title: Sonographic and electrodiagnostic features of hereditary neuropathy with liability to pressure palsies.
abstract: In hereditary neuropathy with liability to pressure palsies (HNPP), the increase in distal motor latencies (DMLs) is often out of proportion to the slowing of conduction velocities, but the pathophysiological mechanism is still unclear. We used a combined electrophysiological and ultrasonographic (US) approach to provide insight into this issue. Twelve HNPP subjects underwent extensive electrophysiological studies and US measurements of the cross-sectional area (CSA) of several peripheral nerves. US nerve enlargement was only observed in the carpal tunnel, Guyon's canal, the elbow and the fibular head. We did not observe US abnormalities at sites where nerve entrapment is uncommon. An increase in DMLs was observed regardless of US nerve enlargement. The increased nerve CSA only in common sites of entrapment likely reflected the well-documented nerve vulnerability to mechanical stress in HNPP. No morphometric changes were seen in the distal nerve segments where compression/entrapment is unlikely, despite the fact that the DMLs were increased. These data suggest that factors other than mechanical stress are responsible for the distal slowing of action potential propagation. We speculate that a mixture of mechanical insults and an axon-initiated process in the distal nerves underlies the distal slowing and/or conduction failure in HNPP.
authors.affiliation: Department of Neurological, Neurosurgical and Behavioural Sciences, University of Siena, Siena, Italy. ginanneschi@unisi.it
authors.forename: Federica
authors.initials: F
authors.lastname: Ginanneschi
authors.forename: Georgios
authors.initials: G
authors.lastname: Filippou
authors.forename: Fabio
authors.initials: F
authors.lastname: Giannini
authors.forename: Maria A
authors.initials: MA
authors.lastname: Carluccio
authors.forename: Antonella
authors.initials: A
authors.lastname: Adinolfi
authors.forename: Bruno
authors.initials: B
authors.lastname: Frediani
authors.forename: Maria T
authors.initials: MT
authors.lastname: Dotti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Rossi
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D000328:Adult; D019412:Anatomy, Cross-Sectional; D001176:Arthrogryposis / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D004558:Electric Stimulation; D004568:Electrodiagnosis / Q000379:methods*; D055724:Electrophysiological Phenomena; D005260:Female; D015417:Hereditary Sensory and Motor Neuropathy / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010525:Peripheral Nerves / Q000000981:diagnostic imaging / Q000473:pathology; D011237:Predictive Value of Tests; D014463:Ultrasonography; D055815:Young Adult