Reference Values for Upper and Lower Limb Nerve Conduction Studies among Filipino Adults using the E-Norms Method

This paper aims to propose reference values for nerve conduction studies of routinely tested nerves for the adult Filipino population aged 18-60 years old using patient data and its relationship with multiple patient demographic/anthropometric variables through the E-norms method - a relatively novel, adaptable, undemanding, and validated statistical technique; providing a quicker, more practical, reproducible way to identify reference value for different populations and laboratories. The study included all adult Filipinos aged 18-60 who underwent nerve conduction studies at The Medical City in the Philippines over four months (October 2022-January 2023). The study was comprised of clinical assessment and clinical laboratory measurements. A total of 600 patients (1200 limbs) were included in this study. The E-norms results showed slightly faster latencies but relatively comparable amplitudes and conduction velocities compared to our laboratory and AANEM NDTF reference values. This study also showed that as the participants aged, the amplitudes, conduction velocities, and latencies of most nerves tested showed decreased, slowed, and prolongation of the measurements, respectively. This study also observed a positive correlation between the limb length of the upper limbs and the latencies. Furthermore, a negative correlation existed between height and conduction velocity and BMI and amplitudes. In conclusion, using the E-normsmethod, this study produced a set of reference values generally applicable to the adult Filipino population. Standardizing nerve conduction parameters canpave the way for modifying diagnostic criteria for peripheral nerve disorders inFilipinos.