Pathophysiology and markers of very early classic Guillain-Barré syndrome

Guillain-Barré syndrome is a rare neurological disorder characterized by the body's immune system mistakenly attacking the peripheral nerves. This condition often follows an infection and can lead to varying degrees of muscle weakness or paralysis. The aim of this review is to analyze the initial pathology and pathophysiology of classic Guillain-Barré syndrome, which is largely determined by the efficiency of the blood-nerve barrier, and then to address the question of various markers at early stages of the syndrome. Inflammatory edema of proximal nerve trunks, particularly spinal nerves, is the main pathogenic lesion in any subtype of very early classic Guillain-Barré syndrome (≤ 4 days after onset), which may result in ischemic conduction failure when neither demyelination nor Wallerian-like degeneration has reached the scene. Similar chronopathology occurs in P 2 -induced experimental autoimmune neuritis. Under such circumstances, the dichotomous division between demyelinating and axonal Guillain-Barré syndrome usually requires serial electrophysiological studies. In both severe Guillain-Barré syndrome and P 2 -induced experimental autoimmune neuritis, the pathologic background can be divergent: pure demyelination in intrathecal spinal roots and a combination of Wallerian-like degeneration and demyelination in more distant nerve trunks. Imaging techniques, including magnetic resonance imaging and ultrasonography, corroborate the presence of proximal nerve trunk lesions in any early classic Guillain-Barré syndrome subtype. Nerve ischemia may account for nerve inexcitability at the first electrophysiological examination. In the first few days, albumin-cytological dissociation in the cerebrospinal fluid occurs in approximately half of the patients; the presence of neutrophils should not be a criterion for the exclusion of Guillain-Barré syndrome. From the first days of the clinical course, there is an almost constant increase in the serum levels of neurofilament light chain and peripherin, both in the demyelinating and the axonal forms of Guillain-Barré syndrome, suggesting that there is a common pathogenic mechanism, which consists of ischemic damage to the nerve trunks due to inflammatory edema with the subsequent critical elevation of endoneurial fluid pressure. As a corollary, there is a rational basis for the use of corticosteroids in the early stage of severe Guillain-Barré syndrome.