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Spinal stenosis

This document discusses spinal stenosis, covering its anatomy, classification, symptoms, diagnostic studies, and treatment options. It highlights the evolution of surgical techniques and emphasizes the importance of proper patient selection for achieving favorable outcomes. The document also addresses complications and postoperative rehabilitation considerations.

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Spinal stenosis

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Spinal Stenosis Dr.Mukhtar Neurosurgery HMC
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Roadmap 1. BasicAnatomy 2. Classification & Description 3. Symptoms & Signs 4. Diagnostic Studies 5. Pathology mimicking stenosis 6. Associated conditions 7. Nonsurgical vs Surgical Management 8. Pre and Postop considerations 9. Minimally invasive Surgery 10. Expansive Laminoplasty 11. Open Decomp 12. Outcome 12.Surgical Techniques 13.Complications 14.Postop rehabilitation
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Historical perspective
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• 1803 =>Portal of France postulated the cause of back & legs pain • 1893 => Lane of England performed first laminectomy • 1911 => Bailey & Casamajor on spinal pains & facet joint exostosis • 1954 => Verbiest described the syndrome of lumber stenosis • 1978 => Kirkaldy-Willis et al on pathology & pathogenesis (Three Joints Complex)
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Basic Anatomy
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Lumber Spine
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Spinal Canal
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Diameters • APDiameter: 15-27 mm • Lateral Recess: 3-4 mm • AP diameter < 12 mm is stenotic (10 mm is definite) • Lateral Recess < 3 mm is stenotic
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The Lateral Recess
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Classification & Description
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Aetiological Classification •Congenital-developmental stenosis • Idiopathic • Achondroplastic • Acquired stenosis • Degenerative (most common type) • Combined congenital and degenerative stenosis • Spondylitic/spondylolisthetic • Iatrogenic (i.e., postlaminectomy, postfusion) • Posttraumatic • Metabolic (i.e., Paget’s disease, fluorosis)
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Anatomic Classification •Central Canal Stenosis: Narrowing of the AP dimension • Foraminal stenosis • Lateral recess stenosis
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Mechanistic Classification •Stable: Facet & LF hypertrophy with disc degeneration • Unstable: Stable form with spondylolisthesis &/or scoliosis
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• Contributing factors: • Thick laminae, arthrotic facets, exaggerated lordotic curvatures, infolding of hypertrophied LF, ossification of posterior longitudinal ligament (OPLL) • Paget’s disease, acromegaly, fluorosis as well as achondroplasia • L4-L5 is the commonest level • L3-L4, L2-L3, L5-S1 & L1-L2 in descending order of frequency
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Clinical
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• Neurogenic Claudication(pseudoclaudication) • From Latin Claudico = to Limp • Uni- or bilateral buttock, hip, thighs or leg discomfort • Precipitated by standing or walking • Relieved by change in erect posture • Pain may not be the major complaint • Paraesthesias or leg weakness with walking • Muscle cramping, especially in the calves
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• Neurogenic claudication:(moderately sensitive but highly specific) • direct mechanical compression • Indirect vascular insufficiency • Lordosis increased in standing & walking, hence more pain • Recumbence & sitting reverses lordosis, canal opens, blood flow improves, distracts the facet joints and pain is relieved
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• Anthropoid posture • Shopping cart sign
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• Normal neurologicexam in 18% (normal SLR & stretch tests) • L5, L4, L3 & S1 root syndromes • Ankle & Knee Jerk tests • Pain on lumber extension tests • Bladder dysfunction • Uncommon in younger patients • 60% elderly subjectively improved 6 months after laminectomies
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Neurogenic vs VascularClaudication Feature Neurogenic claudication Vascular claudication Pain distribution Dermatomal Sclerotomal Sensory loss Dermatomal Stocking type Aggravating factors • Variable amount of physical activity • Pain on standing (65%) • Coughing (38%) • Fixed amount of activity • Rest pain rare • Pain on standing (27%) Relief with rest • Slow (> 30 min) • Special posture Immediate No special posture Claudication distance Variable day to day (62%) Constant (88%) Lifting or bending Pain common (67%) Uncommon (15%) Limb elevation No pallor Profound Pulses Normal Absent or decreased Skin temperature Normal Decreased
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Differentials • Vascularinsufficiency • Hip disease • Disc herniation • Baastrup’s syndrome • Arachnoiditis • Spinal tumour • Diabetic neuritis • Delayed onset muscle soreness (DOMS) • Functional aetiologies
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Diagnostic studies
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Plain radiography •Bony abnormalities • Number of vertebrae • Curvatures • Olisthesis & instability • > 4 mm translation • 10 – 12 degrees angulation Normal AP Diameters on Lateral Film Average 22 – 25 mm Lower normal 15 mm Severe stenosis < 11 mm
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• Interpediculate distance • Denotes the transverse diameter • < 25 mm suggests stenosis • (Lumbar level + 12) 1.5 Interpedicular distance on AP X-ray T10 16-22 mm T11 17-24 mm T12 19-27 mm L1 21-29 mm L2 21-30 mm L3 21-31 mm L4 21-33 mm L5 23-37 mm
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CT scan •Canal morphology • Diameters • Ligaments • Facet joints • Annulus • Disc • Hairline fractures & pseudoarthroses Normal measurements on CT AP ≥ 11.5 mm Interpedicular Distance ≥ 16 mm Canal cross-sectional area ≥ 1.45 cm2 Ligamentum flavum thickness ≤ 4- 5 mm Lateral recess height ≥ 3 mm
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MRI • Bestsoft tissues assessment but NOT bone • Neural structures impingement • Ligamentous morphology & Disc assessment • Multidimensional views without bony pathology details • Facet joints fluid volume assessment • width of fluid in both facet joints divided by sum of the width of both facets • Increased facet fluid indicates instability • Contrast MRI differentiates scar from disc • Thoracolumbar junction, differentiation of tumour, demyelination, arachnoiditis & infective spondylitis • 1/3rd of asymptomatic pathology revealed on routine MRIs
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Pathology mimicking stenosis
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• Tumours locatedproximally contributing to lumbar complaints • Ependymomas, neurofibromas, meningioma, mets • Thoracic disc herniation, Scheuermann’s disease, Paget’s disease, hip arthritis • Amyloid crystal deposition in ligamentum flavum • Diabetic peripheral neuropathy in diabetics • Femoral amyotrophy or angiopathy • Diabetics exhibited only 39% good or excellent outcome as compared to 95% for those without diabetes • Peripheral vascular disease may present alone or in the presence of stenosis
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Associated conditions
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• Tandem stenosis: • 10% of patients with lumbar stenosis • Surgery is dictated by the severity of stenosis • Relative vs absolute stenosis • Radiculopathy vs Myelopathy • Elderly (> 65 y) need stringent search for proximal stenosis before surgery
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1) Ossification ofthe Yellow Ligament (Ligamentum Flavum) 2) Ossification of the Posterior Longitudinal Ligament (10%) 3) Ankylosing Hyperostosis 4) Disk Herniation with and without Olisthesis 5) Limbus Vertebral Fracture 6) Far Lateral Disk Pathology 7) Synovial Cysts 8) Degenerative Spondylolisthesis
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Nonsurgical versus surgicalmanagement
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• Role ofthe multidisciplinary pain management teams • Severe comorbidities or preference for conservative treatment • Several studies have shown similar outcome in surgical vs medically treated groups • Other studies have shown improved outcome for surgical intervention (63% vs 25%)
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Preop vs postopconsiderations
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• Medical &psychological comorbidities negatively impact postop outcome • Comorbid factors: • Cardiac • Older patient population more prevalent with cardiac comorbids • Preop psychiatric clearance • Significant effect of depression on postop outcome • Up to 20% found depressed preoperatively • Non-depressed patients good overall outcome
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• Preoperative Bathing • Twice a day with soap & water (during a week before surgery) • Chlorhexidine-impregnated sponges a night before & morning of surgery • Prophylactic antibiotics • Reported incidence of infection = 3% to 12% • Comparable infection rates in multiple vs single dose antibiotics regimens (1.15% vs 1.49%) • Ideal prophylactic antibiotic = second generation cephalosporin within 15-30 min of incision • Gentamicin 80 mg preoperatively confers protection against MRSA • Irrigation with bacitracin & polymyxin B every 15 min • These measures reduce perop culture positivity from 64% to 4%
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• Silver-Impregnated Dressings • Inhibit proinflammatory cytokines, upregulates zinc metabolism, increasing epithelialisation • Postoperatively, a silver-impregnated dressing should be applied to the wound • Effective against MRSA, Pseudomonas, VRE • Coexisting Cervical Disease • Careful handling/positioning/intubation of the patient • Sensory or Motor evoked potentials
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• Prophylaxis forDVT & PE • Careful risk assessment for DVT & PE • DVT risk is at 43% • Low dose heparin may cause epidural haematomas (0.7%) • Compression stockings reduce incidence of DVT to 2% • Compression stockings are a recommendation (Intraop & postop)
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Surgical options
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• Surgical options 1. laminectomy: posterior (direct) decompression of central canal and neural foramina without or with fusion. • Expansive laminaplasty • Laminotomy • Bilateral laminotomy (fenestration) • Coronal hemilaminectomy Fusion options: a. posterolateral fusion ± pedicle screw/rod fixation b. interbody fusion: generally not done as a “stand-alone” i. posterior lumbar interbody fusion (PLIF) ii. transforaminal lumbar interbody fusion (TLIF)
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2. Procedures toincrease disc space height and thereby indirectly decompress neural foramina without direct decompression a) anterior lumbar interbody fusion (ALIF): through laparotomy b) lateral lumbar interbody fusion: some techniques trademarked as extreme lateral interbody fusion (XLIF™) or direct-lateral (DLIF™) c) axial lumbar interbody fusion (Ax-LIF): L5-S1 only 3. Limitation of extension by interspinous spacer: e.g. X-Stop®
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Choosing the rightprocedure
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1. Indirect Decomp(lateral interbody fusion) a. When foraminal stenosis is dominant b. Previous spine surgery 2. Direct Decomp (Laminectomy) a. Pinpoint central canal stenosis b. When major compression is due to focal, correctable lesion 3. Motion preservation surgery a. When adjacent level shows degenerative changes
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4. Need fora fusion (in addition to decomp): a. Spondylolisthesis b. Dynamic instability on flexion/extension x-rays c. Potential spinal destabilisation after surgery d. Recurrent surgery at the same level (≥ 3rd times)
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Techniques
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Laminectomy/Laminotomy • Position:Prone or in some cases lateral decubitus • Surgical unroofing • Spines, lamina, ligamentum flavum • Assess foraminal stenosis • Foraminotomies if narrowing present • Undercutting of superior articular facet is usually necessary • Nearby moderate stenoses warrant concomitant decompression • Laminotomies or fenestrations in case of adjacent lateral recess stenosis
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MISS decomp •‘mini-open’ technique with 1” incision • Bilateral laminotomies or • Bilateral decomp via unilateral laminotomy • 3.5 to 4 cm off the midline • Laminectomies & facet takedown • Open ligamentum flavum to visualise plane under the bone • Ligamentum flavum left intact while drilling • Contralateral drilling followed by ligamentum flavum removal • Foraminotomies if required • Pedicle screws placed through the open side and percutaneously contralaterally
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Interspinous process decomp/stabilisation/fusion • Interspinous spacers (X-Stop) • Interspinous plates (Aspen, Affix, Spire) • Spacers prevent narrowing of neural foramina & off load facet joints in extension • Plates clamp across two spinous processes to fixate them, limiting extension • Success rate of X-stop = 63% at 2 years • Stability & strength similar to pedicle screws
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Contraindications to spacers/plates • Spondylolisthesis > Grade • Scoliosis with Cobb angle ≥ 25⁰ • Cauda equina syndrome • Spinous process fracture • Bilateral pars defects • Osteoporosis (hip T-score on Dexa < -2.5)
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Outcome
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• Poor outcomein: • Females • Those involved in litigation or compensation cases • Those with previous failed surgeries • Those with new sensory deficits postoperatively • Poor prognostic factors: • Diabetes, prior hip surgery, osteoporosis or preop spine fracture
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• Morbidity/mortality •In-hospital mortality = 0.32% • Unintended durotomy (0.32% to 13%) • Deep infection (5.9%) • Superficial infection (2.3%) • DVT (2.8%) • Damage to cauda equina • Non-union (Risk factors) • Smoking • Levels • NSAIDs use (Ketorolac)
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• Success ofoperation • No RCT comparing conservative to surgical treatment exist • Improvement in patients with a postural component (96% good outcome) • More improvement in legs pain than back pain • Relapse of symptoms • 30% to restenosis at the operated level • 30% to stenosis at new level • 75% responds to redo surgery
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• Early failureof pain relief • Erroneous patient selection • Technical failure (not decompressing the foramina in presence of stenosis) • Missed diagnoses • Long term outcome • Good to excellent outcome after surgery with a mean of 64% • 37% much improved & 29% somewhat improved • 78% to 88% success rate at 6 weeks to 6 months and 70% at 1 year and 5 years • Success rates slightly lower for lateral recess syndrome
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Conclusion
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• Spinal stenosisis a predominantly surgical disorder • Surgery has good to excellent outcome in those who have been properly selected • Comorbids, psychiatric illness and redo surgeries carry risk of poor or no response in terms of pain relief • Endoscopic facetectomy has been evaluated with documented good results
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thanks

Editor's Notes

#7 In 1803, Portal of France postulated that back and leg pain could be caused by bone impingement on the nerves. 1893, Lane of England did a decompressive laminectomy to relieve a woman of cauda equina syndrome caused by spinal stenosis
#9 A complete understanding of the pathologic anatomy of lumbar spinal stenosis is important to correlate the history, physical examination, and radiographic findings in assessing the patient with clinically symptomatic lumbar spinal stenosis.
#10 There are three variations of the spinal canal: a round canal, an ovoid canal, and a trefoil canal. The lateral recesses of the trefoil canal can render the lumbar roots particularly vulnerable to compression by a herniated disc. The trefoil canal is seen in 15% of spinal canals and predisposes to lateral recess stenosis.
#11 The diameter of the normal lumbar spinal canal varies from 15 to 27 mm. Lumbar stenosis results from a spinal canal diameter of less than 12 mm in some patients; a diameter of 10 mm is definitely stenotic. Anatomically spinal stenosis can be subdivided into central stenosis and lateral stenosis.
#14 most commonly acquired, superimposed on congenital stenosis
#15 Classified as: 1. central canal stenosis: narrowing of the AP dimension of the spinal canal. The reduction in canal size may cause local neural compression and/or compromise of the blood supply to the spinal cord (cervical) or the cauda equina (lumbar) 2. foraminal stenosis: narrowing of the neural foramen. May be the result of any combination of: foramina! disc protrusion, spondylolisthesis, facet hypertrophy, disc space collapse, hypertrophy of uncovertebral joints (cervical), synovial cyst 3. lateral recess stenosis (lumbar spine only):
#16 stable form of lumbar spinal stenosis: hypertrophy of facets and ligamentum flavum accompanied by disc degeneration and collapse unstable: have the above with superimposed: degenerative spondylolisthesis: the unisegmental form degenerative scoliosis: the multisegmental form
#20 Often presents as neurogenic claudication, (claudicate: from Latin, claudico, to limp) AKA pseudoclaudication. To be differentiated from vascular claudication (AKA intermittent claudication) which results from ischemia of exercising muscles. NC characteristics: unilateral or bilateral buttock, hip, thigh or leg discomfort that is precipitated by standing or walking and characteristically relieved by a change in posture. Pain may not be the major complaint, instead, some patients may develop paresthesias or leg weakness with walking. Some may complain of muscle cramping, especially in the calves.
#21 NC is only moderately sensitive ( .. 60%) but is highly specific for spinal stenosis Symptoms of stenosis or neurogenic claudication are attributed to direct mechanical compression or indirect vascular insufficiency involving the lumbar nerve roots or cauda equina. Standing and walking increase lordosis and transiently exaggerate infolding of the ligamentum flavum, while sitting and recumbence reverse the lordosis, open the canal, improve blood flow, distracts the facet joints (which enlarges the neural foramina) and often temporarily relieve complaints Favoured positions include sitting, squatting and recumbency NC is thought to arise from ischemia of lumbosacral nerve roots, as a result of increased metabolic demand from exercise together with vascular compromise of the nerve root due to pressure from surrounding structures.
#22 Patients may develop "anthropoid posture (exaggerated waist flexion). "Shopping cart sign• patients often can walk farther if they can lean forward e.g. as on a grocery cart. Riding a bicycle is also often well tolerated.
#23 The neurologic exam is normal in ... 18% of cases (including normal muscle stretch reflexes and negative straight leg raising). Descending order, these are L5 root syndromes (L4-5 disease), L4 root syndromes (L3-4), L3 root syndromes (L2-3), and S1 root pathology (L5-S1) Absent or reduced ankle jerks and diminished knee jerks is common Pain may be reproduced by lumbar extension Bladder dysfunction is rare in young patients but is frequently encountered in the geriatric population with lumbar spinal stenosis. Patients averaging 71 years of age and undergoing two- to four-level laminectomies for severe lumbar stenosis exhibited a significant degree of both preoperative and postoperative bladder compromise Six months following laminectomies, although only 45% of patients showed cystoscopic or urodynamic evidence of improved urinary function (i.e., decreased postvoiding residual volumes), 60% of patients reported a subjective recovery of urinary function.
#25 vascular insufficiency: (AKA vascular or intermittent claudication) hip disease: trochanteric bursitis/ Degenerative joint disease disc herniation (lumbar or thoracic) Baastrup’s syndrome AKA arthrosis interspinosa. Radiographically: contact of adjacent spinous processes ("kissing spines") with enlargement, flattening and reactive sclerosis of apposing interspinous surfaces. Produces localized midline lumbar pain & tenderness on back extension relieved by flexion, local anaesthetic injection or partial excision of the involved spinous processes arachnoiditis Intraspinal tumour diabetic neuritis: with this, the sole of the foot is usually very tender to pressure from the examiner's thumb delayed onset muscle soreness (DOMS): onset usually 12-48 hours after beginning a new activity or changing activities (NC occurs during the activity). Symptoms typically peak within 2 days and subside over several days functional aetiologies
#27 Plain anteroposterior radiographs demonstrate the number of lumbar vertebrae and help determine whether there is a lumbosacral bony anomaly (frequency, 7%). Lateral radiographs reveal the curvature of the lumbar spine and the presence or absence of static or dynamic olisthesis or instability, defied by greater than 4 mm of translation and greater than 10 to 12 degrees of angulation at the level of olisthy
#28 The transverse diameter of the spinal canal. On plain AP x-ray oflumbar spine, an IPD < 25 mm suggests stenosis.
#29 Computed Tomography CT scan (either routine, or following water-soluble myelography): classically shows "trefoil" canal (cloverleaf shaped, with 3 leaflets). CT also demonstrates AP canal diameter, hypertrophied ligaments, facet arthropathy, and bulging annulus or herniated disc. CT is poor for demonstrating spondylolisthesis although the pars defect may be seen. Routine and two- and three-dimensional reconstructed CT images in multiple planes (axial, coronal, sagittal) confirm the diagnosis of lumbar stenosis. They also contribute to the recognition of accompanying disk disease, limbus fractures, olisthesis or instability, ossification of the posterior longitudinal ligament (OPLL), ossification of the yellow ligament (OYL), and progression of fusion in a posterolateral fusion mass. In a series of 48 patients who were symptomatic following lumbar fusion, CT identified 157 abnormalities; 12 of 27 major lesions included fusion mass fractures, hairline pseudoarthroses, and residual spinal stenosis (all confirmed during second operations). Myelographic CT studies are now rarely performed because the majority of pathologic findings can be confirmed noninvasively with varying combinations of MRI and CT evaluations.
#30 Demonstrates impingement on neural structures and loss of CSF signal on T2WI at severely stenotic levels. MRI is poor for visualizing bone which contributes significantly to the pathology (may be helpful for surgical planning). Good for evaluating nerve impingement due to spondylolisthesis (possibly better than myelogram/CT) and juxtafacet cysts. Asymptomatic abnormalities are demonstrated in up to 33% of asymptomatic patients 50-70 years old Increased lumbar facet fluid (indicating instability) positively correlated with sagittal instability documented on dynamic x-ray studies obtained at the L4-5 level (focus of degenerative changes). Contrast-enhanced MRI also accurately differentiates scar from disk (96%), visualizes the cervicothoracic or thoracolumbar junction, and helps differentiate among tumour, demyelinating syndromes, adhesive arachnoiditis, and infection
#32 Some patients with lumbar stenosis may have more cephalad tumours contributing to seemingly “lumbar” complaints. These typically include ependymomas, neurofibromas, meningiomas, and metastatic lesions. In one study, a patient with an unresolved right footdrop following lumbar surgery was found to have a left-sided parasagittal convexity meningioma; resection resulted in complete resolution of the deficit. Other degenerative, metabolic, endocrine, and vascular disorders may mimic the signs and symptoms of lumbar stenosis. These include thoracic disk herniation, Scheuermann’s disease, Paget’s disease, and arthritis of the hips. In one series, amyloidosis and its characteristic crystals contributed to hypertrophy of the yellow ligament in 12 of 97 patients undergoing lumbar surgery for stenosis. Diabetes, contributing to diabetic peripheral neuropathy, femoral amyotrophy, or angiopathy, can also be misdiagnosed as lumbar stenosis. Of note, among diabetics with lumbar stenosis, only 39% exhibited good or excellent outcomes, compared with 95% good or excellent results for those without diabetes. Peripheral vascular diseases resulting in vascular rather than neurogenic claudication, characterized by pain associated with ambulation but relieved with rest alone, may be present alone or exist simultaneously with lumbar stenosis
#34 For patients with tandem lesions, decompression or excision of the cephalad pathology may result in partial and occasionally marked improvement in lumbar complaints the order of surgery is dictated by the severity of the stenosis For patients with absolute stenosis (canal ≤ 10 mm) and myelopathy, often with superimposed pathology such as OPLL, cervical surgery should typically precede lumbar intervention For patients with relative stenosis and a canal depth of 11 to 13 mm correlated with radiculopathy rather than myelopathic symptoms, lumbar surgery often takes precedence over cervical intervention For the former patients, preliminary cervical decompression often results in improvement of seemingly “lumbar” complaints in more than one third. Although tandem cervical-lumbar stenosis occurs in only 10% of patients, it should be anticipated in patients older than 65 years, and these individuals should undergo more stringent screening for tandem cervical disease
#35 OYL may significantly contribute to lumbar stenosis. OYL presents as an initial ingrowth of fibrocartilage attributed to the proliferation of type II collagen Hypertrophy or OYL begins laterally at the enthesis and extends medially. In 110 predominantly geriatric individuals undergoing multilevel laminectomies (average, five levels) with noninstrumented fusion, the 10 who developed intraoperative dural tears exhibited severe OYL; this extended to or through the dura in 3. 34 For the remaining 100 patients, 57 showed moderate OYL, and 22 showed marked OYL. The frequency of OPLL in the proximal lumbar spinal canal is 10%, with another 10% being found in the proximal thoracicspine (T1-4) spine; the majority (80%) of OPLL is found in the cervical spinal canal. OPLL and OYL may both contribute to thoracic or lumbar stenosis. Of 1100 patients having surgery for spinal stenosis from 1986 to 1997, 26 (2.3%) hadOYL or OPLL (11 OPLL, 12 OYL, 3 OYL and OPLL). Analysis of a fluid collection in the lumbar spine using β2-transferrin may help document the presence of a fistula Ankylosing hyperostosis may also contribute to lumbar stenosis The characteristic CT findings include anterior or posterolateral marginal, somatic osseous proliferation and proliferative changes involving the posterior facet joints, articular capsules, yellow ligament, or supraspinal ligaments. Disk herniations occur in up to 45% of patients undergoing surgery for lumbar stenosis with or without olisthesis (in a series of 857 individuals) Disk herniations in conjunction with stenosis alone were reported in 15% to 45% of cases. In 60 patients undergoing multilevel laminectomies (average, 5.4 levels) for lumbar stenosis using lamina autograft and β-tricalcium phosphate ( β-TCP) for one- to two-level noninstrumented posterolateral lumbar fusion, disk herniations were observed in 20 patients (33.3%). Of 95 patients undergoing one-level instrumented posterolateral lumbar fusion using lamina autograft supplemented with demineralized bone matrix, 13 patients(13.6%) without preoperative olisthesis underwent unilateral or bilateral facetectomy for far lateral disks or stenosis. Among 100 patients undergoing multilevel laminectomy (3.6 levels) with one-level (78 patients) and two-level (22 patients) instrumented fusion using lamina autograft and β-TCP, 57 herniated disks were found in 50 patients: 21 were routine disks, 7 were foraminal disks, 24 were far lateral disks, and 5 were recurrent disk herniations.Lower frequencies of disk herniation (4.3% to 20%) have been reported for patients undergoing lumbar decompression in the presence of olisthesis. In one study evaluating 290 patients with olisthesis, 20% had disk herniations; 47 were routine, and 12 were foraminal or far lateral Patients with lumbar stenosis may also exhibit one of four types of limbus vertebral fractures, which are better visualized on CT than MRI. Type I consists of a shelf of cortical bone traversing the canal, type II involves predominantly a large central fragment, type III is characterized by a lateral or far lateral calcified fragment, and type IV is defined by a massive fragment extending across the entire width of the spinal canal from one interspace to the next. These fragments are typically extremely large, include both cortical and cancellous elements, and warrant more extensive resection to afford access for adequate decompression. For foraminal and far lateral lesions, unilateral facetectomy is typically warranted. Furthermore, resection requires piecemeal removal; this is most safely carried out by first creating a defect or depression at the level of the disk space and then morcellatingthe limbus fracture into fragments using a down-biting curet, tamp, and mallet technique, which allows delivery into the defect and safe removal. In some cases, intraoperative monitoring (somatosensory evoked potentials [SEPs] or electromyography [EMG]) may be useful to minimize undue retraction or manipulation and subsequent neurological injury. In the lumbar spinal canal, lumbar nerve roots may become trapped by disk herniation or stenosis extending into the far lateral compartment, which is bordered superiorly by the pedicle, anteriorly by the disk, medially by the vertebral body and superior articular facet, and laterally by fat Far lateral disks, which typically originate at the inferior interspace and migrate superolaterally, constitute 7% to 12% of all disk herniations. Other factors contributing to far lateral pathology include spondylostenosis, arthrosis, limbus vertebral fractures, olisthy with or without lysis, and scoliotic deformity. Far lateral disk pathology compresses the cephalad rather than the caudad exiting nerve roots at any lumbar disk space level. For example, the most common disk herniation at L4-5 compresses the superior, far laterally exiting L4 nerve root rather than the typical compression of the L5 root that traverses the disk space itself. Similarly, L3 compression results from far lateral disks at the L3-4 level, L5 root compression at the L5-S1 level, and L2 root compression at the L2-3 level. Because the dorsal nerve root ganglion is typically compressed with far lateral disks, the pain is often unrelenting and exquisite. Furthermore, the nerve root compression often begins beyond the lateralmost extent of the dural sleeve, making MRI and CT studies paramount but often less effective in establishing the diagnosis. Three surgical techniques are used to approach far lateral disk herniations that accompany lumbar stenosis. Only rarely can a far lateral disk be removed through a medial facetectomy at the L5-S1 level; most cases require either the intertransverse approach or a full facetectomy.49,51 Notably, the L5-S1 level is the widest and least stenotic, and very laterally located facet joints may allow adequate access to the foraminal and proximal far lateral portion of a far lateral disk. The intertransverse procedure combines a medial facetectomy-foraminotomy and far lateral exposure (Wiltse approach), thus preserving the pars interarticularis; risks, however, include delayed fracture of the pars interarticularis, retention of disk material, or damage to the nerve root secondary to incomplete exposure. Finally, the full facetectomy, which is the safest approach, fully visualizes the root along its entire course, along with OYL, synovial cysts, spondylostenosis, and olisthesis; however, it does increase the risk of instability. Although in the past many patients undergoing full facetectomies for far lateral disks were not fused, these patients typically undergo simultaneous noninstrumented or instrumented fusion today. Synovial cysts may contribute to the pathology of lumbar spinal stenosis In one series, outcomes were assessed in 45 patients with stenosis and synovial cysts versus 35 with stenosis and degenerative spondylolisthesis using the SF-36 questionnaire. The procedures in these patients required laminectomy at an average of 3.8 and 3.5 levels, respectively. Five of the 45 with synovial cysts developed instability postoperatively, and 11 of 35 with preoperative olisthesis developed further progression. After a minimum of 2 postoperative years, good or excellent results were observed in only 58% and 63% of patients, respectively (Physical Function Scale +44 and +38). Because synovial cysts indicate intrinsic disruption of the facet joint and, therefore, instability, it is likely that more primary fusions should be considered in these patients to improve outcomes. In a subsequent series of 110 mostly geriatric patients undergoing, on average, five-level laminectomy with primary noninstrumented fusion, a high frequency of synovial cysts was encountered in those who developed dural tears. Of note, 5 of 10 patients with dural tears had synovial cysts (with severe OYL in all 10), whereas only eight synovial cysts were encountered among the remaining 100 without dural tears. In the lumbar spine, degenerative olisthesis or spondylolisthesis (with an intact neural arch) occurs when facet joints are congenitally oriented in a sagittal rather than a coronal position Progressive arthrotic changes of the facet joints contribute to a grade I or 25% anterolisthesis or olisthesis, frequently resulting in progressive cauda equina and nerve root compression. Resultant hypertrophied facet joints contribute to dorsolateral intrusion on the thecal sac and superiorly exiting nerve roots as they exit the spinal canal foraminallyand far laterally. Simultaneously, the inferiorly exiting nerve root is compressed in the lateral recess by hypertrophied yellow ligament, disk “bulges,” or arthrotic spurs. Patients with degenerative spondylolisthesis are typically women (2 : 1 female-to-male ratio) 50 to 60 years of age whose symptoms have evolved over decades but have been exacerbated over months to years. Neurological deficits appear late in the clinical course and may be correlated with the onset of neurogenic claudication or radiculopathy associated with proximalweakness or a partial footdrop. The L4-5 level is most commonly involved, followed in descending order by L3-4, L2-3, and L5-S1. Olisthesis is rare at L5-S1 because this level is typically located below the intercrestal line and is therefore supported by longer transverse processes and the iliotransverse ligaments. Of 290 patients with degenerative spondylolisthesis, 86% had olisthy at one level, and the remaining 14% had two-level olisthesis.
#38 A subset of patients with spinal stenosis of differing severities might be managed conservatively without surgery. For example, both young and old patients with severe comorbidities that may preclude risky surgical intervention and with severe MRI- and CT-documented stenosis or olisthesis may benefit from treatment at multimodality pain centres. In one series, the Oswestry Disability Index (ODI) and surgeons’ clinical assessments were used to compare outcomes for 54 matched pairs with lumbar stenosis treated conservatively (nonoperatively) versus with laminectomy. No statistically significant differences in outcomes between the two groups were revealed. Other studies have documented the superiority of surgery for lumbar stenosis, including decompression or decompression with fusion, compared with nonsurgical alternatives. In a randomized controlled trial involving 94 patients with stenosis, the results of no surgery (44 patients) versus surgical decompression (50 patients) were compared; the latter included undercutting laminectomies for stenosis, with 10 undergoing additional fusions. Outcomes, based on the ODI and self-reported measures, revealed that patients in both groups improved over the 2-year postoperative interval, but surgical patients achieved greater relief of leg and back pain and demonstrated less overall disability. In a nonrandomized cohort study of patients with lumbar stenosis, better outcomes were observed following decompression (54 patients) and decompression with fusion for degenerative spondylolisthesis (42 patients) compared with nonoperative intervention (29 patients). Based on Roland Morris questionnaires to assess outcomes, patients undergoing either of the surgical procedures exhibited higher scores than those treated conservatively (6.9 and 6.1 versus 1.2). Similarly, better outcomes were observed for the decompression and decompression and fusion groups compared with those who chose nonsurgical alternatives (63.3% and 61.5% versus 25%). In another study, patients with stenosis and degenerative spondylolisthesis from 13 centres, randomly enrolled in two treatment groups, demonstrated substantial gains in pain relief and function following decompressive laminectomy with or without fusion (304 patients) compared with no surgery (303 patients). Patients were evaluated with the SF-36 and a modified ODI 1.5, 3, 6, 12, and 24 months postoperatively. Surgical patients demonstrated significant advantages at 3 months, which increased at 1 year and were only minimally diminished at 2 years postoperatively. On the SF-36, Bodily Pain and Physical Function scores showed a net gain of 18.1 and 18.3 points, respectively, whereas the net ODI was –16.7.
#40 In an observational study of 3482 patients undergoing surgery for lumbar stenosis, medical (headache, depression, central nervous system disorders) and psychosocial comorbid factors (active compensation cases, self-reported poor health, smoking) negatively impacted 3-month and 1-year SF-36 and ODI postoperative outcomes. Cardiac ComorbiditiesCardiac disease is present in more older than younger patients undergoing lumbar decompression and fusion. In 168 older patients (average age 67.5 years) undergoing multilevel laminectomies with noninstrumented fusion for multilevel stenosis or instability, 19% exhibited significant cardiac disease (atrial fibrillation, prior bypass surgery, new stents, defibrillators, arrhythmias). In comparison, only 2% of 248 younger patients (average age 51 years) undergoing laminectomies and instrumented lumbar fusion demonstrated substantial cardiac pathology (cardiac bypass surgery, stents, myocardial infarction). Preoperative Psychiatric ClearanceDepression significantly affects the outcome of patients undergoing lumbar spine surgery. In one study of 99 patients undergoing surgery for lumbar stenosis, questionnaires were completed preoperatively and 3 months postoperatively. The Beck Depression Inventory, ODI, Stucki Questionnaire, and Visual Analogue Scale were used. Before surgery, 20% were considered depressed. This factor positively correlated with increased postoperative disability based on the multiple questionnaires; those with continuous depression showed less improvement in symptom severity, pain intensity, walking capacity, and overall disability score. When preoperative depression improved or resolved, the postoperative Beck Depression Inventory outcomes were comparable to those in patients without a history of depression. In another series, 66% of 95 patients with lumbar stenosis were satisfied with their postoperative results; they were typically younger and exhibited less severe preoperative symptoms and disabilities.Depression in particular had a uniquely negative impact on their outcomes. In another series, the perceived quality of life (expectations, level of optimism) was evaluated in 57 patients before and 3 months after lumbar spine surgery; higher preoperative expectations and optimism correlated with a better quality of life postoperatively
#41 Preoperative bathing: To avoid infections, patients undergoing surgery for lumbar stenosis with or without fusion should be carefully prepared with specific bathing protocols and prophylactic antibiotics. Twice a day during the week before surgery using soap & water Additionally, chlorhexidine-impregnated sponges to be used the night before and the morning of surgery at the intended surgical site. Prophylactic antibiotics: Centres for Disease Control and Prevention recommends prophylactic antibiotics for lumbar surgery to limit spine infections, protocols vary from single-dose to multiple-dose regimensIn one study involving patients undergoing comparable but varied lumbar procedures, including stenosis with and without olisthesis and with and without instrumentation, theefficacy of multiple- (5 to 7 days) versus single-dose prophylactic antibiotic regimens employing a fist-generation cephalosporin were compared. Of interest, although the infection rates for the two groups proved comparable (0.8% of 1133 multidose versus 0.4% of 464 single-dose patients), five of the six infections in themultidose patients proved to be caused by resistant bacteria, compared with none of the three organisms seen in the single dose patients. In another retrospective series of patients undergoing lumbar discectomy alone, comparable infection rates were encountered in the multidose (5 of 434 patients [1.15%] whoreceived one preoperative and at least three postoperative doses of antibiotics) and single-dose (3 of 201 [1.49%] patients who received a single dose of preoperative antibiotics) populations.Based on laboratory studies , the ideal prophylactic antibiotic for spine surgery is a second-generation cephalosporin, typically cefazolin, administered at a dose of 2 g within 15 to 30 minutes of the skin incision. Nevertheless, the reported incidence of infection may vary from 3% for noninstrumented to 12% for instrumented procedures.68 Additionally, the frequency of infection is higher for posterior spine procedures than for anterior operationsIn addition to 2 g of a second-generation cephalosporin 15 minutes before the incision, 80 mg of gentamicin is given by intravenous Soluset over 30 minutes before surgery, providing increased protection against methicillin-resistant Staphylococcus aureus (MRSA). Other adjuncts include irrigation with bacitracin and polymyxin B sulfate every 15 minutes during the actual operative procedure. In one study, constant irrigation with saline and 50,000 units each of bacitracin and polymyxin B sulphate was used for clean procedures performed at two community hospitals; the infection rate was impressively reduced to 0%. The frequency of intraoperative bacterial growth (cultures from the wound and other sources) with this irrigation was reduced from 64% to 4% when both antibiotics were used
#42 Postoperatively, a silver-impregnated dressing should be applied to the wound over the staples or sutures Silver easily binds to negatively charged proteins. Nanocrystals slowly release the silver ion for up to 7 days (sustained release). Silver inhibits proinflmmatory cytokines and upregulates zinc metabolism, thereby increasing epithelialization and potentiating wound healing. These dressings are uniquely effective against resistant organisms (MRSA, Staphylococcus epidermidis, Pseudomonas aeruginosa, vancomycin-resistant enterococcus, and others) Coexisting cervical disease Patients with significant cervical spondylostenosis and cord compression documented on MRI or CT studies may require prophylactic awake intubation, awake positioning (three-pin head holder), and electrophysiologic monitoring before lumbarsurgery. After the patient has been mildly sedated, the three-pin head holder is placed using local anaesthesia at each pin site following skin preparation in the supraorbital and retroauricular regions with alcohol or iodine-based products. Once the patient is prone, the head holder is affixed to the Mayfield headrest, taking care to maintain the patient’s neck in a neutral position.All pressure points are appropriately padded. Before induction of anaesthesia, the patient’s neurological examination is checked and correlated with SEPs that have been monitored throughout the entire process
#43 Prophylaxis for DVT & PE There is an increased risk of deep venous thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing lumbar surgery, particularly if there is a history of malignancy, DVT, or PE during previous surgery, hypercoagulable syndromes, significant cardiac disease, obesity, or long surgical procedures. For lumbar surgery performed without any type of prophylaxis, the risk of DVT approaches 43%. Despite the efficacy of low-dose heparin or low-molecular-weight heparin derivatives in the prevention of DVT and PE, the associated risk of major haemorrhage (0.7%) must be carefully considered. For patients undergoing lumbar decompressive procedures with or without fusion, DVT and PE prophylaxis may consist of alternating compression stockings alone. Studies of compression stockings for prophylaxis have revealed a 2% incidence of DVT. Prophylaxis with compression stockings in 139 patients undergoing multilevel laminectomies (average, 3.8 levels) and instrumented fusion (average, 1.4 levels) resulted in 4 cases (2.8%) of DVT (2 to 6 days postoperatively) and 1 case (0.7%) of PE.
#45 Surgical options laminectomy: posterior (direct) decompression of central canal and neural foramina without or with fusion. Fusion options: posterolateral fusion ± pedicle screw/rod fixation interbody fusion: generally not done as a “stand-alone” (i.e. usually requires additional stabilization, options here include: pedicle screws, facet screws, facet dowels, spinous process clamp) posterior lumbar interbody fusion (PLIF): usually bilateral graft placement transforaminal lumbar interbody fusion (TLIF): unilateral graft placement though a facet take-down on that side (see page 193) procedures to increase disc space height and thereby indirectly decompress neural foramina without direct decompression anterior lumbar interbody fusion (ALIF): through laparotomy lateral lumbar interbody fusion: some techniques trademarked as extreme lateral interbody fusion (XLIF™) or direct-lateral (DLIF™) axial lumbar interbody fusion (Ax-LIF): L5-S1 only 3. limitation of extension by interspinous spacer: e.g. X-Stop®
#48 Choosing which procedure to use consider indirect decompression (lateral interbody fusion (e.g. XLIF® or DLIF®), interspinous decompression (e.g. X-Stop): when foraminal stenosis appears to be the dominant problem (e.g. with loss of disc space height, facet hypertrophy, on the concave side of a scoliotic curve) previous spine surgery that might make exposure of the nerves more difficult or risky consider direct decompression (e.g. laminectomy) “pinpoint” central canal stenosis especially when disc height and neural foramina are well preserved where the majority of the compression is due to a focal, correctable lesion, such as a herniated disc, synovial cyst, intraspinal tumour consider motion-preservation surgery when a fusion is undertaken at a level and the adjacent level is already starting to show some degenerative changes that have not yet reached a surgical magnitude. Motion preservation at this adjacent segment theoretically shield it from some of the transmitted stresses from the fused level
#49 situations where a fusion should be considered in addition to direct or indirect decompression of the nerves: spondylolisthesis (especially > Grade I) dynamic instability on flexion/extension lateral lumbar spine x-rays expectation that the decompression will destabilize the spine (e.g. facet takedown for a TLIF) multiply recurrent herniated disc (when this is the third or more operation for the same disc controversial situations: e.g. a “black disc” on MRI with positive concordant discogram at this level: fusion without decompression has been advocated when there is no neural compression
#51 Laminectomy/Laminotomy Position: either of the following is acceptable prone: on a frame or chest rolls or knee-chest position to decompress the abdomen to decrease venous pressure and thus reduce bleeding lateral decubitus position: if there is no laterality to symptoms, right lateral decubitus (left-side-up) is easier for most right-handed surgeons to use angled Kerrison rongeur parallel to nerve roots Posterior approach with removal of the spines and lamina of affected levels (surgical “unroofing”), along with the associated ligamentum flavum. Individual nerve roots are palpated for compression within their neural foramen, with foraminotomies performed at appropriate levels. Doing a total L4 laminectomy for stenosis allows access to the L4-5 foramen, and the upper part of the L5-S1 foramen. If, in addition, the lower part of L3 is also removed, access is gained to the inferior pedicle of L3 and thus the L3-4 neural foramen. Undercutting the superior articular facet is often necessary to decompress the nerves in the foramen. Treatment of moderate stenosis at adjacent levels appears warranted as these levels have been shown to have a significant likelihood of becoming symptomatic later. Alternatively, laminotomies (as opposed to laminectomies) may be performed in cases where the central canal has a normal AP diameter, but the lateral canal gutter is stenotic. Multilevel subarticular fenestrations are another slight variation on this theme.
#53 Minimally invasive spine surgery (MISS) decompression Usually a “mini-open” technique using ≈ 1” incisions and expandable retractors. options include bilateral laminotomies (see above) bilateral decompression through a unilateral laminotomy entry site: 3.5-4 cm off the midline to permit the needed angle when using a retractor with an “open side” orient the retractor with the open side facing laterally (e.g. with the Nuvasive Maxcess® place the handles medially) to permit the angle needed for contralateral decompression the laminectomy and facet takedown (usually for a TLIF) are done open the ligamentum flavum on the side you’re working on, to visualize the posterior extent of the spinal canal, to permit finding the plane between the posterior part of the ligamentum flavum and the undersurface of the bone the ligamentum flavum is left in place on the contralateral side to protect the dura during drilling complete the decompression and disc removal on the side you’re working on the undersurface of the bone (spinous process and contralateral lamina) are then drilled to decompress the contralateral side once the undersurface of the contralateral posterior canal has been drilled, the ligamentum flavum is removed with pituitary rongeurs. It is possible to even do a contralateral foraminotomy at this point (curved Kerrison rongeurs are very helpful for this) pedicle screws are placed through the open side, and then percutaneously through the contralateral side
#55 Interspinous process decompression/stabilization/fusion Interspinous spacers (e.g. X-Stop™ (Medtronic)) limit extension at 1 or 2 levels (without fusion), preventing narrowing of the associated neural foramen, and may also off-load the facet joints and even the disc. “Success rate”: 63% at 2 years. This device may be used as a standalone. Interspinous plates (e.g. Aspen® (Lanx), Affix™ (Nuvasive), Spire® (Medtronic)) clamp across two spinous processes to fixate them (unlike X-Stop™ which just limits extension). The Aspen® clamps have a space for a graft which may optionally be used to promote fusion between the spinous processes. Interspinous plates may be used to augment other constructs e.g. lateral interbody fusion, but are not intended for standalone use. Biomechanical stability is reported to be similar to bilateral pedicle screws in flexion, and unilateral pedicle screws in lateral bending
#57 Contraindications (includes exclusionary criteria from the IDE study): instability at level considered for procedure: spondylolisthesis > Grade 1 or scoliosis with Cobb angle ≥ 25° (see page 430) cauda equina syndrome acute fracture of the spinous process bilateral pars defects (disconnects spinous process from the anterior elements) osteoporosis. Contraindications per the IDE: DEXA scan with spine or hip T-score < –2.5 (i.e. more than 2.5 SD below the mean for normal adults) in the presence of ≥ 1 fragility fractures. Concerns: spinous process fracture at the time of insertion, or late subsidence due to microfractures. However, Kondrashov327 interprets a T-score < –2.5 anywhere as indicative of osteoporosis (even without fragility fractures). Options here include: augmenting the spinous processes by injecting ≈ 0.5-1 cc of PMMA into each spinous process (SP) with a 13 Ga needle inserted ≈ halfway into the SP on lateral fluoro327 prior to dilating the interspace or placing the X-Stop. Verify central position within SP on AP fluoro, and monitor injection on fluoro use of an X-Stop made of PEEK (modulus of elasticity of PEEK is closer to bone than titanium) - available now in Europe, soon in the U.S. ankylosed level (i.e. already fused) L5-S1 level: the spinous process of S1 is usually too small (not usually an issue since symptomatic stenosis at L5-S1 is rare) age < 50 years: not studied in IDE investigation
#61 Morbidity/mortality Risk of in-hospital mortality is 0.32%. Other risks include: unintended durotomy (0.32% to ≈ 13%), deep infection (5.9%), superficial infection (2.3%), and DVT (2.8%) Nonunion Risk factors for non-union (does not necessarily correlate with success of operation): cigarette smoking delays bone healing and increases the risk of pseudoarthrosis following spinal fusion procedures, especially in the lumbar spine295 number of levels: in lumbar fusions, fusing 2 levels resulted in increased non-union rates compared to fusing 1 level334 NSAIDs: controversial short-term (≤ 5 days) post-op use: high-dose ketorolac (120-240 mg/d) was associated with increased risk of non-union, but low-dose ketorolac (≤ 110 mg/d), and celecoxib (200–600 mg/d) or rofecoxib (50 mg/d) were not some feel that long-term NSAID use does lower fusion rate
#62 No randomized study exists comparing surgery to “conservative” treatment. Patients with a postural component to their pain had much better results (96% good result) than those without a postural component (50% good results), and the relief of leg pain was much more successful than relief of back pain. Surgery is most likely to reduce LE pain and improve walking tolerance. Surgical failure may be divided into two groups: 1. patients with initial improvement who develop recurrent difficulties. Although short-term improvement after surgery is common, many patients progressively deteriorate over time. One study found a 27% recurrence of symptoms after 5 years follow-up (30% due to restenosis at the operated level, 30% due to stenosis at a new level; 75% of these patients respond to further surgery). Other aetiologies include: development of herniated lumbar disc, development of late instability, coexisting medical conditions 2
#63 . patients who fail to have any post-op pain relief (early treatment failures). In one series of 45 such patients: A. the most common finding was a lack of solid clinical and radiographic indications for surgery (e.g. non-radicular LBP coupled with modest stenosis) B. technical factors of surgery had less influence on outcome, with the most common finding being failure to decompress the lateral recess (which requires judicious medial facet resection or undercutting the superior articular facet) C. other diagnoses (e.g. arachnoiditis), missed diagnosis (e.g. spinal AVM) Long term outcome: Literature review with long-term follow-up found good or excellent outcome after surgery with a mean of 64% (range: 26-100%). A patient satisfaction survey indicated that 37% were much improved and 29% somewhat improved (total: 66%) post-op. A prospective study found a success rate of 78-88% at 6 weeks and 6 months, which dropped to ≈ 70% at 1 year and 5 years. Success rates were slightly lower for lateral recess syndrome.

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