There is an excellent patient information resource about pelvic floor Botox available from WHRIA (Women's Health and Research Institute of Australia).
The Pelvic Pain Foundation of Australia also has useful information about painful sex, as well as the International Urogynaecological Association.
Botox is a brand name for Botulinum Toxin A, a toxin produced by the bacteria Clostridium botulinum. This particular toxin has a property of paralysing muscles with an effect that lasts around six months. This happens by blockage of the signal from nerves to muscles. Botox has many uses in medicine, for example in cerebral palsy where people may have spasticity in particular muscles; in the bladder to prevent overactivity and in cosmetic procedures to prevent frown lines.
In the pelvic floor, we utilise Botox to target overactive muscles that can be contributing to pain and other problems. Botox will temporarily block the overactivity of these muscles. This can play a key role in allowing pelvic physiotherapy and other techniques to succeed in overcoming the long term problems associated with overactivity in these muscles.
We prefer to give Botox with a general anaesthetic (where you are completely asleep). This is because injections into the pelvic floor can be painful, especially inpatients who already have pain in this area.
We administer a pudendal nerve block before the procedure. The pudendal nerve controls the sensation for all structures between the clitoris and the anus, and by injecting local anaesthetic near this nerve the area becomes numb for a few hours. This is done with an injection deep in the vagina on each side. You can expect this area to be numb after the surgery. This nerve runs very close to the sciatic nerve which controls the legs; rarely the local anaesthetic can also affect the sciatic nerve, which can cause weakness of the legs for a few hours after surgery.
The Botox is injected into the levator ani muscles (lower part of the vagina, just beyond the entrance) and the obturator internus muscles (upper part of the vagina, just behind the pubic bones. The injection is done with a nerve stimulator needle, that uses a very small electrical current to cause the muscles to twitch, ensuring that the Botox is injected into the correct muscles. The Botox is mixed with local anaesthetic to numb the muscle.
The images above show the outermost muscles (bulbospongiosus and transverse perineal muscles) - these are not targets for the Botox. One layer deeper is the levator ani muscles, which can often be felt as a small ridge on the lower part of the vagina, just inside the entrance. This is the target for Botox, as well as the obturator internus muscle, which can be felt on the upper part of the vagina, just beyond the pubic rami (bones).
After the Botox administration, you can expect to wake up with some numbness in the area. You shouldn't have any significant pain initially. The local anaesthetic will wear off after a few hours, and you may start to get more sore. You will get a prescription for pain relief for this.
The Botox can take several weeks to take effect. The muscles will be sore and inflamed from the procedure, so there will usually be a flare of pain for the first few weeks after the procedure. This is usually able to be well managed with painkillers.
It is important to book a follow up pelvic physiotherapy session 1-2 months after the procedure, when the physiotherapist will assess the pelvic floor; the expectation will be that the Botox will be an important adjunct to allow physiotherapy to progress.