vertebral herniation clinical orthopedic.pptx

Vertebral herniation

1. Anatomy of lumer vertebre

2. Anatomy of the lumber Spain ( ligament )

3. Anatomy of the disc

4. Definition of disc herniation A spinal disc herniation ( prolapsus disci intervertebralis ) is a medical condition affecting the spine due to trauma, lifting injuries, or idiopathic, in which a tear in the outer, fibrous ring ( annulus fibrosus ) of an intervertebral disc (discus intervertebralis ) allows the soft, central portion ( nucleus pulposus ) to bulge out beyond the damaged outer rings. Tears are almost always postero -lateral in nature owing to the presence of the posterior longitudinal ligament in the spinal canal. This tear in the disc ring may result in the release of inflammatory chemical mediators which may directly cause severe pain, even in the absence of nerve root

5. herniation history of disc The “age of the disc” was heralded by Mixter and Barr in 1921 when, during surgery, they discovered what they initially thought to be a tumor and was found to be a herniated disc. Since that time the disc has taken a central role in spinal pathphysiology and symptomatology . The advent of CT and MRI, however, has clearly shown that quite frequently, even in the presence of a frank disc herniation , patients remain asymptomatic.

6. ETIOLOGY OF LUMBAR HERNIATION This is a multifactoral problem and we still do not understand the precise cause for lumbar disc herniation in any given patient. Why is it that one person develops a lumbar disc herniation and another person does not? recent work by Haro et al. (6) suggests that a local inflammatory process in the epidural space may stimulate host macrophages to resorb the displaced disc tissue

7. From a biomedical perspective, Farfan (4) has shown that lumbar disc herniation may be reflective of high stresses at the posterolateral region of the disc secondary to torsion. These high loads cause fatigue failure of the annulus fibrosis that enables the inner nucleus pulposus to penetrate the laminations of the annulus gradually until a herniation occurs (4). Because the region of the disc with the highest torsional stresses is adjacent to the nerve root, these posterolateral herniations nearly always affect the exiting root or the central thecal sac. Less commonly, the disc may protrude into the extraforaminal area and produce compromise of the more proximal exiting root (e.g., L-4 for a lateral L4–L5 herniation ).

8. The factors that seem to emerge as possibly being predictive include tall men, heavy women, individuals with a small spinal canal, and those who work in an environment with considerable vibration, such as that of airplane pilots and heavy equipment operators (2).

9. Pathophysiology

10. Pathophysiology Currently most authors believe that annular tears, leading to disc herniation , occur secondary to repetitive stress, especially torsional stress, in a disc that has already undergone degenerative changes. Annular tears initially appear in the outer layers of the annulus pulposus . Because these layers are innervated, it is reasonable to assume that these tears may elicit axial pain. The tears may progress to involve the whole annular width and subsequently may result in disc herniation . Nucleus pulposus herniation provokes a local inflammatory response, and when it is close to a nerve root, may involve and compress it and bring about radicular pain. Occasionally the herniated disc material loses its connection with the “mother” disc, resulting in a sequestrated disc. The separated piece may migrate in the canal cranially or caudally and at times may settle in the lateral recess or within the intervertebral foramen or, rarely, penetrate through the dura

11. Thereis ample documentation that extruded discs, even large ones, shrink in size over time and may, over two to three years, disappear altogether. The direction of herniation , size of the herniated disc, and proximity to the neural elements will, to a large extent, determine the presence or absence of symptoms. Posterolateral disc herniation will bring about radicular pain. The patient will complain of pain in the upper or lower extremity with or without axial (spine) pain. Posteriorly directed herniations in the cervical or thoracic region may compromise the spinal cord and bring about progressive neurological deficits with bilateral long-tract signs. In the lower lumbar region posterior herniation of the same size may cause axial pain without any radicular symptoms. Large fragments, however, may compress the whole cauda equina and result in severe neurological compromise. “Pure” lateral herniations that end up in the intervertebral foramen frequently result in unremitting pain due to compression of the dorsal root ganglion (Figures 3-6A, 3-6B, and 3-6C). Anteriorly directed herniations , however, are frequently seen on imaging studies without any clinical problems.

12. Clinical features Acute disc prolapse may occur at any age, but is uncommon in the very young and the very old. The patient is usually a fit adult aged 20–45 years. Typically, while lifting or stooping he has severe back pain and is unable to straighten up. Either then or a day or two later pain is felt in the buttock and lower limb (sciatica). Both backache and sciatica are made worse by coughing or straining. Later there may be paraesthesia or numbness in the leg or foot, and occasionally muscle weakness. Cauda equina compression is rare but may cause urinary retention and perineal numbness.

13. The patient usually stands with a slight list to one side (‘sciatic scoliosis’). Sometimes the knee on the painful side is held slightly flexed to relax tension on the sciatic nerve; straightening the knee makes the skew back more obvious. All back movements are restricted, and during forward flexion the list may increase. There is often tenderness in the midline of the low back, and paravertebral muscle spasm. Straight leg raising is restricted and painful on the affected side; dorsiflexion of the foot and bowstringing of the lateral popliteal nerve may accentuate the pain. Sometimes raising the unaffected leg causes acute sciatic tension on the painful side (‘crossed sciatic tension’). With a high or mid-lumbar prolapse the femoral stretch test may be positive

14. Neurological examination may show muscle weakness (and, later, wasting), diminished reflexes and sensory loss corresponding to the affected level. L5 impairment causes weakness of knee flexion and big toe extension as well as sensory loss on the outer side of the leg and the dorsum of the foot. Normal reflexes at the knee and ankle are characteristic of L5 root compression. Paradoxically, the knee reflex may appear to be increased, because of weakness of the antagonists (which are supplied by L5). S1 impairment causes weak plantar-flexion and eversion of the foot, a depressed ankle jerk and sensory loss along the lateral border of the foot. Occasionally an L4/5 disc prolapse compresses both L5 and S1. Cauda equina compression causes urinary retention and sensory loss over the sacrum

15. Imaging X-rays are helpful, not to show an abnormal disc space but to exclude bone disease. After several attacks the disc space may be narrowed and small osteophytes Appear .

16. Herniated discs cannot be seen in plain films. When they herniate through the vertebral endplate, however, a situation that is frequently seen and believed to be secondary to endplate injury, they become visible. These herniations are called Schmorl’s nodes. They are commonly seen in spinal X-rays as small circumscribed endplate defects that are continuous with the discs

17. Myelography ( radiculography ) using iopamidol ( Niopam ) is a fairly reliable method of confirming the nerve root distortion resulting from a disc protrusion, localizing it and excluding intrathecal tumours ; however, it carries a significant risk of unpleasant side effects, such as headache (in over 30 per cent), nausea and dizziness. Myelography is unsuitable for diagnosing a far lateral disc protrusion (lateral to the intervertebral foramen); if this is suspected CT or MRI is essential.

18. CT and MRI are more reliable than myelography and have none of its disadvantages. These are now the preferred methods of spinalimaging . FIGURE Sagittal T2WI showing Schmorl’s nodes. Around some of them a small area of hyperintensity is seen (arrows).

19. FIGURE 3-13 A large herniated disc at L3-L4 level obliterating the spinal canal FIGURE 3-12 Sagittal T2WI of a degenerative spine. Note the anteriorly directed discal herniation (arrow).

20. Disc prolapse – imaging (a) Radiculogram in which the gap in the contrast medium (arrow) shows where a disc has protruded. (b) CT scan showing how disc protrusion can obstruct the intervertebral foramen. (c) MRI, axial view, showing the relationship of the disc protrusion to the dural sac and intervertebral foramen.

21. SURGICAL TECHNIQUES I perform all lumbar disc procedures under general inhalation anesthesia. Once anesthesia has been administered, place the patient prone on a Jackson table with slight hip flexion. This table enhances intraoperative positioning by accommodating a wide range of patient sizes. The abdominal viscera hang free without pressure on the venous plexus. The knees are well supported, and the lumbar spine can be flexed adequately. Transient paresthesias in the lateral femoral cutaneous nerve distribution are common postoperatively. In addition, some patients complain of mild postoperative discomfort over the greater trochanter . To prevent irritation of the brachial plexus, the arms must not be elevated excessively in relation to the trunk.

22. As an example, I describe the approach to the right L4–L5 disc level for the treatment of L-5 radiculopathy . Once the patient is properly positioned and carefully checked for pressure areas, especially the eyes, prepare and drape the lower back in sterile fashion. Palpate the iliac crests to locate the suspected L4–L5 level. Compare the clinically observed level of the iliac crests with preoperative radiographs, and label the level with a marking pencil.

23. Make a vertical midline incision over the appropriate spinous processes. After the skin incision is made, complete the remaining portion of the dissection to the bony lamina using electrocautery . Extend the dissection to the lumbodorsal fascia. Identify the spinous processes of L-4 and L-5, and use the cautery unit to incise the fascia directly over the spinous processes. Use pickups to apply tension or a Cobb elevator as a gentle retractor

24. Dissect the fascia away from the spinous processes of L4–L5 and the inferior portion of L-3. By using Cobb elevators, carefully strip the paraspinous muscles from the spinous process to the lamina. Take care to maintain a subperiosteal approach. Blood loss is markedly reduced by avoiding the muscle envelope. Once the periosteum is stripped, insert a self-retaining retractor. Irrigate the wound and clearly identify the interlaminar space of L4–L5

25. Place a towel clip through a spinous process, and obtain a lateral radiograph to confirm the level. Once you are satisfied that you are operating at the proper level, continue dissection by partially resecting the inferior portion of the L-4 spinous process and the superior portion of the L-5 spinous process:

26. Examine the interlaminar space. With a Penfield 1 elevator, strip the ligamentum flavum from the inferior and anterior surface of the lamina of L-4

27. Use a Harper 45 rongeur to excise part of the middle portion of the L-4 lamina

28. Carry the dissection cephalad until the midline raphe of the ligamentum flavum can be identified. Insert a Penfield 3 elevator in the midline from proximal to distal immediately anterior to the ligamentum flavum (Fig. 144.3). Using a #15 blade knife, divide the ligamentum flavum in the midline

29. Carry the dissection laterally toward the lateral recess, again using the Penfield 1 or Penfield 3 elevator to protect the underlying dura (Fig. 144.4). Dissection can be accomplished using either a scalpel, curets , or a rongeur with a 45 آ° angle

30. Once the bulk of the ligamentum flavum has been removed, examine the epidural fat and dura to determine the degree of lateral wall dissection necessary to identify and retract the displaced nerve root safely. In this chapter, I have chosen to depict a less common form of disc herniation to emphasize the pitfalls of root

31. injury (Fig. 144.5). When the disc herniation is medial to the root, the lateral portion of the dura may be misinterpreted as being the lateral border of the nerve root. Such a misinterpretation can result in division of the nerve root or at least injury to the nerve root. Take extreme care to identify the nerve root.

32. Resection of the lateral wall of the spinal canal using a rongeur with a 45 آ° angle is necessary in most cases. Once the nerve root is identified and the disc herniation is visualized, remove a portion of the herniation . Then medially displace the root and excise the remaining portion of the displaced disc (Fig. 144.6).

33. A disc herniation is categorized as being extruded when the annulus is disrupted, and the herniated portion of the disc is categorized as being protruded when the annulus is intact but eccentrically displaced. The term sequestered is applied to a free fragment of intervertebral disc lying in the spinal canal with no defect evident in the annulus fibrosus . Seventy-five percent of lumbar disc herniations are of the extruded variety, whereas sequestered disc fragments are far less common (less than 5%). Dissect from the medial portion of the dura laterally, using a Penfield 4 elevator in the dominant hand and a Freer elevator in the other hand. Take extreme care to identify the displaced nerve root. Use of surgical loupes with 2.5 magnification and a fiberoptic headlight is essential for optimal visualization in this operation. Once

34. the nerve can be displaced medially, insert a Love root retractor to displace the nerve root and dura gently medially, so that the extruded disc herniation can be excised (Fig. 144.6). A sharp incision into the annulus is seldom necessary because the pseudomembrane overlying an extruded disc can nearly always be dissected using a Penfield 4 elevator. In protruded disc herniation , however, the annulus must be incised. Once the disc has been removed, free the nerve root of tension and carefully inspect the neural foramina. The nerve root should be able to be displaced at least 1 cm medially (Fig. 144.7).

35. Take care to ensure that no disc material is present between the annulus and the posterior longitudinal ligament. Once the disc has been excised, irrigate the wound and place an interposition membrane of Gelfoam or fat over the laminotomy . At present, I prefer to use Gelfoam (Fig. 144.8).

36. Then close the wound in layers. Use figure-8 sutures to achieve watertight closure of the fascia; I prefer subcuticular stitches for the skin. Apply a dry, sterile bandage. Gently straighten and rotate the patient onto the stretcher for extubation . Following extubation , take the patient to the recovery room. Blood transfusion is seldom necessary for a primary lumbar discectomy because blood loss usually averages less than 100 ml. I have used this technique successfully for the past 15 years with no incidence of recurrent disc herniation ( Dan M. Spengler ) over that reported by others (2%).

37. FAR LATERAL AND INTRAFORAMINAL DISCS Far lateral and intraforaminal disc lesions cannot be easily removed through a midline approach (Fig. 144.9). Although taking down the entire facet is one alternative advocated by some (1), the extraforaminal approach has been advocated by Wiltse (21,22). The proponents of going from the midline through the facets suggest that instability is not a subsequent problem and believe the nerve root can be more easily identified. Furthermore, they believe the surgeon can have greater confidence of complete decompression. However, many do not share this view.

38. The paramedian approach popularized by Wiltse (21,22) is a muscle-splitting approach. Make the incision 5 cm from the midline, followed by blunt dissection of the paraspinal muscles (Fig. 144.10).

39. At this point, take radiographs to verify the level and clear the transverse processes of soft tissues. Enter the intertransverse ligaments and fascia with a knife or curet , then remove those structures between the transverse processes. Identify the nerve, which is usually 2 to 4 mm anterior to the fascia and directed at a 45 آ° angle (Fig. 144.11).

40. Follow the nerve medially and identify the disc. If a free fragment is present, remove it. If only a bulge is present, incise the annulus and remove easily identifiable fragments. When the nerve root is easily mobile, sufficient disc has been removed. If the lesion is intraforaminal , take down a portion of the facet laterally to expose the nerve root canal. McCulloch and Young (12) point out, however, that this procedure is rarely necessary because of the the usual anatomic location of these lesions. Closure in both instances is routine, using a free fat graft or Gelfoam to cover the nerve.

41. POSTOPERATIVE CARE AND REHABILITATION In most patients, the preoperative radicular symptoms are improved when they awaken in the recovery room. On the evening of surgery, the patient is permitted to stand. By the first postoperative day, the patient is allowed to ambulate. If a dural leak occurs, ambulation is delayed by 24 to 48 hours. An abdominal binder is used for 4 weeks as partial protection for the patient. Rehabilitation is initiated 4 weeks after surgery and continued indefinitely. Patients are advised to maintain ideal weight and

42. develop good abdominal and trunk extensor muscle tone. Aerobic activity is encouraged and is initiated 4 weeks following surgery. Patients are discharged from follow-up approximately 12 months after surgery.

43. PITFALLS AND COMPLICATIONS The primary consideration is the selection of appropriate patients for surgical repair of lumbar disc herniations . The use of an objective method to accomplish this, as described in this chapter, will lessen the incidence of negative explorations (19), which is less than 2% in my experience. Although technical errors infrequently account for persistent pain after surgery, such errors invariably compromise the outcome. In a patient with established disc herniation , exploration at the wrong intervertebral level will not benefit the patient (10). Avoid this mistake by taking an intraoperative radiograph to confirm the appropriate level. If a disc herniation is not found, consider exploring additional levels after an intraoperative radiograph to confirm the proper level. Explorations at the wrong level are more common in patients who have transitional lumbar vertebrae.

44. Poor technique can prolong postoperative pain. Because excessive traction of neural tissue can cause irreversible nerve damage, use loupe magnification and fiberoptic lighting. These technologies have done much to minimize injury to neural tissue. Likewise, the use of an interpositional membrane (either free fat grafts or Gelfoam ) at the completion of surgical exploration may minimize long-term perineural scar formation. Presently, newer antiadhesion barriers are being investigated in the United States. Experience in Europe has suggested that such barriers may lessen scarring within the spinal canal and perhaps even enhance clinical outcome. Additional evaluations are necessary to support these early but exciting assertions scientifically

45. Technical errors can also result when the surgeon fails to detect a fragment of disc tissue that has migrated from the level of herniation , either cephalad in the canal or laterally into the extraforaminal area, trapping nerve roots (10). Because the only patients who should undergo surgery are those with objective findings, explore the canal thoroughly if no specific pathologic changes are encountered at the suspected level. Because the nerve root should be able to be displaced easily for a distance of approximately 1 cm medially, a nerve root that is tight in the canal and cannot be displaced suggests either a sequestered fragment along the nerve root or a stenotic lateral recess (10).

46. Gently palpate the cauda equina to ensure that an intradural disc herniation is not present. Although a neoplasm involving the neural elements of the lumbar spine is always a possibility, it is distinctly uncommon. The most likely neoplastic lesion encountered in the lumbar vertebral canal is a metastatic extradural lesion. Hemostasis is essential in lumbar disc surgery. With proper technique, blood loss should be minimal, rarely exceeding 150 ml. Generally, epidural bleeding is easily controlled with bipolar coagulation, packing, or both.

47. Always be prepared to expand the surgical exposure. A straightfoward unilateral lumbar disc herniation rarely requires a complete laminectomy ; however, when the surgical findings do not explain the preoperative symptoms, more open exposure is necessary. Inadequate exposure can also present problems. Identify the dura and the nerve root, and expose the lateral wall adequately before examining the nerve root. Attempting to extract a large, extruded fragment through a small incision may traumatize the involved nerve root unnecessarily.

48. This point is especially important when dealing with a patient who presents with a cauda equina syndrome or a large central herniation without neurologic involvement. In these situations, remove the ligamentum flavum on both sides of the spine. Because the dura mater will be displaced posteriorly , a careful dissection is essential to avoid injury. A laminectomy may be the most appropriate exposure to ensure adequate visualization of the thecal sac and the exiting nerve roots on both sides. Often, the most appropriate beginning may be to perform an annulotomy and discectomy on the side with least herniation to debulk the herniation and to provide easier access to the root under maximal tension.

49. In patients older than 40 years of age, exploration of the neural canal must include a careful assessment of the lateral recess to interpret pathologic changes accurately. Performing a discectomy in a patient who also has lateral entrapment of the nerve root will not reduce the patient's symptoms. Careful probing of the neural foramina at the completion of the lumbar discectomy will locate the narrowing of the neural foramina. If stenosis of the lateral recess is the only manifestation, lumbar discectomy may not be necessary.

50. As with any surgical procedure, a list of potential complications that might occur would be exhaustive. Dural tears may occur during a lumbar discectomy . Such tears are more common in patients who undergo surgery for spinal stenosis or revision procedures. I recommend primary repair of dural tears with 5-0 Dermalon . Injuries to the iliac arteries and veins and viscera, including any structure from the appendix to the ureter , have been reported in association with a lumbar discectomy (15). Errors in diagnosis may occur. The patient may have symptoms suggestive of a lumbar disc herniation , which may, in fact, be related to intra-abdominal pathologic processes such as an aneurysm or a malignancy. Minimize these unusual complications by performing a thorough diagnostic

51. assessment and decision analysis before a decision to operate on the spine. With proper patient selection and careful operative technique, lumbar disc surgery is highly successful and yields gratifying results for both the patient and the surgeon

52. Treatment no surgical Heat and analgesics soothe, and exercises strengthen muscles, but there are only three ways of treating the prolapse itself – rest, reduction or removal, followed by rehabilitation: .

53. Rest With an acute attack the patient should be kept in bed, with hips and knees slightly flexed. A nonsteroidal anti-inflammatory drug is useful. Reduction Continuous bed rest and traction for 2 weeks may reduce the herniation . If the symptoms and signs do not improve during that period, an epidural injection of corticosteroid and local anaesthetic may help

54. Chemonucleolysis dissolution of the nucleus pulposus by percutaneous injection of a proteolytic enzyme ( chymopapain ) – is in theory an excellent way of reducing a disc prolapse . However, controlled studies have shown that it is less effective (and potentially more dangerous) than surgical removal of the disc material (Ejeskar et al., 1982)

55. REFERENCES Chapman's Orthopaedic Surgery 3ed Navigating the Adult Spine Apley__039_s_System_of_Orthopaedics_and_Fractures__9th_Edition Some picuter fro the net