Frequency-Dependent Conduction Block In Demyelinating Focal Neuropathies
type: CreativeWork
description: It is the objective of this thesis to demonstrate conduction block across regions of focal demyelination by utilizing a conventional electrophysiological technique used frequently in the diagnosis of peripheral nerve disease. Specifically, patients with moderate to severe carpal tunnel syndrome (CTS), but, with no evidence of conduction block via conventional motor nerve conduction study techniques, were assessed in the initial studies of this thesis for evidence of frequency-dependent conduction block (FDB) by way of high-frequency nerve stimulation (HFNS) applied across the region of entrapment. The final studies examined whether FDB could be demonstrated along the median motor fibers in mild cases of CTS, despite the presence of normal motor nerve conduction studies and lastly, whether other focal entrapment or compressive neuropathies behaved similar to the results obtained from CTS patients. The application of HFNS (30-Hz, 20 stimuli) was successful in demonstrating FDB in the median motor fibers across the region of the carpal tunnel (CT), in moderate to severe CTS patients (experiment 1). FDB was shown to be rate dependent and was more demonstrable using higher stimulus frequencies in cases with greater prolonged distal motor latencies. Unlike previous studies, these results suggest that demyelination plays a role in the pathophysiology and focal conduction slowing in CTS patients and that FDB may be responsible for the grip weakness and fatigue often described by these patients, particularly in the absence of conduction block. FDB was successfully demonstrated again across the region of the CT, similar to experiment 1, but was also observed more distally across the distal margins of the palmar aponeurosis and motor terminal axon (experiment 2). These results suggest that demyelination may occur distal to the lesion in CTS, supporting previous morphological and histological observations. Further, this data also suggests that the safety margin for impulse tran…
abstract: It is the objective of this thesis to demonstrate conduction block across regions of focal demyelination by utilizing a conventional electrophysiological technique used frequently in the diagnosis of peripheral nerve disease. Specifically, patients with moderate to severe carpal tunnel syndrome (CTS), but, with no evidence of conduction block via conventional motor nerve conduction study techniques, were assessed in the initial studies of this thesis for evidence of frequency-dependent conduction block (FDB) by way of high-frequency nerve stimulation (HFNS) applied across the region of entrapment. The final studies examined whether FDB could be demonstrated along the median motor fibers in mild cases of CTS, despite the presence of normal motor nerve conduction studies and lastly, whether other focal entrapment or compressive neuropathies behaved similar to the results obtained from CTS patients. The application of HFNS (30-Hz, 20 stimuli) was successful in demonstrating FDB in the median motor fibers across the region of the carpal tunnel (CT), in moderate to severe CTS patients (experiment 1). FDB was shown to be rate dependent and was more demonstrable using higher stimulus frequencies in cases with greater prolonged distal motor latencies. Unlike previous studies, these results suggest that demyelination plays a role in the pathophysiology and focal conduction slowing in CTS patients and that FDB may be responsible for the grip weakness and fatigue often described by these patients, particularly in the absence of conduction block. FDB was successfully demonstrated again across the region of the CT, similar to experiment 1, but was also observed more distally across the distal margins of the palmar aponeurosis and motor terminal axon (experiment 2). These results suggest that demyelination may occur distal to the lesion in CTS, supporting previous morphological and histological observations. Further, this data also suggests that the safety margin for impulse tran…
author: Watson, Brad V
language: en_ca
keywords: frequency-dependent conduction block, activity-dependent conduction block, demyelination, high-frequency nerve stimulation, carpal tunnel syndrome, ulnar neuropathy, electrophysiology, nerve conduction studies, neurophysiology, peripheral nervous system, focal entrapment neuropathies
date published: 2012-09-11
date modified: 2026-07-27T21:56:16Z
provider: Western University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Western Ontario

PropertyValue
property ID: Handle
value: https://hdl.handle.net/20.500.14721/32403