Male Erectile Response and Enhancement

Some men can attain an erection after SCI either through the psychogenic (i.e., through mental stimulation; T11-L2) or reflexogenic (i.e., through direct physical stimulation; S2-S4) pathways, depending on the level and completeness of injury; men with complete lower motor neuron (LMN) injuries involving either the conus medullaris or the exiting nerve roots (cauda equina) typically experience loss of reflexive arousal and erectile dysfunction in this group that is more difficult to treat (Previnaire et al. 2017). Most men with upper motor neuron (UMN) lesions have reflex erections, however, these erections often cannot be maintained for the duration of penetrative activities (Gowinnage et al. 2022; Linsenmeyer, 1991).

Treatments for erectile dysfunction (ED) in men with SCI have advanced considerably in recent years with the availability of phosphodiesterase type 5 inhibitors (PDE5i) taken as a tablet orally (Rizio et al. 2012) either on demand (prn) or daily (Elliott et al. 2025). However, other methods are available when oral medication is ineffective or unaffordable. There is stronger evidence for treatment of ED than other areas of sexual health in SCI, primarily due to the advent of the PDE5i and their effectiveness in this population.

Therapies for erectile dysfunction (ED) include:

1. Oral medications, which indirectly relax the penile smooth muscle through the NO-cGMP system, enhance an erection attained by sexual stimulation. These oral l phosphodiesterase 5 inhibitors [PDE5i] include sildenafil (Viagra®), vardenafil (Levitra®) and tadalafil (Cialis®). Avanafil (Stendra®) is available in the USA and potentially soon in Canada. Viagra has recently become available as an orodispersible film.
2. Intracavernosal injectable medications, which directly relax the penile smooth muscle by injecting the neurotransmitter that creates an erection, includes prostaglandin E1 penile injections [Caverject® or compounded] and other injectable combinations of papaverine and phentolamine, and occasionally, atropine.
3. Topical agents for penile smooth muscle relaxation (e.g., prostaglandin, minoxidil, papaverine and nitroglycerine).
4. Intraurethral preparation of prostaglandin E1 (MUSE®), which are not effective.
5. Mechanical methods, such as vacuum devices and penile rings.
6. Surgical penile implants.
7. Behavioural methods (perineal muscle training).
8. Psychological and sex therapy (non-medicinal) adjunct to medical therapies after SCI.

All methods except penile implants are clinically reversible. The use of implantable sacral stimulators to assist an erection through stimulation of S2 and S3 anterior roots has not been well explored due to its limited use in those with complete SCI lesions (Brindley et al. 1989). The detrimental effects on erectile function of baclofen and baclofen pumps are noted, but they appear to be clinically reversible with discontinuation of baclofen use (Elliott et al. 2025).