Epiduroscopy Equipment

6 Epiduroscopy Equipment


Günter Schütze


6.1 Introduction


The technical requirements for spinal endoscopy systems for clinical use in the diagnosis of and therapy for neuraxial pain syndromes are regulated, for example, in the United States by the Food and Drug Administration (FDA). A large number of endoscopic instruments, including the necessary tools for epiduroscopy, are licensed under the FDA 510(k) process and under country-specific or European medical product licensing statutes, respectively. For example, the steerable, flexible Karl Storz 2.8-mm outside-diameter endoscope with effective length 70 cm or 40 cm, equipped with a working channel, has had an 501k license since 1992; the Myelotec endoscope (Myeloscope) received one (K960194) in 1996 as did the Racz catheter (K954584).1,2


The complex endoscopic diagnostic and therapeutic systems for spinal endoscopy are benefiting from the newest technologies, such as high-definition endoscopy, digital chromoendoscopy (with FICE or SPIES), image-enhanced endomicroscopy (with NBI or i-SCAN), chip-on-the-tip technology, and autofluorescence and spectroscopy. With the new flexible video endoscopes, for example, the image information collection and transfer occurs through chip-on-the-tip technology from an image sensor in the tip of the endoscope.


In addition to having a digital endocamera system, a fluoroscopic unit (an X-ray image converter or C-arm), an infusion system, and a sophisticated integrated epiduroscopic-sono-graphic-laser system, sterile microsurgical and microinvasive instruments should be provided for performing spinal endoscopy and microsurgical endoscopic procedures.


Regardless of the invasive intervention planned, spinal endoscopy (epiduroscopy) must be performed under adequate, continuous monitoring of vital functions with an anesthesiologist in attendance and only under absolutely sterile conditions in a suitable operating room (OR). There is no distinction in hygienic requirements between inpatient and outpatient spinal endoscopies. Along with surgical hand disinfection, the wearing of sterile gloves, smocks, masks, and caps, and the use of sterile drapes and of sterile single-use materials (covering of light guide, laser, image converter, etc.) is essential. High standards for the preparation (disinfection and sterilization) of reusable endoscopes have been established and must be met.3


A basic prerequisite for the use of the flourscopic unit (X-ray image converter or C-arm) for spinal endoscopy is the observance of the respective ordinances about protection against injury from ionizing radiation. When using a laser, the observance of nationally established laser operator instructions to prevent laser complications is essential as is the observance of general accident prevention prescriptions.


6.2 Equipment for Endoscopic Spinal Diagnostics


The complexity of epiduroscopic diagnosis requires the option of simultaneous co-observation and complete documentation, which can be accomplished above all through high-quality information and communication technology, including high-quality digital video technology.


By exploiting the technical possibilities of telemedicine, epiduroscopic diagnosis and therapy could be optimized and further developed. Considering that the interventional pain therapist could use telemedicine in the future as a significant instrument for achieving more and ensuring quality in pain medicine, the development of a structural recommendation for an international telemedicine network for interventional pain therapy would be a worthwhile goal.


6.2.1 Epiduroscopes


The first clinically useful flexible epiduroscope was described by Schütze and Kurtze in the 1993 publication “Percutaneous investigation of the epidural space using a flexible endoscope.”4 The first black-and-white endoscopic images from the epidural space of patients with pain syndromes were produced with this percutaneous flexible endoscopic system for the neuraxial region (images Fig. 6.1).5


In the flexible epiduroscopes currently available, optical lenses conduct the image from the epidural space to a video camera, which is located at the end of the endoscope. Up until recently the entire spinal canal, from the sacral to the cervical region, could be reached only with flexible epiduroscopes equipped with fiber optic technology (a technique employing an organized bundle of glass fibers for image transport). Now some epiduroscopes available on the international market are equipped with tiny charge-coupled devices (CCD) chip or complementary metal-oxide–semiconductor (CMOS) chips integrated into the very tip of the endoscope and the image information is converted into a video signal there and reaches the monitor over a thin cable. A distinction must be made between the two different types of sensor technology (fiber optic versus chip-based) according to their capabilities. The image quality of the fiber optic endoscopes is not equal to that from the high pixel count CCD or CMOS sensors. As a rule, the CCD chip endoscope is superior to the fiber optic (glass fiber) endoscope and CMOS chip endoscope on account of the optical image quality. The image quality is dependent on the combination of video sensor, optical lens system, luminance, and image monitor.



images

Fig. 6.1 (a) An illustration representing the principle of a percutaneous flexible epiduroscopic unit (1994) for epidural diagnostics in pain patients.5 (b, c) Endoscopic representation of epidural adhesions and fibroses from the epidural space with the percutaneous flexible epiduroscopic unit (1990).



In some videoscopes, external light projectors have been replaced by light-emitting diode (LED) illuminators integrated into the endoscope tip or even into the handgrip. In the latter, the light is conducted from the handgrip over built-in glass fibers to the tip. Very uniform illumination occurs with LEDs built into the tip of the instrument (images Fig. 6.2). Admittedly, the luminance of an external xenon light projector has not yet been matched by LEDs.


On the basis of their differing technical quality, endoscope length, reusability, external diameter, working channel, flexibility, image quality, ease of repair, etc., most endoscopes do not meet the high technical requirements for spinal endoscopy.



Technical Note


The flexible epiduroscope, a complex and delicate precision technical instrument for medicine, is built with various materials, for example, plastic, metal, and glass, bonded together in a watertight manner.


Functional Properties of Epiduroscopes

To fulfill the requirements of the various certifications for clinical use in spinal endoscopy, epiduroscopes (flexible, reusable endoscopes) should meet the following specifications for these important functional properties:3,4,6


• External diameter, effective length, and working channel.


images Since the usual sagittal diameter of the spinal canal varies between 15 and 20 mm,7 an epiduroscope should have an external diameter between 2.4 and 3.8 mm, a sufficient effective length of 90 cm, and a working channel with a diameter of 0.9 to 1.5 mm.


• Steerability, flexibility and strength of materials, and laser protection.


images Through a special shaft construction method, a direct transmission of torque can be attained by which a better steerability of the epiduroscope is possible within the anatomical boundaries of the epidural space. The epiduroscope should be built with a certain hardness and buckling strength for spinal navigation. To guarantee the epiduroscope protection against laser radiation, a Laserite ceramic tip, for example, should be incorporated at the distal end of the working channel.


• Image quality and image capture.


images On a small video camera at the ocular of the epiduroscope, image capture takes place. The optical system is divided: one part conducts the image information to the investigator’s eye, and the second part converts the image information into a video signal at the camera.


images In state-of-the-art epidiuroscopes, image capture takes place at an image sensor (a chip at the tip of the epiduroscope), which decomposes the image into a raster of electronic signals. In contrast to conventional fiber-optic epiduroscopes, this chip technology yields brilliant, true-to-life image quality and significantly improved, contrast-rich representation. An integrated LED illuminator also provides improved illumination in the neuraxial region.


• Reusability, cleaning, disinfection, and sterilization.


images In principle, cleaning, disinfection, and sterilization of operating instruments or instrument systems should be carried out according to proper, validated procedures, such that the result of these procedures is retraceably and the safety and health of patients, operators, or third parties is not endangered.



 


Some available epiduroscopes do not meet these high quality requirements, they are inadequate or unsuitable for spinal endoscopy.


Selection of Epiduroscopes

The following selection of epiduroscopic (EDS) systems for diagnosis of and therapy for neuraxial pain syndromes are used in our pain clinic:


• Karl Storz Epiduroscope (Karl Storz, after G. Schütze).


images This is the first flexible epiduroscope (after G. Schütze), with an outside diameter of 2.8 mm, a 40-cm or 70-cm effective length, and containing a 1.2-mm diameter working channel. The distal end can be steered upward to 120° and downward to 170°.6,8


• Karl Storz Flexible Epiduroscope with FLEX-X (images Fig. 6.3).9


images At the distal end of the working channel is a Laserite ceramic tip, which guarantees protection against laser radiation.


images The eyepiece of the endoscope is attached to a camera system.


images A digital three-chip camera system has also proved itself in clinical practice, because the endoscopic image is transferred on three separate color chips. Thereby color, contrast, and resolution can all be optimized directly at the camera head (images Fig. 6.4).


• Richard Wolf BOA vision Flexible Endoscope.


images The BOA vision endoscope for spinal endoscopy, with an effective length of 68 cm and a shaft diameter of 8.7 Fr, features, above all, an excellent image sensor at the tip of the endoscope. An oblique atraumatic cylindrical stainless steel tip has an outside diameter of 6.6 Fr (images Fig. 6.5). The maximum flexibility is 270°. The upward/downward deflection is possible even with suitable auxiliary instruments and laser fibers.


images The BOA vision endoscope image-sensor system is state of the art, yielding brilliant, true-to-life image quality and significantly improved, contrast-rich representation. Manual focusing and white adjustment are not required.


images The integrated LED technology provides homogeneous and improved illumination in the neuraxial region.


images The endoscope possesses a very high shaft stiffness, which is significant for introduction over the introducer sheath and the sacral segments.


• Myelotec Flexible Fiber Optic Endoscope.


images This epiduroscope, mainly used in the United States, is available in external diameters of 0.9 mm, 1.2 mm, and 1.3 mm and can be placed with the help of a steerable, video-supported 2.7-mm or 3.0-mm video-guided catheter. This catheter contains two working channels (images Fig. 6.6). The 3000E endoscope has 0.9-mm diameter; a 10K-pixel fiber bundle; approximately 40 × magnification, depending on the eyepiece coupler and the video system; a 70° field of view; a 0° angle of view; a 32-mm eyecup; and an 85-mm effective length. It can be used with universal camera systems (images Fig. 6.7).



images

Fig. 6.3 Flexible endoscope FLEX-X.9 (Courtesy of Karl Storz, Tuttlingen, Germany.)





images Kawanishi et al10 reported that since 1996 they have introduced Myelotec epidural endoscopes with 0.9-mm diameters through the sacral hiatus to investigate the lumbar epidural space. The authors note that some problems of these epiduroscopes must still be solved. However, they rated them as very promising diagnostic tools.


• Karl Storz Flex-XC Flexible Endoscope.


images This new flexible endoscope (11278 VS Video-Flex-X SPIES) has an effective length of 70 cm with an outside diameter of 8.4 Fr (2.8 mm). The flexible endoscope is equipped with a CMOS chip and a Laserite ceramic liner at the distal end of a 3.6-Fr (1.2-mm) diameter working channel. The endoscope allows a maximum deflection of 270° in either direction and has automatic focus and illumination. Through the SPIES Spectra, even the finest tissue structures can be imaged by filtering out the deep red section of the visible spectrum. Through the simultaneous presentation of white light and a SPIES mode image, the tissue structures can be compared directly on the monitor intraoperatively, which makes endoscopic diagnosis easier (images Fig. 6.8).




6.2.2 Camera and Video Techniques and Equipment


Chip-on-the-Tip

At the very tip of the endoscope, tiny CCD or CMOS chips are integrated as image sensors. The image information is converted into video signals in the image sensors and conducted over a thin glass fiber to the monitor. CCD chip technology allows for the collection and analysis of more than a million pixels per image resulting in better resolution in these firstgeneration high-resolution video endoscopes.11 To date, chip-on-the-tip endoscopes have, however, used fixed-focus optics, which can represent objects at only one distance optimally. If the object is located at a different distance, the image loses sharpness.


High-Definition Endoscopy

High-definition television (HDTV), whose high-resolution images surpass in quality those from the older phase-alternating line (PAL) transmission, has recently been introduced into endoscopy.


Video from the new miniaturized endoscopic color chips, which collects and analyzes more than 1 million pixels per video image, can now can be played on a standard HDTV television with up to 1080 lines per video image.12 The currently available high-resolution HD endoscopy systems achieve a resolution of 1400 × 1080 image points.


Karl Storz Image 1 video camera

The most commonly used Image 1 digital video camera is for the PAL and NTSC color system. But with the introduction of the new digital epiduroscopic 3-chip Image 1 video camera with a digital image processor (an integrated image-processing module [IPM]), our expectations for significantly improved image quality for epiduroscopic diagnostics have been fulfilled. Images are transmitted in 16:9 format with 1080-pixel resolution, allowing for full high-definition images with 2 million image points. For medical applications, the highest possible image resolution is needed. Image 1 is a video camera system in which the optical analog images of the CCD sensor are directly converted to digital form behind the sensor while still in the camera head. This has the advantage that the image data is always in digital form and at the highest resolution throughout the entire camera system. In addition to insensitivity to noise, such as that from high-frequency (HF) surgery, this camera and processing system also brings with it the advantages of digital image optimization. This is a capability is available in all Karl Storz video systems, the standard models through to the digital IPM models.


Karl Storz Tricam 3D

With the Endovision Tricam 3D, Karl Storz has introduced a three-dimensional 3-chip endoscopic video system for the PAL and NTSC color system. The modular construction offers the possibility of integrating central steering, data processing and conversion, and telemedicine in the pain operating room (OR). Because all camera heads from Karl Storz work with one camera control unit (CCU), the operators can use each Image 1 camera head for all endoscopic interventions, not just those in the spinal region. Moreover, all new Image 1 products are fully compatible with extant Image 1 systems.


With the optical parfocal zoom (up to 2 ×) and digital endoscope filtration, the autoclavable Image 1 cameras automatically achieve image optimization on all epiduroscopes. The use in the sterile OR is made easy by push-button operation of all camera functions.


Along with being able to output analog signals, the Image 1 video camera system is also able to output digital signals such as digital video (DV) and serial digital interface (SDI) without restriction, which makes possible high-resolution, true-to-life digital images.


Richard Wolf Endocam Logic HD

The BOA vision flexible endoscope (Richard Wolf) contains a sensor unit that works with the current Endocam Logic HD camera platform, which consists of the Endocam Logic HD controller, the hand remote, 8-GB USB flash memory, CAN-BUS terminator, 3.0-m lockable HDMI/DVI-D cable, network cable, and DVD license.


The new Endocam Logic HD camera platform is one of the latest developments in camera systems from Richard Wolf. Endocam Logic HD’shigh-resolution image is developed within the endoscope The camera is a component of a new generation of digital camera heads, intelligent LED light sources, light guides, monitors, and the highly developed chip-on-the-tip technology.


The important parameters of dialog-capable instruments are displayed on the monitor. This dialog function also allows for automatic regulation of the light source over the camera; it is advantageous that the operator needs to make no further adjustments. Endocam Logic HD possesses a large number of rapidly selectable tested clinical application profiles, the menu for which is simple to navigate. The physicians are also able to specify a large number of settings themselves and define their own profiles.


In our pain OR, SDI is the preferred method for signal transmission, image recording, and display. This technique makes it possible for the new ergonomic thin-film-transistor (TFT) liquid-crystal–display monitors to supply true-to-life, brilliant video sequences. For a brilliant endoscopic image, the Radiance 26-in. G2 high-bright liquid-crystal–display (HB LCD) monitor by Richard Wolf is recommended.


Endomicroscopy

New techniques in endoscopy, such as high-definition endoscopy, digital chromoendoscopy (with FICE or SPIES), image-enhanced, endomicroscopy (with NBI or i-SCAN), chip-on-thetip technology, and use of autofluorescence and spectroscopy are rapidly being developed.


The systems recommended for use for endomicroscpy are high-definition video endoscopes. These instruments are equipped with special color-encoding properties (called chromoendoscopy).



 


In connection with the i-SCAN technology, high-resolution (HD +) endoscopy makes more details of the mucosal surface visible, which could lead to substantial improvements in spinal endoscopic diagnostics.


• Confocal microscope


images Confocal endomicroscopy (confocal laser endomicroscopy [CLE]) is a special medical endoscopic investigative technique. During endoscopic examination with CLE, cellular, vascular, and connective tissue structures can be differentiated in high resolution (1000 × magnification) by means of laser-supported, confocal fluorescence technology.13


CLE systems are available as handheld devices that can be inserted through the working channel of an endoscope or as a miniaturized system integrated into the distal end of an endoscope. In the endoscopic image, the mucous membrane is made visible in various fluorescent colors.


• The confocal argon laser works as follows to produce an image:


images After application of the fluorescent dye, the confocal (endomicroscopy) argon laser strikes the sample with a wavelength of 488 nm (blue laser light). The 1012 × 1012-pixel endomicroscopic image obtained can be analyzed and evaluated on a miniaturized scanner in the endoscope. The tissue remains unharmed.


images During the endoscopic investigation, many histologic images can be recorded, which makes a more accurate assessment of the tissue possible.


images The magnification is so high that even individual blood corpuscles in the vessels can be seen.


images Normal, noninflamed tissue usually presents with low background fluorescence that as a rule does not suffice to produce a sufficiently strong signal for endomicroscopy. Therefore, fluorescent dyes (fluorescein sodium) must be applied a few seconds before endomicroscopy.


Virtual chromoendoscopy

Using virtual chromoendoscopy, a histologic analysis of tissue is possible during an endoscopic investigation.11 Comparison of the results of CLE and standard biopsy show. However, that CLE has a high sensitivity and specificity for the correct diagnosis.14,15 Using this technology, tissue sampling can be better targeted and the total number of necessary biopsies can be reduced.


Autofluorescence and spectroscopy

In comparison to normal tissue, a number of pathologic processes such as inflammation, ischemia, and dysplasia show distinctive fluorescence behavior. The principle of fluorescence diagnostics rests on the recognition that light with a defined wavelength (400–500 nm) not only is absorbed and reflected in tissue but also causes autofluorescence in natural or introduced fluorophores, such as 5-aminolevulinic acid.16,17



 


Endomicroscopy provides a magnified image of the endoscopically investigated tissue and allows for histologic evaluation during endoscopy, that is, cellular level in vivo diagnosis, which is referred to as an optical biopsy.


Light-filtering image-enhancement technologies: NBI, i-SCAN, FICE, and SPIES

In virtual chromoendoscopy, various color spectra are produced through modulation of incident light with filters (NBI) or through software-based follow-up processing of reflected light (i-SCAN, FICE, or SPIES)15 and through this process the individual components of the mucous membrane, such as its surface or vascular structure, are more clearly represented. NBI, i-SCAN, FICE, and SPIES are light-filtering systems that alter the wavelength ranges of reflected light thereby enhancing or augmenting vessels and various tissue structures in the images as an optical follow-up.


NBI (Narrow-Band Imaging; Olympus, Tokyo, Japan) is the oldest established process of virtual chromoendoscopy and is based on narrowband incident light that consists of only two wavelengths, 415 nm (blue light) and 540 nm (green light). NBI is a technique for optical contour emphasis of blood vessels and mucous membrane structures.


“I-SCAN is a software-based, image-enhancement technology that is classified as a digital contrast method among endoscopic imaging techniques.”18 The technology (Pentax Medical, Tokyo, Japan) is based on an integrated software tool that magnifies the surfaces with the help of a surface refinement function, and the virtual chromoendoscopy is made possible by the additional application of specific color filters.


FICE (Flexible Spectral Imaging Color Enhancement; Fuji Film, Tokyo, Japan) and SPIES (Storz Professional Image Enhancement System; Karl Storz) are systems for computer-supported virtual chromoendoscopy. The SPIES CLARA and CHROMA systems improve the endoscopic representation of detail through homogeneous illumination and contrast emphasis (LED technology). While perserving natural coloring, superficial structures are crisply imaged (by the complementary metal-oxide semiconductor [CMOS] technology).


6.2.3 Equipment for Documentation


For OR data recording and transfer, we use AIDA 2.0 (Advanced Image and Data Acquisition 2.0; Karl Storz), a modular system. Image, video, and audio data of the diagnostic or therapeutic intervention are recorded and saved directly from the sterile operating room (OR) by touch screen, foot switch, or camerahead key.


The system is geared to the activities and requirements in the OR and offers step-by-step exactly the functionalities needed, from the recording of patient data to the definition of the use of that data. The documentation of an endoscopy examination includes:


• Patient identification and indication of the investigation.


• Identification of the investigator and his or her assistants.


• Endoscope type and record of instruments.


• Time record of the investigation and intervention process.


• Endoscopic diagnosis and therapy.


• Coding by ICD (International Classification of Diseases) and OPS (Operations and Procedures Manual, OPS is an adaptation of the English version of the International Classification of Procedures in Medicine).


• Report of findings with endoscopic image material (images Fig. 6.9).


The consensus committee of the World Initiative on Spinal Endoscopy19 agreed in 2006 in Graz, Austria, that the data for documentation should include the following: epiduroscopy type (purely diagnostic or therapeutic); subsequent treatments (laser, radio frequency (RF), or mechanical adhesiolysis); instrument type; volume of injected irrigation fluid; length of the procedure; side effects and complications.


May 20, 2018 | Posted by in NEUROLOGY | Comments Off on Epiduroscopy Equipment

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