Laparoscopic treatment of intrapelvic entrapment of sacral nerve roots by abnormal piriformis bundles causing sciatica, pudendal neuralgia, and pelvic floor dysfunction
IUGA Academy. Lemos N. Jun 30, 2018; 213282; 150 Topic: Pelvic Pain
Dr. Nucelio Lemos
Dr. Nucelio Lemos

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Laparoscopic treatment of intrapelvic entrapment of sacral nerve roots by abnormal piriformis bundles causing sciatica, pudendal neuralgia, and pelvic floor dysfunction

Li, A1; Polesello, G2; Tokechi, D3; Cancelliere, L1; Sermer, C1;Lemos, N1

1: Functional Pelvic Surgery and Neuropelveology, Department of Obstetrics and Gynecology, University of Toronto; 2: Division of Hip Surgery, Department of Orthopedics and Tramatology, Faculdade de Ciencias Medicas da Santa Casa de Sao Paulo, Brazil; 3: Division of Musculoskeletal Imaging, Department of Radiology, Hospital Sirio-Libanes, Sao Paulo, Brazil

Introduction: First described in 1937, piriformis syndrome is caused by these abnormal variations of the piriformis muscle compressing the sciatic nerve, leading to pain in the buttocks, hips, and/or lower limbs. It accounts for 5-6% of sciatica and can be challenging to both diagnose and cure.

Objective: We present a video of a case of a right-sided intrapelvic entrapment of sacral nerve roots by the piriformis and review our initial results.

Methods: A 36 year-old man was seen with a 8-month history of moderate sciatica, describing aching pain in the gluteal region and sharp pain in the lower limbs. Hip abduction aggravated the pain, while ambulating alleviated his symptoms. He denied erectile dysfunction. Associated urinary symptoms were frequency, urgency, and urge incontinence. Regular medications included pregabalin 75 mg twice daily and dipyrone 1 g every six hours. Past medical history included dyslipidemia. Examination revealed allodynia in the proximal scrotum, along the S2 dermatome. Urodynamic investigations suggested urinary incontinence due to detrusor overactivity. Magnetic resonance imaging showed an anomalous piriformis bundle compressing L5 to S2 nerves.

Results: Laparoscopy was performed under general anesthesia. After developing the pre-sacral space, an anomalous piriformis muscle bundle compressing the S2 and S3 nerve roots was observed. The muscle fibres were divided, and the right sacral nerve roots then revealed. The previously divided muscle fibres were then mobilized to retract into the deep gluteal space.

Post-operatively, the patient reported full resolution of his urinary and motor symptoms. However, generalized sciatica occurred at 6 weeks post-operatively due to the retraction of the distal portion of the transected piriformis muscle into the deep gluteal space, which fibrosed and adhered to the sciatic nerve at that level. A second operation was ultimately required, utilizing a transgluteal approach to detrap the sciatic nerve.

Three additional patients underwent a similar operation. Of four patients, the average age was 42.5 ± 11.7 (36 – 60) years, and three (75%) were female. The average time from symptom onset to diagnosis was 6.2 ± 6.2 (0.7 – 15) years, and patients had undergone 1.8 ± 2.1 (0 – 4) surgeries. Prior to our surgery, the VAS score was 9.3 ± 1.0 (8 – 10); however, post-operatively, this decreased to 2.0 ± 1.8 (0 – 4). The average surgical time was 119 ± 39.5 (66 – 161) minutes. None of the other three patients experienced recurrent symptoms or required a second transgluteal approach.

Conclusion: Intrapelvic entrapment of sacral nerve roots by abnormal piriformis muscle bundles is a possible extra-spinal cause of sciatica and neurogenic pelvic floor dysfunction that can be treated successfully by laparoscopy.


  • Beaton LE and BJ Anson. 1937. The Relation of the Sciatic Nerve and of its Subdivisions to the Piriformis Muscle. The Anatomical Record 70:1-5.
  • Possover M, Quakernack J, Chiantera V. 2005. The LANN Technique to Reduce Postoperative Functional morbidity in Laparoscopic Radical Pelvic Surgery. J Am Coll Surg 201:913-7.


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