MULTIPLE SCLEROSIS

AXONAL DAMAGE

SIGNIFICANT IN MS

Although we normally think of MS as a demyelinating disease, loss of nerve fibres (called axonal degeneration) also occurs. Axonal damage in MS is now being shown to be far more extensive than was earlier thought, occurring throughout the central nervous system (CNS). A recent international workshop organised by the American MS Society reviewed the evidence of axonal injury in MS and possible ways to prevent it.

The significance of axonal damage and loss is that it causes permanent disability in MS. Less importance was given to axonal until relatively recently, with new technologies allowing researchers to study it in detail. The need for treatment to prevent it happening has become increasingly clear.

Loss and damage to axon can be seen on examination of tissue under the microscope and by MRI. There is now abundant evidence that axonal damage occurs at the earliest stages of MS and continues to occur throughout the course of the disease.

One of the controversies  is whether axonal injury is a result of inflammation. The US workshop participants agreed that, on current evidence, axonal injury always occurs in the presence of inflammation. However, neurodegeneration can and does occur at other stages independent of inflammation.

Possible Prevention

Much discussion at the workshop centred on the specific mechanisms of axonal damage, with many different molecules and cells identified as being able to cause damage. Drugs could be produced to counter these damaging cells and molecules, but so-called `neuroprotective` drugs are only in the early stages of development and testing.

Lessons from other neurodegenerative diseases such as Parkinson`s Disease and strokes were discussed at the workshop. It seems likely that if drugs work in these diseases, there is protential for MS because, however damage occurs, neurodegeneration follows similar patterns. So far, however, these used in other diseases have given disappointing results. Because of the complex mechanisms of axon damage it was debated that a cocktail of drugs would be a better strategy than having just one drug. Workshop participants also recognised that drug delivery methods need to be addressed to ensure thet get to the CNS.

The key message was that, in order to avoid acute inflammatory damage to axons, people with MS should be treated with anti-inflammatory agents at the earliest possible stage. In summing up of the meeting it was stated that we should `get in quick and treat aggressively with anti-inflammatory drugs as the die is cast early. We need to prevent axonal damage, not treat it later`.

This information was extracted from MS Societies Teamspirit magazine May 2001 issue.