Lumbar Discography

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Various techniques have been described for lumbar discography. In our practice and experience,12,13 patients are placed prone on a tilting fluoroscopic table having a multidirectional movable top and rotational tilt. Either foam pillows or pads are placed beneath the upper abdomen and lower chest both to reduce lumbar lordosis and to elevate the side of the patient into which we will be introducing the needle(s). We advise needle introduction from the side opposite the area under investigation if the patient's pain is clearly lateralized. In cases of midline and/or bilateral pain, the side of needle placement can be based upon individual preference and circumstances.

When the patient has been positioned, fluoroscopy is performed with the C-arm to identify the route of optimal access for needle placement into each disc. We usually mark the lumbosacral disc access route first (assuming that it is to be studied), since this disc proves to be the most challenging level in most individuals. Typically, the C-arm is rotated approximately 30 to 45° away from the midline and 10 to 45° cepha-lad to visualize this optimal route directly into the lumbosacral disc. Upper lumbar discs (above L3-4) generally require caudal angulation of the fluoroscopic access route. Dorsolateral fusions and/or instrumentation can be very challenging with a dorsolateral approach. Some with fusions may require a midline or paramidline transdural approach, all to be determined fluoroscopically prior to sterile preparation, draping, and needle introduction.

After a route to the disc has been identified, the patient's skin is indented with a device that will leave a small, lasting skin imprint that will be recognizable after skin cleansing and the application of drapes. Many C-arms, including some of the ones we operate, have an optional laser light to assist with needle guidance. We still indent the skin prior to needle introduction, since patients often move slightly as the procedure begins.

It is vital to thoroughly cleanse a wide area of the patient's skin with either iodine solution or an iodine-free soap (if allergy to iodinated compounds exists), to make sure that the disinfectant enters small cracks and pores. Most documented cases of postdiscography discitis are due to the introduction of skin and/or dermal appendage bacterial contaminants (Staphylococcus aureus/epidermitis primarily). If iodine solution is utilized, it needs to be left on the skin for at least 2 minutes prior to alcohol rinse to exert optimal bactericidal affect.

After disinfectant solutions have been applied to the skin, contrast and other injectable media are drawn up. We employ the low osmo-lar, nonionic contrast solutions (e.g., Iohexol, 240 mg/mL), unless con trast allergy exists. We draw up 10 to 12 mL (mixed with Cefazolin unless allergic) into a 10 to 12 mL syringe for a lumbar discogram. If more than three levels are to be studied, and/or if degeneration of multiple segments is noted on imaging studies, we may draw up a second syringe in advance. If there is allergy to iodinated compounds, we use either sterile saline (with or without Cefazolin) or intradiscal Gadolinium mixed with sterile saline in a mixture of 0.15 cc Gadolinium into 30 cc sterile saline. We perform MR immediately after these cases where we inject intradiscal Gadolinium and saline. After we have drawn up our injectable solutions, the skin cleansing solution is rinsed from the patient's skin with alcohol, a sterile, fenestrated drape is placed over the prepared site, and the procedure is begun.

Both single-needle and coaxial, two-needle techniques have been described. Having tried both techniques, we now use a single, 3.5 to 8 in. (depending upon patient size) 22-gauge spinal needle for dor-solateral placement on all our patients. If we are forced to perform a transdural approach, we will use either a single, 26-gauge or 25-gauge needle of 3.5 to 5 in. We have found the coaxial technique to be unnecessary. It makes for a slower procedure, and may (not proven however) increase the risk of infection. We believe that procedural speed is vitally important at each disc level studied. Our needles are usually inserted for only 1 to 3 minutes each. As soon as each disc has been injected, filmed, and later anesthetized (if necessary), the needle is removed.

When approaching a lumbar disc obliquely, we most often use a 22-gauge, 5 in. spinal needle; however, 6, 7, and 8 in. needles are also used, depending upon patient dimensions. Following skin puncture, the needle is incrementally advanced along the fluoroscopic access to the inferior margin of the disc to be punctured. Live fluoroscopy during needle advancement is unnecessary. Instead, the needle is advanced incrementally, with intermittent fluoroscopic checks lasting milliseconds, performed with our hands removed from the field, while we stand behind a shield. Directional control of the needle is achieved by bevel rotation prior to and/or during each advancement.

When the needle tip reaches the disc annulus (generally perceived as a firmness), it is firmly advanced 1.5 to 2 cm into the center of the disc nucleus. Fluoroscopy is then rotated typically to either a lateral or anteroposterior (AP) projection (based upon proceduralist preference), to confirm the depth and location of the needle tip within the disc center. Optimally, the needle tip is located as near to the center of the disc as is possible in all dimensions. During advancement of the needle to the external annular margin, it is relatively common to either hit or irritate a traversing lumbar nerve root, especially at L5-S1, where the route of access is small. If a nerve is inadvertently hit or irritated, the needle should be withdrawn slightly and repositioned, if possible, in an attempt to avoid the nerve. By inserting the spinal needle from the site opposite the clinical pain under investigation, one can avoid unintended provocation of pain closely resembling the pain under investigation, which could cause confusion in the interpretation of the response at this level.

Following needle placement, contrast agent is injected under live fluoroscopic observation. In cases of contrast allergy, exposures of the disc should be obtained in both AP and lateral projection prior to the introduction of sterile saline (with or without Gadolinium). When contrast is used, films need not be obtained until contrast injection has taken place. While the discographer observes the disc on the fluo-roscopy monitor, the assisting technologist(s) carefully observe(s) the patient for any signs of pain perception. The disc is injected either to capacity or until extradiscal leakage of contrast is observed (Figures 6.1-6.6). If sterile saline is being used, injection continues until one of the following occurs.

1. An end point is reached, preventing further injection.

2. Pain manifestations are observed.

3. At least 4 mL of saline has been injected, indicating leakage.

Frequently observed sites of contrast leakage include the epidural space (Figure 6.2C), vertebral body medullary space, paraspinous veins (Figures 6.2B and 6.5A), paraspinous tissues (Figure 6.2B), and the epidural veins (Figure 6.5B). It is crucial to adequately inject each disc in terms of volume. A typical intact lumbar disc (Figure 6.1A,B) will accept approximately 1.5 to 3.5 mL of fluid, depending upon the size of the individual and state of the disc. If no leakage is observed, the disc should be injected to at least 4 to 5 atm of pressure (120-150 mmHg if a manometer is being employed), provided that this distention is not painful. Adequate distention of an intact, or nonleaking disc is required, since only with annular distention is a reliable sensation provoked in most circumstances (mechanically sensitive discs). In normal discs, either no sensation or "pressure" is the perception most often described during injection. If the patient describes or manifests obvious pain or distress, the injection is voluntarily terminated. The total volume of injected material is recorded (along with injection pressure if manometry is employed), injection end-point characteristics are recorded (leakage, gradual, or firm), and if leakage is observed, the sites of leakage are recorded by filming. We have observed venous opacification to be present during injection of most discs (lumbar, thoracic, and cervical) harboring full-thickness annular tears. We recommend the filming of each disc during active injection in at least two perpendicular projections, most often AP and lateral. These views will in most cases optimally demonstrate both nuclear morphology and annular pathology that might exist.

Immediately after filming, the patient is questioned about the experience during injection. Patients are asked to describe in detail their perceptions, whether pain, pressure, or no sensation at all. On occasion, patients are asked to draw with a felt-tipped marker on the front and back on a human figure where they perceived the sensation(s). They are asked whether the sensation(s) perceived was/were familiar or unfamiliar (concordant vs nonconcordant) relative to their clinical complaints. Patients are thereafter requested to rate the maximum intensity of the experience on a scale of 0 (no sensation whatsoever) to 10 (extreme pain/pressure). This intensity rating (given as, e.g., 1/10, 8/10), and the concordance versus nonconcordance of the experience

Figure 6.1. Painless (1/10 nonconcordant pressure) injection into an L1-2 disc exhibiting minimal fissuring; images obtained during distention of the disc with contrast agent. (A) AP projection reveals minimal grade I fissuring (arrows) toward both sides. (B) Disc appears completely normal on lateral projection.

Painful Injections Buttocks
b
Approach For Lumbar Discography Prone

Figure 6.2. Painfully deranged lumbar discs. (A) AP image obtained during disc injection reveals a grade III-IV tear (arrow) posterolaterally, opposite needle placement. Patient reported 9/10 concordant ipsilateral back, buttock, hip and dorsolateral leg pain. (B) AP and (C) lateral films of the L4-5 disc during injection. Note full-thickness lateral tear (arrow in B) opposite side of needle placement.

Central Defect The Vertebral Body Lumbar Epidural Veins

Figure 6.2. Continued. On lateral view (C), there is epidural leakage of contrast (curved arrow). Patient reported 8.5/10 concordant central and left-sided back, buttock, hip and leg pain, slightly different from the pain provoked at L5-S1 (A).

Figure 6.2. Continued. On lateral view (C), there is epidural leakage of contrast (curved arrow). Patient reported 8.5/10 concordant central and left-sided back, buttock, hip and leg pain, slightly different from the pain provoked at L5-S1 (A).

during injection, are recorded at this point. It is common for patients to initially describe an extremely painful experience as "nonconcor-dant" when in fact the pain they experienced was otherwise in a typical location. One must be aware that discography may, and in fact often does, provoke pain that is more intense than the clinical pain under investigation. The discographer must carefully question each patient to determine why an experience is concordant or nonconcordant, since otherwise a true positive (concordant intensity rating of >7/10, with annular tear) disc may be incorrectly recorded as "nonconcordant." Pain that is, in fact, familiar in location but worse than usual should be recorded as "concordant."

If the injection was painful, and the disc exhibited annular pathology and was given a high intensity rating, we often thereafter inject local anesthetic (2-4% lidocaine or 0.5% bupivacaine, 1 to 3 mL in total volume) into the disc prior to needle removal. This injection generally relieves pain within minutes. We have found that injecting a local anesthetic into painful discs decreases the likelihood of producing false positive results later in studies of adjacent discs. The transmission of pain to an already sensitive, adjacent, torn disc can and does

Lumbar Discogram
Figure 6.3. Painfully deranged L4-5 disc exhibiting a focal grade III posterior tear (straight arrow). Lateral view of L4. Patient reported 7.5/10 concordant central and bilateral back pain. L5/S1 disc fusion with metal cage (curved arrow) in place.

occur and can be decreased or eliminated by administration of in-tradiscal anesthetic. In some cases, if the painful disc is filled to capacity and no more contrast can be injected, anesthetic injection will be impossible. In isolated cases of this type, subsequent levels may possibly need to be studied (restudied if the results are suspect) at a later date, when the distended disc has completely decompressed, and is no longer painful. We have found that even if the local anesthetic leaks out of the disc and into the epidural space, adjacent levels can be validly studied if this is done within minutes of anesthetic administration. After the initial lumbar disc level has been studied and the results recorded, the needle is removed and the procedure repeated at subsequent levels using the same technique just described.

In our practice, the most frequently requested lumbar discography procedure involves the study of three or four segments, most often L5-S1 upward to and including either L3-4 or L2-3. Experienced surgeons like to define at least one, or in some cases, two pain-free and anatomically normal or minimally deranged levels adjacent to (above and/or below) painfully deranged segments. Postdiscography computed tomography (CT)35,45 may be employed upon individual discs; however,

Schmorl Node
Figure 6.4. Painfully deranged L4-5 disc due to endplate infraction (Schmorl's node and arrow). Lateral view obtained during injection of disc. Patient reported 8/10 concordant central low back and sacral pain.

this is not a routine in our practice. Because of the high quality of prior MR imaging studies and of the films we obtained during discography, we have found postdiscography CT to be generally unnecessary. MR imaging follows all cases where intradiscal Gadolinium is employed.

Prior research demonstrates that annular tears, either full thickness or extending from the nuclear space into the outermost portions of the disc annulus, are generally observed in discographically painful discs (Figures 6.2, 6.3, 6.5, 6.6).16,45 A morphological scale describing the types and extent of lumbar disc annular tears is presented in Table 6.1. Morphologically normal discs and discs with only internal grade I fissures should not be painful to discographic injection.17,22,40 It is reasonably common to note the provocation of pain from an immediately adjacent, painfully deranged and not anesthetized disc when a normal disc is distended to capacity. It is this important fact that underlies our advocacy of studying suspect discs (abnormal appearance on MR imaging studies), initially followed by the use of intradiscal local anesthetic into painfully deranged discs before control levels are studied. When the abnormal levels first are studied, local anesthetic may be injected into the disc, rendering it pain free for the later study of adjacent segments. We frequently observe a higher intensity response at

Cervical Discography

Figure 6.5. Painfully deranged L4-5 disc with nuclear space-epidural and para-spinous-venous communication. (A) AP and (B) lateral images obtained during active injection reveal opacification of paraspinous (arrows in A) and epidural (arrow in B) veins. Patient reported 10/10 concordant back, buttock, hip and leg pain, ipsilateral to the left-sided tear (opposite the side of needle placement).

Anatomy Lumbar Discography

Figure 6.6. Diagnostic (A) and therapeutic (B) disco-grams in painfully deranged disc with classic high-intensity zone (HIZ) lesion noted on MR (not shown). (A) Lateral film obtained during disc injection reveals full-thickness tear posteriorly and inferi-orly (arrow). (B) Lateral view revealing fluid-fluid level following therapeutic intradiscal injection of mixture of water-soluble steroid and local anesthetic. Arrow denotes fluid level between contrast (on left) and therapeutic substances (posteriorly and on right). Film obtained by using horizontal lateral projection with patient prone.

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Responses

  • Cordelia
    What is discogram transdural approach lumbar l5?
    8 years ago
  • tuija
    How to do lumbar discography?
    8 years ago
  • Katrin Durr
    What is the worst grade lumbar annular tear?
    8 years ago
  • cheyenne
    What is a dorsolateral annular tear?
    6 years ago

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