Title : Distal and proximal conduction abnormalities in acute Guillain–Barre syndrome: An NCS-based study
Abstract:
Guillain–Barre Syndrome (GBS) is an acute immune-mediated polyradiculoneuropathy traditionally characterized by peripheral nerve involvement; however, early disease stages may reflect combined distal and proximal conduction abnormalities. While nerve conduction studies (NCS) are routinely used for diagnosis, their potential to capture integrated electrophysiological signatures of disease severity remains underexplored. In this pilot study, seven patients with clinically confirmed GBS within ten days of symptom onset were compared with seven age-matched healthy controls using comprehensive motor and sensory NCS. Motor parameters, including distal latency, compound muscle action potential (CMAP) amplitude, and conduction velocity, were recorded across multiple nerves, along with proximal indices such as F-wave latency, persistence, and chronodispersion. Patients demonstrated significant prolongation of distal motor latencies, reduced CMAP amplitudes, and slowed conduction velocities (p < 0.05), along with evidence of temporal dispersion, suggesting demyelinating pathology. F-wave analysis revealed prolonged latencies, increased chronodispersion, and reduced persistence (p < 0.05), indicating significant proximal nerve root involvement. Sensory studies showed relative preservation of sural responses compared to upper limb nerves, consistent with a sural sparing pattern. Importantly, abnormalities in CMAP amplitude and F-wave parameters showed moderate correlations with clinical disability scores (r ≈ −0.6, p < 0.05), suggesting that combined distal and proximal conduction dysfunction may reflect early disease severity. This study suggests that early-stage GBS is characterized by combined distal conduction failure and proximal nerve root dysfunction, which can be effectively captured using advanced nerve conduction parameters. Beyond routine diagnosis, detailed NCS profiling may provide insights into disease mechanisms, subtype differentiation, and early severity prediction. These findings highlight the potential of electrophysiological markers in improving early clinical stratification and guiding management in GBS.
