|Complete spinal cord injury||12%||47%||55%|
|Incomplete spinal cord injury||33%||53%||78%|
|Complete lesion of the
sympathetic centres (T12 to L2)
|Complete lesion of the parasympathetic
and somatic centres (S2 – S4)
|Complete lesion of all
spinal ejaculation centres (T12 to S5)
|Complete lesion strictly
above Onuf's nucleus (S2 – S4)
|Complete lesion of the S2 – S4 segments||none||none|
It can depend on one or more of several causes, including:
- Sexual inhibition
- Pharmacological inhibition. They include mostly antidepressant and antipsychotic medication, and the patients experiencing that tend to quit them
- Autonomic nervous system malfunction
- Prostatectomy - surgical removal of the prostate.
- Ejaculatory duct obstruction
- Spinal cord injury causes sexual dysfunction including anejaculation. The rate of being able to ejaculate varies with the type of lesion, as detailed in the table at right.
- Old age
Anejaculation, especially the orgasmic variant, is usually indistinguishable from retrograde ejaculation. However, a negative urinalysis measuring no abnormal presence of spermatozoa in the urine will eliminate a retrograde ejaculation diagnosis. Thus, if the affected person has the sensations and involuntary muscle-contractions of an orgasm but no or very low-volume semen, ejaculatory duct obstruction is another possible underlying pathology of anejaculation.
Anejaculation in spinal cord injury
The first-line method for sperm retrieval in men with spinal cord injury is penile vibratory stimulation (PVS). The penile vibratory stimulator is a plier-like device that is placed around the glans penis to stimulate it by vibration. In case of failure with PVS, spermatozoa are sometimes collected by electroejaculation, or surgically by per cutaneous epididymal sperm aspiration (PESA) or testicular sperm extraction (TESE).
- Chehensse, C.; Bahrami, S.; Denys, P.; Clément, P.; Bernabé, J.; Giuliano, F. (2013). "The spinal control of ejaculation revisited: A systematic review and meta-analysis of anejaculation in spinal cord injured patients". Human Reproduction Update. 19 (5): 507–526. doi:10.1093/humupd/dmt029. PMID 23820516.
-  Archived 2008-02-08 at the Wayback Machine (in Italian) and  (in Italian)