Objective

To examine the diagnostic accuracy of nerve ultrasound in a prospective cohort of consecutive patients with a clinical suspicion of chronic inflammatory neuropathies, including chronic inflammatory demyelinating polyneuropathy, Lewis Sumner syndrome and multifocal motor neuropathy, and to determine the added value in the detection of treatment-responsive patients.

Methods

Between February 2015 and July 2018, we included 100 consecutive incident patients with a clinical suspicion of chronic inflammatory neuropathy. All patients underwent nerve ultrasound, extensive standardized nerve conduction studies (NCS) and other relevant diagnostic investigations. We evaluated treatment response using predefined criteria. A diagnosis of chronic inflammatory neuropathy was established when NCS were abnormal (fulfilling criteria of demyelination of the EFNS/PNS) or when the degree of nerve enlargement detected by sonography was compatible with chronic inflammatory neuropathy and there was response to treatment.

Results

A diagnosis of chronic inflammatory neuropathy was established in 38 patients. Sensitivity and specificity of nerve ultrasound and NCS were 97.4% and 69.4%, and 78.9% and 93.5%, respectively. The added value of nerve ultrasound in detection of treatment-responsive chronic inflammatory neuropathy patients was 21.1% compared to NCS alone.

Conclusions

Nerve ultrasound and NCS are complementary techniques with superior sensitivity in the former and specificity in the latter. Addition of nerve ultrasound significantly improves the detection of chronic inflammatory neuropathies. Therefore, it deserves a prominent place in the diagnostic workup of chronic inflammatory neuropathies.

Classification of Evidence

This study provides Class I evidence that nerve ultrasound is an accurate diagnostic tool to detect chronic inflammatory neuropathies.

File contents overview

Table e-1 Final diagnoses

Legend

The final diagnoses of 100 patients in whom there is a clinical suspicion of chronic inflammatory neuropathy; data are shown as number of patients.

Abbreviations

ALS = amyotrophic lateral sclerosis, CIAP = chronic idiopathic axonal polyneuropathy, CIDP = chronic inflammatory demyelinating polyneuropathy, Classical = classical phenotype of CIDP, GBS = Guillain-Barré syndrome, HNLPP = hereditary neuropathy with liability to pressure palsies, MGUS = monoclonal gammopathy of undetermined significance, MMN = multifocal motor neuropathy, LSS = Lewis Sumner syndrome, PSMA = progressive spinal muscular atrophy, Pure motor = pure motor phenotype of CIDP, Pure sensory = pure sensory phenotype of CIDP

Table e-2 Patient characteristics per subgroup

Abbreviations

Anti-GM1 = anti-GM1 antibodies, CIAP = chronic idiopathic axonal polyneuropathy, CIDP = chronic inflammatory demyelinating polyneuropathy, CSF = cerebrospinal fluid, GBS = Guillain-Barré syndrome, MGUS = monoclonal gammopathy of undetermined significance, MMN = multifocal motor neuropathy, NCS = nerve conduction studies, PNP = polyneuropathy, PSMA = progressive spinal muscular atrophy, Ultrasound = nerve ultrasound

NA= not applicable, NP = not performed; “-”  = normal test result, “+”  = abnormal test result

Table e-3 Treatment response per subgroup

Abbreviations

CIAP = chronic idiopathic axonal polyneuropathy, CIDP = chronic inflammatory demyelinating polyneuropathy, HHD = Hand Held Dynamometry, ISS = INCAT Sensory Sum Score, MCID = minimal clinically important difference, MMN = multifocal motor neuropathy, MRC = Medical Research Council, ODSS = Overall Disability Sum Score, PSMA = progressive spinal muscular atrophy, RODS = Rasch-built Overall Disability Scale, Treatment response = treatment response according to predefined criteria

NA = not applicable, NP = not performed, NT = not treated, “-”  = no improvement or no response, “+” = improvement or response