Do I Need A Spinal Tap To Diagnose MS?
Testing for multiple sclerosis (MS) is a multi-step process as there is no single test or biomarker that defines the disease. Diagnosis requires that evidence of demyelination be detected in more than one location of the central nervous system, occurring in at least two points in time, and that all other potential causes of symptoms are eliminated.
For some patients, magnetic resonance imaging (MRI) and clinical evidence are unequivocal and diagnosis is straightforward. For others, further investigation is necessary to meet diagnostic criteria.
I’ve mentioned before that I first had a blinding case of optic neuritis in 2000, but was not diagnosed with MS at the time. Five years later, I began having more obvious symptoms related to spinal lesions. This was before the 2005 and 2010 revisions to MS McDonald diagnostic criteria, which allow for an earlier diagnosis, had been implemented. My diagnosis required an MRI, evoked potential testing, and cerebrospinal fluid analysis. Although results from these tests were abnormal, I still had to wait until additional lesions developed and clinical symptoms worsened before an official diagnosis was made.
What is cerebrospinal fluid?
The central nervous system (CNS) is bathed in a clear, colorless liquid, called cerebrospinal fluid (CSF), that cushions and protects the brain and spinal cord. CSF is produced in the ventricles and helps to transfer waste products from the brain to the vascular system. It can also deliver nutrients and hormones to the brain. CSF is composed of cells, water, proteins, sugars, and other vital substances. Examining the fluid can help doctors to identify diseases affecting the central nervous system, including MS.
How is CSF collected?
Cerebrospinal fluid is obtained through a needle that is inserted into the spine during a procedure called lumbar puncture or spinal tap. For this procedure, the patient will usually lay on their side with their back arched (chin and knees tucked toward the chest). An area of skin on the lower back is cleaned before the procedure.
After the area is anesthetized (numbed), a thin and hollow needle is carefully inserted between two lumbar bones into the spinal canal, the space where the CSF circulates.
You may feel slight pressure as the needle is inserted. It’s very important to stay perfectly still during the procedure.
A small amount of fluid, about one tablespoon, will be withdrawn for laboratory testing.
A lumbar puncture may be performed in a doctor’s office by a skilled physician, or it may be performed in an out-patient hospital setting where the procedure can be guided by radiographic technology to assist with needle placement. Before or after the procedure, blood will be withdrawn from a vein in the arm to compare to the CSF.
Why test CSF in MS patients?
Cerebrospinal fluid obtained through a lumbar puncture is tested for red and white blood cells, protein, sugars, clarity, color, and presence of bacteria, viruses, or abnormal cells.
The CSF of people with MS often contains:
- Elevated levels of IgG antibodies that protect the body from infection
- Oligoclonal bands, a type of protein that suggests CNS inflammation
- Other proteins that result from the breakdown of myelin
Each of these results can indicate an abnormal immune response occurring in the central nervous system; however, abnormal immune responses detected in CSF are not unique to MS. When oligoclonal bands, also referred to as O-bands or OCBs, are present in the CSF, but absent in the blood, multiple sclerosis is often suspected. Studies show that patients diagnosed with clinically isolated syndrome (CIS) that have O-bands are more likely to develop MS (Huss 2016; Schwenkenbecher 2016).
While most patients diagnosed with MS will have O-bands in the CSF, a small percentage (five to 10 percent) of patients with MS will never show this abnormality. A 2014 study showed that patients who test positive for O-bands experience greater brain atrophy than those who test negative for O-bands. Researchers further suggest that OCB-negative patients represent a unique subgroup that may experience different disease progression or response to treatment.
CSF analysis is not required to make an MS diagnosis, but it can be helpful when the evidence of disease is unclear or ambiguous. It may be that, in the future, CSF analysis could be used to help guide treatment decisions. More research is needed in this area.
How to prepare for the lumbar puncture?
Inform the physician if you are taking antibiotics, have an infection or fever, take blood thinners, or may be pregnant. Other options may be discussed.
Do not eat or drink anything three hours before the procedure. You may drink enough water to comfortably swallow medications taken as usual.
Bring a friend or family member who can drive you home following the procedure as you will not be able to drive for 24 hours.
You will be required to lay flat for at least one hour after the procedure to reduce the risk of CSF leakage and a resulting spinal headache. Continuing to lay flat or stay reclined at home and limiting yourself to very light activity during the rest of the day are also helpful.
Tell your doctor if you develop a persistent headache lasting more than a few hours, drainage of blood or pain at the injection site, inability to urinate, or experience numbness and tingling when you change positions.
If you do experience a spinal headache, a “blood patch” may be helpful. This involves the physician taking some of your blood from a vein and injecting it near the location of the spinal tap to seal any holes or leaks that may have developed.
See More Helpful Articles:
Huss AM, Halbgebauer S, Ockl P, et al. Importance of cerebrospinal fluid analysis in the era of McDonald 2010 criteria: a German-Austrian retrospective multicenter study in patients with a clinically isolated syndrome. J Neurol. 2016 Oct 11. [Epub ahead of print]
Schwenkenbecher P, Sarikidi A, Wurster U, et al. McDonald Criteria 2010 and 2005 Compared: Persistence of High Oligoclonal Band Prevalence Despite Almost Doubled Diagnostic Sensitivity. Int J Mol Sci. 2016;17(9). pii: E1592.