Clinical and electrophysiological study of Miller-Fisher syndrome and Bickerstaff’s brainstem encephalitis

Abstract

Objective To investigate the underlying mechanisms of Miller-Fisher syndrome (MFS) and Bickerstaff’s brainstem encephalitis (BBE) by studying their clinical and electrophysiological characteristics. Methods The clinical and electrophysiological characteristics of 13 MFS and 7 BBE cases in Peking Union Medical College Hospital between 2000 and 2011 were retrospectively analyzed. The electrophysiological parameters included sensory and motor nerve conduction, electromyography, F wave, sympathetic skin response and 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 had cerebrospinal fluid albuminocytological dissociation and positive serum anti-GQ1b 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 were 6/13, 2/7 respectively, with prominently reduced sensory nerve active potential amplitude, normal or slightly slowed sensory conduction velocity; Motor nerves abnormality ratios were 2/13, 1/7 respectively, with slightly prolonged distal motor latency and normal compound muscle action potential; Electromyography abnormality ratios were 1/7, 0/4 respectively; F wave frequency abnormality ratios were 3/13, 5/7 respectively, and in some cases, F wave frequency would restore; Sympathetic skin response abnormality ratios were 1/2, 1/3 respectively; Blink reflex abnormality ratios were 1/2, 1/1 respectively, with central involvement in BBE; Brainstem auditory evoked potential abnormality ratios were 3/5, 1/4 respectively, with waveⅠlatency 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. Key words: Miller Fisher syndrome; Encephalitis; Electrophysiology; Gangliosides; Antibodies