Amyotrophic lateral sclerosis (ALS) is a degenerative central nervous system disorder caused by
death of motor neurons in the brain and spinal cord. The clinical syndrome is characterized by muscle
weakness, often beginning focally and gradually progressing over 1 or more years to involve muscles
diffusely. The diagnosis is established by documenting clinical evidence of both upper and lower motor
neuron dysfunction and by performing diagnostic tests to exclude many other disorders of the central
and peripheral nervous system that might alternatively account for the clinical presentation. The
revised El Escorial criteria for ALS may be useful for patients participating in research studies.
Recognition of clinical features, clinical variants, and mimicking disorders is important because several
are potentially treatable or may not carry the same grave prognosis as ALS and the precise diagnosis
of ALS can promote more clinical trials for ALS.

KEYWORDS : Amyotrophic lateral sclerosis, ALS, Motor neuron