13 doctors weighed in:

Is it likely that I have MS if my spinal tap is completely negative?

13 doctors weighed in
Dr. Glenn Skow
Family Medicine
8 doctors agree

In brief: Possible

Each test has a false negative and false positive rate.
Some better than others. While you may be able to diagnose MS by spinal tab, that is usually positive a little more than 80% of the time. This means some who do have it might test negative. A brain MRI is positive in more than 95% of cases. If you are still having symptoms of ms, see your doctor to consider an mri.

In brief: Possible

Each test has a false negative and false positive rate.
Some better than others. While you may be able to diagnose MS by spinal tab, that is usually positive a little more than 80% of the time. This means some who do have it might test negative. A brain MRI is positive in more than 95% of cases. If you are still having symptoms of ms, see your doctor to consider an mri.
Dr. Glenn Skow
Dr. Glenn Skow
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2 doctors agree

In brief: Is possible

If you have MRI lesions which are c/w MS, but spinal fluid is normal, that would indicate a far better prognosis.
Spinal fluid is helpful in 95% of cases, but that leaves a small number of equivocal situations. We try to resolve by follow-up MRI's, seeking whether changes are occurring. Chances are, that you probably do NOT have MS.

In brief: Is possible

If you have MRI lesions which are c/w MS, but spinal fluid is normal, that would indicate a far better prognosis.
Spinal fluid is helpful in 95% of cases, but that leaves a small number of equivocal situations. We try to resolve by follow-up MRI's, seeking whether changes are occurring. Chances are, that you probably do NOT have MS.
Dr. Bennett Machanic
Dr. Bennett Machanic
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Dr. Joshua Davidson
Internal Medicine - Allergy & Immunology
1 doctor agrees

In brief: Possibly

A negative spinal tap is usually a good sign in terms of ruling out ms, but it's not the only sign, and it depends on the tests performed on the spinal fluid.
A negative brain MRI is more supportive of a negative evaluation, as is the absence of certain proteins that are often found in spinal fluid of MS patients. I would talk to your doctor about a MRI and about these proteins in the fluid.

In brief: Possibly

A negative spinal tap is usually a good sign in terms of ruling out ms, but it's not the only sign, and it depends on the tests performed on the spinal fluid.
A negative brain MRI is more supportive of a negative evaluation, as is the absence of certain proteins that are often found in spinal fluid of MS patients. I would talk to your doctor about a MRI and about these proteins in the fluid.
Dr. Joshua Davidson
Dr. Joshua Davidson
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