There are several diseases that primarily involve motor neuron system and mimics amyotrophic
lateral sclerosis. Even though they share several common features of lower motor neuron or/and
upper motor neuron signs with amyotrophic lateral sclerosis, they have specific feature in clinical,
electrophysiologic, laboratory and pathologic characteristics that can be differentiate from
amyotrophic lateral sclerosis. Understanding the entity of atypical motor neuron diseases and
clinical clue to differentiate amyotrophic lateral sclerosis from atypical motor neuron disease is
important to support the early diagnosis of amyotrophic lateral sclerosis and to prevent misdiagnose
a treatable or more benign disease as an amyotrophic lateral sclerosis.



KEYWORDS
Motor neuron disease,
Amyotrophic lateral sclerosis,
Atypical motor neuron disease,
Mimics,
Variants