Pathophysiology of conduction block in neuromuscular diseases

Czech version

Authors: E. Ehler ¹; I. Štětkářová ²
Authors‘ workplace: Neurologické oddělení, Pardubická krajská nemocnice, a. s. ¹; Neurologické oddělení, Nemocnice Na Homolce, Praha ²
Published in: Cesk Slov Neurol N 2008; 71/104(2): 139-147
Category: Review Article

Overview

Polarization of axonal membrane is necessary for impulse conduction in peripheral nerve fibers. Smooth functioning of ion channels is responsible for proper excitability of axonal membrane. In myelinated fibers there is possibility to differentiate various regions of one segment: nodal, paranodal, juxtaparanodal and internodal. Among the most frequent sodium channels there are 3 types with the highest occurrence in the nodal region. Potassium channels can be divided into 3 voltage-operated subtypes. Appearance of fast K⁺ channels is limited to juxtaparanodal segment. Testing of ion channels and membrane excitability is possible with double-stimulation technique or with the electrotonus threshold assessment. Conduction block can be divided into „activity dependent“ and „activity independent“. We present patients with chronic demyelinating polyneuritis, multifocal motor neuropathy and compressive mononeuropathy as clinical case reports.

Key words:
conduction block – excitability of membrane – ion channels – threshold electrotonus

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