There is no specific disease known as Motor Neuron Syndrome - to my knowledge.
There are a group of motor neuron diseases. They are a group of progressive muscle diseases that affect cells that control muscle activity. Common MND's include amyotrophic lateral sclerosis (ALS), progressive bulbar palsy, primary lateral sclerosis, and progressive muscular atrophy.
Further tests like an MRI and nerve conduction studies can be done to rule out other causes, and I would discuss these findings with a neurologist.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.