Amazingly, questions arise on the Women’s Health Board about vibrating sensations in the vagina or pelvic floor at least once a month. I have done MULTIPLE literature searches at the National Library of Medicine site, and other search engines – none of which have ever yielded a conclusive answer. My best GUESS is fasciculations – small nerve twitches which induce small muscle twitches. This would be analogous to twitches of the muscles of the eye lid.
Most of us have had these uncontrollable eye lid spasms (“blepharospasms”) at one time or another. The triggers for eye lid spasms are fatigue, caffeine use, stress. Some treatments are pressure applied near to the twitching muscle, or even Botox.
There is another name for involuntary sustained muscle contractions which can lead to abnormal movements. They are called focal dystonias. Most of the focal dystonias include the neck, eye lid, mouth/jawbone, even writer’s cramp. The start of such conditions can be after a trauma to the body part – or they can arise without apparent cause. There may be a genetic predisposition. The exact cause is not well understood, but the area can be injected with botox which causes the affected muscle to relax.
For more information on the more severe forms of focal dystonias, the Dystonia Society website offers a good overview.