Pre-Clinical Applications of High-Definition Manometry System to Investigate Pelvic Floor Muscle Contribution to Continence Mechanisms in a Rabbit Model

External anal sphincter (EAS), external urethral sphincters and puborectalis muscle (PRM) have important roles in the genesis of anal and urethral closure pressures. In the present study, we defined the contribution of these muscles alone and in combination to the sphincter closure function using a rabbit model and a high-definition manometry (HDM) system. A total of 12 female rabbits were anesthetized and prepared to measure anal, urethral, and vaginal canal pressures using a HDM system. Pressure was recorded at rest, and during electrical stimulation of the EAS and PRM. A few rabbits (n=6) were subjected to EAS injury and the impact of EAS injury on the closure pressure profile was also evaluated. Anal, urethral, and vaginal canal pressures recorded at rest and during electrical stimulation of EAS and PRM demonstrated distinct pressure profiles. EAS stimulation induced anal canal pressure increase whereas PRM stimulation increased the pressures in all the three orifices. Electrical stimulation of EAS after injury resulted in about 19% decrease in anal canal pressure. Simultaneous electrical stimulation of EAS and PRM resulted in an insignificant increase of individual anal canal pressures when compared to pressures recorded after EAS or PRM stimulations alone. Our data confirm that HDM is a viable system to measure dynamic pressure changes within the three orifices and to define the role of each muscle in the development of closure pressures within these orifices in preclinical studies.

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Direct epidural electrical stimulation of the optic nerve: a new method for intraoperative assessment of function

Journal of Neurosurgery ◽

10.3171/jns/2008/109/10/0647 ◽

2008 ◽

Vol 109 (4) ◽

pp. 647-653 ◽

Cited By ~ 13

Author(s):

Roman Bošnjak ◽

Mitja Benedièiè

Keyword(s):

Electrical Stimulation ◽

Optic Nerve ◽

Optic Canal ◽

Tumor Removal ◽

Tuberculum Sellae Meningioma ◽

Close Relationship ◽

Tuberculum Sellae ◽

The Impact ◽

Light Flashes ◽

Stimulation Of

Intraoperative visual system monitoring of lesions with a close relationship to the optic apparatus by using light flashes reportedly is difficult to perform, and the results are too unreliable to interpret. The authors used direct epidural electrical stimulation of the optic nerve (ON) during surgery instead of light flashes. Four patients were included in this feasibility study. In 3 patients—1 each harboring a planum sphenoidale meningioma, a tuberculum sellae meningioma, and an intraorbital ON sheath meningioma—2 stimulating needle electrodes were placed on each side of the ON just anterior to the optic canal, before unroofing the optic canal and an extradural anterior clinoidectomy. In the fourth patient, who harbored a frontotemporal astrocytoma, stimulation was applied at the exit of the ON from the canal. The electrically induced visual evoked potentials (eVEPs) were recorded from the scalp before, during, and after tumor removal. A typical eVEP consisted of N20 and N40 waves. The amplitude of the N40 wave varied up to 25% prior to tumor removal. In the patient with a symptomatic tuberculum sellae meningioma, the decompressive effect of opening the optic canal and the impact of manipulation during piecemeal tumor removal were detected by the eVEPs. In the patient with an ON sheath meningioma and light sensation, only the N20 wave was observed. Epidural electrical stimulation of the ON is a safe means of providing a stable signal and real-time information on nerve conduction during surgery. It may be a useful adjunct in improving visual outcomes postoperatively. Further clinical studies are necessary.

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Measuring length-tension function of the anal sphincters and puborectalis muscle using the functional luminal imaging probe

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00414.2017 ◽

2018 ◽

Vol 315 (5) ◽

pp. G781-G787 ◽

Cited By ~ 3

Author(s):

Lori J. Tuttle ◽

Ali Zifan ◽

Catherine Sun ◽

Jessica Swartz ◽

Sophia Roalkvam ◽

...

Keyword(s):

Anal Canal ◽

Anal Sphincter ◽

Puborectalis Muscle ◽

Sphincter Muscle ◽

Anal Sphincters ◽

Cross Sectional ◽

Imaging Probe ◽

Nulliparous Women ◽

Functional Luminal Imaging Probe ◽

Vaginal Canal

The functional luminal imaging probe (FLIP) has been used to measure the distensibility of the anal canal. We hypothesized that with increasing distension of the anal canal with FLIP there will be an increase in length of the anal sphincter muscle allowing measurement of the length-tension function of anal sphincter and puborectalis muscles (PRM). We studied 14 healthy nulliparous women. A custom-designed FLIP bag (30-mm diameter) was placed in the vagina and then in the anal canal, distended in 10-ml steps with volumes ranging from 30 to 90 ml. At each volume, subject performed maximal voluntary squeezes. Length-tension measurements were also made with a manometric probe system. Tension was calculated (pressure × radius) in Newtons per meter using a custom software program. Peak tensions at different FLIP volumes were compared with the manometric data. No change in the luminal CSA was noted at low fluid volumes; the sphincter muscles were able to fully collapse the FLIP bag within the anal canal/vagina even at rest. At larger volumes, with each squeeze there was an increase in the bag pressure and reduction in the cross-sectional area, which represents concentric contraction of the muscle. Both rest and squeeze tension increased with the increase in volume in the anal as well as vaginal canal indicating that the external anal sphincter and puborectalis muscles produce more tension when lengthened. FLIP device, which has been used to describe the distensibility of the anal canal can also provide information on the length-tension function of the anal sphincters and PRM. NEW & NOTEWORTHY The functional luminal imaging probe (FLIP) has been used to describe the distensibility of the anal canal. This report is the first to describe the use of the FLIP in the vaginal canal and the anal canal to provide information on the length-tension function of the anal sphincter and puborectalis muscles, which may provide clinicians with additional information regarding the active components of muscle contraction involved in the anal closure function.

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