Summary: Treatment for ED
Even though fewer studies include people with SCI in general, there is enough evidence to recommend PDE5i as the first choice of treatment for erectile dysfunction in people with SCI; it has excellent effectiveness (about 70-80% success rate) with limited side effects and/or few adverse events. Tadalafil (i.e., Cialis®) is longer-acting (i.e., 24-36 hours) so may be advantageous in men wishing for more spontaneous sexual activity, whereas sildenafil (i.e., Viagra®, Levitra ®) are more ‘on-demand’ typically acting in 1-4 hours).
In general, PDE5i works best in people with upper motor neuron (UMN) lesions in comparison to those with lower motor neuron (LMN) lesions whose nitric oxide release at the nerve end terminal may not be as consistent. Effectiveness of sildenafil in men with LMN is reported to be between 28-50% (Del Popolo et al. 2004, Khorrami et al. 2010). A lesion above the sacral spinal tract and a higher reflexive erection are favorable parameters for a positive response to all PDE5i. Short term side effects are about the same as men in the general population such as headache and flushing (between 10-15% occurrence), dyspepsia (about 5%), and visual disturbances noted in higher doses. But it is important to differentiate the side effects of the PDE5i with symptoms of autonomic dysreflexia (AD) – especially the presence of headache. Men taking nitrates and those with symptomatic hypotension and/or tetraplegia should err on the side of caution when taking PDE5i due to its hypotensive effect. Long-term side effects have not been evaluated in the SCI population, but it appears that becoming accustomed to PDE5i and reductions in their effectiveness is rare.
At the present time, there is not enough evidence to suggest either sublingual apomorphine or oral fampridine-SR are useful in the SCI population for the treatment of ED. Injectable medications have better efficacy (90%) than PDE5i, but are more invasive, and have a higher risk of short-term side effects, especially prolonged erection in the SCI population (Deforge et al. 2004a). Careful teaching of correct injection technique and dose titration can largely eliminate this problem. PGE1, papaverine and phentolamine all require refrigeration, with PGE1 being the least stable at room temperature (Deforge et al. 2004b). Prolonged use of papaverine is more likely to cause cavernosal fibrosis due to its low pH of 3-4, and therefore is more commonly used in conjunction with other medications (commonly phentolamine or atropine). Injection with any of these medications can cause subcutaneous hematomas, cavernosal or tunica fibrosis (usually small and reversible with time) or mild edema. The use of intraurethral prostaglandin (MUSE®) and topical preparations have not been that successful in the SCI population and therefore are rarely used. Penile implant surgery is reserved now for those men with failed or unacceptable reversible methods (ICI, oral therapy or vacuum device), although some men with difficulties attaching external drainage devices may find penile implants helpful. We found one study (Glina et al. 2024) that produced positive results on erectile function with an implantable neurostimulator unit (CaverSTIM); however, these results are preliminary and further research is required to establish its effectiveness.
More recently, researchers have investigated perineal (pelvic-floor) muscle training and type of neuromodulation (i.e., intrathecal baclofen, transcutaneous electrical nerve stimulation or TENS) in an effort to find more effective and less invasive treatments for erectile dysfunction. Preliminary results are promising that pelvic-floor muscle training and non-invasive stimulation produce positive effects on bladder and erectile function. Intrathecal baclofen produces positive results on minimizing spasticity and bladder dysfunction, however may impede erectile function.
