Poser (1983) Diagnostic Criteria for Multiple Sclerosis

Diagnostic Category	Diagnostic Criteria
1. Clinically Definite Multiple Sclerosis (CDMS)	1. Clinical evidence of two attacks and two separate lesions 2. Clinical evidence of two attacks, one lesion, and subclinical evidence of another lesion
2. Laboratory-Supported Definite Multiple Sclerosis (LSDMS)	1. Two attacks during the disease course with one clinical or subclinical evidence, CSF OB/IgG 2. One attack during the disease course with two separate lesions' clinical evidence, CSF OB/IgG 3. One attack during the disease course with one lesion's clinical evidence and subclinical evidence of another lesion, CSF OB/IgG
3. Clinically Probable Multiple Sclerosis (CPMS)	1. Two attacks during the disease course with one lesion's clinical evidence 2. One attack during the disease course with clinical evidence of two lesions at different sites 3. One attack during the disease course with one lesion's clinical evidence and subclinical evidence of another lesion
4. Laboratory-Supported Probable Multiple Sclerosis (LSPMS)	Two attacks during the disease course, CSF OB/IgG, with the two attacks involving different CNS sites, separated by at least one month, and each attack lasting at least 24 hours

OB/IgG: IgG Oligoclonal Bands; CSF: Cerebrospinal Fluid.