From the Research
The specificity of CSF protein in Multifocal Motor Neuropathy (MMN) is relatively low, with approximately 90% of MMN patients having normal CSF protein levels, which is a useful diagnostic feature when differentiating MMN from other conditions like Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) 1. The normal CSF protein levels in MMN likely reflect the limited involvement of the proximal nerve roots and the predominantly peripheral nature of the immune attack on motor nerves. This is in contrast to conditions like CIDP where inflammation affects the nerve roots more extensively, leading to protein leakage into the CSF. Some key points to consider when evaluating CSF protein in MMN include:
- Normal CSF protein levels are common in MMN, but not specific enough for diagnosis on their own 2.
- The presence of anti-GM1 antibodies in serum (found in 30-80% of MMN cases) combined with normal CSF protein provides better diagnostic specificity for MMN 1.
- Other clinical features and tests are necessary to confirm the diagnosis of MMN, as normal CSF protein alone is not sufficient 2.
- The diagnostic value of CSF protein levels can be compared to other biomarkers, such as those used in the diagnosis of Alzheimer's disease, Creutzfeldt-Jakob disease, and narcolepsy, which have higher sensitivity and specificity 3.