Like Guillain–Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a syndrome with both classic and variant phenotypes. In the case of GBS, the classic phenotype is referred to as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), a disorder characterized by areflexia, generalized and usually symmetric weakness, and sensory involvement. Likewise, the classic phenotype of CIDP, typically referred to simply as CIDP, shares many of the characteristic clinical and electrodiagnostic (EDX) features as GBS.
As the cause of CIDP is unknown and there is no universally agreed upon diagnostic gold-standard for CIDP (15 CIDP and 16 EDX-proposed diagnostic criteria paradigms to date), the classification of the chronic acquired demyelinating neuropathies remain in flux.1,2 This chapter will address the majority of the chronic, acquired, predominantly demyelinating, and presumably inflammatory neuropathy syndromes. POEMS, with its associated CIDP-like neuropathy phenotype, will be the notable exception, discussed separately in Chapter 19.3,4
Current classification schemes often consider any neuropathy that fulfills the EDX criteria for CIDP to be categorized as CIDP or a CIDP variant. Multifocal motor neuropathy (MMN) is the notable exception, now being considered as a separate entity by virtually all neuromuscular experts.5 We however, consider the CIDP spectrum to include only those disorders which have common phenotypic, EDX, cerebrospinal fluid, and therapeutic responsiveness features with the classic syndrome.2,6,7 Included in this category are multifocal acquired demyelinating and sensory motor neuropathy (MADSAM) (a.k.a. Lewis Sumner syndrome) as well as some pure motor and pure sensory variants. Conversely, we will consider other chronic, acquired, and predominantly demyelinating neuropathy syndromes as separate entities if they differ significantly, particularly in consideration of their phenotype, natural history, and their therapeutic responsiveness profiles. We do so even if they fulfill EDX criteria for CIDP. Within this latter category, we will discuss distal acquired demyelinating sensorimotor (DADS) neuropathy, MMN, chronic immune sensory polyradiculopathy (CISP), and multifocal acquired motor axonopathy (MAMA) and attempt to distinguish them based on clinical, EDX, natural history, and response to treatment data (Table 14-1).
TABLE 14-1.COMPARISON OF THE CHRONIC ACQUIRED IMMUNE-MEDIATED DEMYELINATING POLYNEUROPATHIES |Favorite Table|Download (.pdf) TABLE 14-1.COMPARISON OF THE CHRONIC ACQUIRED IMMUNE-MEDIATED DEMYELINATING POLYNEUROPATHIES
| ||CIDP ||DADS ||MADSAM ||MMN |
|Clinical Features |
|Weakness ||Symmetric proximal and distal ||None or only mild symmetric distal ||Asymmetric, distal > proximal, arms > legs ||Asymmetric, distal > proximal, arms > legs |
|Sensory loss ||Yes; symmetric ||Yes; distal and symmetric ||Yes; asymmetric ||No |
|Reflexes ||Symmetrically reduced or absent ||Symmetrically reduced or absent ||Asymmetrically reduced or absent ||Asymmetrically reduced or absent |
|CMAPs ||Demyelinating features including CB ||Demyelinating features excluding CB ||Demyelinating features including CB ||Demyelinating features including CB |
|SNAPs ||Abnormal ||Abnormal ||Abnormal ||Normal |
|Laboratory Findings |
|CSF protein ||Usually elevated ||Usually elevated ||Usually elevated ||Usually normal |
|Monoclonal protein ||Occasionally present, usually IgG or IgA ||IgM usually present (most anti-MAG) ||Rarely present ||Rarely present |