New research involving spina bifida patients uses fMRI brain mapping to investigate sensation in a newly innervated penis.
Spina bifida is a congenital neural tube defect which may result in little or no maintained penile sensation. This is particularly troublesome for patients when they reach sexual maturity.
An experimental surgical procedure called TOMAX (TO MAX-imize sensation, sexuality, and quality of life) could work to innervate the penis. The method involves joining two sensory nerves: the ilioinguinal nerve, which is not affected in spina bifida, and the dorsal nerve of the penis.
When TOMAX is successful, sensation shifts from the groin to the penis in about a year. This means that patients may eventually feel pleasure when sexually stimulated.
To evaluate how the brain adapts following TOMAX, a group of Dutch scientists performed fMRI scans on three men who had previously undergone the procedure. The men’s ages were 19, 38, and 23. At least two and a half years had passed since each man’s surgery. All of the men had some sexual experience (either with a partner or solo) after the procedure.
To evaluate sensation, a small paint brush was used to stimulate each man’s glans penis, groin, and index finger. In total, 150 separate stimulations were conducted.
In the resulting images, the researchers looked for activation of the primary somatosensory cortex (SI) and the functional connectivity between the SI and other areas of the brain.
Stimulation of the re-innervated side of the penis and the contralateral groin area activated similar areas of the SI. However, distinct SI networks were found in the connectivity analysis.
“Using nonsexual, nonpainful brush stimulation, we found that brain activity because of penile glans and inguinal stimulation remained similar in SI, but was different in terms of the functional associations of SI with other parts of the brain (SI networks). These effects were consistent across the stimulation sessions and across the three patients who were included,” the authors explained.
More research is needed, they added, especially since their sample group was small and results might be different if the stimulation were erotic.
The study was first published online last month in The Journal of Sexual Medicine.
The Journal of Sexual Medicine
Kortekaas, Rudie, PhD, et al.
“Central Somatosensory Networks Respond to a De Novo Innervated Penis: A Proof of Concept in Three Spina Bifida Patients”
(Full-text. First published online: August 21, 2015)
“Spina Bifida – Topic Overview”
(Last updated: September 9, 2014)