Utility of Serial Nerve Conduction Studies in the Electrodiagnosis of Guillain–Barre Syndrome

Background: Guillain–Barre syndrome can be electrophysiologically classified into demyelinating and axonal subtypes and nerve conduction studies remain the mainstay in electrodiagnosis. Accurate electrodiagnosis has both therapeutic and prognostic significance and different criteria sets have been proposed for classification. Objectives: To electrophysiologically classify GBS patients into AIDP and axonal subtypes according to various published criteria (Cornblath, 1990: Hadden, 1998, Rajabally, 2015), investigate if serial NCS changes the classification, and to identify additional parameters which may support the electrodiagnosis. Materials and Methods: In a retrospective study, we included all patients aged 15 to 80 years, admitted with a diagnosis of GBS between August 2015 and July 2017, who had at least two serial NCS. The various published criteria were applied to the two serial NCS and subtype classification along with diagnostic shifts on serial NCS were ascertained. Results: At the first test, the established criteria gave a yield of 45.2% to 71% for AIDP, while 29% to 54.8% of patients were classified as axonal GBS. In the second study, there was a change in electrodiagnosis, ranging from 9.6% to 16.1%. The resolution of reversible conduction failure and misclassification of subtypes were the major reason for diagnostic shifts. Sural sparing pattern, facial nerve dysfunction, abnormal blink reflex, and phrenic nerve dysfunction were more common in AIDP. Conclusions: Serial nerve conduction studies allow an accurate electrodiagnosis of GBS subtypes, which has both therapeutic and prognostic implications. Also, the use of additional parameters such as blink reflex facial and phrenic nerve conduction may supplement routine NCS.