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.

Lack of association between the LRRK2 A419V variant and Asian Parkinson's disease.

INTRODUCTION: The G2385R and R1628P LRRK2 gene variants have been associated with an increased risk of Parkinson's disease (PD) in the Asian population. Recently, a new LRRK2 gene variant, A419V, was reported to be a third risk variant for PD in Asian patients. Our objective was to investigate this finding in our cohort of Asian subjects. MATERIALS AND METHODS: Eight hundred and twenty-eight subjects (404 PD patients, and 424 age and gender-matched control subjects without neurological disorders) were recruited. Genotyping was done by Taqman® allelic discrimination assay on an Applied Biosystems 7500 Fast Real-Time PCR machine. RESULTS: The heterozygous A419V genotype was found in only 1 patient with PD, compared to 3 in the control group (0.4% vs 1.3%), giving an odds ratio of 0.35 (95% confidence interval (CI), 0.01 to 3.79; P = 0.624). CONCLUSION: A419V is not an important LRRK2 risk variant in our Asian cohort of patients with PD. Our data are further supported by a literature review which showed that 4 out of 6 published studies reported a negative association of this variant in PD.