Lubar Arthritis : Lumbar Stenosis by Pablo Pazmino, MD

Lumbar Stenosis Pablo Pazmi ño, MD Curitiba, Brazil

Lumbar Spinal Stenosis

Definition

Epidemiology

Classification

Anatomy & Morphometrics

Mechanics of the Neural Arch and Stenosis

Pathophysiology

Differential Diagnosis

Physical Exam

Imaging

Treatment Options

Conservative

Operative

Spinal Stenosis:

The term "stenosis" itself is derived from the Greek word stenos, which means narrow.

Narrowing of the spinal canal, lateral recess, or the foramen that leads to neural compression, producing radiculopathy or neurogenic deficit.

Epidemiology

Disease of the older population

Increase in median age from 32.9 years in 1990 to 35.3 in 2000 now 37.6

34.9 million >65yo

Degenerative lumbar spinal stenosis is seen primarily in patients older than 60, with an average age of 73 at presentation.

Females are predominantly affected, with reported female-to-male ratios ranging from 3:1 for all types of stenosis

First appearace of disc degeneration is in 3 rd decade females, males 2 nd decade Miller Spine ’88:13

Anatomy

Structural Relationship between neural elements, discs, facets, hypertrophic ligaments, and bony elements.

The degree and location of stenosis produce the different clinical presentations.

Centrally

Lateral recess: Subarticular(anterior SAF)

Entrance Zone

C. Foraminal : Between pedicles

Midzone

D. Extraforaminal: Lateral to pedicle

Exit Zone

Anatomy

Centrally

Entrance Zone

Midzone

Exit Zone

Anatomy

Centrally

Entrance Zone

Midzone

Exit Zone

Anatomy

Centrally

Entrance Zone

Midzone

Exit Zone

Anatomy

Centrally

Entrance Zone

Midzone

Exit Zone

Foramen

On the diagram 2 is

the nerve exiting the spine through a hole called the Foramen

From here the nerve will provide sensation and strength to the legs

PLL Posterior Longitudinal Ligament This is a ligament that sits against the bone and thickens with arthritis It is a Denticulated flat broad attachment at level of disc and has a narrower course across midportion of concave posterior wall of the vertebral body Sagitally oriented deep layer connects periosteum along vert body, T/Y shaped in transverse sections. Vertical T dissappears at disc level Dual aspect Proprioceptive function Suspensory ligament for dural sac

PLL Anatomy

Epidural space anterior to PLL is filled by AIVVP: Anterior Internal Vert Ven Plexus and adipose tissue

Medial Venous Plexus: segmental

Lateral Longitudinal vein of the anterior cmpt

Batson’s Plexus: lies ventral and laterally from the deep PLL layers

Ligamentum Flavum: Posterior Epidural Region Yellowish 80% Elastin fibers Spans between the adjacent laminae and fills the interlaminar space. The capsular part of the ligament is thinner than the interlaminar portion. 2 Layered aspect: firmly attached, diverge caudally at the upper rim of laminae, superficial thickness 2.5-3.5mm / 1mm deep OlszewskiSpine ’96:21 Tented recess filled with homog epid adipose adherent at the apex of the ligament.

Nerve root organization This is how the nerves are arranged within the thecal sac

Facet Joints

Essential for control of normal motion and based on orientation control anteroposterior slippage

Compromised facets will alter the distribution of mechanical forces throughout the spine

Mechanics of Neural Arch

Torsion: Axial rotation 1-2 º CW /CCW, more with cartillage thinning (apophyseal jts)

Flexion: Capsular ligaments of Apophy Jts resist. In full flexion 40% resistance (Disc 30%,Supra Intersp lig 20%,LF 10%)

Failure: SSLig  CLig  Disc

Compression:

Flattened (erectsitting /lifting)  all resisted by disc.

Lordotic (erect std)facet tips contact laminae of subadj vertebrae and bear 1/6 th cmpr force

(Extension)Disc narrowing 70% cmprs transmitted across apophyseal joints

Diurnal Changes Diurnal changes in fluid content, disc height, and disc bulge. 19mm variation, from 1.5mm ht of each lumbar disc. Sleep: loading on discs reduced and discs absorb fluid and increase vol Absorbed fluid is expelled during day with loading through Creep/Walking: Lose height, increase bulge

Morphometric Data: Variable Shapes of Central Lumbar Canal

A. Round

B. Triangular

C. Trefoiled: architectural form having the appearance of a trifoliate leaf ,3 lobed arcs arranged in a circle (15-25% @L5). Dvlpmtnl: Small midsagittal, interpedicular diameter continues to increase up puberty. Shallow  Trefoil

D. Trefoiled and Asymmetric: Lumbar roots prone to compression in the lateral recess, not a certainty Lee Spine ’80:13

Spinal Stenosis Normal is on Top Left Stenosis is on Bottom Right

Normal AP >12mm and Cross Sectional Area 77+/- 13mm2 Schonstrom Spine JOR ’88:13

AP Diameters Decrease L1 to L3

Increase L3 to L5

Transverse diameters increase L1 to L5

Cross Sx Areas Decrease L1 to L2

Constant L2-L4

Marked Increase L5

A fair amount of Left- Right Asymmetries. Suggests an asymmetric lever arms for muscles.

Tropism of the facet jts, pedicles, laminae and vertebral bodies influence the size and shape of canal.

Pathophysiology This is an “Axial View” Look at the Arthritis/Stenosis that develops

Extension

Shortens spinal canal

Broadens Nervous tissue

Shortens and broadens ligamentum flavum,

Posterior disc protrusion causes nterference of circulation of C Equina and Nerve roots)

Brieg Biomechanics of CNS, 1960

Flexion Foraminal size increases in flexion, and decreased in extension. Nondegenerated foramina>>Degenerated foramina Foramina open 24% during flexion and closed 20% during extension Less significant changes with lateral bending and axial rotation Stenotic spines: Flexion increases SAC by reducing disc bulge, stretching ligamentum flavum, Panjabi Spine’83:4

3 Joint Complex: Kirkaldy-Willis 1978

Tripod: Disc, Facets where a change in one joint leads to abnl stresses in the others (Usually disc Videman showed in only 20% facet degen preceeds)

Disc degeneration:

Anteriorly: Bulging Annulus fibrosus: narrows central anterior spinal canal

Posteriorly: Facets develop bony osteophytes, hypertrophy and ligament buckling

Fibrous border of NP coalesces with AF and after 2nd decade indistinct. Next as disk degenerates its unable to absorb load at the nucleus pulposus. The force is redirected unequally down the annulus fibrosus, causing it to tear circumferentially and these combine and expand radially to the periphery of the endplate. Dessication, degeneration, cavitation and calcium deposition. Due to mechanical changes the disc space collapses Collapse leads to posterior fissuring and bulging along PLL

Disc Degenerative Cycle: A remodeling process in response to mechanical alterations. Occurs initially in the more mobile segments then progress cephalad

Unstable phase:

Alters kinematics of motion segment. Assoc with disc height rdxn, ligamentous laxity, and facet jt degeneration.

Remodeling phase:

Osteophyte formation re-stabilizes motion segment, stenosis ensues

Dysfunction  Instability  Restabilization

Etiological Theories

VASCULAR: Dynamic component

MECHANICAL

Diverse presentation of signs and symptoms because of variability in size of Lumbar spinal canal, size of Nerve roots, and induced pressures.

Degenerative processes in spine result in mechanical, compression, ischemia, altered metabolism, and neural inflammation.

Theories for Stenosis VASCULAR

Impair proper vascular and nutritional supply to the nerve root you will contribute to edema, fibrosis, inflammation, ischemia, and altered metabolic processes. Dynamic/brought on by activity

Vertebral Venous HTN : Arnoldi CORR ’76:115

Arterial Hypovascular Vaso Nervorum: Intersection of central and radicular within Cauda Equina and Spinal Nerve Roots

3. Dorsal Root ganglion extensive vascular network,increased permeability and metabolic fcn. Parke Spine ’85:10 , JBJS ’81:63A

Mechanical

Collapse disc height: overriding of articular surfaces, narrowing of neuroforamen in cross section and impingement on exiting nerve root.

Stenotic canal reduces further while walking. Epidural pressures increase 20mm Hg with each step, due to complex rotary sp segment mvmts during walking that in turn reduces cross section.

Takahaski Spine ’95:20

Mechanical Theory: Intraneural edema formed as a result of compression injury leads to an intraneural compartment syndrome. Venous congestion at 5-10mmHg ◙ Rate dependent: More pronounced after rapid than slow onset compression ◙ Long standing edema leads to intraneural fibrotic scar ◙ This delays long convalescence scenario ◙ Impairs nutrition Olmarker Spine ’89:14

Remember this slide ? This is the Foramen (The Nerve’s hole where it exits)

On the diagram #2 is

Keep this in mind for the next slide !!!!!!!!!!!!!!!!!!!!!!!!!!

Notice the Fibrosis/Scarring that develops with time inside the Foramen This is what happens with Stenosis with time !!!!

Mechanical and Vascular Theories: Decrease in Cross Sectional Area Neurogenic claudication began with venous congestion of the nerve root and DRG. With increasing compression motor and sensory deficits occurred and blockage of axoplasmic flow (50-75%). Constriction of more than 50% was the critical point that resulted in loss of Cortical evoked potentials, neurologic deficits and histologic abnormalities. Delamarter JBJS ’90A:110

Degenerative Spinal Stenosis: Etiology due to altered mechanical forces

Osteophyte formation

(90%M >50, 100%F>60)

Disc Bulging

Facet Jt Hypertrophy

Lamella subluxation

Ligamentous thickening

Naylor JBJS ’79:61B

Presentation

Age : Mid 50’s –Early 60’s

Females present with greater frequency

Symptoms exacerbation of symptoms with standing and walking, and improve with lying down, sitting or leaning on a shopping cart or kitchen counter .

Neurogenic Claudication

Radicular Symptoms 5th Lumbar root is most often involved. (75%) Sensory,motor,and reflex changes

Pain burning, numbness, tingling, heaviness, cramping and weakness of both lower extremities (One)

Leg Pain (Not back pain: common but not cause for seeing MD) Radiates to the buttocks and thighs and progressively radiates below the knees to the feet.

Differential Diagnosis

Peripheral Neuropathy

Vascular Disease: starts distally with cramping, calf pain and progresses proximally

Lumbar Disc Disease

Osteoarthritis of other joints (SI,hip,knee,lumbar, etc.)

Myelopathy from cord compression

Comparison of Neurogenic and Vascular Claudication in Spinal Stenosis Symptom or Sign Neurogenic Claudication Vascular Claudication Distal pulses Normal Diminished or absent Skin changes None Mottled or atrophic Loss of pretibial hair growth Positional change Pain improved with lumbar flexion (eg, sitting, stooping) Pain unaffected by lumbar posture Walking distance Variable Fixed distance before onset Increased pain with increased distance ambulated Relationship of pain to cessation of ambulation

Physical Exam No definitive signs or findings Gait: Posture: LB: ROM: Neurologic exam : Tension signs Pulses and trophic changes: Radiologic imaging studies confirm stenosis, clarify Forward flexed posture with limited pelvis rotation Forward flexed, coronal imbalance No specific tenderness, spasm (HNP) Pt tenderness overf SI jts/Sciatic Notch Good forward flexion, painful extension Often normal L4-5 Level Commonly: Weakness EHL, Tib Ant SLR often negative Reflex testing unreliable, absent/hypoactive common, hyperactive reflexes and long tract signs prompt search for compressive lesion (SLR,Naffziger,Kemp,Cram)are often negative unless Foraminal involvement Vascular

Plain films

Radiographs usually reveal findings consistent with degeneration of the lumbar spine, such as

Disc space narrowing

Endplate sclerosis

Formation of osteophytes

Facet joint hypertrophy and arthritis

Degenerative scoliosis or spondylolisthesis

Settling of spinous processes

Instability

CT MRI Findings

CT&MRI

1. Identify location, degree of stenosis (15% trefoil)

2. Absolute stenosis lateral recess diameter <3mm, relative 3-5mm

3. Sagittal absolute <10 , relative <12

Ciric JNeurosurgery ’80:5

Verbeist JBJS B’77:59

4. Cross sectional area <100mm2 absolute stenosis

Bolender JBJS ‘85: 67A

5. The critical height of the intervertebral foramen is believed to be 15 mm and posterior disc height of 3 mm. N Root compression 80% when below

Myelography Through 1980’s

Hourglass constriction at one or more levels

Scans in extension, hyperextension

High sensitivity and specificity

Bell Spine ’84:9

False positives 24% in asymptomatic pts

Transition to MRI occurred in 90’s

Accuracy of MRI and CT combined was 92.5% Modic AMJR ’86:147

Helps differentiate nondiscogenic lumbar radiculopathy An SUSCTMRI ’93:14

Older population higher incidence of false +

Over 60% of pts >60yo have degen changes,sten

Reading CT/MRI Disc: Herniated Vertebrae: Endplate, Osteophytes Facets: Orientation, Arthroses, Synovial Cysts, Capsular hypertrophy, Tropism, Subluxation Nerve Root entrapment Foramina Lateral Recess Thecal Sac: Degree of deformity Canal: Trefoil, round, etc Instraspinal Masses Fat: Prominent epidural fat, epidural lipomatosis Ligamentum Flavum

Central Stenosis

Present with neuronal claudication, and pathology can entail single-level or multi-level involvement.

Thecal sac can be compressed laterally, anteriorly and/or posteriorly, and circumferentially.

Lateral compression may result from medial hypertrophy of the facet.

Posterior disk protrusion may account for anterior central stenosis, whereas alterations of the ligamentum flavum may contribute to posterior compression .

Circumferential or Multi-directional combination of compressive forces upon the thecal sac.

Lateral stenosis

Largely accounts for radiculopathic symptoms and entails the lateral recess and the intervertebral foramen.

The incidence of lateral nerve root entrapment is 8 to 11% in stenotic patients.

Unrecognized foraminal stenosis accounts for 60% of failed back patients with persistent postoperative symptoms.

MRI

Useful indicator of significant foraminal stenosis is absence of well defined perineural fat signal of parasagittal T1 weighted images

Blk Arrows DRG

White Arrowhead A radicular vein anterior

Axial T1 MRI shows disc and osteophyte protruding in the foramen, which obliterates the fat anterior to the Nroot

Axial MRI can show Central and Lateral recess stenosis by Lig flavum hypertrophy and facet hypertrophy

Disc bulging, compromises canal anteriorly

Hypertrophy of the facets and lig flavum indents the Subarachnoid space posteriorly

MRI better for LRStenosis: T1 parasagittal scans show the N root cmprs or deformed by disc/ facet subluxation with lig flavum impingement on N root

L4-5 Level: MRI T1 Parasagittal scan

The nerve (black circle/ dot) is being pinched within the foramen

Remember this slide ? This is the Foramen (The Nerve’s hole where it exits)

On the diagram #2 is

Foraminal Stenosis

Here you can see how the nerve can be pinched within the foramen (the nerve’s hole through which it must exit)

Conservative Treatment Options

Early stages intermittent symptoms (neural inflammation)

Activity modification

Staying in shape physically/aerobically

Avoid longterm bedrest

Avoid certain activities : bending,twisting, lifting, unnecessary walking…..Usually eases pain

PTherapy: stretching and isometrically strengthening atrophied muscles

Modalities: heat, U/S, Whirlpool, massage

Conservative Therapy

Avoid Narcotic medications and muscle relaxants (depression/sedation)

Support grps and antidepressant meds (help insomnia, clinical depression, neurogenic pain)

Anti-inflammatory meds

Calcitonin

Bracing

Epidural steroids and oral steroid ‘dose packs’ relieve pain and inflammation and allow aerobic conditioning and incr fcn

All temporary not a cure for stenosis, and gives indication of severity

The Natural Course of Lumbar Spinal Stenosis Johnsson CORR ’92:279

There are No well designed, long-term, prospective studies describing the true nature of stenosis

There also are No single randomized trials which compared surgery vs conservative.

The largest and best study followed 32 patients preselected for surgery, at 4yr period had no proof of severe deterioration and unchanged stenosis. (Non randomized comparison design)

Immediate operation should be advised only if neurologic symptoms devolop or if pain is intolerable

Natural Course of NonOperative versus Operative Treatment

Operative Treatment This condition will not progress to paralysis or bowel/bladder dysfunction, if activities are curtailed symptoms may generally relieve This ultimately is about the Quality of life and level of function/activity desired by the patient Significant ability to walk/stand due to claudicant leg pain.

One year Outcomes Surgical procedures increase the relative odds of definite improvement 2.6 fold compared with nonop Atlas Spine ’96: 21 Maine observational cohort study: Although improvement 55% nearly twice as good 28% improvement by conservative.

Surgical Decompression Divided into decompressive procedures With and Without a fusion

Results

Good to excellent outcomes 72%.

Keep in mind there are no randomized clinical trails comparing surgical and conservative treatment.

We can offer two types of procedures

Limited Procedures

Single level Hemilaminectomy

Hemilaminotomy

Laminoplasty

Global Procedures

Multilevel bilateral laminectomy with bilateral facetectomies and formainotomies

Laminectomy Bilateral Laminectomy : Lamina and Lig Flavum are removed on both sides of stenotic level(s) to the lateral recess. Proceed Caudal to Cranial. Decompressed until lateral edge of the nerve root is decompressed Preserve Pars Interarticularis- to minimize instability by inadvertent sacrifice of superior facet. If disc herniation: Discectomy is performed,then consider arthrodesis. Finally lateral decompression of the foraminae(probe foramen dorsal and ventral to Nerve root, and rtrxn 1cm medially).

Decompression without arthrodesis is the preferred treatment unless instability or structural abnormalities are present.

One or Two level stenosis: Laminectomy preferred with care to minimize damage to pars and facets.

If more than one facet jt sacrificed at any segmental level then prophylactic fusion to minimize risk of subsequent spinal instability if disc and posterior structures violated

Multiple Stenotic Levels

“ It is wise to decompress all stenotic levels but to do so in a limited fashion” McCulloch: Mastercases in Spine Sx

Multilevel laminotomies are preferred to laminectomy

These can be unilateral or bilateral

Unless there is instability there is no need for fusion

Indications for Fusion

Fusion Procedures

ALIF Anterior Lumbar Interbody Fusion

PLIF Posterior Lumbar Interbody Fusion

Posterior fusion

Posterolateral (Intertransverse or bilateral lateral) fusion

Noninstrumented

Instrumented

Nonsegmental Instrumentation

Segmental (Pedicle Screw) Instrumentation

Role of Fusion

Rigid vs Semirigid

Overall fusion rate 65% Noninstrumented

77% Semirigid fixation

95% Rigid fixation

Overall trend for better clinical outcome with increasing rigidity of fixation

Grob Humke JBJS ’95:77

Comorbidity

Complications are more frequent with

Advancing age

Increased complexity of diagnosis

Comorbid conditions

Katz, Lipson JBJS’91:73

Correlation with excellent outcome

Preoperative duration of symptoms of less than 4 years

No preoperative low back pain

No significant comorbidities

Katz, Lipson JBJS’91:73

Case

79 yo male complains of Right sided> Lsided leg back, mild back pain, weakness.

Has noted difficulty with walking long distances which brings on his pain

Has relief of pain while lying supine

Has no difficulty while shopping, which he loves to do as long as he can use a shopping cart

Degenerative Discs: Blackened, Bone on bone, decreased in height

L3 4 Stenotic Canal (Triangular shape)

L 4 5 Stenosis trefoiled/triangular canal Synovial cyst

L5 S1

1/14/06 Patient underwent multilevel decompression surgeries

L3 L4 Hemi laminectomy for facet cyst, foraminotomies

Lumbar hemilaminectomy for Herniated Nucleus Pulposus L5 S1

Patient doing well. Stayed in the hospital for 3 days, passed a course of therapy, noticed resolution of leg pain & back pain.

Surgical Procedures

Surgery should be a last resort, when conservatives measures fail.

In some cases surgery needs to be done sooner than later, or even urgently, depending on the physical exam, history, neural deficits, and size of the herniation.

Dr Pazmiño: Orthopaedic Spine Dr Lauryssen: Neurological Spine

Minimally Invasive

All our procedures are performed in a minimally invasive manner.

All patients receive a plastics closure and are followed closely afterwards

Iguacu Falls. Brazil

Thank you for your time.

If you know someone who could benefit from a consultation for Lumbar Pain/Stenosis please refer them to our online website or call toll free to schedule an appointment