Tehran University of Medical Sciences Current Journal of Neurology 2717-011X 13 3 2014 09 15 138 143 Samira Yadegari Department of Neurology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Shahriar Nafissi Department of Neurology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Neda Kazemi Department of Neurology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 14 Background: Incidence and predominant subtype  of Guillain-Barre syndrome (GBS) differs geographically. Electrophysiology has an important  role in early diagnosis and  prediction  of prognosis. This study  is conducted to determine the frequent  subtype  of GBS in a large group of patients  in Iran and compare  nerve conduction studies in axonal and demyelinating forms of GBS. Methods:   We  retrospectively   evaluated   the   medical records and electrodiagnostic study (EDS) of 121 GBS patients  who  were  managed in our  hospital  during  11 years. After regarding  the exclusion criteria, patients classified as three groups: acute inflammatory demyelinating    polyneuropathy   (AIDP),   acute    motor axonal  neuropathy  (AMAN),  and  acute   motor  sensory axonal neuropathy (AMSAN). The most frequent  subtype and then electrophysiological  characteristic based on the time  of EDS  and  their  cerebrospinal  fluid (CSF)  profile were assessed. Results: Among 70 patients  :nally included in the study, 67% w re  men. About  63%, 23%, and  14% had  AIDP, AMAN,  and  AMSAN, respectively.AIDP  patients represented a wider range  of ages compared  with other groups.  Higher  levels  of  CSF protein,  abnormal   late responses  and sural sparing were more frequent  in AIDP subtype. Five AMSAN patients  also revealed sural sparing. Conduction   block  (CB)   was  observed   in  one   AMAN patient. Prolonged  F-wave latency was observed  only in AIDP cases. CB and inexcitable sensory nerves were more frequent  after 2 weeks, but  reduced  F-wave persistency was more prominent in the early phase. Conclusion: AIDP was the most frequent  subtype. Although  the  electrophysiology  and  CSF are  important diagnostic tools, classification should not be made based on a distinct finding. https://ijnl.tums.ac.ir/index.php/ijnl/article/view/606 https://ijnl.tums.ac.ir/index.php/ijnl/article/download/606/196