In the last issue of The Communicator I wrote an article discussing how CIDP is diagnosed. My focus was that diagnosis may be complicated because patients with CIDP can be affected in a number of different ways. In my attempts to explain this I produced some confusion as we received a number of responses requesting clarification. The questions involved two issues: asymmetry and rate of onset. I commented that the presence of asymmetrical symptoms or a sudden onset of symptoms made diagnosing CIDP easier because these features are very different from those seen in most other types of nerve disease. I then explained that other patients with CIDP may experience symmetry and slow progression. Readers questioned whether asymmetry or rapid onset was incompatible with a diagnosis of CIDP.

It is not surprising that these concepts produced confusion because they remain a source of great confusion and controversy among CIDP experts. Both of these topics have been discussed previously in prior issues of The Communicator (the article "What's In a Name? Important Differences Between GBS, CIDP and Related Disorders" by me in the 2006 Summer issue and the article "The Alphabet soup of Acute Et Chronic Immune-Mediated Demyelinating Polyneuropathies: Similarities Et Differences" by Drs. Richard Barohn and Richard Lewis in Spring 2005 issue). These articles are available on the GBS/CIDP Foundation International website.

Let me first address the issue of asymmetry. Some experts use the term CIDP only for patients with symmetrical numbness or weakness. For patients with asymmetrical manifestations, they may diagnose "multifocal acquired demyelinating motor and sensory neuropathy" (MADSAM) or "Lewis-Sumner Syndrome." Other experts lump all patients - symmetrical or asymmetrical - together under the term CIDP. It is unclear whether or not CIDP and MADSAM neuropathy are the same disorder, but all experts accept that they are related conditions as these patients all have similar laboratory test findings and respond to the same treatments.

The progression of a patient's symptoms is important for distinguishing between CIDP and Guillain-Barre Syndrome (GBS). By definition, progression that stops by 4 weeks is GBS and progression beyond 8 weeks is CIDP. Therefore, a patient may have symptoms that come on abruptly, but if the symptoms continue to get worse (progress) for more than 8 weeks, that patient has CIDP (however, most patients with CIDP will experience a gradual onset and progression of their symptoms). Some CIDP patients will have symptoms that resolve on their own but then return later (in this circumstance, it is called "relapsing-remitting CIDP"). Hopefully, these clarifications have addressed the questions generated by my previous article.