Technical Product Details
Give This Electrode a Try
We look forward to having you try this electrode… and hearing your story of what monitoring the external urinary (urethral) sphincter adds to your practice.
Gold Patient Electrical Contacts
Unisex design was a primary design goal. The male external urinary sphincter sits more distal to the bladder opening that does the female urinary sphincter. Contacts running down the length of the catheter sitting under both potential urinary sphincter locations was the solution.
Urethral Catheter Electrode Features:
* 5 year shelf life
* Unisex function
* Standard foley placement
* 100% silicone foley catheter
* Fits standard urimeter bags
* Sizes 6Fr, 8Fr, 10Fr, 12Fr, 14Fr, 16Fr, and 18Fr
* Fits standard neurodiagnostic machines
* Pre-wired 2 meter twisted pair leadwires
* Cleared for both recording and stimulation
* Secure and flexible low profile gold contacts
* Consistently low impedances
Urethral Catheter Electrode Gentle Form Factor
The electrode material is all extremely flexible. What fun to know that the OR staff doesn’t mind a new electrode you ask them to use. It has been extremely satisfying to know that placement of this electrode has been widely accepted without issue.
Urethral Catheter Electrode Sizes
The Urethral Catheter Electrode is built on a foley catheter that is 100% silicone to avoid any latex concerns by the OR staff. Sizes are available from 6 French to 18 French.
Note that sizes 6, 8, and 10 French are monopolar, while sizes 12 French to 18 French are bipolar.
Urethral Catheter Electrode Performance
The gold patient contact surface is sitting against the epithelial lining of the urethra. During design, one unknown was how much volume conduction loss would occur by the time the EMG conducted from the bulk of the striated muscle through the layers of the urethra to get to the contacts. It has been a pleasant surprise to see how well these contacts record the EMG cutaneously. The EMG signal is not showing the high frequency responses that intramuscular EMG would yield, but the recordings are typically proving to be robust and complex EMG.
In addition, the mucosa of the urethral lining against the electrode contacts is proving to yield consistently low impedance values that remain stable throughout the case in clinical application.
Clinical Use and Data
IONM Data Set #1
This case highlights a side-by-side comparison of TcMEP and triggered EMG recordings from both the external urinary sphincter (with the catheter electrode) and the external anal sphincter (with 13mm subdermal needles). Of note:
In this case, the TcMEP recordings were arguably more consistently present in the external urinary sphincter than the external anal sphincter.
While the external urinary sphincter recordings have some high frequency loss compared to the external anal sphincter recordings, the urethral recordings are still consistently complex EMG.
IONM Data Set #2
This case highlights a side-by-side comparison of TcMEP recordings from both the external urinary sphincter (with the catheter electrode) and the external anal sphincter (with 13mm subdermal needles). Of note:
In this case, the recordings were arguably more consistently present in the external urinary sphincter than the external anal sphincter.
The EMG recordings from the urethral sphincter show as much complexity as do the recordings from the intramuscular needles in the anal sphincter.
UE 60Hz Skin Artifact Pathway
It is always helpful to hear feedback from customers… especially when the feedback is less than stellar as that becomes an opportunity to make improvements! A few clinicians have experienced this electrode to be more susceptible to stimulus artifact and 60 cycle artifact than subdermal needles in the anal sphincter.
This video demonstrates one way that unwanted artifact can enter our recordings. Take home message… avoid direct skin contact with the exposed portion of the catheter and urimeter bag tubing. If you tape the catheter to the patient’s skin to maintain gentle catheter traction, it is best to place a gauze or towel between.
More
Pelvic Floor Neuromonitoring Webinar
Signal Gear was excited to co-host this webinar on Pelvic Floor Neuromonitoring. If you were unable to watch or would like to watch again, here is the link.
History of This Electrode
Recording and stimulation of the striated muscle of the external urinary (urethral) sphincter has been discussed in the historic scientific literature and intraoperative neuromonitoring (IONM) practice, though consistent use of the technique in IONM has been rare. The rarity likely being due to poor electrode options.
This electrode was designed as a safe, gentle solution with goal of not altering the feel or function of the foley. It has been fun watching the electrode successfully implemented!
What Data Awaits Your IOM Practice?
Some somatic fibers from the pudendal nerve travel to the striated muscle of the external urinary (urethral) sphincter while sister fibers from the pudendal nerve travel on to the external anal sphincter. Is monitoring the external urinary sphincter in addition to the external anal sphincter adding a new tool to your IONM toolbox? There is a growing set of data that shows the side by side responses from the external urinary sphincter and external anal sphincter may well be more than just redundancy. The two pathways may indeed yield different, meaningful IONM data. We invite you to add to the data set.
When your surgeon is concerned about urinary incontinence, being able to directly monitor the striated mass of the external urinary sphincter is very nice!