The dorsal nerve runs alongside the top of the penis. Placing electrodes near this nerve results in a characteristic sharp pain. This placement is usually avoided.

Introduction

A 4-electrode configuration on the penis is used for testing.

What we would like to see is that stimulation of the mid electrode generates local sensations under the electrode contact area. But for specific placements, this is not the case due to the presence of nerve bundles.

A low intensity signal will first activate the nerve endings and generate a local sensation. As the stimulus intensity grows, it will also activate the nerve bundles that go towards the glans, this causes a sensation in the glans (a referred sensation).

For this specific electrode placement it almost always is described as a sharp pain in the glans. Many electrodes have been developed to prevent stimulation of these areas.

Joanne's reviews brand electrode featuring conductive rubber contacts and a 3D printed shield for the dorsal nerve.

Measurements

I performed measurements to investigate the activation of these nerve bundles. In these experiments I increased the power to the mid electrode until I felt a sharp glans pain.

Numbers are signal amplitude with 1700Hz carrier frequency.

With the mid electrode as a 3x3cm conductive rubber pad:

path	intensity
mid to base	36 mA
mid to tip	36 mA
mid to bottom	55 mA
mid to base and tip (50% each)	40 mA

With the mid electrode as a 3x3cm sticky pad:

path	intensity
mid to base	34 mA
mid to tip	36 mA
mid to bottom	not tested
mid to base and tip (50% each)	38 mA

With the mid electrode as a 3x1.5cm rubber pad:

path	intensity
mid to base	27 mA
mid to tip	28 mA
mid to bottom	not tested
mid to base and tip (50% each)	26 mA

Conclusions:

• Swapping flat rubber for a sticky pad has little effect on bundle activation.
• A smaller electrode results in more bundle activation at equivalent signal amplitude. This is probably a result of current density.
• Whether the current flows to base or tip, or a mixture, has little effect on the sensation.
• Current that flows directly opposite to the shaft results in reduced bundle activation.

We are not sure how to explain the last observation, regardless of the direction of current, the current density directly under the pad appears to be almost identical. Our best guess is that the angle of current vs nerves results in reduced activation, since current that flows parallel to the nerves is more likely to result in activation.

Regardless, the most obvious solution is to avoid this placement.

Illustrations

Below are some illustrations showing the position of the nerve bundles.

The sensory penis: A comprehensive immunohistological and ontogenetic exploration of human penile innervation

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