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Peripheral Nerve Inflammation and Central Pain
Reflex Sympathetic Dystrophy

A number of people with chronic infection with Chlamydia pneumoniae, whether or not they have MS, can get what can be described as a deep, grinding bone pain; it has a crushing quality. It does not correspond to any recognised area supplied by a sensory nerve, and it can travel along a limb, one moment being in the shoulder and the next in the fingers. It can suddenly go, and just as suddenly return. In its more severe form it is accompanied by a redness of the limb, dilation of the superficial veins and an increase in sweating in the limb. Use of the limb may be limited. There is often an exaggerated perception of skin stimuli; a light breeze over the limb may be felt as painful.

This pain is typical of damage to a large peripheral nerve; it is called Reflex Sympathetic Dystrophy. It is caused by injuries - often quite minor - to a nerve; it may occur after a virus infection, particularly shingles.

In chronic Chlamydia pneumoniae infection Reflex Sympathetic Dystrophy may be caused by acute inflammation associated with the destruction of a local bacterial collection.

The mechanism of the pain is not fully understood, but is thought to involve stimulation of the thalamus, an area of grey matter deep in the brain. The pain is thus generated in the brain. It is common in those with a chronic Chlamydia pneumoniae infection, and many people develop it during bacterial killing. Its severity seems to depend on bacterial load and placement. Fortunately it is usually mild and often does not last long, though the limb can remain red or mottled for some months. In my experience complete resolution is the rule.

Reflex Sympathetic Dystrophy can also occur in MS and is usually long-lasting. Pain as described above which goes after a week or so, and which is related to a bacteria-killing agent (when metronidazole, for instance, is added to protein-synthesis inhibitors) is more likely to be due to transient inflammation in a peripheral nerve rather than a relapse.

Other transient phenomena seen during chronic infection with Chlamydia pneumoniae include painful tics. Muscle fasciculations may also occur.