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Also known as
PSR, PSRG/F (Penile Sensitivity Ratio using Glans and Finger), Penile Vibratory Threshold Ratio
Definition
The Penile Sensitivity Ratio (PSR) is a standardized biothesiometry parameter used to quantify and assess changes in penile sensitivity by comparing the vibratory threshold of the penile glans to a reference body part.1 It is calculated by dividing the average biothesiometry threshold for sensation of the dorsal and ventral glans by the average sensation threshold of a reference body part, typically the index finger.2 PSR is inversely correlated with penile sensitivity, meaning that a higher PSR value indicates diminished penile sensitivity.1 This non-invasive, painless, office-based measurement provides clinicians with an objective tool for evaluating penile sensory function in various urological and sexual health conditions.1 The most validated version of PSR (PSRG/F) uses the threshold for vibratory detection from the dorsal glans divided by the mean value from the left and right index finger, which has been shown to correlate significantly with patient-reported diminished penile sensitivity.1
Clinical Context
The Penile Sensitivity Ratio (PSR) is primarily used in urological and sexual medicine settings to objectively evaluate penile sensitivity, which can be affected by various conditions including diabetes, Peyronie’s disease, and neurological disorders.1 The measurement involves using a biothesiometer, which applies vibration to specific areas of the penis (typically the dorsal and ventral glans) and a reference body part (usually the index finger).1 The patient indicates when they first perceive the vibration, establishing their threshold for vibratory sensation.3
The most validated version of PSR (PSRG/F) is calculated by dividing the average vibratory threshold of the dorsal glans by the average threshold of the left and right index fingers.1 This standardization helps control for individual variations in overall sensitivity and provides a more reliable measure of penile-specific sensory function.1 In a large study of 1,239 men, PSRG/F was found to be significantly different between patients reporting diminished penile sensitivity and those without reported diminished sensitivity.1
Clinical applications of PSR include:
- Diagnosing and monitoring penile neuropathy2
- Evaluating sensory changes in patients with erectile dysfunction1
- Assessing the neurological impact of diabetes on penile function1
- Monitoring sensory changes before and after treatments for Peyronie’s disease1
- Evaluating patients with ejaculatory dysfunction1
Research has shown that PSR values correlate with patient-reported symptoms of diminished penile sensitivity, making it a valuable objective measure to complement subjective patient assessments.1 On multivariate analysis controlling for age, diabetes, ejaculatory dysfunction, and Peyronie’s disease, a higher PSRG/F was associated with older age and lower in patients with Peyronie’s Disease.1