Nerve ultrasound score in distinguishing chronic from acute inflammatory demyelinating polyneuropathy

Objective: Aim of this study was to develop and evaluate the applicability of an ultrasound score (Bochum ultrasound score - BUS) in distinguishing chronic (CIDP) from acute inflammatory demyelinating polyneuropathy (AIDP).

Methods: Step 1: For the development of BUS 75 healthy-controls, 20 CIDP, 20 AIDP patients underwent US 4.55 ± 3.5 and 3.4 ± 2.91 years, respectively after onset. After comparing the distribution pattern and frequency of pathological US changes between the two study groups, we developed BUS, summarizing the cross sectional area (CSA) of: (1) the ulnar nerve in Guyons' canal, (2) the ulnar nerve in upper-arm, (3) the radial nerve in spiral groove, (4) the sural nerve between the gastrocnemius muscle. Step 2: The BUS underwent blinded evaluation in further 10 CIDP, 21 AIDP patients 3.8 ± 2.7 and 2.3 ± 1.5 years, respectively after onset. Step 3: The BUS underwent blinded, prospective evaluation in 8 patients with acute/subacute polyradiculoneuropathy (5 CIDP, 3 AIDP) 2.6 ± 1.8 weeks after onset.

Results: The BUS showed a sensitivity of 90% and specificity of 90.4% (positive predictive value, PPV=81.8%; negative predictive value, NPV=95%) in distinguishing CIDP from AIDP, when they showed no differences in disease duration (p=0.0551).In addition, the BUS distinguished subacute-CIDP from AIDP with a sensitivity of 80%, specificity of 100% (PPV=100%, NPV=75%).

Conclusion: The BUS seems to allow a reliable distinction of CIDP from AIDP.

Significance: The BUS may be helpful in distinguishing subacute-CIDP from AIDP.