E‐norms: A method to extract normal values from a laboratory population

Stimulated jitter analysis for the evaluation of neuromuscular junction disorders in children

“…The mean of the mean MCD recorded from the orbicularis oculi using facial CNE in subjects without NMJ defects in our study was similar to recently published normal values (22 ± 2.83 µs) in healthy infants and children by Jabre et al…”

“…Recordings were made using a commercially available electromyograph with the stimSFEMG program (Synergy, Natus Neurology Incorporated, Middleton, Wisconsin). The study was considered abnormal if the mean of the mean consecutive difference (MCD) exceeded 26 µs or > 10% of spikes had increased jitter with or without blocking …”

Estimation of reference intervals for transcranial magnetic stimulation: Derived parameters via the hoffman indirect method

“…I read with great interest the report by Nandedkar et al The authors describe the E‐Ref procedure, which expands on the previously reported E‐Norms method for determining reference values from electrodiagnostic data obtained during clinical testing. Both E‐Norms and E‐Ref are remarkably similar to the work of Hoffman, who described a method for obtaining reference intervals using available test results from a laboratory's database.…”

Reply

“…It was interesting to read how Hoffmann stated the problem and proposed plotting the CDF versus the measurements. Our awareness of similar plots described by Jabre and colleagues stimulated our development of the E‐Ref method. There are some differences between the E‐Ref and the Hoffmann methods (HM); analysis of jitter values from the extensor digitorum muscle illustrates these differences:…”