Pattern analysis of nerve enlargement using ultrasonography in chronic inflammatory demyelinating polyneuropathy

•Ultrasonography revealed widespread hypoechoic enlargement of nerves, especially in proximal regions and non-entrapment sites, in CIDP patients.•Enlargement of the nerve cross-sectional area correlated well with nerve conduction velocity.•Five sites are identified as screening points for nerve CSA measurements to evaluate CIDP.

ObjectiveFocal nerve enlargement is a characteristic finding in chronic inflammatory demyelinating polyneuropathy (CIDP). We performed this study to assess the distribution of nerve enlargement through ultrasonographic examination of peripheral nerves and to correlate the ultrasonographic findings with clinical features.MethodsTo compare the ultrasonographic features of 10 subjects with CIDP with those of 18 healthy controls, we bilaterally measured the cross-sectional areas (CSA) of the vagus, brachial plexus, musculocutaneous, median, ulnar, radial, sciatic, tibial, common peroneal, and sural nerves. We also analyzed correlations between CSAs and various clinical and electrophysiological features.ResultsMean CSAs were significantly larger in CIDP patients than controls, especially at proximal and non-entrapment sites. CSAs were significantly correlated with muscle strength at initial presentation, but not at the time of ultrasonography. The CSAs of the median and ulnar nerves at the mid-forearm, tibial nerve at 7 cm proximal to the medial malleolus, and sural nerve correlated with the nerve conduction velocity of the corresponding region.ConclusionUltrasonography revealed widely distributed nerve enlargement, especially in proximal regions and non-entrapment sites, in patients with CIDP compared with healthy controls. Nerve enlargement correlated well with the electrophysiologic function of the nerve, but not current clinical status.SignificancePattern analysis of nerve enlargement using ultrasonography is a supportive tool in the diagnosis of CIDP.