Unfortunately, semen quality is also noted to decline after SCI (Deforge et al. 2005). Semen obtained by EEP in the first 2-3 days after injury was scant, but had normal quality by 6-10 days post-injury (Mallidis et al. 1994). After approximately 2 weeks semen quality deteriorates to levels approaching those observed in males with chronic SCI. After 6 months to 1 year, there is no relationship between duration of injury and sperm quality (Sarkarati et al. 1987). Semen quality in men with chronic SCI is reported to have decreased motility and viability, although total numbers of sperm tend to remain high (Brackett et al. 1997b; Ibrahim et al. 2009). Sperm DNA damage, which is another method of assessing semen quality, has also been shown to be higher among men with SCI when compared to able-bodied controls (Brackett et al. 2008). The following studies investigate the effects of various factors on sperm quality, including: repeated ejaculations, different methods of bladder management, antegrade versus retrograde ejaculation, vibratory stimulation versus electroejaculation, surgical extraction, heat and alterations to seminal plasma. In their chapter on fertility after SCI in the book Spinal Cord Injury Rehabilitation, Brackett and Ibrahim (2009) also provide a review of other areas related to sperm quality.
Results from studies have varied, however, in general have shown similar reductions in sperm parameters in antegrade and retrograde samples, except for decreased motility in non-alkalinized retrograde samples and one study which showed antegrade samples were better in motility and viability than retrograde samples (Ohl et al. 1997). There is also some evidence to suggest that vibratory stimulus seems to produce more viable samples than electroejaculation in terms of motility (Ohl et al. 1997; Le Chapelain et al. 1998). Semen quality appeared to improve with repeated ejaculations in some series (Matthews et al. 1996; Giulini et al. 2004; Hamid et al. 2006), and not in others (Sarkarati et al. 1987; Das et al. 2006). It has been suggested that parameters improve with consecutive days of electroejaculation (Mallidis et al. 2000). Once-weekly vibrator stimulation resulted in an increase of semen volume and of fructose and acid phosphatase levels in the seminal plasma (suggesting improved function of the seminal vesicles and prostate) (Siösteen et al. 1990), whereas other investigators reported that too frequent ejaculation caused semen quality to deteriorate (Wang et al. 1992). The possibility of improvement in semen parameters appears to be related to consistency of ejaculations over a regulated time period. One study found improved sperm motility after 3 months of weekly PVS performed by patients at home (Beretta et al., 1989). The majority of studies, however, found no statistically significant improvement in sperm motility after regular ejaculation by PVS or EEJ (Siosteen et al., 1990; Sonksen et al., 1999; Das et al., 2006; Hamid et al., 2006).
Poor sperm motility may be due in part to the seminal plasma secondary to disturbed nervous systems and anejaculation (Brackett et al. 2000; 2007a), and there may also be alterations in testicular function or morphological anomalies in the sperm (Chapelle et al. 1988; Elliott et al. 2000; Monga et al. 2001). Sperm aspirated from the vas prior to exposure to seminal fluid in men with SCI had significantly better motility (54% vs 14%) and greater viability (74% vs 26%) in comparison to sperm retrieved from same group by VS or EE (Brackett et al. 2000). These researchers had previously demonstrated an inhibitory effect of SCI seminal plasma on normal sperm motility, as well as improvement of SCI sperm motility when prepared with normal seminal plasma (Brackett et al. 1996). In addition, the same group (Brackett et al. 2007a; Cohen et al. 2004) have recently shown that cytokines in the semen of men with SCI may play a key role in inhibiting sperm motility, with inactivation of the relevant receptors leading to improved sperm motility. Both studies (Cohen et al. 2004; Brackett et al. 2007a) examined the effect of treating semen with different combinations of antibodies on motility and both found that sperm motility significantly increased with the combination of antibodies that acted against all 3 relevant cytokines. In a prospective controlled trial, Ibrahim et al. (2008) found no damage to sperm treated with cytokine inhibitors and suggested that further studies investigating cytokine inhibitors as a therapy for low sperm mobility are warranted. Probenecid has shown promising results to improve sperm motility (Ibrahim et al. 2017).
Once ejaculated, sperm motility in men with SCI declines rapidly, and storing at body temperature (in a 37°C incubator) may exacerbate this (Brackett et al. 1997b). Bladder management also seems to affect sperm quality, with low pressure emptying by clean intermittent catheterization improving semen quality over indwelling catheterization, reflex voiding or straining (Ohl et al. 1989; Rutkowski et al. 1995). Ibrahim et al. (2014, 2015) found that slight improvement in sperm motility were achieved after treatment with anti-ASC polyclonal antibody (mean sperm motility increased from 11.5% to 18.3%) and after probenecid treatment (sperm motility increased from 18% to 25%).
Padron et al. (1994) showed a similar reduction in sperm motility (65%) in men with SCI to normal with thawing after cryopreservation, preferring the vapor only method. Krebs et al. (2015) found that complete tetraplegia has a negative effect on pre-cryopreservation sperm viability and post-cryopreservation motility, and that there were no differences between the semen parameters of samples collected early (up to 3 weeks) after SCI, those collected later, or those collected using assisted ejaculation techniques. Given this and reported reliability of retrieval methods, there seems no point in cryopreserving semen for later insemination unless collected acutely within the first 1-2 week window while sperm quality is still normal (Mallidis et al. 1994).
Botox treatment for detreusor dyssynergia has beneficial and detrimental effects on ejaculation function (Caremel et al. 2011). The detrimental effects involve retrograde ejaculation and reduced semen volume, which result from reduce contraction of the smooth muscle sexual accessory due to the toxin. A beneficial effect is improved semen quality due to the reduced contamination of the semen by urinary infection.
There is level 2 evidence (from 1 weak RCT; Brackett et al. 2002) that sperm obtained by antegrade samples has better motility than retrograde samples and that interrupted current produces higher sperm motility than continuous current.
There is level 4 evidence (Rutkowski et al. 1995) that bladder management by clean intermittent catheterization (with low pressure filling and emptying) may improve semen quality over indwelling catheterization, reflex voiding or straining.
There is level 4 evidence (Caremel et al. 2011) that botox injections to the overactive bladder may reduce semen volume, but increase semen quality.
There is level 4 evidence (Hibi et al. 2008) that retrograde vasal sperm aspiration can retrieve sperm of sufficient motility to afford pregnancy.
There is level 2 evidence that SCI sperm quality can be improved by placing sperm from SCI in able-bodied seminal plasma (Brackett et al. 1996), and that aspirated sperm from the vas deferens has better motility than that ejaculated (Brackett et al. 2000), demonstrating the etiology of poor semen quality may lie within the seminal plasma in men with SCI. These techniques have not been studied clinically with respect to pregnancy rates.
There is level 2 evidence (Ibrahim et al. 2009) that monoclonal antibodies and receptor interference agents do not change the degree of DNA fragmentation in sperm from subjects with SCI.
There is level 3 evidence (Kanto et al. 2008) that testicular sperm extraction followed by intracytoplasmic injection is an effective way to induce pregnancy, with fresh sperm giving better results than frozen-thawed sperm.
There is Level 2 evidence (Ibrahim et al 2014, 2015) that found slight improvements in sperm motility were achieved after treatment with anti-ASC polyclonal antibody (mean sperm motility increased from 11.5% to 18.3%) and after Probenecid treatment (sperm motility increased from 18% to 25%).
There is Level 5 evidence (Krebs et al. 2015) that found complete tetraplegia has a negative effect on pre-cryopreservation sperm viability and post-cryopreservation motility, and that there were no differences between the semen parameters of samples collected early (up to 3 weeks) after SCI, those collected later, or those collected using assisted ejaculation techniques.