Chapter 66. Spinal Canal Endoscopy

The epidural space was first shown to be important in radicular pain states by Lindahl and Rexed in 1950.1 Subsequently, Goebert performed the first reported epidural steroid injection.2 Since that time physicians have used the epidural space to gain direct access to traversing nerve roots and indirect access to the intrathecal space for medication delivery.

Anatomically, the epidural space is tubular and exists as a potential space. This tubular three-dimensional structure surrounds the dura and spinal cord. It extends from the foramen magnum to the upper sacrum. When examined in transverse plane, its external boundaries are the ligamentum flavum posteriorly, lamina and pedicles laterally, and the vertebral body and intervertebral disc anteriorly. The internal boundary is the dura.

Medication administration into the epidural space has been used to treat both acute and chronic pain. Examples include regional anesthesia for surgery, trauma, and labor. Dilute local anesthetic infusions have been used to treat postherpetic neuralgia, complex regional pain states, and cancer-related pain. Opioids and sympathomimetics have been added for synergy. Epidural steroids have been used to treat inflammatory nerve root irritation. Volumemetric injections and flouroscopically guided catheters have been used to direct medication delivery, wash away inflammatory mediators, lyse epidural adhesions, and deliver anti-inflammatory medication.

Efficacy of epidural treatment for radiculopathy is determined by multiple factors. Medical factors influencing outcome include accuracy of diagnosis, presence of nerve root inflammation, symptom duration, previous surgical intervention, patient age, and clinician ability to place the epidural steroid at the level of pathology.3 Treatment outcome also depends on psychological and social issues. Abram delineated factors correlating with treatment failure at twice the rate expected. These factors include poor education, unemployment, pain constant in nature, sleep disturbance, nonradicular diagnosis, duration >6 months, change in recreational activities, and tobacco use.4

Epidural space endoscopy or spinal canal endoscopy may improve outcome by addressing some of the medical factors discussed above. The region of erythema that is likely related to inflammation is visually confirmed with the endoscope. Fluoroscopy is used to confirm the spinal level. The flexible steerable handle allows placement of medication in the lateral gutter adjacent to the nerve root. Reproduction of pain during the procedure while exploring pathology helps to confirm diagnosis.5

Psychological and social factors are more difficult to treat and unfortunately they are not amenable to procedural intervention. These factors cannot be ignored, however, because they are of equal or greater importance than the medical pathology.6 Therefore attempts to address these issues by modification of behavior, structured water or land exercise programs, tobacco cessation, and improved sleep hygiene need to be made. Interventions such as targeted pharmacologic therapy to enhance restful sleep and programs to structure daily activity to enhance self-esteem are no less important. Lastly, functional goals should be set. To focus on complete pain cessation in the patient suffering from chronic pain distracts from attainable goals and ultimately is detrimental and nonproductive.

One might ask the question, “Why spinal canal endoscopy and why now?” Historically, there has been no way to ensure directed delivery of medication to the area of pathology within the epidural space. Fluids flow according to physical laws of pressure and resistance. Flow of contrast solution is observed to flow from suspected pathologic sites, which are regions of low compliance toward normal higher compliance areas. We believe that all epidural solutions flow in the same manner. The technique of spinal canal endoscopy allows the operator to administer medication directly to the site of suspected pathology and is not dependent on compliance of the epidural space. This is possible because of improvements in fiberoptic technology, development of steerable catheters, and use of the caudal approach, which separates the region of procedural trauma from the suspected site of pathology. These cumulative developments culminate in the ability to examine spinal anatomy in its native state and to identify pathology that may exist there. This in itself is unprecedented and not duplicated by either surgical or radiologic technology.

Orthopedic surgeon Michael Burman became the first to document use of a primitive arthroscope on cadaveric spinal preparations in 1931.7 The arthroscope’s diameter (9.5 mm) was larger than the spinal canal, which severely limited its use in patients. The arthroscope’s built-in light source and rudimentary optics precluded miniaturization.

Elias Stern, an anatomist at Columbia University, developed a spinascope in 1936.8 The instrument was manufactured by American Cystoscope Makers, Inc. There is record of its clinical use in seven volunteer patients for in vivo examination of the neuraxis. Intrathecal anatomy was described. The scope was rigid and used direct-through-the-scope optics, which limited its use. Lighting continued to be poor. The technique was further limited by trauma at the spinal level of interest and resultant hemorrhage that obscured visualization. It was designed for intrathecal use during spinal anesthesia.

In 1942 Pool published a series of 400 myeloscopic procedures.9,10 His myeloscope used a cannula over guide-wire technique to access the intrathecal space. Once access was confirmed, the lens and the light source were placed through the cannula and the operator observed directly through an eye piece.

Perhaps Pool’s greatest achievement was his atlas of hand-drawn images of intrathecal anatomy. Unfortunately, this was also his limitation: He was technically limited by his inability to photographically record his findings.

Dr. Pool used his myeloscope to confirm a clinical diagnosis or to establish an alternative one in his clinical practice. He described and recorded neuritis, disc herniation, hypertrophied ligamentum flavum, neoplasms, varicose vessels, and arachnoid adhesions.

The literature was silent until 1969 when Yoshio Ooi published his paper on the intrathecal lumbar endoscope.11 Miniaturization was possible in the 1970s with the advent of fiber optics and cool indirect lighting. A rigid scope continued to be used. Access continued to be at the level of interest, limiting epidural observation to a small area and increasing the risk of trauma and bleeding into the field of view. Seventy percent of the 86 patients in his series developed a post-dural puncture headache but no serious complications were reported. Photographs were obtained but they continued to be of poor quality.12

Rune Blomberg was the first to publish his experience with visualization of the epidural space in 1985. He described his experience both in cadaveric and living bodies.13

Video imaging technology became available in 1980. Koki Shimoji was the first to describe subarachnoid endoscopy using thin (0.5 to 1.4 mm) flexible epidural fiber-optic myeloscopes and used this technology in 1991.14 Epidural visualization continued to be difficult due to the use of the lumbar paramedian approach, which required the angle of attack to be between 45 and 90 degrees. Additionally, the problem of consistent expansion of the epidural space to facilitate optics and maintain focal length remained unsolved.

Shimoji used the technique of awake pain mapping in his patients. Arachnoiditis was identified. Subarachnoid myeloscopy was possible to the cisterna magna in four of his patients. X-ray technology was used to confirm myeloscope level.

In 1991, Saberski and Kitahata solved several of the problems that had limited study and visualization of the epidural space. The caudal approach to the epidural space allowed the fiber-optic scope to be inserted distal to the area of interest, permitting inspection of native tissues free of procedural trauma.15 This approach also solved the problem encountered with sharp attack angles: The scope could now be advanced parallel to the dura mater, which facilitated steering of the device. To further enhance steering, a disposable steering handle was developed in conjunction with Myelotec Corporation (Roswell, Ga). This steering device incorporated the port for the fiber-optic device and a separate port for fluid administration. This additional port solved the problem of maintaining a dilated epidural space needed for optical focal length and clear visualization. Lastly, the fiber-optic diameter was reduced to 0.8 mm, necessary to facilitate passage through a steering handle port and into the caudal canal. At last the technical issues limiting spinal canal endoscopy were resolved.

New technology seems to always expand the worldview of the field that it affects and thereby expands the possibilities for clinical use. Spinal canal endoscopy is no different. Multiple factors will determine the potential use of this technology. Diagnostically, spinal canal endoscopy allows one to directly visualize the epidural space. As such, it will expand medicine’s ability to make a clearer and more specific diagnosis of epidural-based pathology. Dr Pool’s early myeloscopic work demonstrated this. He visually identified pathology that had never before been considered through his pioneering myeloscopic work. We can expect similar identification of new unrecognized pathology.

The ability to visually explore the epidural space opens a new world of possibilities both for treatment and for diagnosis. However, before pathology can be categorized, the normal anatomy of the in vivo epidural space must be categorized and understood. This process is well under way.

Currently, the spinal canal endoscope is available to practitioners under a 510 K Food and Drug Administration (FDA) market approval for diagnosis and drug delivery. The market approval was granted in September of 1996 to Myelotec Corporation (Alpharetta, Ga, unpublished data, 9/4/96 and 8/11/98). As the field grows in this technology, one may expect the indications and use of this technology to grow.

With this caveat in mind, the current use of spinal endoscopy in low back and radicular pain is limited to pain generator mapping, normal saline lavage, and visually directed delivery of anti-inflammatory medication.

The indication for this procedure is lumbar or sacral radiculopathy, either from presumed nerve root irritation without compressive lesion or minimally compressive nerve root foraminal stenosis. Spinal canal endoscopy appears to be most effective when treating inflammatory radiculopathy, with or without signs of compressive lesion in the neurologically stable patient. Signs of motor weakness, bowel, and bladder or erectile dysfunction in the acute setting or unstable neurologic picture in the chronic setting suggest the need for neurosurgic consultation and collaboration.16

Contraindications to the procedure include patient refusal, pathology at the site of the sacral hiatus (e.g., pilonidal cyst), active untreated infection, osteomyelitis, bleeding diathesis, lack of sacral hiatus, increased intracranial pressure, inability to tolerate the prone position, allergy to proposed medications, new motor weakness or acute bowel, and bladder or erectile dysfunction.

Relative contraindications include poorly controlled diabetes mellitus, immunocompromised states, active legal issues impacting the painful condition, and active, untreated psychiatric disorders.17

Patient selection based on case reports suggest better results in the subgroup of patients with an acute or subacute disc-related spinal pain syndrome who have not undergone back surgery and do not associated pain behaviors.18,19 This subgroup of patients may be most responsive to “washout” of chemical irritants and corticosteroid anti-inflammatory effect. This subgroup of patients may also have not undergone central remodeling and secondary hyperalgesia.

At any rate, spinal canal endoscopy is indicated for radicular pain syndromes secondary to inflammation, epidural adhesion, Tarlov’s cyst, post-laminectomy syndrome, and mild to moderate spinal stenosis. It is these patients who seem at this time to benefit most from this procedure.

Spinal canal endoscopy is not indicated in those patients who suffer from biomechanical pain syndromes such as lumbar facet syndrome, sacroiliac joint dysfunction, or myofascial pain syndrome.

Prior to spinal canal endoscopy, all patients must undergo a complete history and physical examination. Care should be taken to document this examination carefully, with special attention to the full neurologic examination. Imaging studies and special testing such as electromyography and nerve conduction studies should be reviewed.

Lumbosacral, flexion, extension and oblique views may be considered to rule out disease not amenable to epidural procedures. Magnetic resonance imaging of the lumbar and sacral spine should be considered to rule out compressive radiculopathy and severe spinal stenosis.

Preparation

Nonsteroidal anti-inflammatory drugs, aspirin, and other platelet inhibitors and anticoagulants should be discontinued before the procedure to allow the coagulation system to normalize.20 This must be done with the prescribing physician’s knowledge and consent to avoid possible medical complications. Appropriate laboratory studies may be ordered to document normal coagulation.

The patient is directed to use an antibacterial scrub the evening before the procedure and is directed to not eat or drink after midnight.

Equipment should be inspected and all disposables must be in place. The procedure should be scheduled with fluoroscopy, video monitor, and camera.

Preprocedure discussion with consultant anesthesiologist should include patient positioning (prone) and the need for an awake patient responsive to verbal interrogation.

Informed consent must be obtained. We use a standardized video informed consent for this procedure. This standardized informed consent process provides documentation of the content discussed.

Procedure

We advise that contact is maintained with the patient at all times during the procedure. We avoid producing severe discomfort in our patients and will frequently equilibrate the system to atmospheric pressure and administer fluids slowly.

As a prophylactic, a first-generation cephalosporin is given immediately prior to the start of the procedure.

The technique of spinal canal endoscopy follows:

• 1. The patient is placed prone on the fluoroscopy table with a pillow under the abdomen. Identify the sacral hiatus and mark it. Preparation is done from mid-thoracic spine to buttocks and from flank to flank. Apply drapes. Drape the fluoroscope.
• 2. With the fluoroscope tube directed laterally, the position of the sacral hiatus is confirmed using a radiopaque epidural needle.
• 3. Anesthesia is obtained by injecting a small volume of local anesthetic at the sacral hiatus. The 25-gauge 1.5-in. needle may be used as a finder to ensure proper angle of attack.
• 4. Insert the 17-gauge Touhy needle through the sacral hiatus to access the caudal epidural space. This can be done under real-time fluoroscopy if necessary. The loss of resistance technique to saline may help to identify the caudal epidural space.
• 5. The guide wire is placed through the epidural needle and followed using fluoroscopy to demonstrate easy passage through the caudal epidural space. It should pass easily without resistance. Non-ionic contrast may be used to prove needle placement within the caudal canal if the guide wire is not easily passed.
• 6. The fluoroscope then should be placed in the posterior-anterior (PA) position. Confirm proper threading of the guide wire. Once confirmed, the Touhy needle is removed.
• 7. The dilator is then passed over the wire. A No. 11 blade is used to make a vertically oriented stab incision along the wire to the level of the sacral hiatus. The dilator is then passed into the caudal canal. Some caudal canals are quite tight. The dilator is gently past several times in and out of the caudal canal. Care is taken to ensure that the guide wire continues to thread easily and is not kinked. If there is any question, fluoroscopy is used to confirm position. The dilator is removed.
• 8. Next assemble the dilator-sheath unit. Thread this unit over the guide wire and place the unit into the sacral canal. Ensure that the sheath is fully inserted and remove the dilator and the guide wire.
• 9. Flush the side arm of the introducer with 5 mL of sterile, preservative-free normal saline. Ensure that there is no cerebrospinal fluid (CSF) or blood on aspiration prior to this injection.
• 10. Set up the fiber-optic cable and the steering handle. Connect a 100-mL bag of sterile, preservative-free normal saline to a three-way connector using the sterile intravenous tubing supplied in the access kit. Flush the tubing. Apply the 10-mL epidural syringe to the three-way connector. Attach the three-way connector to the tubing of the steering handle and flush the system.
• 11. Place the fiber-optic cable through the opposite port of the steering handle. Obtain a video image and focus.
• 12. Advance the steering handle fiber-optic unit into the caudal epidural space. Use fluoroscopy to advance the steering handle to the site of interest. The steering handle may be placed in the same fashion as a percutaneous stimulation lead. Once the tip of the steering handle is at the desired location, gentle pulsatile saline administration may be used to dilate the epidural space, facilitating focal length and optical resolution.

It is an important practice to sustain pressure in the epidural space for no more than 2 to 3 minutes at a time. This should prevent compromise of profusion. We limit total epidural fluids to <100 mL. Most procedures last 20 to 30 minutes after saline administration and epidural viewing has begun.

After the procedure is completed, a dressing is applied and the patient is taken to the recovery area.

Post-Procedure

In the recovery room a post-procedure neurologic examination is performed. Any new deficits should be clearly detailed and followed serially. Alternatively, consultation with the neurosurgery department may be considered.

Patients are instructed not to bathe for 5 days, but showers are acceptable. Hygiene instructions are important: perineal cleaning after bowel movement should be directed away from the procedural site. The discharge instruction sheet is helpful in outlining these instructions as well as wound care and “call-for” contingencies.

The patient should be discharged with a driver and should be observed by a friend or family member for the immediate post-procedure period. A 2- or 3-day supply of post-procedural short-acting opioid such as a codeine, hydrocodone, or oxycodone preparation is appropriate.

Potential Complications

Complications attributable to the operative phase of the procedure appertain to the generation of excessive epidural pressure.21 Excessive pressure can affect both local and more distant perfusion. Scapular or neck pain may portend retinal hemorrhage. Patient complaints of pain from small volume distention of the epidural space usually signifies a noncompliant epidural space and may transmit high pressure far from the site of fluid administration. We are careful to keep epidural fluid volumes low and to maintain contact with our patient throughout this procedure.

Other potential complications include post-dural puncture headache, epidural hematoma, infection, increased pain, and transient dysthesias. It is reassuring, however, that there has been no permanent injury reported after approximately 6000 spinal endoscopy procedures preformed throughout the world (Myelotec Inc, Alparetta, Ga, unpublished data).

Hard outcome data for spinal canal endoscopy is in development. To date, there have been no randomized, controlled trials regarding the efficacy of spinal canal endoscopy or other forms of therapy both surgical and nonsurgical. However, one pre- and post-procedural survey utilizing data from 77 patients demonstrated decreased medication use and improved functional capacity up to 6 months after spinal endoscopy.

Insurers typically cover procedures and devices that meet the following criteria: The device is medically necessary to treat the patient’s condition, and the device is used according to the labeled indications approved by the FDA.

Although we offer several possible billing codes for this procedure, individual insurance companies will only honor certain ones. It is important that providers communicate with individual payers to understand their requirements.

In this complex and changing health care environment, insurance coverage is never a guarantee of payment. Insurers vary widely in the services they cover. Even among patients insured by the same insurance company, benefits may vary according to the specific plan. Some plans may be unfamiliar with spinal canal endoscopy. Educating insurers about the procedure may be necessary before a coverage decision can be made. We suggest that claims are filed manually with a complete operative report and hard copy of all supporting radiographs.

There are no available CPT codes specific to epidural diagnostic and therapeutic procedures using the spinal endoscope. Acceptable CPT codes vary from insurer to insurer. Several possible codes are listed below. As discussed, individual payers may have specific policies regarding the use of CPT codes.

Coding for Diagnosis (ICD-9-CM)

Diagnosis and the diagnostic codes must be supportive of the medical necessity for procedures and service rendered. The diagnostic codes below may be appropriate for epidural endoscopy.

• 353.1 Lumbosacral plexus lesions
• 353.4 Lumbosacral root lesions, not elsewhere classified
• 722.83 Post-laminectomy syndrome; lumbar region
• 724.4 Lumbosacral radiculitis
• 724.9 Other unspecified back disorder; Compression of spinal nerve root, NEC
• 953.2 Injury to lumbar nerve root
• 953.3 Injury to sacral nerve root
• 953.4 Injury to lumbosacral plexus

Procedure Coding

Code 64722: Decompression; unspecified nerve(s) (specify). This code requires specific identification of nerves involved. Some payers consider this code to be applicable only to “open” procedures.

Code 62289: Injection of substance other than anesthetic, antispasmodic, contrast or neurolytic solutions; lumbar or caudal epidural (separate procedure). This code is the standard epidural injection code and may be considered when injecting a steroid or multiple medications (e.g., steroid, anesthetic, opioid).

Radiographic Coding

Code 76000: Fluoroscopy (separate procedure), up to 1 hour physician time. This code may be considered for the technical component of fluoroscopy. A 26 modifier is required when billing for the professional component. Some payers do not allow for separate billing of the professional fee.

Code 62278: Injection of diagnostic or therapeutic anesthetic or antispasmodic substance (including narcotics); epidural, lumbar, or caudal, single. This code may be considered if a contrast study is performed. The report must include a radiologic review of normal and abnormal anatomy, comparison of previous studies with a discussion of any change over time, anatomic space where the contrast is injected, vertebral level of the injection and position within the space, and the extent of flow including upper and lower vertebral boundaries and any filling defects after a 5-mL contrast injection.

Code 72100-26: Radiologic examination, spine, lumbosacral; anterioposterior and lateral. This code is used for the professional interpretive component of the 62278 procedure.

Code 64999: (Unlisted procedure, nervous system).

Three Coding Scenarios

• Scenario 1: Code 64722 as the primary code and 62289, 76000-26, 62278, and 72100-26 as secondary codes.
• Scenario 2: Code 64999 as the solitary and primary code. Bundle the value of 64722, 62289, 76000-26, 62278, and 72100-26 into this solitary code.
• Scenario 3: Code 62289-22 as the solitary and primary code. Bundle the value of 64722, 62289, 76000-26, 62278, and 72100-26 into this solitary code.

Modifiers

“A modifier provides the means by which the reporting physician can indicate that a service or procedure that has been performed has been altered by some specific circumstance but not changed in its definition or code.”22 The following modifiers are applicable to spinal endoscopy procedures:

• 22: Unusual Procedural Service: This modifier is used when the service provided is greater than that usually required for the procedure. It implies that additional effort was made to make a diagnosis or perform a procedure.
• 26: Professional Component: Appropriate for use with codes 72100 and 76000.
• 50: Bilateral Procedures. Medicare requires a separate port of entry for use of this modifier.
• 51: Multiple Procedures: This modifier may be used when multiple levels are involved.

The technology of spinal canal endoscopy has developed slowly during the 20th century. Contributions have been made by many innovators; however, only recently has this technique been developed and refined sufficiently to be used clinically.

Further study is needed to determine whether this technique holds advantages over alternative currently used techniques of medication delivery into the epidural space. Real-time direct-visual examination of epidural anatomy currently enables the identification of epidural diseases and localization of pain generators there. This ability to examine epidural pathology apart from operative trauma and to direct the delivery of medication is not duplicated by any other technique available at this time. The technology holds the promise of minimally invasive and effective therapy for both radicular and perhaps other forms of disabling back pain.

Other exciting possibilities for this technology may include removal of extra- or intradural scar tissue, cyst drainage, biopsies, studies of cell biology and inflammatory mediators, and retrieval of foreign bodies. We feel that the possibility of modifying the inflammatory process by blocking the mediators of inflammation holds the greatest promise.

Today, the technique can be used safely and effectively to deliver medication to pathology under direct vision. It opens new doors for the diagnosis and treatment of disease accessible through the epidural space.