CHICAGO – Botox injections help alleviate chronic pelvic pain in patients with pelvic floor tension myalgia and associated conditions.
"For pelvic floor tension myalgia, Botox is definitely beneficial," Dr. Michael Hibner said at the annual meeting of the International Pelvic Pain Society. "We do it quite often, almost on a daily basis."
Pelvic floor tension myalgia is caused by painful involuntary spasms of the pelvic floor musculature, often as result of previous pelvic surgery, trauma to the perineum, or childbirth. Treatment includes physical therapy, relaxation exercises, and more recently, onabotulinumtoxinA (Botox and Botox Cosmetic).
Dr. Hibner and his colleagues at the Arizona Center for Chronic Pelvic Pain at St. Joseph’s Hospital in Phoenix identified 75 patients with chronic pelvic pain secondary to pelvic floor tension myalgia who did not respond to physical therapy and were treated at the center with Botox injections between January 2008 and August 2010. A bilateral block of the pudendal nerves was performed in the operating room using 0.5% bupivacaine with epinephrine. Botox (200 units diluted in 20 cc of 0.9% saline) was then injected transvaginally in 1-cc increments into pelvic muscles that had previously been identified on exam as tender. Pain was measured pre- and postoperatively on the Visual Analog Scale (VAS), with a change of 20% or more considered significant.
In all, 97 Botox procedures were performed, of which 68% resulted in a significant improvement in VAS scores after a mean follow-up of 76 days, said Dr. Hibner, who is also the director of gynecologic surgery at St. Joseph’s Hospital.
Patients with pudendal neuralgia had significantly less improvement (40%) than did those with painful bladder syndrome (73%) or endometriosis (59%). Age, body mass index, psychosocial history, previous surgeries, and location of pain did not correlate with outcomes.
A comparison of 77 procedures that were followed with physical therapy vs. 20 procedures without subsequent PT showed significant improvements in both groups (69% vs. 65%), suggesting that patients may still benefit from Botox injections when physical therapy is not available, Dr. Hibner said.
In all, 16 patients had multiple injections, with 14 (88%) improving after each injection. The average time between injections was 137 days (range, 84-190 days). "Physical therapy does not extend the time between injections," he said.
Complications were rare, with 2 of 75 patients developing temporary urinary retention that resolved in about 5-7 days.
Dr. Hibner said that Botox injections also can enhance the effectiveness of cytoscopy hydrodistention in patients with interstitial cystitis. Botox (100 units) is injected into the bladder rather than the pelvic floor, and the bladder is then stretched with water for 30 minutes.
Among 28 consecutive patients at the center who had interstitial cystitis, VAS scores improved 55% at 3 months in those treated with the combination therapy vs. 18% for those treated with hydrodistention alone, Dr. Hibner said. Overall, 56% of patients saw some improvement, 44% saw no improvement, and 9% had worsening. The mean duration of improvement was just 2 months (range, 1 week to 24 months).
Dr. Hibner noted that he uses Botox (200 units) injected into the levator and obturator muscles in patients with pudendal neuralgia, but mostly to rule out pelvic floor muscle spasm as a source of pain. "Botox helps with muscle spasm, so by injecting Botox, one may differentiate between pain which is due to muscle spasm, and pain which is due to nerve injury," he said.
Although Botox seems to help about 80% of patients with interstitial cystitis, only 30% of patients with pudendal neuralgia gain relief. Pudendal neuralgia is best treated by avoidance of additional insult; physical therapy in conjunction with Botox and medical therapy; and – if everything else fails – surgical decompression, he said.
In a separate study presented at the meeting, Botox and bupivacaine appeared to allow a longer dosing interval than did bupivacaine alone in 21 women receiving trigger point injections for chronic pelvic pain.
The mean number of weeks between injections was 23 weeks with Botox and bupivacaine in 4 patients vs. 10 weeks with bupivacaine in 17 patients, Dr. Andrea Skorenki, chief resident in ob.gyn. at the University of Alberta, Edmonton, and her colleagues reported in a poster. The average number of Botox plus bupivacaine injections was 3 (range, 2-4) vs. 12 bupivacaine injections (range, 1-55).
Patients receiving Botox and bupivacaine reported symptom improvement at 79% of their follow-up visits, compared with 41% for those receiving bupivacaine alone.
In addition, Botox was associated with two reports of abdominal cramps and diarrhea, compared with 16 reports of side effects with bupivacaine including injection site pain or bleeding, bladder prolapse, and difficulty with bladder emptying, Dr. Skorenki noted.