A motor nerve conduction block is defined as a reduction of either amplitude or area of the compound motor action potential elicited by proximal vs. distal motor nerve stimulation. The ...pathophysiological mechanisms leading to a figure of conduction block include segmental demyelination, recent axonal interruption, or various axonal excitability abnormalities due to ion channel dysfunction or membrane potential changes. These processes can be related to compressive, ischemic or dysimmune inflammatory causes. The etiologic diagnosis is established on the combination of clinical, electrophysiological, and biological data. Among the neuropathies that feature nerve conduction blocks, there is a group of particular dysimmune multifocal neuropathies characterized by long-term persistent conduction blocks, including pure motor forms and sensori-motor forms. The clinical, electrophysiological, biological, and therapeutic specificities of these two types of neuropathy will be discussed.
Inflammatory demyelinating neuropathies can be classified according to the topography of the nervous lesion. Acute and chronic polyradiculoneuritis are characterized by diffuse and multifocal, but ...predominantly proximal lesions, multifocal motor and sensory-motor neuropathies with persistent conduction blocks are restricted to some nerve trunks, while neuropathies due to monoclonal IgM with anti-MAG (Myelin Associated Glycoprotein) activity show distal and symmetric distribution. The clinical characteristics of inflammatory demyelinating neuropathies vary according to the type of neuropathy. Their course can be remittent or progressive but is especially marked by the risk of definitive axonal lesions, source of permanent neurological deficits. These neuropathies correspond to various mechanisms, which can be differentiated according to the antigenic target, the type of immunological disorder (with respect to cellular or humoral predominance), and the adapted therapeutic strategy. The inflammatory process is accompanied by energetic failure, leading to Na+/K+ pump impairment and intra-axonal Na+ accumulation. This failure results in Na+/Ca2+ exchanger activation, provoking neuronal Ca2+ influx, enzymatic proteolysis and axonal degeneration.
Diphtheritic neuropathy Créange, A; Meyrignac, C; Roualdes, B ...
Muscle & nerve,
December 1995, Letnik:
18, Številka:
12
Journal Article
Recenzirano
A 29-year-old Haitian man had a sore throat with a marked tonsillar exudate followed by the onset of increasingly blurred vision with swallowing difficulties and, then, a diffuse acute demyelinating ...neuropathy. Cerebrospinal fluid showed moderate pleiocytosis and elevated protein content. Serological testing for diphtheria, but not for tetanus and poliomyelitis, was markedly positive. Other tests including HIV1 and 2, HTLV1 and Lyme disease were negative. Diphtheritic neuropathy should be considered in the differential diagnosis of Guillain-Barré syndrome in nonvaccinated patients.
