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Sentio IP Portfolio Recognized by Crain’s Detroit Business!

June 30, 2014 Sentio, LLC, of Wixom, Michigan, announce […]

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Radio Interview: Sentio LLC Receives Patent Approvals – Core Technology Wins Protection

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Sentio MMG®

Sentio MMG® is a surgical access tool. It is intended to locate and map motor nerve roots and their peripheral extensions originating from spinal levels C3-T1 and L2-S2.

Sentio MMG® smart-sensors are different from all other forms of neuromonitoring electrodes. In contrast to electromyography, or EMG, which relies on needles to detect subtle changes in electrical signals in muscle, Sentio MMG® smart-sensors employ proprietary accelerometer technology. These non-invasive accelerometer-based sensors measure MMG (mechanomyography) activity, or the mechanical “twitch” associated with muscle contraction. When MMG activity is detected, the surgeon is provided with a ‘STOP’ alert indicating a nerve has been identified. The result is an intuitive, surgeon-directed tool for establishing safe access in a variety of surgical applications.

Sentio MMG® was specifically designed to facilitate safe lateral transpsoas surgery.  Sentio believed there was a better way to identify and map nerves during lateral surgery that did not require EMG. Design objectives included:

 

  1. Simple setup, eliminate needles
  2. Eliminate the complexity and variability of interpretation, no training or technician required
  3. Surgeon directed, empower surgeon to control system from sterile field
  4. Overcome the technical limitations of EMG, eliminate electrical interference and related false positives
  5. Ensure compatibility with all lateral systems, enabling the surgeon to use Sentio MMG® with their hardware company of choice

While Sentio MMG® has seen immediate success in lateral surgery, it is also experiencing rapid adoption throughout a number of other surgical applications where nerve mapping is paramount to nerve preservation, including:

So How Does It Work?

  1. Sentio MMG® smart-sensors are adhered to the surface of the skin directly overtop the muscles innervated by the nerves the surgeon wishes to identify
  2. The surgeon is provided with a sterile Sentio MMG® stimulator probe
  3. Based on the surgical procedure, the Sentio MMG® stimulator probe is manipulated about the surgical site to ‘stim’ for the presence of motor nerves
  4. When a nerve is identified, the surgeon is provided with a ‘STOP’ alert
  5. At any time the surgeon is stimulating and receiving a ‘GO’ alert, the surgeon can infer that a ‘GO’ when using stimulation current at:
    1. 1mA means the Sentio probe is at least 1mm from the nerve
    2. 5mA means the Sentio probe is at least 5mm from the nerve
    3. 15mA means the Sentio probe is at least 15mm from the nerve

The following chart describes the relationship between the MMG sensor signal and nerve distance. By knowing the level of stimulation current being used, MMG signals can be measured, and ultimately one can derive nerve distance.

img_sentio_2

How does Sentio MMG® compare to EMG?

  • Sentio MMG® measures the same physiological phenomena associated with muscle contraction as EMG, but does so via mechanical means as
    opposed to electrical1
  • Sentio MMG® does not involve needles, therefor reducing the risk of needle sticks to the surgeon and OR staff and further reducing the
    chance of infection to the patient and OR personnel2
  • Sentio MMG® does not require any skin prep3
  • Sentio MMG® readings require only a single sensor patch to be adhered to the skin, whereas EMG requires three electrode areas to be
    prepared4
  • Sentio MMG® can detect nerves faster than EMG5
  • Sentio MMG® can detect nerves at lower levels of stimulation current than EMG6
  • There is a direct relationship between the Sentio MMG® signal and nerve distance, Sentio is not aware of any such data that exists for EMG.7
  • Sentio MMG® does not require a technician, ultimately simplifying interpretation to ‘STOP’ or ‘GO’. The quality of interpretation is no longer
    dependent on the skill and experience level of the technician. Removing the human factor eliminates variability in interpretation. MMG delivers
    a consistent message and is not prone to human error.8
  • Sentio MMG® has a greater signal to noise ratio than EMG, allowing Sentio to detect MMG activity when EMG cannot9
  • Sentio MMG® is not affected by stimulation artefact. Stimulation artefact can have a profound effect on EMG by overlapping and obscuring
    useful information10
  • Sentio MMG® is not affected by acoustical or electrical noise, ultimately reducing the likelihood of false-positive events so commonly
    associated with EMG technology11
  • Sentio MMG® is surgeon-directed; there is no handoff of information. The surgeon is in control.
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Surgical Applications

Lateral Transpsoas Approach

Dilator Technique

  • Connect the Sentio dilator probe and set current to 6mA.
  • Advance the dilator probe through the psoas while stimulating.
  • If Sentio triggers a ‘STOP’, reposition the dilator probe to locate a safe entry point by achieving a ‘GO’ at 6mA.
  • If Sentio stays ‘GO’ and the probe is in good position on fluoro, insert the dilators and retractor.
  • Sweep field with 6mA to confirm absence of nerve by maintaining a ‘GO’.
  • {Optional} Confirm the nerve is located behind the retractor blades by positioning the probe behind the retractor blades and obtaining a ‘STOP’.

Dissection Technique

  • Connect the Sentio probe and set current to 6mA.
  • Advance the probe through the psoas while stimulating.
  • If Sentio triggers a ‘STOP’, reposition the probe to locate the nerve. The MMG signal will increase if you are moving toward the nerve. Otherwise, the MMG signal will decrease and turn to ‘GO’ as you move away from the nerve.
  • Locate a safe entry point by achieving a ‘GO’ at 6mA. If Sentio stays ‘GO’ and probe is in good position on fluoro, retract muscle fibers and position retractor.
  • Sweep field with 6mA to confirm absence of nerve by maintaining a ‘GO’.
  • {Optional} Confirm the nerve is located behind the retractor blades by positioning the probe behind the retractor blades and obtaining a ‘STOP’.

Advanced Applications

  • In difficult cases, especially at the L4-5 level, there may be multiple nerves present. You can use the Sentio probe to map these nerves precisely by starting with 1mA and adjusting the current up until a ‘STOP’:
    • ‘STOP’ at 1mA = Probe in contact with nerve
    • ‘STOP’ at 2-6mA = Probe within approximately 2-6mm of nerve
    • ‘STOP’ at >6mA = Safe distance
    • Once the nerves are precisely located, you may be able to establish a safe entry point by gently retracting the nerves posteriorly.
    • Confirm the nerve is located behind the retractor blades by positioning the probe behind the retractor blades and obtaining a ‘STOP’.

LATERAL NOTE: Surgeons less familiar with this technique may consider working at a slightly higher current level such as 10mA rather than 6mA to establish a safe working distance.

Posterior Cervical Spine

  • Drill lateral mass screw holes.
  • After drilling lateral mass screw holes, use the Sentio stimulator probe as a feeler gauge.
  • Stimulate at ≥6mA while palpating the walls to confirm you are in bone
  • Advance probe to the floor of the hole to confirm that the nerve is not located at the floor of the hole.
  • While stimulating, if a ‘STOP’ is triggered at <6mA, back probe out until ‘GO’ to determine a safe length for screw.
  • Pinch the probe to mark the hole depth and insert a screw of appropriate length.

Open Pedicle Screw

  • Prepare pedicle screw hole using pedicle probe.
  • Use the Sentio stimulator probe as a feeler gauge.
  • Stimulate at ≥6mA while palpating the walls to confirm you are in bone.
  • While stimulating, if a ‘STOP’ is triggered at >6mA, hold probe in that position and lower the stimulation current to determine the lowest current that gives a ‘STOP’ response. If a ‘STOP’ is triggered at <6mA, this indicates a nerve is in close proximity. Consider repositioning the hole AWAY from the point at which the ‘STOP’ is elicited.
  • Once a safe hole is achieved, insert screw.

Percutaneous Pedicle Screw

  • Attach the Sentio stimulator clip to an insulated Jamshidi needle.
  • Prepare the pedicle screw hole using the insulated Jamshidi needle while stimulating at 10mA.
  • If a ‘STOP’ response is triggered, reposition the needle. Typical repositioning would be directed lateral and/or superior.
  • Repeat until a ‘GO’ is maintained throughout the path of the Jamshidi.
  • Insert guidewire through the Jamshidi.
  • Insert screw over wire.

SI Screw Percutaneous

  • Attach the stimulator clip to an insulated drill bit. (alternatively you can use a normal drill bit and work through a non-conducting cannula which has been inserted all the way to the bone).
  • Prepare the hole using the drill while stimulating at 10mA and using fluoro as needed to assist with direction.
  • If a ‘STOP’ response is triggered, reposition the drill away from the surface where a nerve is most likely located (usually near the neural foramen, the spinal canal or near the anterior border of S1).
  • Repeat until a ‘GO’ is maintained throughout the path of the drill bit.
  • Insert guidewire through the drill bit.
  • Insert screw over wire.
  • {Optional} Stimulate the screw head by direct contact through the insulated cannula.

Upper Extremity Fxs

  • Connect the Sentio ball tip probe and turn stimulation on.
  • Continue tissue dissection in the usual fashion.
  • Stimulate with the ball tip probe to locate and map nerves.
  • Use the following guidelines:
    • ‘STOP’ at 1mA = Probe in direct contact with nerve
    • ‘STOP’ at 2-6mA = Probe close to nerve, within ~ 2-6mm of nerve
    • ‘STOP’ at >6mA = Safe distance
  • Retract nerves in tissue to avoid injury.
  • This technique is especially helpful for brachial plexus surgery, surgery around the elbow area and for humeral fracture treatment. It may be used anytime nerves are believed to be close to the surgical field and at risk of injury.

Scar Tissue/Trauma

  • Connect the Sentio ball tip probe and turn stimulation on.
  • Continue tissue dissection in the usual fashion.
  • Stimulate with the Sentio ball tip probe to locate and map nerves.
  • Use the following guidelines:
    • ‘STOP’ at 1mA = Probe in direct contact with nerve
    • ‘STOP’ at 2-6mA = Probe close to nerve, within ~ 2-6mm of nerve
    • ‘STOP’ at >6mA = Safe distance
  • When scar tissue in encountered, you can save time by mapping nerves in scar tissue.
  • Once mapped, retract nerves as needed to avoid injury.
  • This technique is especially helpful anytime nerves are felt to be close to the surgical field and at risk of injury.

Revision Spine

  • Connect the Sentio ball tip probe and turn stimulation on.
  • Continue tissue dissection in the usual fashion.
  • Stimulate with the ball tip probe to locate and map nerves.
  • Use the following guidelines:
    • ‘STOP’ at 1mA = Probe in direct contact with nerve
    • ‘STOP’ at 2-6mA = Probe close to nerve, within ~ 2-6mm of nerve
    • ‘STOP’ at >6mA = Safe distance
  • When scar tissue in encountered, you can save time by mapping nerves in scar tissue.
  • You may save time and radiation exposure by quickly locating nerves in scar tissue.
  • Once mapped, you may retract nerves or cut around nerves as needed to avoid injury.
  • This technique is especially helpful anytime nerves are encased in scar tissue and difficult to identify in the surgical field.
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Frequently asked questions

What is MMG?

  • MMG (mechanomyography) is a non-invasive technique used to measure the mechanical activity, or the “twitch”, associated with muscle contraction. MMG activity can be evoked or spontaneous.
    • Evoked MMG occurs when a nerve has been electrically stimulated, most commonly applied through a stimulator probe controlled by the surgeon, resulting in contraction in the innervated muscle. This form of MMG is most common when surgeons wish to locate and map motor nerves.
    • Spontaneous MMG is the mechanical measurement of voluntary muscle contraction or muscle contraction that occurs as a result of the nerve being mechanically stimulated (such as during nerve retraction, compression or other forms of mechanical interaction). Spontaneous MMG is also known as free-run MMG.

What is Sentio MMG®?

  • Sentio MMG® is a surgical access tool. Its intended application is to locate and map motor nerve roots and their peripheral extensions originating from spinal levels C3-T1 and L2-S2.
  • Sentio MMG® smart-sensors employ accelerometer technology to sensitively measure when muscle contraction occurs, as a means to alert surgeons of motor nerve location.
  • Sentio MMG® smart-sensors are also highly sensitive to spontaneous MMG activity, which may indicate to the surgeon that a nerve is “firing” when electrical stimulation is not being used.

How do I setup the Sentio MMG® equipment?

How do I use Sentio MMG®?

  • 1. Sentio MMG® smart-sensors are adhered to the surface of the skin directly overtop the muscles innervated by the nerves the surgeon wishes to identify
  • 2. The surgeon is provided with a sterile Sentio MMG® stimulator probe
  • 3. Based on the surgical procedure, the Sentio MMG® stimulator probe is manipulated about the surgical site to ‘stim’ for the presence of motor nerves
  • 4. When a nerve is identified, the surgeon is provided with a ‘STOP’ alert
  • 5. At any time the surgeon is stimulating and receiving a ‘GO’ alert, the surgeon can infer that a ‘GO’ when using stimulation current at:
    • a. 1mA means the Sentio probe is at least 1mm from the nerve
    • b. 5mA means the Sentio probe is at least 5mm from the nerve
    • c. 15mA means the Sentio probe is at least 15mm from the nerve
  • 6. Click here for a full description of recommended techniques for various surgical applications

How does Sentio MMG® compare to EMG?

  • Sentio MMG® measures the same physiological phenomena associated with muscle contraction as EMG, but does so via mechanical means as opposed to electrical1
  • Sentio MMG® does not involve needles, therefor reducing the risk of needle sticks to the surgeon and OR staff and further reducing the chance of infection to the patient and OR personnel2
  • Sentio MMG® does not require any skin prep3
  • Sentio MMG® readings require only a single sensor patch to be adhered to the skin, whereas EMG requires three electrode areas to be prepared4
  • Sentio MMG® can detect nerves faster than EMG5
  • Sentio MMG® can detect nerves at lower levels of stimulation current than EMG6
  • There is a direct relationship between the Sentio MMG® signal and nerve distance, Sentio is not aware of any such data that exists for EMG.7
  • Sentio MMG® does not require a technician, ultimately simplifying interpretation to ‘STOP’ or ‘GO’. The quality of interpretation is no longer dependent on the skill and experience level of the technician. Removing the human factor eliminates variability in interpretation. MMG delivers a consistent message and is not prone to human error.8
  • Sentio MMG® has a greater signal to noise ratio than EMG, allowing Sentio to detect MMG activity when EMG cannot9
  • Sentio MMG® is not affected by stimulation artefact. Stimulation artefact can have a profound effect on EMG by overlapping and obscuring useful information10
  • Sentio MMG® is not affected by acoustical or electrical noise, ultimately reducing the likelihood of false-positive events so commonly associated with EMG technology11
  • Sentio MMG® is surgeon-directed; there is no handoff of information. The surgeon is in control.

How does Sentio MMG® compare to other surgeon-directed EMG systems?

chart_1

How does Sentio MMG® compare to in-house or third party neuromonitoring service providers?

chart_2

How is the Sentio MMG® technology more accurate and sensitive than other monitoring products today?

  • All other monitoring systems on the market today involve EMG (electromyography) technology. EMG systems monitor for subtle electrical signals that occur in the muscle. Inherent to the operating room environment is a significant amount of electrical noise. Since EMG monitors for very subtle electrical signals, this electrical noise can interfere with the EMG readings and create complex signals that require special filtering or expert interpretation, which can result in delays, false positives and false negatives. The quality of the feedback is therefore directly related to the quality of the filter and the experience level of the EMG interpreter. Sentio MMG® eliminates the variability associated with interpretation and the susceptibility to electrical interference. Thus the mechanical monitoring associated with Sentio MMG® overcomes technological limitations inherent to EMG.
  • Additionally, through the use of our proprietary Sentio MMG® smart sensor technology, Sentio MMG® is able to identify and map the precise location of nerves using lower levels of stimulation current than EMG. This enhanced sensitivity, paired with a greater signal-to-noise ratio and a fixed stimulation current, further enables Sentio to quantify the relationship between MMG signals and nerve distance, as subtle changes in MMG signals can be measured and provided as feedback to the user.

Is there a correlation between the Sentio MMG® signal and nerve distance?

Yes. Sentio MMG® applies an electrical stimulation through various Sentio MMG® stimulation probes. The stimulus can be adjusted by the user from 0-15mA. Since the electrical stimulus employed by Sentio MMG® does not involve a “ramping” or “hunting” algorithm, the current is applied at a constant, fixed value. By holding the current constant and measuring the resulting Sentio MMG®, we are able to infer nerve distance by referencing the following: img_sentio_2

Does Sentio MMG® use a “hunting” algorithm like other surgeon directed EMG systems?

  • No. Sentio MMG® applies a fixed electrical current, user selectable from 0-15mA, at a frequency of 2Hz (2 electrical pulses per second)

Does a patient’s BMI affect the accuracy of the Sentio MMG® system?

  • No. Studies have shown that BMI does not affect the components of the MMG signal that are used in the Sentio MMG® nerve-mapping algorithm

Does a patient’s co-morbidities affect the accuracy of the Sentio MMG® system?

  • The known factors that may influence the accuracy of the MMG system are 1) unhealthy nerves, 2) neuromuscular disease, and 3) neuromuscular blocking agents.
  • If a nerve is unhealthy, MMG (and EMG) signal integrity may be compromised. If the nerve does not cause the muscle to contract, no MMG (or EMG) signals would likely be present.
  • Neuromuscular diseases can significantly compromise the effect of MMG (and EMG) signal integrity.
  • Neuromuscular blocking agents (NMBAs) are well known to block signal transmission at the neuromuscular junction. Accordingly, MMG (and EMG) signals would likely be compromised if NMBAs were employed.

What Sentio MMG® readings are considered safe vs. dangerous?

  • Sentio MMG® is a tool, there are no readings that Sentio MMG® can produce that are “dangerous”. Surgical decisions based on information the Sentio MMG® tool provides the surgeon will ultimately determine “safe” vs. “dangerous” outcomes. “Safe” vs. “dangerous” readings are largely dependent on the surgical procedure being performed and the skill level, knowledge of anatomy, and judgment of the surgeon. Generally speaking, a “STOP” alert at low levels of stimulation current would infer a nerve is in close proximity. The lower the level of current that triggers a “STOP” alert, the closer the nerve. Similarly, a “GO” indication at high levels of stimulation current would infer a nerve is a greater distance away from the stimulation probe. The higher the level of stimulation current used to illicit a “GO” indication, the farther the nerve. Surgeons should use clinical experience and anatomic knowledge to make a determination of “safe” vs. “dangerous”.
  • The following is an example of an implied “safe” scenario when establishing a docking point for a lateral transpsoas approach:
    • The surgeon manipulates the Sentio MMG® stimulation probe about the surgical site and maintains a “GO” reading when stimulating at current levels >6mA. This would be considered an acceptable value and deemed safe to proceed with dilators/retractors.
  • An example of an implied “dangerous” scenario during pedicle screw testing:
    • The surgeon manipulates the Sentio MMG® stimulation probe about the four pedicle walls prior to screw insertion, and elicits a “STOP” at a stimulation current of 2mA on the medial wall. This would likely infer a nerve is in very close proximity to the probe (indicative of a pedicle breach or very thin pedicle wall). In this case, Sentio would advise the surgeon to reposition the screw trajectory and retest until a “GO” was maintained at stimulation currents >6mA, BEFORE any screw was inserted.
  • Click here for a full description of recommended techniques for various surgical applications

With respect to anesthesia, how deep should the patient be to get optimal readings?

  • The use of paralyzing anesthetic agents will significantly reduce, if not completely eliminate, MMG responses to direct or passive nerve stimulation. If neuromuscular blocking agents are used, train-of-four (TOF) testing is required to assure paralytic recovery. Whenever nerve paralysis is suspected, consult an anesthesiologist.

How important is sensor placement vs muscle location?

  • Studies suggest the MMG signal is optimized when placed on the surface of the skin directly over the belly of the muscle to be monitored. Greater MMG activity is recorded when the sensor is placed over the belly of the muscle than over fascia at the muscle borders . To properly locate the center of each respective muscle belly, click here

How can I turn the Sentio MMG® probe on/off and control current from the sterile field?

  • The Sentio MMG® stimulation probe can be toggled ON/OFF by pressing the small circular button on the probe handle for 1 second. When the LED is blue, stimulation is ON. When the LED is off, stimulation is OFF.

What does the LED on the Sentio MMG® probe handle indicate?

  • Blue = stimulation is ON
  • Red = stimulation is ON and a nerve has been identified
  • OFF = stimulation is OFF

What does finding the threshold mean for the surgeon?

  • “Finding the threshold” means determining the minimum amount of current required to elicit a “STOP” alert. This is important when determining whether or not a ‘safe’ working distance with respect to nearby nerves has been established.
  • If a surgeon is presented with a “STOP” alert, he would decrease the stimulation current until the “STOP” turns to a “GO”. For example, let’s assume a surgeon is stimulating the four walls of a pedicle with 15mA. The superior, lateral and inferior walls all yield a “GO” indication as the surgeon palpates up and down the pedicle walls with the Sentio stimulation probe. Now the surgeon moves to the medial wall and receives a “STOP” alert. The surgeon decreases the stimulation from 15, to 14, 13, 12, 11, 10, 9 and then at 8mA the “STOP” turns to a “GO”. The minimum level of current that produced the “STOP” alert was 9mA, therefore, the surgeon “found the threshold” to be 9mA. For this pedicle application, 9mA is commonly accepted to be a ‘safe’ threshold, inferring there is adequate pedicle wall thickness to insert a screw.
  • “Finding the threshold” may also prove to be important in the assessment of nerve health, as a normal healthy nerve should respond to ≤2mA. Studies are underway to assess the utility of MMG for quantifying changes in nerve health during surgical procedures.

Can Sentio MMG® be used in the Thoracic spine area?

  • The FDA has cleared the device for locating and mapping spinal nerve roots and their peripheral extensions, originating from C3-T1 and L2-S2.
  • We are currently working with the FDA to expand our indications to include spinal levels T5-T12.

How did the Sentio developers determine sensor placement?

  • Studies have suggested that MMG recordings are optimized when the MMG sensor is placed directly over the belly of the muscle rather than over fascia at the muscle borders . The sensor placement locations described by Sentio are road maps to the center of these muscle belly’s, which are directly correlated to the innervating nerves originating from C3-T1 and L2-S2.

Can Sentio MMG® monitor sensor nerves?

  • No. Sentio MMG® does not provide any information related to the status of sensory nerves. Sentio MMG® does not employ EMG (electromyography), MEPs (motor evoked potentials), or SSEPs (somatosensory evoked potentials).

Why am I seeing a STOP response when I am in pedicle bone?

Sentio MMG® responses are not related to pedicle wall perforations; rather they infer how close a nerve may be with respect to the position of the stimulator probe. The surgeon may very well see a “STOP” response while in bone, however the bone may be very thin and a nerve lie directly outside the bone in very near proximity.

How can one determine directionality?

  • Speak with your hardware representative to discuss options related to the specific technique and instrumentation used for your procedure.
  • Directionality of nerve location can be determined two ways:
    • Once a “STOP” is presented, keep the stimulation current set at the level that elicited the “STOP” and move the probe in the direction you believe is closer to the nerve. Watch the signal on the Sentio MMG® monitor, if the amplitude of the MMG sensor channel producing the “STOP” increases, then you are moving closer to the nerve. If it decreases, you are moving away from the nerve.
    • Once a “STOP” is presented, decrease the current until the “STOP” turns to “GO”. Then move the probe in the direction that produces another “STOP” alert. The direction in which you repositioned and produced another “STOP” is the direction in which the nerve lies.

When a muscle is twitching under the stimulated instrument and the monitor is showing “GO” what does this indicate?

This is a result of muscle being directly stimulated by the instrument/probe. This is known as “local twitch”, a situation where muscle fibers contract as a result of direct stimulation. Direct muscle stimulation is completely different than nerve stimulation. In most circumstances local twitch has nothing to do with a nerve being identified, and the “GO” indication presented by the system infers that a nerve is not present and it is safe to proceed.

Can we bill for Sentio MMG® monitoring?

  • Sentio does not provide recommendations for billing or reimbursement. At present, there are no known CPT or HCPCS codes related to MMG.

Are the Sentio sales reps credentialed to touch the patient?

  • No. OR staff is responsible for sensor placement and any physical interaction with the patient.

Who is responsible for bringing in and setting up the hardware?

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