[Role of electrophysiology in diagnosis of polyneuropathies]

Most for polyneuropathies present in a uniform, distally accentuated, rather symmetrical pattern, although asymmetric or multifocal distributions occur. The main feature of diagnosis is the history of development and the neurological clinical examination. Neurophysiologic studies, mainly nerve conduction studies (motor and sensory), reflex studies and electromyography are very accurate, but unspecific tools in order to establish the diagnosis of polyneuropathies, define special electrophysiologic features and can also reveal undetected (subclinical) lesions. For clinical purposes most neuropathies can be divided according the nerve conduction studies in axonal, demyelinating and mixed types. In recent years additional electrophysiological features as conduction block have appeared and are still under discussion. The etiology of polyneuropathy has to be determined in each patient with scrutinity. Additionally to general diseases (e.g. diabetes), common toxins (e.g. alcohol), concurrent medication (e.g. some cytostatic drugs) also immunologic (e.g. vasculitis) and hereditary factors have to be considered. A nerve biopsy is only indicated after a thorough consideration of electrophysiology and ancilliary findings. This applies in particular to hereditary neuropathies, where genetic testing has become a highly reliable test replacing biopsy.