Introduction
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is
clinically defined as a “chronically progressive, stepwise or recurrent
proximal and distal weakness and sensory dysfunction of all extremities,
developing over at least 2 months, with absent or reduced tendon
reflexes in all limbs and sometimes with cranial nerve
involvement”1.
Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired
autoimmune disorder directed against the myelin sheath of peripheral
nerves.1 It was initially characterized as chronic
inflammatory polyradiculoneuropathy by Dyck et al in 1975, but cases
consistent with probable CIDP were described as early as
19582,3.
CIDP is difficult to diagnose, but early diagnosis can be crucial to
prevent permanent nerve damage.4
Although CIDP is the most common treatable chronic neuropathy worldwide,
it is still a rare disease.5
The reported prevalence of CIDP ranges from 0.7 to 10.3 cases per
100,000 people6. There is a male predominance, with a
gender rate ratio ranging from 1.5 to 4. CIDP primarily affects adults
and the incidence rises with advancing age. The median age of onset is
not well established. No specific predisposing risk factors for CIDP
have been clearly identified6,7.
There are several clinical presentations, and sensory dysfunction is
frequently present, most usually affecting joint position and vibration
submodalities. Wasting is not prominent early in the disease. There are
atypical forms, such as multifocal acquired demyelinating sensory and
motor neuropathy (MADSAM, or Lewis– Sumner syndrome), pure sensory or
pure motor CIDP and focal or distal forms (distal acquired demyelinating
sensory polyneuropathy (DADS))8.
Most people with CIDP have a progressive rather than a spontaneously
relapsing and remitting course, with a variable balance between motor
and sensory symptoms. The American Academy of Neurology established
diagnostic research criteria for CIDP in 19919 .
However, there is still no gold-standard set of diagnostic criteria for
the electrophysiologic identification of demyelination, or for the
clinical diagnosis of CIDP and its variants, even though multiple sets
of diagnostic criteria have been published10-22.
Differences between these
sets are related to definitions of the clinical picture, the
requirements for nerve biopsy, electrodiagnostic criteria for
demyelination, and the number of features required to make the
diagnosis. The plethora of criteria sets for CIDP illustrate the
difficulty of developing precise standards for problems that have
multiple variations.
When independently validated in a retrospective study, the 2006 EFNS/PNS
criteria had a sensitivity and specificity of 81 and 97 percent,
respectively23, The most frequently used CIDP criteria
in clinical practice and research are the revised European Federation of
Neurological Societies/Peripheral Nerve Society 2010
criteria24.
These and other proposed criteria typically comprise a combination of
clinical and electrophysiological features (there have been 15 formal
sets of published electrophysiological criteria for the diagnosis of
CIDP25). Cases are classified as definite, probable or
possible, depending upon the number of criteria fulfilled. In most
cases, finding a raised CSF protein without CSF
leucocytosis26 further supports the diagnosis. Clear
evidence of macrophage-associated demyelination and remyelination, with
or without a T-cell inflammatory endoneurial infiltrate in a sensory
nerve biopsy, remains the gold standard supportive criterion. There have
been several validations of these diagnostic criteria, though none is
100% sensitive or specific1,9; for example, the
EFNS/PNS criteria1 show a positive predictive value of 97% and negative
predictive value of 92%,6 and different validation cohorts give widely
varying sensitivities and specificities27.