ABSTRACT
Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disease of the motor system, comprising a combination of upper motor neuron (UMN) and lower motor neuron (LMN) symptoms and signs in the four central nervous system regions: brainstem, cervical, thoracic, and lumbosacral. At any given stage of the disease, the clinical manifestations of ALS depend on the regional combinations of UMNs and LMNs involved. Since there is no single biologic marker or investigative test that establishes or confirms a diagnosis of ALS, the identification of the disorder is heavily dependent on clinical recognition of the signs and symptoms.
