17 - oct. - 2017
Guillain-Barré syndrome (GBS) is an immune-mediated cause of acute neuromuscular paralysis. During the last three decades, the Neurology Service (University Hospital Marques de Valdecilla), collaborating with the Clinical Neurophysiology, Radiology, Pathological Anatomy, and the Department of Anatomy and Cell Biology of the University of Cantabria (UC) have done epidemiological, clinical-pathological and nerve ultrasound investigations in GBS.
There had been established that the incidence rate of GBS in Cantabria is 0.95 cases per 100,000 population, and in early stages (first 10 days of clinical course) the inflammatory pathology mainly falls on proximal nerve trunks accentuating in the spinal root transit to the spinal nerve, which correlates well with the predominant alterations of the C5-C7 spinal cord in the ultrasonographic examination. Autopsy studies of early GBS are scanty; Haymaker and Kernohan [Medicine (Baltimore) 1949; 28: 59-141] had described that the initial lesions, consisting of endoneurial oedema, predominate where the spinal roots are joined to form the spinal nerves. This notion had gone largely unnoticed in the neurological literature.
Revising the literature, starting from the original descriptions of the GBS, we have established that in the first days of the clinical course the endoneural inflammatory edema of the spinal nerves is the most relevant pathogenic alteration, which precedes both the demyelination of the nerve fibers as wallerian degeneration, either primary or secondary (Berciano, Journal of the Neurological Sciences 2017, 382: 1-9). Thus, the lesion topography proposed by Haymaker and Kernohan is corroborated. Our studies indicate that early inflammation in epi-perineurial nerve trunks, such as spinal nerves, leads to increased endoneural pressure, a potential cause of compromised transperineural blood flow, which may result in endoneural ischemia with the corresponding failure of the conduction of the nerve impulse. These findings have the following implications: i) proximal conduction block (at the level of the spinal nerves) explains the mechanism of ascending paralysis in cases where conventional neurophysiological studies are normal or insufficiently informative; ii / for early diagnosis, neurophysiological and imaging techniques are needed to detect lesions in the proximal nerve trunks; iii / need to include the spinal nerves in the protocol of autopsy of early fatal cases, in order to detect pathogenic lesions; and iv) the urgent need for new therapeutic approaches to curb the impact of endoneural inflammatory edema on nerve fibers, the consequence of which may be the axonal degeneration responsible for irreversible residual paralysis.
Reference: Berciano J. Spinal nerve involvement in early Guillain-Barré syndrome: The Haymaker and Kernohan's legacy. J Neurol Sci 2017; 382: 1-9.