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15

Lumbar Spinal Stenosis

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Topic updated on 07/07/16 12:34pm
Introduction
  • Reduction in dimensions of central or lateral lumbar spinal canal caused by
    • 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 
Classification
  • Etiologic classification
    • acquired
      • degenerative/spondylotic changes (most common)
      • post surgical
      • traumatic (vertebral fractures)
      • inflammatory (ankylosing spondylitis)
    • congenital
      • short pedicles with medially placed facets (e.g., 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
      • presents with nonspecific root compression or symptoms of lower nerve root (at L4/5 level the root of L5 affected)
    • lateral recess stenosis  (subarticular recess)
      • associated with facet joint arthropathy and osteophyte formation
        • overgrowth of superior articular facet usually primary culprit
      • presents with symptoms of descening nerve root (at L4/5 level the root of L5 affected)
    • foraminal stenosis
      • occurs between the medial and lateral border of the pedicle
      • exiting nerve root compressed by ventral cephalad overhang of the superior facet and the bulging disc
      • present with symptoms of exiting nerve root(at L4/5 level the root of L4 affected)
    • extraforaminal stenosis
      • located lateral to the lateral edge of the pedicle
      • lateral disc herniation causes impingement of the existing nerve root
Presentation
  • Symptoms 
    • back pain
    • referred buttock pain
    • claudication
      • pain worse with extension (walking, standing upright) 
      • pain relieved with flexion (sitting, leaning over shopping cart, sleeping in fetal position) 
    • leg pain (often unilateral)
    • 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 extension of back
    • Straight leg raise (tension sign)
      • is usually negative
    • Valsalva test
      • radicular pain not worsened by Valsalva as is the case with a herniated disc
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

Imaging
  • Radiographs
    • 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
    • findings include
      • 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
      • Boden et al found that three of 14 asymptomatic patients and MRI findings of anatomic spinal stenosis
  • CT myelogram
    • more invasive than MRI
    • findings include
      • 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) effective and may obviate 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 deficit (weakness or bowel/bladder)
      • 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 pedicle-to-pedicle decompression with instrumented fusion
      • indications
        • presence of segmental instability (isthmic spondylolisthesis, degenerative spondylolisthesis, degenerative scoliosis)
        • surgical instability created by complete laminectomy and/or removal of > 50% of facets 
Surgical Techniques
  • Wide pedicle-to-pedicle decompression 
    • a single level decompression at L4/5 would include
      • resect inferior half of spinous process of L4
      • resect L4 lamina to the level of the insertion of the ligamentum flavum
      • resect 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 foramen
        • palpate L4 and L5 pedicle (pedicle-to-pedicle) and be sure nerve root is patent below it.
  • Wide decompression with posterolateral fusion
    • technique
      • 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 complication 
    • wound infection (10%) 
      • deep surgical infections are to be treated with surgical debridement and irrigation 
    • pneumonia (5%)
    • renal failure (5%)
    • neurologic deficits (2%)
  • Minor complication
    • UTI (34%)
    • anemia requiring transfusion (27%)
    • confusion (27%)
    • dural tear  
    • failure for symptoms to improve 

 

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Qbank (20 Questions)

TAG
(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? Topic Review Topic
FIGURES: A   B        

1. Continue routine postoperative care
2. Placement of a lumbar drain with a period of bedrest
3. Hospital admission, IV antibiotics, and serial ESR and CRP
4. CT guided aspiration
5. Surgical irrigation and debridement with commencement of antibiotics after cultures are obtained.

PREFERRED RESPONSE ▶
TAG
(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? Topic Review Topic
FIGURES: A   B        

1. A decompressive laminectomy with bilateral medial facetectomies and foraminotomies
2. A decompressive laminectomy, bilateral medial facetectomies and foraminotomies, and an instrumented fusion
3. A left sided microdiskectomy
4. Continues physical therapy
5. Referral to vascular surgery for evaluation for peripheral vascular disease

PREFERRED RESPONSE ▶
TAG
(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? Topic Review Topic
FIGURES: A   B   C   D   E   F

1. Continued physical therapy
2. L4/5 microdiskectomy with a midline approach
3. L4/5 microdiskectomy with a Wiltse far lateral approach
4. L4/5 laminectomy, bilateral lateral recess decompression and foraminotomies
5. L4/5 laminectomy, bilateral lateral recess decompression and foraminotomies, and instrumented fusion

PREFERRED RESPONSE ▶
TAG
(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. Topic Review Topic
FIGURES: A   B        

1. Segmental instability
2. Postoperative infection
3. Recurrent disk herniation
4. Residual foraminal stenosis
5. Cauda equina syndrome

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

1. Removal of > 50% of the L4/5 nucleus pulpusus
2. Removal of the L4 and L5 spinous process and interspinous ligament
3. A medial facetectomy removing 20% of the right L4/5 facet joint
4. Bilateral resection of the L4 inferior articular process
5. A unilateral hemilaminectomy

PREFERRED RESPONSE ▶
TAG
(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? Topic Review Topic

1. there is an increased risk of wound infection
2. the patient must remain flat in bed for seven days
3. the clinical outcome will not be affected
4. the patient will have a worse clinical outcome
5. the patient should remain on PO antibiotics for ten days following surgery

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

1. Worse clinical outcomes at four years
2. No difference in clinical outcomes at four years
3. Improved clinical outcomes in pain only at four years
4. Improved clinical outcomes in function only at four years
5. Improved clinical outcomes in pain and function at four years

PREFERRED RESPONSE ▶
TAG
(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? Topic Review Topic

1. Viral meningitis
2. Bacterial meningitis
3. Vertigo
4. Cerebrospinal fluid leak
5. Epidural abscess

PREFERRED RESPONSE ▶
TAG
(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. Topic Review Topic
FIGURES: A          

1. Smoking
2. Anterior compression due to disc herniation
3. Comorbid medical conditions
4. Multi-level stenosis
5. Average household income

PREFERRED RESPONSE ▶
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