What are the most reliable tests to establish if you have a neuron disease?

Assume you mean: "motor neuron disease", or als, or lou gehrig disease? Testing includes checking for spinal cord compression, blood studies for muscle disorders, hyperthyroidism, and other metabolic diseases. An EMG study may show characteristic changes, and a muscle biopsy on occasion may be useful. There are many other diseases affecting the nerve cells. Hope the above is what you ask.