MND:The diagnosis help tool is a Proteomic Pattern Analysis (PPA) of cerebrospinal fluid
In layman term: the set of various protein in cells is call proteome. In Proteomic pattern analysis, the proteome of cells from various tissues is analyzed.
This is not a simple method, below is a photograph of typical instrumentation
There is a substantial number of MS like diseases, and identifying which the patient has is obviously going to help target the treatments. Here are the main ones as outlined in the study 
- relapsing remitting-MS (RRMS),
- primary progressive-MS (PPMS),
- anti-aquaporin4 antibody seropositive-neuromyelitis optica spectrum disorder (SP-NMOSD),
- seronegative-NMOSD with long cord lesions of spinal MRI (SN-NMOSD),
- amyotrophic lateral sclerosis,
- or other inflammatory neurological diseases
So Cerebrospinal Fluid (CSF) is collected, and after preparation, the cells yeld their proteome to mass spectrometry, and Doctors hopefully can differentiate between the nervous system diseases.
This diagnosis method is not limited to MS, but is also used in Alzheimer’s  and Parkinsons’s. Quoting: “..[the method]…distinguish AD from other dementia causes, as well as differentiate subtle changes associated with normal aging from true pathology emergence…..”
Furthermore, PPA has beeen used to analyze biopsies of cancer, . So how far is this method from mainstream diagnostics, FDA approved? They are working on it….
 Doctorslounge; Annals Of Neurology ; “Proteomic pattern analysis discriminates among multiple sclerosis-related disorders”; Mika Komori M
Neurology Research; “Comparative proteomics of cerebrospinal fluid in neuropathologically-confirmed Alzheimer’s disease and non-demented elderly subjects” ; Neurol Res. 2006 Mar;28(2):155-63.
PlosOne; “Integrative proteomic analysis of serum and peritoneal fluids helps identify proteins that are up-regulated in serum of women with ovarian cancer” ; PLoS One. 2010 Jun 15;5(6):e11137.
 Clinical Chemistry ; “The Journey to Regulation of Protein-Based Multiplex Quantitative Assays”; Clinical Chemistry 0: clinchem.2010.156034v2, 2011; 10.1373/clinchem.2010.156034