I never made the connection between itching (also called pruritis) and multiple sclerosis (MS) until someone sent me an e-mail, asking if other people ever experienced this symptom of MS. I hadn't really heard about this, but it did trigger a memory of a time (long before my MS diagnosis) when I had a severe episode of completely unexplained itching all over my back and torso -- no rash or bumps -- nothing, except the redness I had caused by my frantic scratching.
Unlike itching caused by skin irritants like poison ivy, itching in MS is a neuropathic itch. This means it is caused, like most of our other MS symptoms, by demyelination of the nerves of our central nervous system.
However, itching tends to be paroxysmal, meaning it comes and goes pretty quickly. The good news is that these types of symptoms usually do not signal a relapse, but are probably just due to a transmission of nerve impulses across sites where they do not normally occur and where there has been previous damage. (Read more: Paroxysmal Symptoms of Multiple Sclerosis)
Characteristics of Itching in Multiple Sclerosis
Itching as a symptom of MS has been found to have the following characteristics, although not everyone experiences all of them:
Paroxysmal: The itching starts and stops abruptly.
Frequent: The itching episodes happen as often as six times per day –- sometimes even more.
Short duration: It lasts from a couple of seconds to a couple of minutes.
Nocturnal: The itching often occurs at night, waking the person from sleep.
Connected to other symptoms: In some patients, trigeminal neuralgia follows the itching. In some others, the itching follows pain or sensory disturbances such as dysthesias. There seems to also be a connection with L'hermitte's sign, an electric-shock type of sensation that runs down the spine when the head is bent forward.
Symmetric: The itching can happen on the face, torso, arms and legs (basically anywhere on the body) and usually happens on both sides of the body, meaning both arms would be affected or both sides of the face. Occasionally, though, the itching may be on only one side.
Triggers: Some patients find that itching is triggered by heat, such as being outside on a warm day or taking a hot bath. It is often triggered by movement.
Treatment of Itching in Multiple Sclerosis
While no studies have been conducted on neuropathic itching, several things have been shown to help. Anticonvulsants (such as carbamazine) and antidepressants (such as paroxetine and mirtazapine) are often used off-label for this symptom. Once treated, the itching often doesn’t return.
Itching in MS can be extremely frustrating, especially since Benadryl or any topical products that you use are unlikely to provide any relief. If you have MS and have itching, see your doctor for some medicine that can help.
Rarely, some of the disease-modifying therapies (including Copaxone, Tysabri, and Avonex) can cause itching, which signals an allergic reaction. Often this reaction is accompanied by hives or redness, which signals that it is not typical MS neuropathic itching. This could be serious and you need to call your doc right away.
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Yamamoto M, Yabuki S, Hayabara T, Otsuki S. Paroxysmal itching in multiple sclerosis: a report of three cases. J Neurol Neurosurg Psychiatry. 1981 January; 44(1): 19–22.
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