Diagnosis and laparoscopic repair of type I obturator hernia in women with chronic neuralgic pain.

 Perry CP, Hantes JM. Journal of the Soc of Laparoendoscopic Surgeons. 2005;9:138-141.

Cindy Neville, PT, DPT, WCS- January 9, 2013

Primary Aim: To describe results of laparoscopic treatment of obturator hernia (OH) in a small cohort of female patients with obturator neuralgia and chronic pelvic pain.

Background: The obturator foramen is formed by the rami of the ischium and the pubic bone, and is partially closed by a strong musculoaponeurotic barrier consisting of an internal and an external obturator membrane and an internal and an external obturator muscle. The obturator canal is situated in the cranial portion of this membrane with the pubic bone above and the membrane below, and measures approximately 0.2-cm to 0.5-cm wide and 2-cm to 3-cm long through which traverse the obturator nerve, artery ,and vein. The obturator nerve may become compressed in the canal leading to neuralgia.

 Three types of obturator hernias have been described based on the anatomical defect that is present.

·         Type I OH occurs when pre-peritoneal fat and connective tissue (pilot tag) enter the pelvic orifice of the canal. Presumably, the fat tag compresses the obturator nerve causing neuopathic pain symptoms.

·         Type II OH causes dimpling of the peritoneum over the canal, leading to the formation of an empty peritoneal sac.

·         Type III OH aka “thin old lady hernia” occurs on entrance of an organ (bowel, ovary, or bladder) that eventually fails to reduce spontaneously. A partial or complete small bowel obstruction has historically been responsible for the diagnosis of most obturator hernias (88% of all OH).

 Initial diagnosis of obturator neuralgia made by physical exam includes

• c/o pain medial thigh with +/- radiation to hip and behind knee
• Adductor motor weakness +/-
• c/o increased pain with exercise, prolonged standing, prolonged sitting, sitting with legs crossed
• Gait deviation with increased hip abduction
• + Howship/Romberg sign = reproduction of pain produced by palpating the nerve vaginally or rectally in the obturator canal (Figure 1)

Subjects: 7 female patients presenting to chronic pelvic pain clinic between Feb and Nov 2001 diagnosed with type I OH , Median length of follow up 11 months ( 6 – 16), average age 36.2 years (24-48). All subjects had positive Howship/Romberg sign. Authors note that “many of our patients have multiple pain generators including pelvic floor tension myalgia, interstitial cystitis, and adductor muscle spasm”.
Methods: Retrospective “continuous cohort” analysis by chart review of surgical outcomes of 7 female patients with obturator neuralgia who underwent diagnosis and laparoscopic repair of type I obturator hernia. Authors refer to this as a “pilot study review” .
Intervention: Laparoscopic removal of pilot fat tag which is assumed to be compressing the obturator canal (Figure 2) , bilateral repair of obturator foramen with polypropylene mesh (Figure 3).  Unclear if other hernias were repaired in these subjects. Not clear if these subjects did or did not have other pain generators or if they underwent any conservative medical or physical therapy prior to or after the surgical intervention.  

Primary Outcome: Subjects were contacted by mail 6-16 months post op. Pain rating VAS 0-10 where 10= the amount of pain experienced pre-operatively.; i.e. all patients started with 10 /10 pain.

Results: No surgical complications. Changes in pain rating were the primary outcome. (Table 1) All patients reported decreased pain level. 2 pts reported complete relief. All except 1 reported >50%. Mean reduction in pain was 77%. Authors report that the “standard error associated with this estimate is 8.4. This gives a 95% confidence interval (56, 98), which does not contain 0. Further, this interval does not contain 50%, which leads” to their conclusion of at least 95% confidence that the pain reduction achieved is greater than 50%.

Strengths: 

• Description of a rare type of hernia, diagnosis, and repair should be considered in differential diagnosis by PTs treating PFM disorders
• Retrospective case series format – good to know that this is an option for reporting real clinical outcomes

Weakness:

• Was this study approved by an IRB?
• Study design does not allow for meaningful statistical analysis
• Lack of clarity regarding any other interventions before or after surgery
• Pain scale as a mechanism to quantify change in pain assumes  a standardized scale, and we don’t know if the patients were asked to rate their pain or consider the intensity of their pain prior to the surgery.
• Statistical analysis explanation is difficult to understand

Conclusions:

• Type I OH may be a potential cause of chronic pelvic pain.
• Laparoscopic repair may be an effective intervention for reduction pain from hernias.

Implications for clinical practice:

• PTs should be aware of this diagnosis and interventions.
• PTs may use this type of study format to report on clinical interventions in a series of similar patients.

 Questions for Discussion

• Have you worked with a patient with a formal diagnosis of obturator hernia and/or repair?
• What is the profile of a patient in whom this diagnosis should be considered?
• IS this a study design that you might be able to use to report on an intervention that you think is successful?
• What are your thoughts on the use of the VAS where pre surgical pain = 10/10?