Professor of Clinical Neurology, Weill Cornell Medical College

Dr. Rubin reports he is a consultant for Merck Sharp & Dohme Corp.

SYNOPSIS: In a large Italian database-derived, case-control study of dietary and environmental factors, antecedent infections and diet appeared to influence the onset and course of chronic inflammatory demyelinating polyradiculoneuropathy. The diagnosis and treatment of this disorder remain a challenge.

SOURCE: Doneddua PE, Bianchib E, Cocito D, et al. Risk factors for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): Antecedent events, lifestyle and dietary habits. Data from the Italian CIDP Database. Eur J Neurol 2019 doi:10.1111/ene.14044. [Epub ahead of print].

Although the pathogenesis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) remains to be clarified, an autoimmune origin is suspected, with multiple triggers, and with both cellular and humoral components of the immune system contributing. Specific antigens have not been identified, but IgG4 subclass antibodies to neurofascin and contactin, critical structural elements of the paranodal loop attachment to the axolemma, have been reported in small numbers of CIDP patients. They appear to target paranodal proteins, disrupting axon-glial junctions, leading to nerve conduction slowing. Do lifestyle habits, environmental factors, or antecedent infections influence CIDP development, presentation, or clinical course, as they do in other autoimmune diseases?

Doneddua et al used an Italian, CIDP-patient, web-based database to collect information about modifiable environmental factors, antecedent infections, and vaccinations in CIDP patients, with their partners chosen as controls. They performed a gender-matched analysis using randomly selected controls for a 1:1 patient:control ratio. CIDP was diagnosed using European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria, and at enrollment all eligible patients underwent detailed history. Data on the occurrence of antecedent infection up to 42 days prior to CIDP onset were collected, as was information on diet, smoking habits, alcohol and coffee consumption, toxic exposure, recreational drug use, dietary regimen, and consumption frequency of a variety of foods, including pasta, rice, meat, raw meat, white meat, fish, vegetables, fruit, cheese, eggs, sweets, coffee, tea, milk, and soft drinks. Only those who reported no change in lifestyle habits after CIDP onset were included in the analysis.

Data on 323 patients (109 women and 214 men) and 266 controls (180 women and 86 men) were available, of which 195 cases and 195 sex-matched controls were used for analysis. Eating fish at least once weekly or rice thrice weekly appeared to decrease CIDP risk, whereas antecedent infection or vaccination within 42 days prior to CIDP onset was reported in 12% and 1.5% of patients, respectively. Those with prior infection more often had CIDP with acute onset and cranial nerve involvement. Antecedent events were seen in 15.5%
(n = 63) overall, including a flu-like syndrome (8%), upper respiratory or gastrointestinal infection (2% each), swine-flu vaccination (1.5%), surgery (1%), or trauma (0.5%). Diet and antecedent infection may influence CIDP risk and clinical presentation, but other antecedent events are unlikely to play a role.

COMMENTARY

While the etiology remains a mystery in CIDP, making the diagnosis and administering adequate treatment appear to be a challenge as well. Using a self-administered 42-item questionnaire, the investigators performed a quantitative, cross-sectional survey of 100 experienced community neurologists who manage CIDP, representing 31 of the 50 states in the United States, from both university- and non-university affiliated practices. They found that EFNS/PNS guidelines for CIDP diagnosis were used by only 13%, and approximately 50% endorsed electrodiagnostic criteria that did not support a diagnosis of CIDP. Pain or fatigue were identified among 37% and 35% of neurologists, respectively, as indicators of medically significant inflammatory neuropathies requiring treatment, although neither is a reliable prognostic indicator nor generally used to guide dosing decision making. Treatment often was inadequate, with 43% offering less than the recommended loading dose of intravenous immune globulin (IVIG), or excessive, with 24% recommending both steroids and IVIG together as a first-line treatment. Further research is needed to uncover the cause of CIDP, and additional education is needed for its correct diagnosis and treatment.¹

REFERENCE

1. Gelinas D, Katz J, Nisbet P, England JD. Current practice patterns in CIDP: A cross-sectional survey of neurologists in the United States. J Neuro Sci 2019;397:84-91.