Physiology Of Nerve Guillain-Barre Syndrome

Part1Serial electrophysiological study of Guillain-Barre syndromeObjective:To investigate the serial electrophysiological changes of acute inflammatory demyelinating polyneuropathies(AIDP) and acute motor axonal neuropathy(AMAN) through serial electrophysiological study of Guillain-Barre syndrome(GBS). To electrophysiologically classify GBS patients into AIDP and AMAN subtypes, investigate how serial recordings change the classification, and analyze the causes of classification changes. To investigate the serial electrophysiological changes of conduction block, and analyze the possible underlying mechanisms of conduction block.Methods:Prospectively collected21GBS patients in Peking Union Medical College Hospital between September2010and March2013, and performed at least two serial electrophysiological tests around the second and fourth week after disease onset. Retrospectively collected21GBS patients between1997and2010who had at least two serial electrophysiological recordings. The electrophysiological parameters included motor sensory nerve conduction, F waves and electromyography. Based on the first electrophysiological recordings, electrophysiologically classified GBS patients into AIDP and AMAN subtypes according to Hadden’s classification criteria. Analyzed how GBS patients changed the initial electrodiagnosis after serial electrophysiological recordings, and analyzed the causes of the changes. Compared and analyzed the clinical and electrophysiological characteristics of AIDP and AMAN patients. Analyzed the serial electrophysiological changes of conduction block.Results.At the first test,26of42patients(62%) fulfilled Hadden’s criteria for AIDP,10patients(24%) for AMAN and6patients(14%) were classified as equivocal. After follow-up,17patients(40%) were classified as AIDP,16patients(38%) as AMAN,3patients(7%) equivocal and6patients with rapid electrophysiological recovery(classification unclear). Clinically, preceding gastroenteritis were more common in AMAN group (p=0.032), and sensory symptoms were more common in AIDP group(p=0.015). Between the AIDP and AMAN groups, cranial nerve involvement did not differ significantly, and neither the nadir Hughes grade nor Hughes grade at the forth week differed significantly(t=0.437, p=0.665; t=1.005, p=0.323). Compared with AIDP and AMAN group, nadir Hughes grade of the6patients with rapid electrophysiological recovery did not differ significantly. However, all the6patients showed a markedly rapid clinical recovery(improved by two or more Hughes grades within one month), and compared with AIDP and AMAN group the Hughes grades at the forth week differed significantly(t=2.125, p=0.046; t=3.032, p=0.007).In AIDP group, distal motor latency(DML) prolongation appeared at week1-2, and became prominent at week3-5; The nadir of distal compound muscle action potential(dCMAP) amplitude decrease occurred at week1-2. In AIDP group, the early electrophysiological changes of F waves were decreased frequency with normal F wave latency, and F wave latency prolongation showed up later with nadir abnormality occurring at week4. There were two patterns of CMAP amplitude recovery in AMAN group:rapid increase and persistent at low level, and the two different recovery patterns were found in different nerves of the same patient.The majority of classification changes were from AIDP and equivocal groups by initial electrophysiological tests. The main reason was the recognition by serial recordings of reversible conduction failure(5patients), axonal degeneration(4patients) and transient prolongation of DML(2patients).Conclusion:The clinical severity and prognosis of the AIDP and AMAN groups are similar. In some AMAN patients, the CMAP amplitude can rapidly increase, which could not be explained by axonal degeneration. Besides axonal degeneration, reversible conduction failure might be another underlying mechanisms of AMAN.The causes of classification changes after serial electrophysiological study include:the length-dependent CMAP amplitude reduction, rapid resolve of conduction block, and transient prolongation of DML. Part2Clinical and electrophysiological study of Miller Fisher syndrome and Bickerstaff’s brainstem encephalitisObjective:To investigate the underlying mechanisms of Miller Fisher syndrome(MFS) and Bickerstaff’s brainstem encephalitis(BBE) through study of their clinical and electrophysiological characteristics.Methods:Retrospectively analyzed clinical and electrophysiological characteristics of13MFS and7BBE cases in Peking Union Medical College Hospital between2000and2011. The electrophysiological parameters included sensory and motor nerve conduction, electromyography, F wave, sympathetic skin response, brainstem auditory evoked potential and blink reflex.Results:MFS and BBE had similar clinical characteristics:respiratory symptoms were the most common infectious symptoms before disease onset; Ophthalmoplegia, facial palsy and bulbar symptoms were common; They both have cerebrospinal fluid albuminocytological dissociation and positive serum anti-GQlb antibody. However, BBE had more central nervous system lesion signs clinically such as conscious disturbance, positive Babinski’s sign and central facial palsy. Electrophysiologically, MFS and BBE also had similar electrophysiological features:sensory nerve abnormality ratios were6/13,2/7respectively, with prominently reduced sensory nerve active potential amplitude, normal or slightly slowed sensory conduction velocity; Motor nerves abnormality ratios were2/13,1/7respectively, with slightly prolonged distal motor latency and normal compound muscle action potential; Electromyography abnormality ratios were1/7,0/4respectively; F wave frequency abnormality ratios were3/13,5/7respectively, and in some cases, F wave frequency would restore; Blink reflex abnormality ratios were1/2,1/1respectively, with central involvement in BBE; BAEP abnormality ratios were3/5,1/4respectively, with wave I latency or amplitude abnormality.Conclusion: The similarities of clinical and electrophysiological features suggest that MFS and BBE have the same mechanism and they form a continuous spectrum with variable central nervous system and peripheral nervous system involvement.