[Acute polyneuritis and polyradiculoneuritis: uncommon causes and their pathomechanisms]

Although the total incidence rate of acute inflammatory polyneuropathies is low, it is the most frequent cause of acute progressive, generalized paresis in developed countries (> 50 %). The most common form of the disease is the Guillain-Barré syndrome (GBS). Even though the clinical and pathologic spectrum of GBS has substantially grown over the last decade, about 15 % of cases of acute polyneuritis or polyradiculoneuritis do not fulfil the revised and extended diagnostic criteria and classification for GBS and its variants. The underlying pathogenesis still remains unclear. It is assumed that these "untypical" acute inflammatory polyneuropathies and cases fulfilling the GBS criteria are variants of the same underlying immune disorder, but that pathogenetic mechanisms produce different acute neurological syndromes. Thus, immunotherapy (which is not GBS-specific) is also effective for treating acute inflammatory polyneuropathies that do not fulfil the diagnostic criteria for GBS, and early diagnosis and treatment of these cases is essential. Since no reliable serological and electrodiagnostic markers of autoimmune neuropathies are currently available, the diagnosis is based on its clinical presentation. However, clinical symptoms are variable, and a rational diagnostic decision can be challenging. Thus, it is important to know that acute inflammatory polyneuropathies not fulfilling the diagnostic criteria of GBS are less often preceded by an infective condition but frequently associated with uncommon causes and triggers. This report presents our experiences with uncommon variants of inflammatory polyneuropathies and polyradiculoneuritides that do not fulfil the international diagnostic criteria for GBS. We provide a detailed review of the pertinent literature discussing possible pathomechanisms, its clinical associations and possible dispositions.