THROUGH NO fault of our own, neurologists have suffered from a localization bias when it comes to the diagnosis and follow-up of patients with amyotrophic lateral sclerosis (ALS). We have favored lower over upper motor neurons. This partiality does not arise from any conscious tendency on the part of the examining neurologist, but rather stems from a difficulty in recognizing upper motor neuron dysfunction with the same certainty as identifying lower motor neuron dysfunction. We typically rely on clinical signs to diagnose lower motor neuron injury but can use ancillary tests such as electromyography or muscle biopsy to confirm the clinical impression. For patients with suspected ALS in whom lower motor neuron signs are not apparent, we readily turn to these same tests for help in detecting subclinical lower motor neuron involvement.
Elliott JL. A Clearer View of Upper Motor Neuron Dysfunction in Amyotrophic Lateral Sclerosis. Arch Neurol. 1998;55(7):910-912. doi:10.1001/archneur.55.7.910