<unk>  <unk>  is a very rare neuromuscular disease characterized by progressive muscle weakness in the voluntary muscles.<unk>  belongs to a group of disorders known as motor neuron diseases. Motor neuron diseases develop when the nerve cells that control voluntary muscle movement degenerate and die, causing weakness in the muscles they control.<unk>  only affects upper motor neurons. There is no evidence of the degeneration of spinal motor neurons or muscle wasting (amyotrophy) that occurs in amyotrophic lateral sclerosis (ALS).
Primary lateral sclerosis
Juvenile primary lateral sclerosis
Amyotrophic lateral sclerosis
Surfer's myelopathy
Vascular myelopathy
CMV polyradiculomyelopathy
Tumefactive multiple sclerosis
Multiple sclerosis