Membrane properties in chronic inflammatory demyelinating polyneuropathy

• Published in: Brain (London, England : 1878) Vol. 124; no. 12; pp. 2439 - 2447
• Main Authors: Cappelen-Smith, Cecilia, Kuwabara, Satoshi, Lin, Cindy S.-Y., Mogyoros, Ilona, Burke, David
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.12.2001; Oxford Publishing Limited (England)
• Subjects: Action Potentials - physiology; Adult; Aged; axonal excitability; Axons - pathology; Axons - physiology; Biological and medical sciences; Cell Membrane - physiology; chronic inflammatory demyelinating polyneuropathy; CIDP = chronic inflammatory demyelinating polyneuropathy; CMAP = compound muscle action potential; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Demyelinating Diseases - pathology; Demyelinating Diseases - physiopathology; duration properties; Female; Humans; Male; Median Nerve - pathology; Median Nerve - physiopathology; Medical sciences; Middle Aged; Motor Neurons - pathology; Motor Neurons - physiology; Motor Neurons - ultrastructure; Nervous system (semeiology, syndromes); Neural Conduction; Neurology; Polyradiculoneuropathy, Chronic Inflammatory Demyelinating - pathology; Polyradiculoneuropathy, Chronic Inflammatory Demyelinating - physiopathology; Reaction Time; recovery cycle; strength; threshold electrotonus; Tropical medicine; τSD = strength—duration time constant; Human; Biological properties; Nervous system diseases; Plasma membrane; Median nerve; Excitability; Adult; Axon; Exploration; Chronic inflammatory demyelinating neuropathy; Peripheral nerve disease; Inflammatory disease
• ISSN: 0006-8950; 1460-2156; 1460-2156
• DOI: 10.1093/brain/124.12.2439

Threshold tracking was used to compare excitability properties (stimulus–response curves, strength–duration properties, recovery cycle and threshold electrotonus) of the median nerve in 11 patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and 25 healthy controls. Stimulus–response curves were significantly different: threshold was much higher, the slope of the curves reduced and the spread of the thresholds greater in the CIDP group. The strength–duration time constant (τSD) was significantly shorter and the rheobase higher in the CIDP group. In the recovery cycle, the CIDP group had less refractoriness, supernormality and late subnormality than healthy controls, but the duration of the relatively refractory period was normal. These changes in τSD and the recovery cycle were not those previously predicted. There were no consistent changes in threshold electrotonus, suggesting that, for the studied axons, there are no consistent changes in accommodation properties that depend on internodal conductances. It is difficult to explain these changes in excitability on the basis of a change in membrane potential, or solely as the result of demyelination, and it is possible that other morphological factors such as variable remyelination and inflammatory oedema affected axonal excitability in the patients.