I Guess Diagnosing CIDP Really is Complicated
David S. Saperstein, M.D.,
Phoenix Neurological Associates, Phoenix, Arizona
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.