Which CSF finding supports a diagnosis of multiple sclerosis?

Which CSF finding supports a diagnosis of multiple sclerosis?

• A. Oligoclonal bands with an elevated IgG index in CSF.
• B. Elevated neutrophils.
• C. Reduced total protein.
• D. Decreased IgG index.

Answer: (A)

In multiple sclerosis, the hallmark CSF change is intrathecal IgG synthesis. This is seen most clearly as oligoclonal bands on CSF electrophoresis and an elevated IgG index. Oligoclonal bands are IgG proteins produced within the CNS, so they appear as extra bands in CSF not matched in the serum, reflecting localized immune activity against myelin. The IgG index quantifies this synthesis by comparing CSF and serum IgG relative to albumin; an increased index indicates more IgG being made inside the CNS. Together, these findings strongly support MS. Elevated neutrophils would suggest an acute infectious process like bacterial meningitis; MS typically has little to no neutrophilic pleocytosis and more lymphocytic predominance. Reduced total protein and decreased IgG index are not characteristic of MS; they do not reflect intrathecal IgG production.

In multiple sclerosis, the hallmark CSF change is intrathecal IgG synthesis. This is seen most clearly as oligoclonal bands on CSF electrophoresis and an elevated IgG index. Oligoclonal bands are IgG proteins produced within the CNS, so they appear as extra bands in CSF not matched in the serum, reflecting localized immune activity against myelin. The IgG index quantifies this synthesis by comparing CSF and serum IgG relative to albumin; an increased index indicates more IgG being made inside the CNS. Together, these findings strongly support MS.

Elevated neutrophils would suggest an acute infectious process like bacterial meningitis; MS typically has little to no neutrophilic pleocytosis and more lymphocytic predominance. Reduced total protein and decreased IgG index are not characteristic of MS; they do not reflect intrathecal IgG production.