Science News: Focal Chronic Inflammatory Demyelinating Polyradiculoneuropathy: Onset, Course, and Distinct Features

Submitted by: Pritikanta Paul, MD

Benoit C, Svahn J, Debs R, et al. Focal chronic inflammatory demyelinating polyradiculoneuropathy: Onset, course, and distinct features. J Peripher Nerv Syst. 2021;26(2):193-201. doi:10.1111/jns.12438

Summary: Focal CIDP, described as involvement of brachial or lumbosacral plexus, or one or more peripheral nerves in one upper or lower limb, can pose diagnostic challenge.
 
This retrospective study looked at 30 patients with focal CIDP and reviewed their clinical course. CIDP diagnoses were based on the EFNS-PNS clinical criteria along with definite or probable EDX criteria, or at least two supportive criteria when EDX criteria were not available. Patients were divided into three groups: 1) Focal brachial or lumbosacral inflammatory demyelinating plexus neuropathy (F-PN) (N=18) who had plexus involvement in one limb. 2) Focal demyelinating sensory and motor neuropathy (F-SMN) (N=7) with clinical and electrophysiological involvement in one individual nerve (non-entrapment site). 3) Focal demyelinating motor neuropathy (F-MN) (N=5) having  pure motor clinical and electrophysiological abnormalities involving one or more nerves, median follow-up times were 7.5 years, 5 years and 5 years respectively.
 
Only one-third of F-PN had EMG demyelinating features fulfilling EFNS/PNS diagnostic criteria for CIDP (definite or possible) in contrast to all F-SMN and F-MN patients. However, plexus MRI and SSEPs were helpful in diagnostic evaluation in those F-PN cases. Demyelinating features in asymptomatic limbs were more frequent in F-SMN and F-MN group. Clinical manifestation of the other limbs rarely occurred in F-PN patients while multifocal involvement of other limbs was more common in other two groups but never evolved into a symmetric pattern. Most patients responded to immune treatment. Interestingly, 50% of F-PN patients’ symptoms stabilized without treatment suggesting favorable prognosis.
 
The authors conclude F-PN variant tends to have a slowly progressive, focal and likely benign course as compared to F-SMN and F-MN variants that are more likely to evolve into a multifocal involvement. F-PN was also more likely to have a pure sensory involvement (56%) with rare motor nerve conduction abnormalities and diagnosis of CIDP mainly supported by SSEP (80%) and MRI (100%) studies.
 
A major drawback of this study is absence of histopathological correlation.

Comments: This is an excellent study looking at distinct clinical features including clinical course and treatment response in patients with focal variants of CIDP and how MRIs and often underused SSEPs can be of immense help in diagnostic workup.

Article of Similar Interest: Fargeot G, Maisonobe T, Psimaras D, et al. Comparison of Lewis-Sumner syndrome with chronic inflammatory demyelinating polyradiculoneuropathy patients in a tertiary care centre. Eur J Neurol. 2020;27(3):522-528. doi:10.1111/ene.14101