A group of progressive degenerative disorders affecting the lower motor neurons and the upper motor neurons.
The result of dysfunction of upper motorof neurons in the pre-central gurus of the frontal lobe or lower motor neurons in the ventral horn of the spinal cord
Weakness can be restricted to the muscle, the neuromuscular junction, the motor nerve, the CNS or to a combination of above processes.
Motor neuron diseases cause weakness without notable sensory symptoms or pain.
Muscle atrophy and fasciculations suggest lower motor neuron disease.
Intoxication with heavy metals, particularly lead, can manifest with a pure lower motor neuropathy.
Hyper1eflexia and pathologic reflexes suggest an upper motor neuron disease.
Frequently causes death within 5 years of diagnosis and mostly due to lung complications related to respiratory muscle weakness and bulbar involvement.
The most common motor neuron disease is ALS.