Purpose: The diagnosis of Guillain-Barre syndrome (GBS) in the very early stage may be challenging. Our aim was to report the neurophysiological abnormalities in GBS within 4 days of clinical onset. We expected that GBS will be diagnosed by the assistance of neurophysiological study in the very early stage. Methods: We prospectively recruited patients with a diagnosis of GBS discharged from First Affiliated Hospital of Xi’an Jiaotong University and Xi Jing Hospital. Patients were classified into 3 groups according to the onset of symptoms to electromyography examination interval (OEI). The neurophysiological findings were carried out using standard procedures. All patients were examined by the same experienced neurophysiologist. Results: There were not significant group differences in abnormal rate, distal motor latency (DML), motor nerve conduction velocity (MNCV), F response (FR), compound muscle action potential (CMAP), conduction block (CB), sensory nerve action potential (SNAP), and sensory nerve conduction velocity among OEI ≤4 days, 4< OEI ≤10 days, and OEI > 10 days groups. Motor nerves were more affected than sensory nerves in neurophysiological presentation in very early stage patients. The difference of motor nerves and sensory nerves was statistically significant in lower limbs, but was not in upper limbs. In motor nerve conduction studies, the abnormal rate of DML, MNCV, FR, CB was more common seen in ulnar and peroneal nerve than median and tibial nerve, the abnormal rate of CMAP was the same in ulnar, median, peroneal and tibial nerve. In sensory nerve conduction studies, the abnormal rate of ulnar nerve and median nerve was higher than the superficial peroneal nerve and sural nerve. The OEI was not correlated with the SNAP decrease rate of median (r = 0.10, p = 0.23) and ulnar (r = 0.26, p = 0.06) but was statistically correlated with sural SNAP decrease rate (r = 0.29, p = 0.04). The sural-sparing pattern phenomenon was the most commonly discovered phenomenon in very early stage patients (OEI ≤4 days), followed by patients with 4< OEI ≤10 days, ultimately found in patients with OEI > 10 days. Conclusions: We suggest performing neurophysiological examination as soon as possible for suspected GBS patients, particularly focusing on multi-spots inspection of ulnar and peroneal nerves, and paying close attention to sural-sparing patterns.
A selective remarkably low M-wave amplitude in tibial nerve is characteristic in motor nerve conduction in spinal muscular atrophy type 2 and 3
