Positive Treatment Effects of Immunomodulatory Therapy in CIDP Still Observed in Patients Lacking Nerve Conduction Studies

A recently published study showed that patients with clinical and supportive features of chronic inflammatory demyelinating polyneuropathy (CIDP) lacking nerve conduction studies (NCS) evidence of demyelination had a positive treatment response to immunomodulatory therapies. Overall, these data raise the consideration of a trial testing an immunomodulating treatment in this patient population, especially when there is MRI lumbosacral root or plexus enhancement.^1,2

Published in Muscle & Nerve, 232 patients were assessed and treated for presumed CIDP, of whom 20 met all criteria for the study. Among the included patients, 18 received intravenous immunoglobulin, 10 received corticosteroids, 1 received plasma exchange, and 6 received other immunomodulatory therapies. In follow-up, 12 patients had a sustained positive treatment response by Medical Research Council sum score (MRCSS) or modified Rankin scale (mRS). Of these, 7 patients met the criteria for improvement in either scale at the 3-month follow-up visit, 1 at 6 months, 3 at 12 months, and 1 at 2 years.

“While CIDP over-diagnosis can lead to unnecessary and potentially harmful immunomodulating therapy, CIDP underdiagnosis and delay in treatment can lead to the accumulation of disabling symptoms,” lead author Patrick A. Curry, MD, assistant professor in the department of neurology at University of Rochester Medical Center, and colleagues wrote.¹

Investigators had all patients treated for presumed CIDP identified through electronic search of their medical records between October 1995 and October 2021. Although the patients included in the analysis did not have NCS criteria of demyelination, they did have supportive cerebrospinal fluid (CSF protein > 45 mg/dL, 94% [17/18]), MRI ( MRI lumbosacral root or plexus enhancement, 43% [6/14]) or US (enlarged proximal nerves on US, 67% [4/6]) features consistent with CIDP. Authors defined a positive treatment response from the disease modifying therapies given to participants as at least a 1-point improvement in the mRS, or a 4-point increase in the MRCSS. Researchers had data collected at baseline pre-treatment and then post treatment at 3 months, 6 months, 1 year, and each year after until the last follow-up visit.

Top Clinical Takeaways

Immunomodulatory treatments can be effective for CIDP patients even without NCS-confirmed demyelination, particularly if MRI indicates nerve root or plexus enhancement.
MRI remains valuable for evaluating CIDP, especially for detecting lumbosacral root or plexus involvement not visible on other diagnostic tests.
The study's retrospective nature, small sample size, and varying diagnostic methods limit its conclusions, underscoring the need for larger, standardized trials to refine treatment recommendations.

Authors observed no clinical features associated with a positive clinical response. Of the supportive laboratory features, investigators reported that only MRI nerve root enhancement was associated with a positive treatment response on the MRCSS or mRS in the participants. Additionally, neither the presence of enlarged proximal nerves on US nor an elevated CSF protein greater than 45 mg/dL or even greater than 100 mg/dL was reported as associated with a positive treatment response. Among the 6 patients with contrast enhancement on MRI, 4 met criteria for polyradicular CIDP, and 2 had multifocal presentations with lumbar or brachial plexus involvement, 1 of which had a confirmatory brachial plexus fascicular nerve biopsy.

“In our study, MRIs were all performed with and without gadolinium, were evaluated by experienced neuroradiologists, and focused on the presence or absence of nerve or root enhancement, a potential marker of active disease,” Curry et al noted.¹ “Six of the 20 patients (30%) had root or plexus enhancement, suggesting that MRI is still useful to evaluate patients with potential immune-mediated neuropathies preferentially affecting proximal lumbosacral roots or plexus, not evaluable with US, and in whom routine distal NCS show only axonal physiology.”

Authors noted that the current study had several limitations such as its retrospective design, lack of a standardized diagnostic evaluation and treatment protocol, and small sample size. Researchers reported that although 90% of patients had CSF data available, only 70% had contrasted MRI of nerve roots, and 30% had US imaging, which was noted as a newer diagnostic method. Additional limitations recognized by the authors included the restriction of the assessment for treatment responses with MRCSS and mRS because of their availability over the 26-year period. Furthermore, the investigators used the 2010 EFNS/PNS guidelines in the study, which included MRI as supportive for CIDP, whereas the 2021 guidelines no longer endorse MRI findings because of issues with reproducibility.

“In the absence of demyelination on NCS, our data support the view that a trial of immunomodulating treatment should be strongly considered in patients with clinical features of CIDP with other supportive laboratory and imaging features, especially nerve root or plexus enhancement on MRI, and that contrast-enhanced MRI still has a role in evaluating patients with selective involvement of proximal nerve segments,” Curry et al noted.¹ “However, definitive treatment recommendations for this subgroup of patients await an adequately powered placebo-controlled trial with a standardized treatment protocol and outcome assessments.”