The use of penile vibratory stimulation (PVS) to induce penile erection and ejaculation was first described by Sobrero and colleagues in 1965 in men without spinal cord injury (SCI) [Sobrero et al. 1965; Sonksen and Ohl, 2002]. The first reported use of PVS in a man with SCI was with a hand device in 1970 [Sonksen and Ohl, 2002]. Refinements in technique, advancements in technology and portability led to the first US Food and Drug Administration (FDA) approved penile vibratory stimulator for ED in July 2011.
Viberect, developed by Reflexonic, Chambersburg, Pennsylvania, is an FDA approved class II medical device used to provoke penile erection in men with ED and to provoke ejaculation in men with SCI (Figures 3 and 4).
Figure 3: Viberect device. The blue circular pads are placed in contact with the penile shaft and using a touch pad on the dorsal aspect of the device the individual is able to customize activation. Source: www.reflexonic.com
Figure 4: Demonstration of the external handheld shockwave device being applied to the penile shaft and crura. Source: Vardi et al. .
The device has received an abundance of online and commercial press. The mechanism of action of the device is through vibratory stimulation to branches of the pudendal nerve along the penile shaft.
Penile erection requires a complex interplay of the central nervous system, local and endothelial mediators. Sexual stimulation causes a release of neurotransmitters from the cavernous nerve terminals. Specifically, stimulation of the pudendal nerve causes a reflex parasympathetic erection through an activation of the parasympathetic pathway by pelvic nerves and nonadrenergic noncholinergic (NANC) fibers [Everaert et al. 2010]. Nitric oxide (NO) is the neurotransmitter released by NANC fibers. NANC fibers play a pivotal role in achieving tumescence after central nervous system stimulation by way of facilitating the release of NO and vasoactive intestinal polypeptide (VIP) and inhibiting noradrenaline release from the sympathetic fibers. The cumulative and downstream effect is a dilation of cavernosal and spongiosal smooth muscle through the activation of intracellular second messengers such as cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP). The Viberect handheld device utilizes exogenous stimulation of cavernousal nerve fibers by way of vibratory frequencies to release NO from nerve terminal endings [Tajkarimi and Burnett, 2011]. It may serve as an option for penile rehabilitation after nerve sparing radical prostatectomy. However, well designed clinical trials are needed to evaluate its efficacy.