Why are the eye muscles usually spared in ALS?

Eye movements are of great importance in human evolution. Movements, as well as head and gaze shifts, require extremely rapid and precise adjustment of the eyes (in relation to the head and the environment). Along with manual functions, eye motor control is one of the body’s most sophisticated fine-motor skills. Consequently, the motor system of the eye muscles is particularly well “equipped”: A large number of nerve cells (located in the midbrain) are responsible for controlling a relatively small number of muscle cells that govern eye movement. It can be assumed that the particularly well-equipped nature of the eye muscles, with their controlling nerve cells, is responsible for the extensive preservation of eye motor function. Furthermore, it can be assumed that the neurobiological properties of the motor neurons responsible for eye control (ocular motor nuclei) differ from those of other motor neurons and are more “resilient” to neurodegeneration