Evidence-based recommendations for examination and diagnostic strategies of polyneuropathy electrodiagnosis

The purpose of this report is to recommend evidence-based strategies for polyneuropathy (PNP) electrodiagnosis based on a large cohort of patients examined prospectively. Nerve conduction studies (NCS) of bilateral tibial, peroneal and sural nerves, the latter with both near-nerve-technique (NNT) and surface recordings, were done in 313 patients with clinically suspected PNP. Bilateral dorsal sural and medial plantar nerves, and unilateral median and ulnar nerves were further examined in a subgroup of patients. The final clinical diagnosis retrieved from the patientś medical records 1-6 years after the neurophysiological investigation served as diagnostic reference standard. The clinical follow-up diagnosis confirmed PNP in 219 patients. The tibial nerve was the most sensitive nerve (75%), with prolonged tibial F-wave as the most sensitive parameter (72%). Sural NNT recordings were more sensitive (66%) than surface recordings (49%) (p < 0.05), however, dorsal sural (68%) and medial planter (70%) nerves had similar sensitivities as NNT. There was no side difference in the incidence of abnormality for any nerve. Based on these results, we recommend a strategy starting with tibial and sural NCS on one side for electrophysiological screening for distal symmetric PNP. If one of these is abnormal, we recommend examining the other lower and upper extremity nerves, including distal sensory nerves, particularly if NNT is not applicable. While one abnormal parameter is sufficient to interpret a nerve as abnormal, we recommend at least two abnormal nerves for PNP diagnosis, preferentially one being the sural nerve. We believe that the strategies recommended in this study may improve PNP electrodiagnosis.