Side effects of intradetrusor botulinum toxin injections on ejaculation and fertility in men with spinal cord injury: preliminary findings

Abstract

Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? The beneficial effect of intradetrusor botulinum toxin (BT) injections on hyperactive bladders in individuals with spinal cord injury is known from the literature, but its potential effect on ejaculation and fertility through diffusion is not. As BT injection paralyses the bladder muscle, it may also paralyse the muscular envelopes of the adjacent reproductive organs and lead to potential negative side effects, which have not been studied yet. This study provides preliminary data on the potential negative side effects of BT injections on semen volume and retrograde ejaculation, as well as some potential beneficial effects on semen quality.

Objective: To investigate the effect of botulinum neurotoxin A on ejaculation potential and fertility. Intradetrusor injection of botulinum neurotoxin A is most commonly used nowadays to treat overactive bladder in patients with spinal cord injury (SCI).

Patients and methods: Retrospective analyses were carried out of 11 patients with complete lesions from C5 to T6 who had received botulinum (BT) injections for their overactive bladder and who had undergone ejaculation tests before and after BT treatment.

Results: BT treatment was found effective in improving bladder function in up to 85% of the cases. While no patients maintained natural ejaculation following their SCI, BT treatment was found to increase the incidence of retrograde ejaculation (vibrostimulation) in 46% of cases and to diminish semen volume in 77% of cases, from an average of 1.8 mL to 1 mL. Semen quality was slightly improved following BT treatment, sperm mobility increased in 67% of cases, sperm vitality in 50% and semen culture improved in 43%.

Conclusions: BT treatment has beneficial and detrimental effects on ejaculation function. The detrimental effects involve retrograde ejaculation and reduced semen volume, which are explained by the spread of toxin to the bladder neck, reducing its tonus, and to the smooth muscle sexual accessory organs, reducing the strength of their contraction. The beneficial effects are explained by the reduced contamination of the semen by urinary infection, which may improve spermatogenesis and subsequent semen quality. The results are discussed in terms of their clinical implications and advice to patients.