Distinctive patterns of sonographic nerve enlargement in Charcot–Marie–Tooth type 1A and hereditary neuropathy with pressure palsies Stephan H. Goedee a,b,⇑ , Geert J.F. Brekelmans c,d , Leonard H. van den Berg a,b , Leo H. Visser c,d a Department of Neurology, UMC Utrecht, Utrecht, The Netherlands b Brain Center Rudolf Magnus, Department of Neuroscience, UMC Utrecht, Utrecht, The Netherlands c Department of Neurology, St. Elisabeth Hospital, Tilburg, The Netherlands d Department of Clinical Neurophysiology, St. Elisabeth Hospital, Tilburg, The Netherlands See Editorial, pages 1286–1287 article info Article history: Accepted 29 August 2014 Available online 12 October 2014 Keywords: Charcot–Marie–Tooth (CMT) Hereditary neuropathy with pressure palsies (HNPP) Nerve hypertrophy Sonography Polyneuropathy highlights  High Resolution Ultrasonography reveals specific phenotypes differentiating Charcot–Marie–Tooth type (CMT) 1A from hereditary neuropathy with pressure palsies (HNPP).  In CMT-1A sonographic enlargement of nerves and fascicles is multifocal among multiple nerves.  In HNPP nerve enlargement is restricted to sites of entrapment and the swelling ratio is larger in HNPP than in CMT-1A. abstract Objective: The extent of sonomorphologic differences of peripheral nerves between CMT and HNPP is unknown. Methods: We recruited 9 patients with CMT-1A and 9 with HNPP. Patients underwent a standardized sonographic protocol, which evaluated nerve size and vascularization. We quantitatively assessed fascicle size and echogenicity. Results: All 18 patients demonstrated nerve enlargement, but no increased vascularization. HNPP dem- onstrated larger nerves at sites of entrapment (median nerve at the carpal tunnel p = 0.049, ulnar nerve at the sulcus p < 0.001), greater swelling ratios of median (p < 0.001), ulnar (p = 0.017) and fibular nerve (p = 0.005) than CMT-1A. CMT-1A revealed larger nerves proximal to sites of entrapment (median and fibular nerve, brachial plexus p < 0.001). Nerve fascicles where larger (p < 0.001) and more hypo-echo- genic in CMT-1A. Nerve, fascicle size nor echogenicity correlated with age, gender or MRC sum-score. Conclusions: Ultrasonography of nerves reveals specific phenotypes differentiating CMT-1A from HNPP. In CMT-1A enlargement of nerves and fascicles is multifocal among multiple nerves, whereas in HNPP nerve enlargement is restricted to sites of entrapment. Significance: Our findings of specific sonomorphological phenotypes, differentiating CMT-1A from HNPP, may help to improve our pathophysiological insights in CMT and HNPP. Ó 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. 1. Introduction Charcot–Marie–Tooth (CMT) is classified as demyelinating (type I) or axonal (type II) (Lewis et al., 2000; Pareyson and http://dx.doi.org/10.1016/j.clinph.2014.08.026 1388-2457/Ó 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. ⇑ Corresponding author at: UMC Utrecht, Department of Neurology, Heidel- berglaan 100, 3584 CX Utrecht, The Netherlands. Tel.: +31 88 75 588 60; fax: +31 88 75 55494. E-mail address: h.s.goedee-2@umcutrecht.nl (S.H. Goedee). Clinical Neurophysiology 126 (2015) 1413–1420 Contents lists available at ScienceDirect Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph