By Norman Latov, MD, PhD
Synopsis: In this study, the authors describe the clinical, electrophysiological, and radiological features of patients with multifocal chronic inflammatory demyelinating polyneuropathy (CIDP) that presented with monotruncular (monomelic) onset.
Source: Julie P, Etienne F, Emmanuelle SC, et al. Chronic inflammatory demyelinating polyradiculoneuropathies (CIDP) with monotruncular onset: Frequency, clinical features, electrophysiology, and evolution. Eur J Neurol. 2025;32(1):e16560.
Of 145 patients with multifocal chronic inflammatory demyelinating polyneuropathy (CIDP), 16 (11%) had a monotruncular onset. The disease started in the upper limbs in 81% of cases, and the ulnar nerve was the most frequently involved in seven (44%) of the 16 patients. Two of the patients had only sensory symptoms.
At initial evaluation, only five patients (31%) met electrodiagnostic criteria for CIDP and eight patients (50%) met criteria for possible CIDP (demyelinating feature in only one nerve). Twelve of 13 patients tested had proximal conduction block. Three patients did not meet any electrodiagnostic criteria for CIDP, but two had at least two positive supportive criteria, and the third developed multiple proximal conduction blocks at subsequent visits.
Brachial plexus magnetic resonance imaging (MRI) was abnormal in 13 of 15 patients (86%) and bilateral in seven patients (47%), with increased short tau inversion recovery (STIR) signal intensity in one or more trunks of the brachial plexus without contrast enhancement in 11 of 13 patients. Nine of 13 patients had enlargement of the trunks of the plexus and nerve roots. Cerebrospinal fluid (CSF) protein levels were normal in 10 of 12 patients (83%).
Four of the patients underwent nerve decompression surgery, without improvement, prior to the diagnosis of CIDP. Treatment with intravenous immunoglobulin (IVIG) was beneficial in 12 of 15 patients (80%). In a median follow-up period of eight years, 13 of the patients progressed to multitruncular involvement and three patients remained monotruncular. IVIG treatment was started earlier in the patients who remained monotruncular.
Commentary
The takeaway message in this paper is that patients presenting with monotruncular neuropathy may have CIDP, and that early treatment can prevent progression or spread of the neuropathy.
The difficulty arises in identifying patients who have CIDP rather than other causes of monotruncular neuropathy. Subclinical involvement of additional nerves, as determined by MRI or ultrasound, can help distinguish between mononeuropathy and multifocal or polyneuropathy, which could help avoid decompressive surgery. However, it is not diagnostic of CIDP, since it does not distinguish between demyelinating or axonal changes.
Likewise, nerve enlargements can occur in both demyelinating and axonal neuropathies, including brachial plexitis, hereditary neuropathy with predisposition to pressure palsy, vasculitis, sarcoid, neurolymphomatosis, and amyloidosis, among others, and elevated CSF protein concentration is a nonspecific and inconsistent finding.1
The diagnosis of CIDP requires demonstration of multiple demyelinating abnormalities, as detected by the presence of multiple conduction abnormalities that cannot be attributed secondary to axonal degeneration, in the absence of other causes of demyelination. However, as for other diagnostic criteria, there is a tradeoff between sensitivity and specificity. Demyelinating lesions can be missed if they are proximal or distal to the regions tested, or if the nerves are inexcitable.2 Similar issues have confounded the diagnosis of sensory CIDP.3
In this paper, most of the subjects did not fulfill electrodiagnostic criteria for definite or probable CIDP, and those with possible CIDP (or with only one demyelinating abnormality) were diagnosed by proximal conduction studies that are not done in routine practice because of technical or reliability issues. Most of the demyelinating abnormalities were conduction blocks, which, in some cases, can result from axonal lesions.4 However, the patients did respond to immune therapy, confirming they had an immune-mediated neuropathy.
Other authors have reported that patients with multifocal neuropathy of otherwise unknown etiology, with only one or no demyelinating abnormalities, also respond to immune therapy, suggesting that multifocality can be a clue to an underlying immune pathogenesis.5 As such, the finding of multifocal abnormalities in the absence of other causes for neuropathy might identify cases of neuropathy that are amenable to immune therapy, similar to demyelinating abnormalities in CIDP.
The distinction is important, since the neuropathy otherwise would be considered idiopathic, for which there is no treatment. This would need to be tested in prospective clinical trials. However, debates regarding diagnostic criteria and treatment likely are to continue until we have more definitive diagnostic tests.
Norman Latov, MD, PhD, is Professor of Neurology, Weill Cornell Medicine.
References
1. Miller NJ, Meiling JB, Cartwright MS, Walker FO. The role of neuromuscular ultrasound in the diagnosis of peripheral neuropathy. Semin Neurol. 2024; Oct 21.doi.org/10.1055/s-0044-1791577. [Online ahead of print].
2. Latov N. Diagnosis of CIDP. Neurology. 2002;59(12 Suppl 6):S2-6.
3. Shelly S, Shouman K, Paul P, et al. Expanding the spectrum of chronic immune sensory polyradiculopathy: CISP-Plus. Neurology. 2021;96(16):e2078-e2089.
4. Tracy JA, Taylor BV, Kiernan M, et al. Nerve pathology distinguishes focal motor chronic inflammatory demyelinating polyradiculoneuropathy from multifocal motor neuropathy. J Clin Neuromuscul Dis. 2020;22(1):1-10.
5. Magda P, Latov N, Brannagan TH 3rd, et al. Multifocal acquired sensory and motor neuropathy: Electrodiagnostic features. J Clin Neuromuscul Dis. 2005;7(1):10-18.
In this study, the authors describe the clinical, electrophysiological, and radiological features of patients with multifocal chronic inflammatory demyelinating polyneuropathy (CIDP) that presented with monotruncular (monomelic) onset.
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