
List late symptoms.
Cognitive impairment (approx. 15% of ALS patients meet the criteria for frontotemporal dementia)
Autonomic symptoms (e.g., constipation, bladder dysfunction) may develop; the mechanism of development is unclear. [1]
Life-threatening symptoms
Respiratory failure due to paralysis of respiratory muscles
Dysphagia due to bulbar weakness or pseudobulbar palsy
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