MS Alphabet: Lesion, LP, Leukocytes, and Other ‘L’ Words

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by Tamara Sellman |

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Editor’s note: Tamara Sellman continues her occasional series on the MS alphabet with this first of two columns about terms starting with the letter L.

Symptoms of MS


Lesions are a defining feature of MS. They also are referred to as scars or plaques. These areas of damage identify areas in the central nervous system where the immune system has mistakenly attacked the outer coating of nerves, known as myelin. Lesions can be found anywhere, but usually are most common along the optic nerve, spinal cord, and brain stem. They usually are detected using magnetic resonance imaging (MRI).

MS abbreviations

LP (Lumbar Puncture)

Lumbar puncture (also known as a spinal tap) is the procedure used to help identify the presence of MS.

In the procedure, a specialist inserts a long, thin needle into the lower back, or lumbar section of the spine, to extract spinal fluid from the spinal column. Once extracted, it is tested to see if the spinal fluid contains certain protein markers.

The procedure is generally recognized as safe and has few side effects, the most common being a severe spinal headache that can occur up to two days after the procedure.

Specifically, your neurologist orders a lumbar puncture to find out if certain proteins are present in the spinal fluid. These are known as oligoclonal bands (or O bands, for short).

The presence of a certain amount of O bands in one’s spinal fluid can confirm an MS diagnosis.

However, not everyone tests positive for O bands in the spinal fluid. In fact, as many as 10 percent of people with MS do not have a positive LP finding.

Still, lumbar puncture exists as just one of several different diagnostic tests used to identify MS (or to rule it out).

Common MS terms


Lassitude is a form of fatigue that is unique to people with chronic illness.

Beyond basic fatigue that comes from overdoing it (however an MS patient defines what that means), lassitude is a daily fatigue that settles in even before one gets out of bed.

If you wake up in the morning feeling exhausted, it might be lassitude rather than typical fatigue. Some people report lassitude as being much more severe than regular fatigue.

Lassitude tends to worsen over the course of the day. Becoming overheated or stressed also can make it worse.

It’s never a bad idea to mention it to your neurologist if you feel you have lassitude. It might signal another health problem you aren’t aware of, or could signify emerging disease activity.

The biology of MS


When you discuss white blood cell counts with your doctor, you actually are talking about leukocytes. These cells form a major part of the immune system. They exist to fight infection by destroying pathogens as part of the inflammatory response.

Leukocytes are signaling cells, meaning they communicate with each other and with other kinds of cells through special chemical messengers known as cytokines.

Leukocytes in healthy individuals generally don’t cross the blood-brain barrier, which exists to prevent their entry from the bloodstream into the central nervous system.

However, the presence of leukocytes in the central nervous system is considered an early sign of MS, as it corresponds with inflammation of the gray and white matter.

Also, people who take immune system modulating or moderating drugs may discover their bloodstreams have lower-than-normal levels of leukocytes.

This is one reason why neurologists ask to take regular blood samples from their MS patients; if white blood cell counts are too low, it may mean an adjustment in dosage or a switch to a different medication.

Extremely low leukocyte counts leave the body more open to infection and make it harder for them to heal from infections, such as urinary tract infections (UTIs).

MS treatments


Also known as alemtuzumab, Lemtrada is a treatment for MS approved by the FDA in 2014 to treat very active forms of relapsing-remitting MS. A form of monoclonal antibody, Lemtrada is dispensed by drip infusion in two treatment courses that are spread apart by 12 months.

Recent research has shown that Lemtrada usage may lead to the development of other autoimmune conditions, but it is still considered one of the best disease-modifying drugs for treating MS.


Note: Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Multiple Sclerosis News Today or its parent company, BioNews Services, and are intended to spark discussion about issues pertaining to multiple sclerosis.


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