OC08: A-wave serves as a diagnostic measure for demyelinating polyneuropathies

Abstract

A-wave occurs in various neurologic conditions and occasionally, also in healthy elderly subjects, mainly in the tibial nerve. We designed this study to document types of neurological disorders preferentially associated with the occurrence of A-wave and multiple A-waves. The study consists of a retrospective review of clinical and electrophysiologic data in 610 patients. They comprised 74 ALS, 123 radiculopathy, 206 CTS, 100 DPN, 51 GBS and 56 CIDP patients as well as 127 healthy subjects. We divided all patients into simple A-wave, multiple A-wave and non A-wave groups and analyzed their association with gender, age, sensory nerve conduction studies (SNCS) and clinical diagnosis, using R software decision-tree and Random Forest analysis. Specifically, we compared frequencies of median, ulnar and tibial nerve A-wave and multiple A-waves in DPN, GBS and CIDP patients. A-wave group had more older age, male gender, abnormal SNCS and patients diagnosed as DPN, GBS or CIDP than non A-wave group. Compared with simple A-wave group, multiple A-waves group had more absent SNAP. In simple-A group, DPN emerged as the most common diagnosis whereas in multiple-A group, GBS ranked the highest. Compared to healthy subjects, A-wave occurred more frequently in DPN, GBS and CIDP but not in ALS, radiculopathy or CTS. Tibial nerve A-wave as a whole showed no difference among DPN, GBS and CIDP but multiple A-waves occurred more frequently in the order of GBS > CIDP > DPN. We conclude that A-wave, particularly, multiple A-waves, serve as an early diagnostic measure for acute demyelinating polyneuropathies.