Peripheral Neurofilament Levels and Amyotrophic Lateral Sclerosis

Inclusion Criteria: * Patients with lower motor neuron involvement (LMND-ALS), who have visited the Department of Neurology of the Third Hospital of Beijing Medical University since August 2017, meet the diagnostic criteria for ALS in 1998. The main clinical manifestations were muscle weakness with atrophy and bundle fibrillation, the pyramidal tract sign was relatively mild, and extensive neurogenic damage with CMAP amplitude decreased could be seen in patients with electromyography. * LMND-ALS CMAP amplitude \< median array: in line with LMND -ALS inclusion criteria, and CMAP amplitude of peripheral motor nerves (CMAP amplitude of the 10 peripheral motor nerves with the most obvious CMAP amplitude decline was selected as the CMAP amplitude for grouping of the patients) was less than the median of CMAP amplitude of LMND -ALS group. * LMND -ALS CMAP amplitude ≥ median array: meeting LMND -ALS inclusion criteria, and CMAP amplitude of peripheral motor nerves (CMAP amplitude of 10 peripheral motor nerves with the most obvious CMAP amplitude decline was selected as the CMAP amplitude for grouping of the patients) was greater than or equal to the median of CMAP amplitude of LMND -ALS group. * Patients with upper motor neuron involvement (UMND-ALS): patients with ALS who visited the Department of Neurology of the Third Hospital of Beijing Medical University since August 2017 and met the diagnostic criteria for ALS in 1998. The main clinical manifestations were limb stiffness and spasm, obvious pyramidal tract signs, relatively mild muscle atrophy and fasciculation, and no significant decrease in amplitude of electromyography CMAP. * Patients with ALS with flail arm syndrome (FAS) and flail leg syndrome (FLS): patients with ALS who met the diagnostic criteria for ALS in 1998 and visited the Department of Neurology of the Third Hospital of Beijing Medical University since August 2017. The clinical symptoms were confined to upper limbs (FAS) or lower limbs (FLS) for more than 12 months, and the main manifestations were lower motor neuron involvement signs such as muscle weakness and atrophy. Exclusion Criteria: * Merging other nervous system degenerative diseases (Alzheimer's disease, Parkinson's disease, multiple system atrophy, etc.) to take off the sheath, central nervous system disease, multiple sclerosis, optic myelitis spectrum disorders), peripheral neuropathy (GBS, chronic inflammatory more nerve root sheath sex mental derangement, hereditary peripheral neuropathy, diabetic peripheral neuropathy, vice tumor peripheral neuropathy, secondary to autoimmune diseases ), into the group within a month before the cerebrovascular disease or cerebral or spinal surgery patients.