What are the symptoms of the first and second motor neuron?

Symptoms of the first motor neuron (1st MN) are slowed and uncoordinated movements, increased reflexes and spasticity. The most important symptoms of the second motor neuron include muscle weakness (paresis) and muscle atrophy. Other signs and symptoms of the 1st MN and 2nd MN are known, but these are not taken into account for the classification of phenotypes (OPM classification).