Hereditary neuropathy with liability to pressure palsy: the electrophysiology fits the name.
BACKGROUND
Studies of patients with hereditary neuropathy with liability to pressure palsies (HNPP) have shown accentuated distal slowing along with nonuniform conduction abnormalities at segments liable to compression, suggesting a distal myelinopathy as an underlying pathophysiological mechanism.


METHODS
We evaluated 12 patients with HNPP by standard nerve conduction studies and by conduction to more proximal muscles in the arm and leg. Three CMT1A patients and six healthy subjects also were evaluated as controls.


RESULTS
Median and peroneal motor nerves in all HNPP patients showed prolonged distal motor latencies (DML) (mean +/- SE, 5.9 +/- 0.41 and 8.63 +/- 0.58 milliseconds), but the ulnar and tibial DML were minimally prolonged or normal (mean +/- SE, 3.87 +/- 0.16 and 5.66 +/- 0.24 milliseconds). DML to forearm flexor (median and ulnar nerves) or anterior tibial muscles (peroneal nerve) were also normal.


CONCLUSIONS
Accentuated distal slowing is found primarily in median and peroneal nerve segments liable to pressure palsies or repetitive trauma. However, the ulnar and tibial nerves, which are less liable to compression, have minimal changes. In addition, distal latencies to more proximal muscles in the arm and leg do not have distal slowing. These findings do not support a distal myelinopathy as a determinant of the conduction abnormalities in HNPP.
Li
Jun
J
Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA. junli@med.wayne.edu
Krajewski
Karen
K
Shy
Michael E
ME
Lewis
Richard A
RA
D000293:Adolescent; D000328:Adult; D002648:Child; D004594:Electrophysiology; D005260:Female; D009477:Hereditary Sensory and Autonomic Neuropathies / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D009408:Nerve Compression Syndromes / Q000503:physiopathology*; D009431:Neural Conduction / Q000502:physiology*; D010243:Paralysis / Q000503:physiopathology*; D011446:Prospective Studies