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Introduction
  • Overview
    • lumbar spinal stenosis is a degenerative condition characterized by narrowing of the lumbar spinal canal due to 
      • bony structures
        • facet osteophytes
        • uncinate spur (posterior vertebral body osteophyte)
        • spondylolisthesis
      • soft tissue structures
        • herniated or bulging discs
        • hypertrophy or buckling of the ligamentum flavum 
        • synovial facet cysts 
  • Epidemiology
    • incidence
      • most common reason for lumbar spine surgery in patients > 65 years old
      • seen in 20-25%
    • demographics
      • slightly more common in males (1.5:1)
      • average age at presentation is 65 years old
    • location
      • most commonly occurs at L4-5 (91%)
    • risk factors
      • Caucasian race
      • increased BMI
      • congenital spine anomalies (20%)
        • failure of posterior elements to develop, leading to short pedicles and laminae
  • Pathophysiology
    • cell, water, and proteoglycan content in the nucleus pulposus decreases with age
    • degeneration of the intervertebral disk leads to diminished disk height and buckling/bulding of the anulus fibrosus
    • anterior spinal column begins to have decreased ability to absorb stress, leading to an abnormal transfer of force to the posterior elements
    • increased stress through the facets leads to facet joint hypertrophy, osteophyte formation, and ligamentum flavum buckling and hypertrophy
    • combined changes lead to a narrowing of the spinal canal and compression of the neural elements
  • Associated conditions
    • degenerative spondylolisthesis
    • degenerative scoliosis
    • cauda equina syndrome
      • rare
Anatomy
  • Osteology  
    • anterior vertebral body
    • posterior arch
      • formed by
        • pedicles
          • pedicles project posteriorly from posterolateral corners of vertebral bodies
        • lamina
          • lamina project posteromedially from pedicles, join in the midline
    • spinous process
    • transverse process
    • mammillary processes
      • separate ossification centers
      • project posteriorly from superior articular facet
    • pars interarticularis
      • mass of bone between superior and inferior articular facets
      • site of spondylolysis  
  • Articulations
    • intervertebral disc 
      • act as an articulation above and below
    •  facet joint (zygapophyseal joint)
      • formed by superior and inferior articular processes that project from junction of pedicle and lamina
      • facet orientation
        • facets become more coronal as you move inferior
  • Nerve roots
    • nerve root exits foramen under same numbered pedicle
    •  
      • central herniations affect traversing nerve root  
      • far lateral herniations affect exiting nerve root   
  • Blood Supply
    • segmental arteries
      • dorsal branches supply blood to the dura & posterior elements
Classification
  • Etiologic classification
    • acquired
      • degenerative/spondylotic changes (most common)
      • post-surgical
      • post-traumatic (vertebral fractures)
      • inflammatory (ankylosing spondylitis)
      • secondary to systemic diseases (Paget disease, acromegaly, fluorosis)
    • congenital
      • short pedicles with medially placed facets
      • can be subdivided into
        • idiopathic
        • developmental (achondroplasia)
  • Anatomic classification
    • central stenosis
      • cross sectional area <100mm2 or <10mm A-P diameter on axial CT 
      • caused by ligamentum hypertrophy directly under the lamina posteriorly and the bulging disc anteriorly
      • results in thecal sac compression
      • presents with nonspecific root compression or symptoms of lower nerve root (at the L4/5 level, the root of L5 is affected)
    • lateral recess stenosis (subarticular recess)
      • caused by facet joint arthropathy and osteophyte formation
        • overgrowth of the superior articular facet is usually the primary culprit
      • results in nerve root compression
      • presents with symptoms of descending nerve root (at the L4/5 level, the root of L5 is affected)
    • foraminal stenosis
      • occurs between the medial and lateral border of the pedicle
      • caused by a substantial loss of disk height, foraminal disk protrusions or osteophytes, or angulation in the setting of degenerative scoliosis
      • results in nerve root compression by the ventral cephalad overhang of the superior facet and the bulging disc
      • presents with symptoms of exiting nerve root (at the L4/5 level, the root of L4 is affected)
    • extraforaminal stenosis
      • located lateral to the lateral edge of the pedicle
      • caused by far lateral disc herniations
      • presents with symptoms of exiting nerve root (at the L4/5 level, the root of L4 is affected)
Presentation
  • Symptoms 
    • back pain 
    • referred buttock pain
    • leg pain
      • often unilateral
    • neurogenic claudication
      • pain worse with extension (walking, standing upright) 
      • pain relieved with flexion (sitting, leaning over shopping cart, sleeping in fetal position) 
    • weakness
    • bladder disturbances
      • recurrent UTI present in up to 10% due to autonomic sphincter dysfunction
    • cauda equina syndrome (rare)
  • Physical exam 
    • Kemp sign
      • unilateral radicular pain from foraminal stenosis made worse by back extension
    • straight leg raise (tension sign)
      • usually negative
    • Valsalva test
      • radicular pain not worsened by Valsalva as is the case with a herniated disc
    • normal neurologic exam 
      • patients may have no focal deficits, as exam often takes place with patient seated and symptoms may be reproducible or exacerbated only with lumbar extension or ambulation
Differential
  • Important to differentiate symptoms of neurogenic claudication from vascular claudication    
    • flexion improves symptoms in neurogenic claudication because this posture increases the limited area available for the neural elements in the spinal canal and foramen
ff
Neurogenic Claudication
Vascular Claudication
Postural changes
Yes
No
Walking upright
Causes symptoms
Causes symptoms
Standing stationary
Causes symptoms
Relieves symptoms
Sitting
Relieves symptoms
Relieves symptoms
Stair climbing
Up easier (back flexed)
Down easier (back extended)
Stationary bicycle (back flexed)
Relieves symptoms
Causes symptoms
Pulses
Normal
Abnormal
  • Hip-spine syndrome
    • presence of coexisting hip and spine pathology
    • must determine primary pain generatory prior to surgical treatment
    • may require diagnostic injections to aid in diagnosis 
Imaging
  • Radiographs
    • findings do not always correlate with clinical symptomatology
    • standing AP and lateral may show
      • nonspecific degenerative findings (disk space narrowing, osteophyte formation)
      • degenerative scoliosis
      • degenerative spondylolisthesis  
    • flexion/extension radiographs may show
      • segmental instability and subtle degenerative spondylolisthesis
    • myelogram
      • plain film myelography provides dynamic information such as degree of cut off when a patient goes into extension
      • an invasive procedure
  • MRI
    • imaging modality of choice
    • findings
      • central stenosis with a thecal sac <100mm2    
      • obliteration of perineural fat and compression of lateral recess or foramen 
      • facet and ligamentum hypertrophy
    • MRI findings of spinal stenosis may found in asymptomatic patients
  • CT myelogram
    • more invasive than MRI
    • findings
      • central and lateral neural element compression 
      • bony anomalies
      • bony facet hypertrophy
Treatment
  • Nonoperative
    • oral medications, physical therapy, and corticosteroid injections
      • indications
        • first line of treatment
    • modalities include
      • NSAIDS, physical therapy, weight loss and bracing
      • steroid injections (epidural and transforaminal)
        • found to be effective and may obviate the need for surgery
  • Operative
    • wide pedicle-to-pedicle decompression    
      • indications
        • persistent pain for 3-6 months that has failed to improve with nonoperative management
        • progressive neurologic deficits (weakness or bowel/bladder)
    • wide pedicle-to-pedicle decompression with instrumented fusion
      • indications
        • segmental instability (isthmic spondylolisthesis, degenerative spondylolisthesis, degenerative scoliosis)
        • surgical instability
          • created by complete laminectomy and/or removal of > 50% of facets  
        • risk of adjacent segment degeneration >30% at 10 years
Techniques
  • Wide pedicle-to-pedicle decompression 
    • technique
      • a single level decompression at L4/5 would include
        • resection of the inferior half of spinous process of L4
        • resection of the L4 lamina to the level of the insertion of the ligamentum flavum
        • resection of the ligamentum flavum
        • medial facetectomy and lateral recess decompression
          • undercutting of facets and removal of ligamentum flavum from lateral recess
        • exploration and decompression of the L4/5 and L5/S1 foramina
          • palpate L4 and L5 pedicle (pedicle-to-pedicle) and be sure the nerve root is patent below it
    • complications specific to this treatment
      • infection
      • dural tear
      • epidural hematoma
      • instability
    • outcomes
      • improved pain, function, and satisfaction with surgical treatment   
      • most common cause of failed surgery is recurrence of disease above or below decompressed level
      • comorbid conditions are strongest predictor of clinical outcomes after decompression for lumbar spinal stenosis 
  • Wide decompression with posterolateral fusion
    • instrumentation is controversial
    • circumferential fusion (with PLIF or TLIF) is accepted but no studies showing its superiority
Complications 
  • Complications increase with age, blood loss, and levels fused
  • Major complications
    • wound infection (10%) 
      • deep surgical infections are to be treated with surgical debridement and irrigation 
    • pneumonia (5%)
    • renal failure (5%)
    • neurologic deficits (2%)
  • Minor complications
    • UTI (34%)
    • anemia requiring transfusion (27%)
    • confusion (27%)
    • dural tear  
    • failure for symptoms to improve 
 

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Questions (30)
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(OBQ13.222) A surgical procedure is performed that involves removing the spinous process of L4, resecting the inferior 80% of the lamina on the right and the left of L4, and then removing the ligamentum flavum down to the superior lamina of L5. A bilateral medial faceteomy is performed that removed the medial 20% of the facet. The wound is then closed, and no instrumentation or fusion is performed. This procedure would be indicated in which of the following: Review Topic

QID: 4857
FIGURES:
1

28-year old male with severe unilateral leg pain for 8 months that has failed nonoperative treatment. Imaging studies are shown in Figure A.

2%

(56/2250)

2

18-year old female with isolated low back pain that has failed to respond to 6 weeks of physical therapy. Imaging studies are shown in Figure B.

1%

(26/2250)

3

65-year old male with bilateral buttock pain, worse with walking and improves with sitting, that has failed epidural injections. Imaging studies are shown in Figure C.

80%

(1797/2250)

4

22-year old male with isolated low back pain, that has failed non-operative management. Imaging studies are shown in Figure D.

3%

(63/2250)

5

31-year old male with bilateral buttock pain, worse with walking and improves with sitting, that has failed epidural injections. Imaging studies are shown in Figure E

12%

(280/2250)

L 2

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(OBQ13.190) A 58-year-old man presents to the clinic with 9 months of progressive right lower extremity pain. Over the past 4 months, he also notes a decreased ability to walk long distances due to pain, which is relieved by sitting down. Figure A and B are his T2 sagittal and axial MRI scans, respectively. Which of the following statements is true regarding this patient's 4-year outcome in regards to surgical and non-surgical management? Review Topic

QID: 4825
FIGURES:
1

Surgical management will lead to more improvement in pain but not function

7%

(211/3081)

2

Surgical management will have higher 4-year mortality

2%

(47/3081)

3

Surgical management will lead to more improvement in pain, function, and satisfaction

86%

(2649/3081)

4

Nonsurgical management will lead to more improvement in pain but not function

1%

(30/3081)

5

Surgical management will lead more improvement in function, but less improvement in pain

4%

(123/3081)

L 3

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(SBQ12SP.53) A 69-year-old man presents to clinic with 9 months of worsening back and lower extremity pain that is worse with walking. Pain is improved by sitting down and leaning forward. He has attempted physical therapy without improvement in symptoms. A T2-weighted midline sagittal image is shown in Figure A. A T2-weighted axial image at the L4/5 disc space is shown in Figure B. A flexion and extension lateral radiograph are shown in Figure C and D. Performing a lumbar decompressive laminectomy alone at L4/5 will lead to which of the following? Review Topic

QID: 3751
FIGURES:
1

Increased risk of adjacent segment degeneration requiring surgery

9%

(152/1631)

2

No improvement in symptoms compared to epidural steroid injection (ESI) at 4 years

2%

(26/1631)

3

Improvement in pain, function and disability compared to nonoperative treatment at 2 years but not 4 years

12%

(201/1631)

4

Improvement in pain, function and disability compared to nonoperative treatment at 2 and 4 years

69%

(1120/1631)

5

No improvement in pain, function, and disability compared to nonoperative treatment at 2 and 4 years

7%

(110/1631)

L 3

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(OBQ12.44) A 45-year-old male underwent a lumbar discectomy 8 weeks ago. His surgery was remarkable for a dural tear that was repaired. He now presents with recurrence of his leg pain and back pain. Physical exam shows some mild erythema surrounding the incision. An MRI with and without gadolinium is performed and shown in Figure A and B. What is the most appropriate next step in management? Review Topic

QID: 4404
FIGURES:
1

Continue routine postoperative care

1%

(63/4371)

2

Placement of a lumbar drain with a period of bedrest

1%

(32/4371)

3

Hospital admission, IV antibiotics, and serial ESR and CRP

14%

(610/4371)

4

CT guided aspiration

15%

(637/4371)

5

Surgical irrigation and debridement with commencement of antibiotics after cultures are obtained.

69%

(3007/4371)

L 3

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(OBQ10.249) A 62-year-old man presents with 6 months of bilateral buttock and leg pain that is worse with prolonged standing and relieved with sitting. He denies symptoms with exercise on a stationary bike. Initial treatment including physical therapy, NSAIDS, and an epidural steroid injection provided only temporary relief of his symptoms, which have returned and are now severe. On physical exam he has normal motor strength in his lower extremities, negative straight-leg raise tests bilaterally, and palpable bilateral dorsalis pedis pulses. Lumbar flexion-extension radiographs show no spondylolisthesis or instability. A sagittal and axial T2 MRI is shown in Figure A and B, respectively. What is the most appropriate next step in management? Review Topic

QID: 3348
FIGURES:
1

A decompressive laminectomy with bilateral medial facetectomies and foraminotomies

67%

(1725/2590)

2

A decompressive laminectomy, bilateral medial facetectomies and foraminotomies, and an instrumented fusion

28%

(728/2590)

3

A left sided microdiskectomy

2%

(53/2590)

4

Continues physical therapy

2%

(43/2590)

5

Referral to vascular surgery for evaluation for peripheral vascular disease

1%

(22/2590)

L 3

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(OBQ09.148) A 68-year-old man presents with bilateral buttock and leg pain, worse on the right. His pain is worse with prolonged standing and improves with sitting. His symptoms have progressed to the point that it is now difficult for him to walk to the mailbox. His physical exam is remarkable for 4/5 weakness to ankle dorsiflexion on the right. Four months of physical therapy and a series of epidural corticosteroid injections failed to improve his symptoms.

Figure A and B are an AP and lateral lumbar spine radiograph. Figures C and D are flexion/extension radiographs. Figure E is a sagittal MRI, and Figure F is an axial MRI through L4/5. The axial images through L3/4 and L5/S1 do not demonstrate any signs of significant nerve root compression.

What is the most appropriate next step in treatment?
Review Topic

QID: 2961
FIGURES:
1

Continued physical therapy

1%

(25/2224)

2

L4/5 microdiskectomy with a midline approach

15%

(339/2224)

3

L4/5 microdiskectomy with a Wiltse far lateral approach

7%

(146/2224)

4

L4/5 laminectomy, bilateral lateral recess decompression and foraminotomies

53%

(1171/2224)

5

L4/5 laminectomy, bilateral lateral recess decompression and foraminotomies, and instrumented fusion

24%

(525/2224)

L 4

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(OBQ08.256) During lumbar decompression at L4/5, which of the following decompression techniques will destabilize the spine and require a L4/5 fusion. Review Topic

QID: 642
1

Removal of > 50% of the L4/5 nucleus pulpusus

2%

(60/2445)

2

Removal of the L4 and L5 spinous process and interspinous ligament

4%

(106/2445)

3

A medial facetectomy removing 20% of the right L4/5 facet joint

2%

(55/2445)

4

Bilateral resection of the L4 inferior articular process

90%

(2191/2445)

5

A unilateral hemilaminectomy

1%

(16/2445)

L 1

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(OBQ08.209) A 62-year-old female has a decompressive laminectomy for spinal stenosis and symptoms of right leg pain. Preoperative flexion and extension radiographs of the lumbar spine are shown in Figure A. A preoperative sagittal MRI is shown in Figure B. Following surgery she reports no significant improvement in her right leg pain. What is the most likely cause of her residual leg pain. Review Topic

QID: 595
FIGURES:
1

Segmental instability

14%

(330/2434)

2

Postoperative infection

0%

(12/2434)

3

Recurrent disk herniation

5%

(126/2434)

4

Residual foraminal stenosis

80%

(1944/2434)

5

Cauda equina syndrome

0%

(5/2434)

L 2

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(OBQ07.94) A dural tear occurs during a routine lumbar laminectomy for spinal stenosis. A water-tight repair is subsequently performed. How will this affect postoperative care and ultimate clinical outcomes? Review Topic

QID: 755
1

there is an increased risk of wound infection

4%

(93/2301)

2

the patient must remain flat in bed for seven days

4%

(87/2301)

3

the clinical outcome will not be affected

88%

(2036/2301)

4

the patient will have a worse clinical outcome

1%

(30/2301)

5

the patient should remain on PO antibiotics for ten days following surgery

2%

(51/2301)

L 1

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(OBQ06.124) Patients with symptomatic spinal stenosis treated with surgical decompression compared to those treated nonoperatively have what clinical outcomes. Review Topic

QID: 310
1

Worse clinical outcomes at four years

1%

(15/2427)

2

No difference in clinical outcomes at four years

17%

(414/2427)

3

Improved clinical outcomes in pain only at four years

5%

(115/2427)

4

Improved clinical outcomes in function only at four years

5%

(123/2427)

5

Improved clinical outcomes in pain and function at four years

72%

(1752/2427)

L 3

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(OBQ05.167) A 32-year-old man underwent a lumbar microdiskectomy and an incidental dural tear occurred. A hemilaminectomy was performed to obtain adequate visualization of the defect, and primary repair of the tear was performed. One month postoperatively he returns to the office complaining of severe headaches and occasional nausea which is worse with standing. He denies fever or chills. On physical exam his wound is well healed with no cellulitis or erythema. WBC and ESR are within normal limits. What is the most likely diagnosis? Review Topic

QID: 1053
1

Viral meningitis

0%

(11/2493)

2

Bacterial meningitis

0%

(7/2493)

3

Vertigo

1%

(26/2493)

4

Cerebrospinal fluid leak

98%

(2432/2493)

5

Epidural abscess

0%

(10/2493)

L 1

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(OBQ04.5) A 71-year-old female is admitted to the hospital for severe bilateral buttock and leg pain with ambulation that has failed to improve with nonoperative management. An MRI is shown in Figure A. You plan on proceeding with lumbar decompression. What is the most powerful preoperative prognostic factor for clinical outcomes with surgical treatment of this condition. Review Topic

QID: 116
FIGURES:
1

Smoking

19%

(238/1223)

2

Anterior compression due to disc herniation

4%

(54/1223)

3

Comorbid medical conditions

54%

(666/1223)

4

Multi-level stenosis

17%

(211/1223)

5

Average household income

4%

(51/1223)

L 4

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