Sexual Dysfunction and Infertility in Male Spina Bifida

Abstract and Introduction

Abstract

Spina bifida is a congenital neural tube defect with many neurological implications, as well as decreased sexual function and infertility. Few studies have directly investigated infertility in men with spina bifida. Infertility in this special patient population is primarily the result of spermatogenic defects and/or failure of sperm transport due to erectile or ejaculatory dysfunction. The severity of sexual and reproductive dysfunction seems to correlate with higher level of spina cord lesion and presence of hydrocephalus. Phosphodiesterase 5 inhibitors (PDE5is) have been shown to be effective for erectile dysfunction in some men with spina bifida. Surgical sperm retrieval from the genitourinary tract and rectal probe electroejaculation can serve as methods for collecting sperm from those with ejaculatory dysfunction or retrograde ejaculation. Assisted reproductive technology such as intracytoplasmic sperm injection allows isolated sperm from men with infertility to achieve fertilization. Since most spina bifida patients are surviving into adolescence and adulthood due to improved medical and surgical advancements, it is paramount for healthcare professionals to address issues related their sexual and reproductive function.

Introduction

Spina bifida is a congenital form of neural tube defect in which the fetus' spinal cord and the surrounding sac fail to develop properly in-utero, resulting in potential lifelong neurological deficits. Per the Centers for Disease Control and Prevention, spina bifida affects 1,500 newborns a year with the highest prevalence of 3.8 per 10,000 live births in Hispanic mothers.^[1] A separate study by Shin et al. estimated that the prevalence of spina bifida in the United States is 3.1 per 10,000 or approximately 25,000 children and adolescents aged 0 to 19 years in 2002.^[2]

While urologic manifestations of spina bifida such as neurogenic bladder have been extensively examined, few studies have focused on sexual dysfunction and infertility in this patient population. Recent medical advancements have contributed to the increasing life expectancy of spina bifida patients. Unlike the 1960s and 1970s, when the 5-year survival rate for infants with spina bifida was only 37%, nearly 50% of spina bifida patients surveyed in the past decade have survived to at least age 35.^[3,4] Similarly, another study by Shin et al. estimated that from 1983 to 2003, over 85% of spina bifida patients in the United States survived to at least 20 years of age.^[5] In the 1960s, the combined inventions of artificial valves and silicone lead to improvements in ventriculoperitoneal shunting. In addition, the development of aggressive neonatal care and preventative bladder programs in the 1970s further improved survival.^[6] With more spina bifida patients surviving into adolescence and beyond, concerns regarding sexual function and fertility must be addressed.

Various genetic and pathologic defects can contribute to male infertility. In its simplest form, infertility is caused by defects in spermatogenesis and/or failure of sperm transport. Defined as a couple's failure to achieve clinical pregnancy following more than 12 months of unprotected sexual intercourse, it is estimated that more than 72.4 million, or 9% of couples worldwide, suffer from infertility.^[7] Given these statistics on infertility in the general population, it is reasonable to expect that the rate of infertility in the spina bifida population would be at least equal if not much higher. Unfortunately, no study exists to directly estimate the prevalence of infertility among male spina bifida patients. Studies of sexual function in this population have indirectly yielded variable success rates of fertility based on small sample sizes. In a study by Cass et al. involving 12 spina bifida men, only one of the six men who engaged in sexual intercourse achieved fatherhood.^[8] In a separate study by Bomalaski et al. examining 18 men with spina bifida, 13% engaged in sexual intercourse, but only 1 patient (6%) achieved fatherhood.^[9] Likewise, a study by Decter et al. involving 57 men with myelodysplasia found that out of the 11 patients (19%) who attempted to achieve fatherhood, 8 (14%) were successful.^[10] Another study by Lassmann et al. showed that only two out of a cohort of 42 spina bifida men attempted to achieve paternity but both failed.^[11] A survey study of 52 spina bifida men by Cardenas et al. found that rates of paternity may be related to the presence of hydrocephalus associated with spina bifida as 14.8% of men without hydrocephalus reported having children while no men with hydrocephalus claimed to have children.^[12] These statistics shed light on the fact that infertility is prevalent among spina bifida men, yet few large-scale studies have examined its cause and treatment. In addition, all studies using surveys to assess health in the spina bifida population suffer from selection bias and thus may not be accurate.

Numerous studies have suggested that most spina bifida patients have intact libido, and a significant proportion of them wish to have children. Between 80–100% of spina bifida men had normal sexual desires.^[13–16] From video narratives on the lives of 14 spina bifida patients in one study, all of the participants expressed a desire for parenthood.^[17] Obstacles to achieving fatherhood among spina bifida men included erectile dysfunction, anejaculation, poor sperm quality, and physical or social limitations that interfere with sex.^[16] In this review, we examine the major causes of infertility experienced by spina bifida men, the severity of sexual dysfunction and infertility based on the level of neurological lesion, and the treatment strategies available to this patient population. We also explore the possibility of a genetic link between spina bifida and infertility and the need for improved patient education and research in this vulnerable patient population.

Table 1. Characteristics of spina bifida males who are less likely to form relationships, engage in sexual activity, and achieve paternity
Impeding factors to sexual relationships in spina bifida men
Poor ambulatory status (bed-bound, wheel-chair, crutches, braces)
Dependence on others for daily activities
Young age
Lack of self-confidence
Residing with parents
Poor bowel and bladder control

Table 2. Studies on relationship between spinal lesion level and sexual function in spina bifida men
Measure	Reference	# Patients	Findings
Erections	Diamond et al. (29)	52	At or below T10: 64% achieved erections
			Above T10: 14% achieved erections
	Lee et al. (32)	17	Lower spinal lesions correlated with higher erectile function
			For each one descending spinal level, erectile function score in SHIM increased by 47%
Paternity	Decter et al. (10)	57	7 out of 8 men who achieved paternity had lesions at or below L5
Azoospermia	Reilly & Oates (19)	10	100% of spina bifida men with erectile dysfunction were found to be azoospermic after electroejaculation with testicular biopsies revealing Sertoli cells only
Genital sensation	Gatti et al. (35)	120	At or below S1: 53.5% reported normal genital sensation
Genital sensation			At or above L2: 7.2% reported normal genital sensation
Intercourse and relationships	Gatti et al. (35)	120	At or below S1: 30% reported sexual intercourse
			At or above L2: 14.3% reported sexual intercourse
			Those with lesions at or below S1 were 4.2 times more likely to have been in relationships and 3.4 times more likely to have had intercourse compared to those with lesions above S1
	Lee et al. (32)	17	Lower spinal lesions correlated with higher sexual function measured by overall SHIM score
			For each one descending spinal level, average SHIM score increased by 42%