This retrospective single-center observational study will evaluate the impact of age on the diagnostic performance of the sural-to-radial sensory nerve amplitude ratio (SRAR) in patients with length-dependent and non-length-dependent peripheral sensory polyneuropathies. Clinical and electrophysiological data collected during routine care between January 2013 and July 2026 will be analyzed. Diagnostic performance will be assessed using receiver operating characteristic (ROC) curve analysis across predefined age groups to determine whether age-adjusted SRAR thresholds improve the differentiation between the two polyneuropathy phenotypes.
Adults aged 18 years or older.
Diagnosis of peripheral sensory polyneuropathy.
Classification as length-dependent (LDN) or non-length-dependent (NLDN) based on clinical and electrophysiological findings.
Available nerve conduction study including sural and radial sensory nerve amplitudes allowing calculation of the SRAR.
Missing or incomplete clinical or electrophysiological data preventing SRAR calculation.
Unclassifiable neuropathy phenotype.
Technical factors affecting the reliability of nerve conduction studies.