(171 days)
When the Low output is selected the MS-120BK is used as a nerve stimulator for surgical procedures and brain mapping during treatment of patients with seizure disorders.
When High output is selected the MS-120BK is used for the intraoperative diagnosis of acute dysfunction in corticospinal axonal conduction brought about by mechanical trauma (traction, shearing, laceration, or compression) or vascular insufficiency.
The system is intended for use by qualified medical personnel within a hospital or clinical environment. The stimulator is available for use on any patients as determined by the qualified medical personnel.
The Nihon Kohden MS-120BK is a dual (high & low) output constant current stimulator. The high and low setting, stimulation current and frequency of stimulation is selected by the user. The Nihon Kohden MS-120BK is connected to the MEE 1000A through the JB-116BK or JB-132BK amplifier.
In the Low output setting the Nihon Kohden MS-120BK applies cortical stimulation energy through the Nihon Kohden stimulation pod (JS-102B) which is connected to commercially available cortical electrodes (strip and grid electrodes).
In the High output setting, the MS-120BK outputs electrostimulation pulse through the Nihon Kohden extension cord (BM-121B) which is connected to commercially available stimulation electrode(s).
This document describes a 510(k) submission for the Nihon Kohden MS-120BK Electric Stimulator (Extension Unit), primarily focusing on demonstrating its substantial equivalence to previously cleared predicate devices. Therefore, the study doesn't present typical "acceptance criteria" and "reported device performance" in the way one might expect for a novel AI/software device. Instead, the focus is on showing technical characteristics are equivalent and that the device complies with recognized safety standards.
Here's an analysis based on the provided text, addressing your points where information is available:
1. Table of Acceptance Criteria and Reported Device Performance
The submission demonstrates equivalence by comparing the technical characteristics of the new device to predicate devices. The "acceptance criteria" here are effectively that the new device's specifications fall within acceptable ranges similar to or better than the predicate devices, and that it complies with relevant safety and performance standards. The "reported device performance" is a direct comparison of these specifications.
| Characteristic | Predicate Device (Nihon Kohden SEN-4100A) | Predicate Device (Digitimer D185) | New Device (Nihon Kohden MS-120BK) | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|---|---|---|
| High Output Setting | |||||
| Voltage | 1000V | 1000V | 350V | Similar or acceptable range | 350V |
| Current | 1A (1k Ω load) | 1A (1k Ω load) | 200mA (1k Ω load) | Similar or acceptable range | 200mA (1k Ω load) |
| Maximum Stimulation Energy | 50mJ | 50mJ | 40mJ | Similar or acceptable range | 40mJ |
| Output Impedance | less than 120 Ω | less than 120 Ω | 50 Ω | Similar or acceptable range | 50 Ω |
| Stimulation Mode | Constant Voltage | Constant Voltage | Constant Current | Demonstrates different, but acceptable and defined mode | Constant Current |
| Pulse Duration | 50 μs | 50 μs | 50-1000 μs | Similar or acceptable range | 50-1000 μs |
| Output Frequency Range | 1 Hz | 1 Hz | 0.1-1Hz | Similar or acceptable range | 0.1-1Hz |
| Number of Pulse Trains | 1-9 | 1-9 | 1-9 | Matches | 1-9 |
| Interpulse Interval | 1.0-9.9ms | 1.0-9.9ms | 1.0-1000ms | Similar or acceptable range | 1.0-1000ms |
| Limitation of Voltage/Current and Pulses | Varies with predicates | Varies with predicates | Varies (e.g., 200mA: 3 Pulses) | Similar or acceptable range | Varies |
| Polarity Change | OK | OK | OK | Matches | OK |
| Monophasic | OK | OK | OK | Matches | OK |
| Biphasic | NO | NO | OK | Demonstrates additional capability | OK |
| Alternate | NO | NO | OK | Demonstrates additional capability | OK |
| Maximum Charge | 50 micro-Coulomb | 50 micro-Coulomb | 200 micro-Coulomb | Similar or acceptable range | 200 micro-Coulomb |
| Pulse Shape | Rectangular | Rectangular | Rectangular | Matches | Rectangular |
| Maximum Energy Per Pulse | 50mJ | 50mJ | 40mJ | Similar or acceptable range | 40mJ |
| Maximum Energy Per Second | 150mJ | 150mJ | 40mJ | Similar or acceptable range | 40mJ |
| Electrode Minimum Size | 0.5cm2 | 0.5cm2 | 0.5cm2 | Matches | 0.5cm2 |
| Maximum Charge Density | 100 Micro-C/cm2 | 100 Micro-C/cm2 | 400 Micro-C/cm2 | Similar or acceptable range | 400 Micro-C/cm2 |
| Interface Control | MEE-1000A | NO | Only MEE-1000A | Specifies compatibility | Only MEE-1000A |
| Trigger Input | OK | OK | OK*2 | Matches | OK*2 |
| Trigger Output | OK | OK | OK*2 | Matches | OK*2 |
| Foot Switch Control | OK | OK | OK*2 | Matches | OK*2 |
| Low Output Setting | |||||
| Constant Current Stimulator | Yes (Nicolet) | Yes (Ojemann) | Yes | Matches | Yes |
| Maximum Stimulation Charge | 15 micro-Coulomb (Nicolet) | 20 micro-Coulomb (Ojemann) | 4.5 micro-Coulomb | Similar or acceptable range | 4.5 micro-Coulomb |
| Current Stimulation Range | 0.1 to 15mA (peak) (Nicolet) | 0 to 10mA (peak) (Ojemann) | 0 to 15mA (peak) | Similar or acceptable range | 0 to 15mA (peak) |
| Stimulation Frequency | 1 to 100Hz (Nicolet) | 5, 10, 20, 50, 75, 100Hz (Ojemann) | 0.1 to 50Hz | Similar or acceptable range | 0.1 to 50Hz |
| Stimulation Pulse Width Duration | 0.1 to 1.0 msec Per Phase (Nicolet) | 0.1 to 2.0 msec Per Phase (Ojemann) | 0.05 to 0.3 msec Per Phase | Similar or acceptable range | 0.05 to 0.3 msec Per Phase |
| Pulse Shape | Rectangular (Nicolet) | Rectangular (Ojemann) | Rectangular | Matches | Rectangular |
| Electrode Minimum Size | 0.04cm2 (Nicolet) | 0.5cm2 (Ojemann) | 0.04cm2 | Similar or acceptable range | 0.04cm2 |
| Maximum Charge Density | 375 micro-C/cm2 (Nicolet) | 40 micro-C/cm2 (Ojemann) | 113 micro-C/cm2 | Similar or acceptable range | 113 micro-C/cm2 |
| Maximum RMS Current Density Per Pulse | 119 mA RMS/cm2 (Nicolet) | 8.9 mA RMS/cm2 (Ojemann) | 46 mA RMS/cm2 | Similar or acceptable range | 46 mA RMS/cm2 |
2. Sample Size Used for the Test Set and Data Provenance
This is a physical medical device (electrical stimulator), not an AI/software device that processes data. Therefore, the concept of a "test set" with "data provenance" (country of origin, retrospective/prospective) in the context of image analysis or diagnostic algorithms does not apply here.
The "testing" mentioned is focused on verifying the device's hardware and software performance against its specifications and compliance with safety standards. The document states:
- "Testing of the Nihon Kohden System with the MS-120BK was performed in compliance with the Nihon Kohden Corporation design control process."
- "Testing included: Software and hardware verification and validation, and the device is in compliance with the following voluntary industrial standards..." (followed by a list of IEC, EN, and CAN/CSA standards).
This implies standard engineering and regulatory compliance testing rather than a clinical trial with patient data.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
Not applicable. As noted above, this device does not function by interpreting patient data for diagnosis, so there is no "ground truth" established by experts in this context. The "truth" is whether the device meets its technical specifications and safety standards.
4. Adjudication Method for the Test Set
Not applicable for the same reasons as point 3.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size
No. This type of study is typically performed for diagnostic or AI-assisted devices to assess the impact on human reader performance. The MS-120BK is an electrical stimulator, and its effectiveness is determined by its physical output and adherence to specifications, not by how it affects human interpretation of data.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
No. This is a physical stimulus device, not an algorithm. Its operation is inherently with a "human-in-the-loop" (qualified medical personnel).
7. The Type of Ground Truth Used
The "ground truth" for this type of device is its technical specifications and compliance with international safety and performance standards. Testing involved verifying that the device's electrical outputs, timing, and other physical parameters matched the design specifications and met the requirements of standards like IEC 60601-1, IEC 60601-1-2, IEC 60601-2-40, etc.
8. The Sample Size for the Training Set
Not applicable. This device does not use machine learning algorithms that require a "training set."
9. How the Ground Truth for the Training Set Was Established
Not applicable for the same reasons as point 8.
In summary, the provided document is a 510(k) summary for a traditional medical device (an electric stimulator). The "study" referenced is the internal design control process and associated testing to ensure the device meets its technical specifications safely and effectively, and is substantially equivalent to predicate devices, rather than a clinical study evaluating an AI/software's diagnostic or interpretive performance.
§ 882.1310 Cortical electrode.
(a)
Identification. A cortical electrode is an electrode which is temporarily placed on the surface of the brain for stimulating the brain or recording the brain's electrical activity.(b)
Classification. Class II (performance standards).