Blood pressure changes during sexual stimulation, ejaculation and midodrine treatment in men with spinal cord injury

To explore the effectiveness of various sources of self-stimulation, including oral midodrine, in triggering ejaculation in men with spinal cord injury (SCI), and to document the systematic variations in blood pressure at ejaculation and consider a revised definition of autonomic dysreflexia.

The study included 62 men with SCI lesions from C2 to L2. Ejaculation potential was assessed with various sources of stimulation, beginning with natural stimulation, followed, if the test was negative, by penile vibrator stimulation (PVS) followed, if the test was again negative, by PVS combined with oral midodrine, started at 5 mg and increased in 5 mg steps up to 25 mg. The success rate of ejaculation was recorded, as were blood pressure (BP) changes measured at baseline and at ejaculation (or on the last trial if the test was negative). Reported sensations were also recorded and compared during positive and negative tests.

Overall, 89% of the patients reached ejaculation with one mode or another of stimulation. When patients had a negative result with natural stimulation, 56% were salvaged by PVS, and when PVS was negative, another 22% were salvaged by midodrine combined with PVS. The mean systolic BP increased by 35 mmHg at ejaculation during PVS and by 11 mmHg after midodrine, and a subsequent 29 mmHg at ejaculation during PVS combined with midodrine. By contrast, negative tests showed a relatively stable BP; the difference in changes in BP during positive and negative tests was significant (P < 0.01). Increases in BP during positive tests declined significantly more often within the limits of autonomic dysreflexia than negative tests (P < 0.01).

These results support the view that most men with SCI can obtain an ejaculation when a wide spectrum of stimulation is used, including natural stimulation, PVS, and PVS combined with oral midodrine. Positive tests were associated with significant increases in BP, in contrast to negative tests, where BP was relatively stable. This suggests that significant changes in BP are required for ejaculation and that insignificant changes are predictive of future failure. As most changes in BP during positive tests also fall within the criterion of autonomic dysreflexia, a revised definition of autonomic dysreflexia should be considered to encourage safe experiences with ejaculation and safe use of midodrine.