The CNS-hypothalamic causes for abnormalities in sperm include:
(1) Structural lesions
Structural lesions that interfere with the transport of GnRH from the hypothalamus to the pituitary gland may result in FSH and LH concentrations in the low-normal range along with a low circulating testosterone concentration. As with women, these men should have radiologic imaging to specifically rule out an anatomic lesion.
(2) Kallmanís syndrome
This is an uncommon disorder (responsible for less than 1% of azoospermia) in which the GnRH neurons do not develop normally. The GnRH neurons are located near the olfactory neurons (used for the sense of smell) in early development, and the process that causes the GnRH neurons to fail to migrate to their usual eventual location also results in failure of migration of the olfactory neurons. The result is a lack of GnRH effect on the pituitary gland (hypogonadotropic hypogonadism) and anosmia (inability to smell). The infertility caused by this syndrome is treatable by replacement of gonadotropins or GnRH using available fertility medications.
(3) Substance abuse
Illicit drugs (cocaine, opioid compounds, marijuana) are thought to primarily affect the brainís ability to communicate properly with the testes and thereby are disruptive to spermatogenesis.
Available Case Reports: