Single-institutional reference values for concentric needle jitter analysis using the extrapolated reference values procedure: Comparison to published reference values

The extrapolated reference values procedure (E-Ref) was used to compare data from a single institution with the recently published reference value (RV) for concentric electrode jitter.

Data from voluntarily activated concentric needle jitter studies in the frontalis muscle were obtained using retrospective chart review. All measured signals were reviewed for acceptable quality. Cutoff values for increased jitter were calculated using E-Ref, and compared with the published RVs.

At total of 1501 apparent single-fiber action potential (ASFAP) pairs were reviewed; 1371 ASFAP pairs were determined to have acceptable quality. The cutoff value identified by E-Ref from all reviewed ASFAP pairs was 36 microseconds and the cutoff for acceptable pairs was 35 microseconds. Using either of these cutoff values (36 or 35 microseconds) did not result in a significant difference in percentage of jitter recordings considered normal when compared with the recently published RV (38 microseconds).

The single-institution jitter cutoff value obtained by E-Ref gives results that are not significantly different from the reported RV.