Oligoclonal bands in CSF explained: what the test shows in MS

Cerebrospinal fluid (CSF) is the clear fluid that surrounds the brain and spinal cord. The MS Trust explains that, in MS, antibodies cross the blood-brain barrier and attack the myelin surrounding nerves, so the level of antibodies in the CSF of someone with MS is higher than it should be. Oligoclonal bands are a pattern of antibodies made within the central nervous system, which show up as distinct bands when the fluid is tested in the laboratory.

Lab Tests Online UK describes CSF analysis as a way of helping to diagnose conditions affecting the brain and spinal cord, including meningitis, encephalitis, multiple sclerosis, bleeding around the brain and certain cancers. Oligoclonal band testing is one part of the CSF analysis that can be requested when MS or another inflammatory condition is being considered.

The MS Trust describes the usual order of investigation. The first steps are taking a medical history and an initial neurological examination, which is usually followed by an MRI scan of the brain. If those results do not give enough evidence to make a diagnosis of MS, a neurologist may refer you for a lumbar puncture to help confirm MS or rule out other conditions.

The NHS says that if a GP thinks you could have MS they will refer you to a neurologist, and that there is no single test to diagnose it. Lumbar puncture is therefore one of several pieces of information, and it is not needed in everyone. Waiting times vary around the UK, but the MS Trust says typically it should be within a few weeks of referral.

A lumbar puncture involves a needle being inserted into the lower back, between the bones in the spine, to collect CSF in small tubes, according to the NHS. It is usually done in hospital, typically takes around 15 to 20 minutes but can take longer, and is carried out after a local anaesthetic. The MS Trust says the appointment will usually be about an hour, with the procedure itself taking about 20 minutes to half an hour, and that around 20 drops are usually collected in each of three tubes.

For oligoclonal bands specifically, the MS Trust says a blood sample is usually taken at the same time, so the serum can be checked for comparison. The comparison lets the laboratory see whether the bands are present only in the CSF or are also in the blood, which is what the MS Trust describes as the pattern that can indicate MS.

The result is described in terms of whether bands are present in CSF and whether the same bands are present in the serum.

The MS Trust is clear that this test alone cannot confirm or rule out MS. A positive result is supportive but not proof, because bands are also seen in viral encephalitis, bacterial meningitis and lupus. A negative result does not exclude MS, because a minority of people with MS have no bands.

The MS Trust also notes that the white blood cell count in CSF is usually up to seven times higher than normal in MS, and that a count even higher than this is probably due to an infection of some sort. This is one reason the CSF is looked at as a whole rather than the bands alone.

The NHS adds that the type of MS, whether relapsing remitting, secondary progressive or primary progressive, may need symptoms and test results to be monitored for some time before it can be identified, so a single CSF result is only one piece of the picture.

The MS Trust says a newer spinal fluid test has emerged that looks for kappa free light chains (kFLCs), small protein fragments made by antibody-producing cells. Elevated levels could indicate MS. It describes this test as quicker and easier to perform than the one for oligoclonal bands and says it does not require a blood sample for comparison, so it is likely to be used more routinely in the future.

Which test a laboratory uses depends on local services. If your report mentions kappa free light chains rather than oligoclonal bands, it is answering a similar question using a different method.

The NHS says you will usually need to stay at hospital for around 1 to 2 hours to be monitored, and that a headache, back pain and swelling or leakage at the needle site are common side effects that should go away after a few days. The MS Trust says around three in 10 people have a headache following a lumbar puncture, which gets worse when standing and improves lying down, and that less than one in 100 people need a blood patch.

The MS Trust says you should get your results within a few weeks, and that if you have not heard anything after a month you should contact your neurologist. A follow-up appointment may be arranged to discuss the results and what happens next.