1. Electrophysiology in the diagnosis of inflammatory demyelinating neuropathies

Abstract

Inflammatory demyelinating neuropathies constitute a significant proportion of the acquired peripheral neuropathies. They include Guillain–Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy (MMN), multifocal demyelinating neuropathy with persistent conduction block (Lewis–Sumner syndrome), and paraproteinemic neuropathies. Inflammatory demyelinating neuropathies are receiving increasing attention because they are treatable. A proper diagnosis as early as possible is very important because timely immune treatment can largely reduce morbidity and disability. The diagnosis is based on a constellation of clinical and laboratory features, the latter including electrodiagnostic (nerve conduction) studies, spinal fluid examination, and in selected cases serological studies and peripheral nerve biopsy. Electrodiagnostic studies play a key role in the early detection and characterization of inflammatory demyelinating neuropathies. Making the diagnosis of inflammatory demyelinating neuropathy, in particular when the disease course is chronic, is often difficult. Diagnostic criteria are very important but given the lack of a definitive diagnostic marker and the limitations of laboratory studies, it appears impossible to reach a definitive diagnosis in all patients. By definition, electrophysiological criteria for primary demyelination are designed to exclude abnormalities that can be explained by axonal degeneration. Therefore, lesser degrees of demyelination can not be defined with complete certainty electrophysiologically. Optimised electrophysiological criteria are capable, however, to support the diagnosis with different levels of probability (possible, probable, definite) in the very large majority of cases.