Myofascial syndrome is present in up to 85% of patients with endometriosis, affecting the pelvic floor muscles, most frequently involving the obturator internus and puborectalis muscles and its the pelvic floor muscles. This syndrome causes sexual dysfunction and lead the pelvic chronic pain.
In our center, this procedure is indicated for patients with chronic pelvic pain due to a myofascial syndrome that is refractory to treatment, in combination with physiotherapy sessions, making it a multidisciplinary treatment. Before performing the procedure, we administer questionnaires to assess the presence and intensity of pain (VAS), its impact on quality of life (PGI), and its effect on sexual function (FSFI).

Required material:
• 100 IU of botulinum toxin A (BTA) diluted in 6 mL of saline solution, the solution should be gently mixed to prevent protein denaturation.
• Infiltration needle
• Ultrasound device
• A nerve-stimulator
Botulinum toxin infiltration will be performed under sedation. Once the patient is sedated, we will conduct an examination to locate the trigger points to be injected.

Internal Obturator Muscle:
To examine the internal obturator, the index finger is inserted into the vagina and directed anterolaterally. Using a pincer movement, the thumb palpates the obturator foramen. At the level of the clitoris, the muscle can be found. To insert the needle, it is positioned at the clitoral level, near the inguinal fold, and directed laterally. The correct needle placement should be verified using both a nerve stimulator and ultrasound.
Ultrasound verification: The transducer is placed in a parasagittal plane at the inguinal fold, over the anterior pubic ramus.

Nerve-stimulator verification: The power is gradually increased from 0.02 to 1 MHz, allowing for palpation of muscle excitation during the examination.
Once verified, the botulinum toxine is administered. To ensure effective distribution of the medication, 1 cc of saline solution can be injected.

Puborectalis Muscle:
To examine the puborectalis muscle, the finger is inserted into the vagina and moved laterally. Posterolateral pressure is applied to locate the trigger points.
For injection, once the muscle is located, the needle is inserted 1 cm lateral to the perineal body and directed medially towards the vagina. As mentioned earlier, correct needle placement should be verified using nerve stimulation and ultrasound. In this case, the transducer should be placed over the vaginal introitus, and with a lateral sweeping motion, the needle can be located. After proper verification, the medication will be administered.

Post-Procedure Care: 
After completing the infiltration, the patient is awakened and remains under observation for two hours. One of the most common side effects of the injection is mild pain during the week following the procedure. Follow-up evaluations will be conducted at one month, three months, and six months to assess effectiveness and potential improvement using the previously mentioned questionnaires.

Results
A total of 11 patients were evaluated, with one not attending follow-up appointments.
Among the remaining 10 patients:
• 4 had no complications
• 5 experienced episodes of incontinence
• 1 reported an inability to achieve orgasm
A reduction of up to 5 points on the VAS pain scale was observed in 7 out of the 10 patients, indicating a 50% improvement compared to their baseline condition.

Regarding sexual function, the FSFI questionnaire showed a 36% improvement compared to their previous condition. Additionally, based on the PGI questionnaire, which assesses the patient’s selfperception of overall improvement, the median score was 3 (where 1 represents "much better" and 7 represents "much worse").

Botulinum toxin infiltration has been shown to improve chronic pelvic pain, as well as quality of life and sexual function impacted by this condition

Foster L, Clapp L. Botulinum toxin A and chronic pelvic pain: A systematic review. Clin J Pain. 2011;27(3):279-286.
Spruijt MA, Klerkx WM, Kelder JC, Kluivers KB, Kerkhof MH. The efficacy of botulinum toxin a injections in pelvic floor muscles in chronic pelvic pain patients: a systematic review and meta-analysis. Int Urogynecol J. 2022;33(11):2951-2961.
Aredo JV, Heyrana KJ, Karp BI, Shah JP, Stratton P. Relating Chronic Pelvic Pain and Endometriosis to Signs of Sensitization and Myofascial Pain and Dysfunction. Semin Reprod Med. 2017;35(1):88-97.

Continence 15S (2025) 102000
DOI: 10.1016/j.cont.2025.102000