It was a 'guessterlization', based on how what a enhancing/inflammatory lesion is:

It is my understanding that once someone goes from the inflammatory phase of the disease (RRMS, with enhancing lesions), into the progressive phase (SPMS), generally they have few to no relapses, and inflammatory (enhancing) lesions are far less common.

“During periods of multiple sclerosis activity, white blood cells (leukocytes) are drawn to regions of the white matter. These initiate and take part in what is known as the inflammatory response. The resulting inflammation is similar to what happens in your skin when you get a pimple.

During the inflammation, the myelin gets stripped from the axons in a process known as demyelination. The effect of this bears many parallels to the rubber insulation on wire perishing - some or all of the electricity in the wire will short out and the efficient conductivity of the wire will be reduced. When the myelin sheath is damaged, the transmission of nerve impulses is slowed, stopped or can jump across into other demyelinated axons.”

As the disease progresses, axons are also destroyed though not necessarily by the inflammatory response. During the secondary progressive phase of the disease, inflammation becomes less and less common but still the axons continue to die. This degeneration of axons is known as Wallerian Degeneration.”

http://www.mult-sclerosis.org/howms.html

“RRMS is characterised by relapses (also known as exacerbations) during which time new symptoms can appear and old ones resurface or worsen. The relapses are followed by periods of remission, during which time the person fully or partially recovers from the deficits acquired during the relapse.”

“During relapses, myelin, a protective insulating sheath around the nerve fibres (neurons) in the white matter regions of the central nervous system (CNS), is damaged in an inflammatory response by the body's own immune system. This causes a wide variety of neurological symptoms that vary considerably depending on which areas of the CNS are damaged.

Immediately after a relapse, the inflamatory response dies down and a special type of glial cell in the CNS (called an oligodendrocyte) sponsors remyelination - a process whereby the myelin sheath around the axon is repaired. It is this remyelination that is responsible for the remission.”

http://www.mult-sclerosis.org/relaps...sclerosis.html

“After a number of years many people who have had relapsing/remitting MS will pass into a secondary progressive phase of the disease. This is characterised by a gradual worsening of the disease between relapses. In the early phases of Secondary Progressive, the person may still experience a few relapses but after a while these merge into a general progression.”

http://www.mult-sclerosis.org/whatisms.html

“Secondary Progressive Multiple Sclerosis tends to be associated with lower levels of inflammatory lesion formation than in RRMS but the total burden of disease continues to progress. This is thought to be caused by higher levels of axonal loss.”

http://www.mult-sclerosis.org/second...sclerosis.html
The formation of lesions:

http://www.medhelp.org/health_pages/...show/23?cid=36

Cherie