Faculty Book
NANCY L. BRACKETT, Ph.D., HCLD
Research Associate Professor,
Neurological Surgery and Urology
Male fertility following spinal cord injury
Research
Interests
The research in my laboratory is focused on understanding and improving the impairments to male fertility which occur following spinal cord injury (SCI). Following SCI, most men, but not women, experience impaired fertility. Specifically, most men with SCI are anejaculatory, and some experience erectile dysfunction. Although their semen may be obtained by medically-assisted ejaculation procedures, in most cases, semen quality is impaired, specifically, sperm motility and viability are abnormally low, although sperm numbers tend to be normal.
Our research is focused on determining the cause of impaired semen quality in men with SCI. Our studies have shown that factors secondary to SCI are not responsible for impaired semen quality in men with SCI. For example, the condition is not due to scrotal thermoregulatory dysfunction, the method or frequency of ejaculation, the number of ensuing years post-injury, or hormonal alterations. Our recent evidence indicates that the problem is related to the seminal plasma. For example, seminal plasma of men with SCI inhibits sperm motility of able-bodied men. In addition, sperm motility is much higher in men with SCI before the sperm mix with seminal plasma. Substances within the seminal plasma are abnormal in men with SCI, including elevated reactive oxygen species, decreased prostate specific antigen (a marker of prostate function) and decreased fructose (a marker of seminal vesicle function). The semen of men with SCI contains an abnormally high number of non-spermatozoon cells, most of which are leukocytes. Our current research is investigating inflammatory factors, including semen cytokine levels, as contributors to the problem. Our ultimate goal is to develop therapies to normalize semen quality in men with SCI, so that chances of biological fatherhood are increased.
In addition to our investigation of the seminal plasma, we are studying methods to improve semen retrieval and semen processing for assisted conception procedures. Our research has shown that sperm motility is better when obtained by penile vibratory stimulation versus electroejaculation, and that semen of men with SCI should be processed quickly and at room temperature, in contrast to prolonged processing at body temperature typically used for semen from able-bodied men. In addition, we have shown that brown-colored semen is a common occurrence in men with SCI. The cause of the brown color is unknown, and does not harm sperm motility. Contrary to common belief, our research showed that repeated ejaculation does not necessarily eliminate the brown color. We are currently investigating whether oral administration of nifedipine impairs sperm function in men with SCI, and we are investigating methods to improve antegrade semen recovery during assisted ejaculation procedures.
Randall JM, Evans DH, Bird VG, Aballa TC, Lynne CM, Brackett NL: Leukocytospermia in spinal cord injured patients is not related to histological inflammatory changes in the prostate. J Urol. 170: 897-900, 2003. [Abstract]
Brackett NL, Ead DN, Aballa TC, Ferrell SM, Lynne CM: Semen retrieval in men with spinal cord injury is improved by interrupting current delivery during electroejaculation. J Urol, 2002, 167:201-203. [Abstract]
Bird VG, Brackett NL,. Lynne CM. Aballa TC. Ferrell SM. Reflexes and somatic responses as predictors of ejaculation by penile vibratory stimulation in men with spinal cord injury. Spinal Cord. 39:514-9, 2001 [Abstract]
Brackett NL, Lynne CM, Aballa TC, Ferrell SM. Sperm motility from the vas deferens of spinal cord injured men is higher than from their ejaculates. J Urol 2000, 164:712-715. [Abstract]
Brackett NL and Lynne CM: The method of assisted ejaculation affects the outcome of semen quality studies in men with spinal cord injury: a review. Neurorehab 2000;15:89-100. [Abstract]
Wieder JA, Brackett NL, Lynne CM, Green JT, Aballa TC (2000) Anesthetic block of the dorsal penile nerve inhibits vibratory-induced ejaculation in men with spinal cord injuries. Urology 55:915-917. [Abstract]
Amador MJ, Lynne CM, Brackett NL: A Guide and Resource Directory to Male Fertility Following Spinal Cord Injury/Dysfunction. Sponsored by the Paralyzed Veterans of America Education and Training Foundation. Published by The Miami Project to Cure Paralysis, Miami, Florida. 2000.
Last updated April 13, 2004
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