State-dependent biothesiometric assessment of penile sensory function using the penile sensitivity ratio in men evaluated for sexual dysfunction: a retrospective observational study

Penile sensory function is an under-assessed dimension of male sexual dysfunction. The penile sensitivity ratio (PSR), calculated as penile vibration perception threshold relative to index-finger threshold, provides a normalized biothesiometric metric. This study aimed to characterize state-dependent glans PSR and identify clinical factors associated with PSR in men evaluated for suspected sexual dysfunction. We retrospectively analyzed 597 men who underwent biothesiometric assessment between January 2024 and December 2025. Glans PSR was assessed in the flaccid and pharmacologically induced erect states; “erect state” denotes post-PGE1 measurement with an Erection Hardness Score (EHS) ≥3, not natural sexual arousal. Age and psychological symptom scores were analyzed as binary categories. Log-transformed PSR values were used for paired comparisons, multivariable linear regression and direct between-state contrasts. Results were reported as geometric mean ratios (GMRs) with 95% confidence intervals (CIs). Glans PSR was higher in the erect state than in the flaccid state (erect-to-flaccid GMR, 1.339; 95% CI 1.298–1.382; P < 0.001). Erectile dysfunction (ED) and lumbar disc herniation (LDH) were independently associated with higher glans PSR in both states. Adjusted GMRs for ED and LDH were 1.170 (95% CI 1.086–1.259) and 1.237 (1.103–1.388) in the flaccid state, and 1.239 (1.153–1.332) and 1.232 (1.101–1.378) in the erect state, respectively. Exploratory erect-state models also showed associations with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) and Generalized Anxiety Disorder-7 (GAD-7) category. Direct contrasts did not identify different associations between states for CP/CPPS or GAD-7 category. Premature ejaculation was not independently associated with glans PSR after adjustment. In this cohort evaluated for suspected sexual dysfunction, glans PSR differed between flaccid and post-PGE1 measurements and was associated with ED and LDH. These observations do not establish normal or abnormal PSR values or support routine clinical use.