LUMBAR SPINAL STENOSIS

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Dennis Harper
5 years ago
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1 LUMBAR SPINAL STENOSIS Always occurs in the mobile segment. Factors play role in Stenosis Pre existing congenital or developmental narrowing of the lumbar spinal canal Translation of one anatomic segment on the next Shape of the canal: Trefoil canal Degenerative changes reducing canal size [ligamentum flavum hypertrophy, Facetal hypertrophy and annular bulge] Classification I Congenital Achondroplastic II Developmental Idiopathic III Dysplasia Osteopetrosis IV Acquired: Degenerative: Central or Lateral Degenerative spondylolisthesis V Traumatic VI Iatrogenic Post fusion or Post laminectomy VII Miscellaneous Acromegaly, Paget, Fluorosis Pathogenesis Degeneration starts at years and by 50 years most have some degree of degeneration. Common site is at L4 5 and L5 1. Biomechanical Changes in the disc occurs first. Altered disc is less efficient and more stresses are transmitted to facetal joint resulting in degeneration of the facet joint. Enlarged facets and osteophytes cause Stenosis In a normal spinal canal, the nerve moves as much as five mm within the neuroforamen. Because of adhesion, this movement is lost in stenosis causing inflammation. The inflammation of the nerve, causes pain. Stenosis can be bony or soft tissue A. Bony stenosis can be further divided into I Central Stenosis II Lateral Stenosis (Lee):A Entry zone B Mid zone C Foraminal Stenosis B. Soft tissue Stenosis: hypertrophied ligamentum flavum

2 Lateral Stenosis A The entrance zone is the most cephalad part and is located underneath the superior articular facet. The anterior wall is the posterior surface of the disc, and the posterior wall is the facetal joint B The mid zone is located under the pars interarticularis. The anterior border of this zone is the posterior aspect of the vertebral body. The posterior border is the pars interarticularis. The lateral border is the pedicle. The mid zone contains the dorsal root ganglion C. The exit zone is the area surrounding the IVF foramen. Clinical Vague backache and leg complaints Neurogenic claudication. Walking distance get reduced Walking downhill is the problem; Cycling is not a problem Trolley sign [feels better on leaning on the trolley] Have a stooped posture Neurogenic Vs Vascular claudication Vascular Neurogenic Type Sharp/cramping Vague, heavinesss Location Calf Radicular or diffuse Radiation None Proximal to distal Aggravation Walking Walking/standing Relief Standing still Bend/squat Relief Quick slow Neurological symptoms Absent Present Claudication distance Constant Variable Walking uphill, bike Claudication present Absent SLR Negative May be positive

Bizarre neurology: Single or multiple nerve root involvement Sensory more than motor involvement L4 5 lateral recess is commonly involved and transit nerve root [L5] nerve root Look for bowel and

3 Bizarre neurology: Single or multiple nerve root involvement Sensory more than motor involvement L4 5 lateral recess is commonly involved and transit nerve root [L5] nerve root Look for bowel and bladder function Feel pulses in the foot Investigations 1. Radiological a. Rule out any destructive lesion of the vertebra b. Look for disc degeneration and facetal joint arthritis c. Direct spinal canal measurements are not reliable Jones Index: Canal: body ratio 1:2 to 1:4.5 Eisenstein direct Anteroposterior canal diameter < 10 mm is absolute Stenosis 2. Myelographic: Defect increases with extension of the spine Filling defect of the dural sleeve Redundant nerve root Because it is an invasive test, it is hardly indicated these days

4 3. CT: Normal canal area is 100 sq mm In stenosis at the top of the disc area is less than 77 sq.mm 4. MRI Gold standard Gives sagittal, coronal and axial view of the canal Can estimate soft tissue encroachment as well as bony stenosis Look at the level of pedicle for lateral recess stenosis Mean AP diameter: 12 mm (Absolute <10) Minimal cross section area: 77+/ 13 Sq mm(thecal area) Differential diagnosis Natural Course At 4 years follow up on non surgical patients: 70% unchanged; 15% improved and 15% worsened At 4 years of treatment Higher good results with surgical treatment (63%) compared with nonsurgical treatment (42%) Treatment William exercises is recommended to reduce lumbar Lordosis NSAID Swimming Epidural steroid: effective. Results: temporary relief of radicular pain in 50% of patients Calcitonin: May increase blood circulation Flexion brace: indicated for intermittent claudication (Williams brace)

5 Surgical Treatment Central Stenosis 1.Decompression lumbar laminectomy at the stenotic segment. 2.The decompression begin away from the area of maximal stenosis 3.Usually start from the midline and extend laterally 4.Should be carried out from caudad to cephalad direction. 5.Beware of dural adhesions 6.Facets can excised safely by 50% 7.When whole facet removed: need arthrodesis 8.Always check adequacy of decompression in the lateral recess If poor dural pulsations, or tight lateral recess, further decompression is indicated in the lateral direction, usually requiring resection of the medial portion of the superior facets. Lateral Recess Stenosis The lateral Stenosis is usually single level 3 mm Probe tight means mid zone is tight and need complete excision of facet and if it is still tight means exist zone is tight. More decompress is necessary and excise anterior osteophytes and fusion is required if stability is the issue. Width and length of decompression? Not clear and is controversial. It is logical to decompress what is shown on the clinical findings. No need to decompress skip stenosis if there is no clinical indication. But decompress adjacent area. Foramen Stenosis 1. Remove inferior facet 2. Interbody fusion to increase the height 3. Immobilize the segment. When arthrodesis is indicated? 1. Degenerative spondylolisthesis 2. Preexisting scoliosis or Kyphosis. > 20º 3. Recurrent spinal Stenosis/Disc operation 4. Instability: movement more than 4 mm or angular changes over 10º. 5. Nearly sagittal inclination of the facet joint When fusion surgery is indicated: instrumentation is better. With the instrumentation, pseudarthrosis rate is low. However, there is no correlation with clinical outcome and pseudarthrosis. Disadvantages of spinal fusion is 30% transition syndrome at 10 yrs

Results Most authors reported 85% good to excellent results after decompression. In a prospective randomized study, better outcome in the group that had concomitant arthrodesis.

group. They concluded that instrumentation improves the fusion rate but does not change the clinical outcome. Spinous process distraction devices Failed non op treatment for neurogenic claudication 1.

6 Results Most authors reported 85% good to excellent results after decompression. In a prospective randomized study, better outcome in the group that had concomitant arthrodesis. The pseudarthrodesis rate was 36%; but the clinical results were good or excellent Another prospective randomized arthrodesis with or without instrumentation: 83% fusion rate in the instrumented group. They concluded that instrumentation improves the fusion rate but does not change the clinical outcome. Spinous process distraction devices Failed non op treatment for neurogenic claudication 1. Lumbar epidural steroid injections 2. Interspinous process spacers, a relatively new class of technology, are proposed for use in the patient who prefers less invasive surgery or in whom medical comorbidities preclude a major surgical procedure. Sufficient medium and long term data are lacking. Although interspinous process spacers are a promising new technology, the results of longer term clinical follow up studies are needed to more clearly define their role

Peggers Super Summaries: The Aging Spine

Peggers Super Summaries: The Aging Spine Aging Spine: AGING PROCESS Osteopenia 10% of 50 year old males and 25% of 50 year females Disc dehydration Facet degeneration Soft tissue hypertrophy 2 0 deformity Leg pain worse than back pain from nerve