Two sets of nerve conduction studies may suffice in reaching a reliable electrodiagnosis in Guillain-Barré syndrome.

OBJECTIVE Recent studies have advocated the use of serial nerve conduction studies (NCS) in the electrodiagnosis of Guillain-Barré syndrome (GBS). The current study aims to elucidate when and how frequent NCS can be performed to reflect the disease pathophysiology. METHODS A prospective study of GBS patients documenting the initial and final electrodiagnoses following serial NCS performed at three time intervals: 1-2 weeks, 3-8 weeks and 8-12 weeks. RESULTS Twenty-one patients were recruited over a period of 2 years. Electrodiagnosis within 2 weeks revealed 17 acute inflammatory demyelinating polyneuropathy; two acute motor axonal neuropathy and two unclassified. After 12 weeks the final diagnoses were: 12 acute inflammatory demyelinating polyneuropathy; seven acute motor axonal neuropathy and two unclassified. NCS performed within the 3-8 week period reflected the true electrodiagnosis. Patients with acute inflammatory demyelinating polyneuropathy had persistent demyelination features at the 8-12 week NCS. CONCLUSION Two sets of NCS performed within the first 2 weeks and between 3-8 weeks of disease onset is likely to suffice in elucidating the true electrodiagnosis of GBS. SIGNIFICANCE These findings can be incorporated into a much-needed revision of the existing GBS electrodiagnostic criteria.