Neurohormonal influences

Clark et al. (1988) studied 33 patients who had loss of consciousness followed by a least a 24-hour posttraumatic amnesia. They demonstrated a fall in free testosterone, basal follicle stimulating hormone (FSH) and basal leutenizing hormone (LH) levels during the first three days following the head injury apparently due to dysfunction of the hypothalamus. The effect on testosterone, which correlated negatively with severity of the injury on admission, persisted at the 3- to 6-month follow-up in 5 out of the 21 patients who were re-tested. The stress of the injury itself can also alter sexual responses by increasing prolactin levels, thus leading to an automatic decrease in testosterone levels (Zasler, 1998).

It appears that androgen levels are closely linked to seminal emission and sex drive in the human male, and that there is a requirement for a certain minimal level of androgen to be available for sexual function to take place; however, excess amounts of androgen above these levels has minimum effect (Segraves, 1996). In the case of the female subject, current evidence suggests the oestrogen levels are essential to maintain vaginal epithelial integrity and lubrication whereas androgen levels may be related to libido (Segraves, 1996). Hyperprolactinaemia has been associated with decreased libido in both sexes (Segraves, 1988).

TBI can also have profound effects on pregnancy, including threats associated with mechanical trauma, unintended pharmacological injury, and the effect of brain injury on appropriate contraceptive regimes (Patel & Bontke, 1990). Crosby and Castilloe (1977), in their study of 441 pregnant women involved in motor vehicle accidents, noted that foetal loss is usually proportional to maternal injury. The leading cause of foetal death was maternal death and the second most frequent cause was placental separation.

Neuroendocrine disturbance following TBI continues to be a relatively poorly researched and understood aspect of these injuries and considerably more data is yet to emerge on the frequency, specificity, and implication of these changes.

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