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Diagnosis of multiple sclerosis; especially useful in patients with equivocal clinical presentation and radiological findings
The diagnosis of multiple sclerosis (MS) is dependent on clinical, radiological, and laboratory findings. The detection of increased intrathecal immunoglobulin (Ig) synthesis is the basis for current diagnostic laboratory tests for MS. These tests include the cerebrospinal fluid (CSF) IgG index and CSF oligoclonal band (OCB) detection. Abnormal CSF IgG indexes and OCB patterns have been reported in 70% to 80% of MS patients. At least 1 of these tests has been reported to be positive in 90% of MS patients when both test are performed.
Newer methodologies for OCB detection have been reported to be more sensitive, with sensitivities of 90% to 95% in CSF from MS patients.
Increased intrathecal Ig synthesis may occur in other inflammatory CSF diseases and, therefore, this assay is not specific for MS (specificity = 95%).
CSF Olig Bands Interpretation: <4 bands
A finding of 4 or more cerebrospinal fluid (CSF)-specific bands (ie, bands that are present in CSF but are absent in serum) is consistent with multiple sclerosis.
The presence of oligoclonal band is unrelated to disease activity.
These tests are not specific for multiple sclerosis.
In early 2003 we compared the isoelectric focusing (IEF) assay to our previous high-resolution agarose assay as well as the cerebrospinal fluid (CSF) IgG index. The IEF assay requires a smaller volume of CSF and is easier to interpret than the agarose assay. Concordant normal specimens usually had zero bands by IEF but 1 band by agarose. The concordant positive specimens had an average of 11 bands by IEF and 2 bands on agarose.
Among 19 cases of definite multiple sclerosis (MS), the IEF oligoclonal band (OCB) assay had a sensitivity of 95%, the agarose assay had a sensitivity of 63%, and the CSF index had a sensitivity of 74%. Among 57 consecutive non-MS cases, the IEF OCB assay had a specificity of 95% and agarose and CSF index assays had a specificity of 97%. These data demonstrated a 32% increase in sensitivity and a 2% decrease in specificity for IEF.
1. Andersson M, Alvarez-Cermeno J, Bernardi G, et al: Cerebrospinal fluid in the diagnosis of multiple sclerosis: a consensus report. J Neurol Neurosurg Psychiatry 1994;57:897-902
2. Fortini AS, Sanders EL, Weinshenker BG, Katzmann JA: Cerebrospinal fluid oligoclonal bands in the diagnosis of multiple sclerosis, isoelectric focusing with the IgG immunoblotting compared with high resolution agarose gel electrophoresis and cerebrospinal fluid IgG index. Am J Clin Pathol 2003:120:672-675