Clinical Presentations, Diagnostic Criteria, and Lab Testing

Amyotrophic lateral sclerosis (ALS) is the protypical motor neuron disease, which is characterized by the simultaneous presence of upper motor neuron (UMN) and lower motor neuron (LMN) signs in the same extremity or in the cranial-bulbar region. UMN signs at spinal levels include spasticity, slowness of motor activation, hyperactive deep tendon reflexes and extensor plantar responses, whereas UMN signs at the cranial level include spastic dysarthia (slow, labored, nasal); slowness of tongue movements, and hyperactive jaw, gag, and facial reflexes. LMN signs at the spinal level include muscle atrophy, fasciculations, and weakness and LMN signs at the cranial level include tongue atrophy and weakness, facial weakness, tongue and facial fasciculations, palatal weakness, weak cough, and dysphonia. ALA is fatal in 2 to 4 years, and the only medication known to prolong tracheostomy-free survival