Lumbar Stenosis Pathophysiology Lumbar Spinal Stenosis Decreased - - PDF document

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Lumbar Spinal Stenosis

Carole A. Miller, MD, FACS

Professor, Department of Neurosurgery Director Neurosurgery Residency Training Program Director, Ohio State Comprehensive Spine Center

Lumbar Stenosis

• In the lumbar spine developmental, acquired, or a

combined disease may lead to lumbar spinal stenosis with significant neurological sequelae.

• Developmental stenosis in the lumbar region may

involve an isolated segment, causing a ring like constriction of the region or it may involve multiple levels of the entire lumbar segment.

• However, developmental stenosis in and of itself

rarely causes symptoms.

• Combined stenosis is the most common form of

lumbar spinal stenosis giving rise to clinical disease, and it is more common in the lumbar spine than in the thoracic or cervical spine.

Lumbar Stenosis

• Pathophysiology

Decreased volume of the spinal canal due to

• steoarthritis of the disc and facet joints

Less space available for the neural elements Mechanical irritation can incite a local inflammatory response Vascular and conduction changes of neural elements are thought to be responsible for the symptoms Chronic neural compression leads to edema, demyelization and wallerian degeneration of the afferent and efferent fibers Substance P has been proposed as a pain modulator related to involvement of the nerve root and dorsal root ganglion.

Lumbar Stenosis

• Pathophysiology
• Central Stenosis

Ligamentum flavum buckling or hypertrophy Superior facet process hypertrophy or osteophyte formation Intervertebral disc protrusion or osteophyte formation

• Later recess stenosis

Entrance zone: hypertrophy of the superior articular process Mid zone: Fibrocartilage overgrowth of the pars interarticularis defect Foraminal stenosis: Pedicular kinking from scoliosis, foraminal disc herniations, or foraminal collapse secondary to collapse of disc space

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Lumbar Stenosis

• 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 cauda equina

• Foraminal stenosis:

Narrowing of the neural foramen

• Lateral recess stenosis

Lumbar Stenosis

• Central Canal Stenosis

Congenital as in achondroplastic dwarf Acquired most commonly superimposed on congenital

• Important*

Stenosis in the lumbar region causes the syndrome of neurogenic claudication In the cervical region cervical myelopathy and ataxia (from spinocerebellar tract compression) may be present

• In 5%, lumbar and cervical stenoses are

symptomatic simultaneously

• Symptomatic spinal stenosis in the thoracic

region is rare.

Lumbar Stenosis

• Key points in Lumbar Stenosis:

Caused by hypertrophy of the facets and ligamentum flavum, may be exacerbated by disc bulging or spondylolisthesis, may be superimposed on congenital narrowing Most common at L4-5 and then L3-4 Symptomatic stenosis produces gradually progressive back and leg pain with standing walking that is relieved by sitting or lying (neurogenic claudication) Generally occurs in patients with congenitally shallow lumbar canal with superimposed acquired degeneration Symptoms differentiated from vascular claudication which is usually relieved at rest regardless of position Usually responds to surgery; fusion may be an adjunct

Lumbar Stenosis

• The transverse diameter can be determined on conventional x-rays

sagittal diameter required myelography, CT or MRI

• Lumbar spinal stenosis in the adult is indicated ay an AP diameter of

<13 mm or a transverse diameter of <20 mm measured on the CT

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Lumbar Spinal Stenosis

• Often presents as neurogenic claudication (NC)

aka pseudoclaudication. Ischemia of LS nerve roots and increased metabolic demand from exercise together with vascular compromise of the nerve root due to pressure from surrounding structures

• Must be differentiated from vascular claudication

aka intermittent claudication, resulting form ischemia of exercising muscles

Clinical features distinguishing neurogenic from vascular claudication

decreased Normal Skin temp feet marked None Foot pallor on elevation Infrequent (15%) Common (67%) Discomfort on lifting or bending Decreased or absent Normal Peripheral pulses Constant day to day in 88% Varies day to day in 62% Claudicating distance Almost immediate not dependent on posture (relief

• f walking induced symptoms

with standing is a key differentiating feature Slow often > 30 min; usually positional; *standing and resting usually not sufficient Relief with rest Reliably reproduced with fixed amount of exercise; rare at rest Exercise with maintenance of a given posture (65% have pain with standing at rest); coughing produces pain (38%) Inciting factors Stocking distribution Dermatomal Sensory loss Muscular group (sclerotomal) dermotomal pain

Vascular claudication Neurogenic claudication Feature

• Vascular insufficiency
• Trochanteric bursitis
• Lumbar or Thoracic Disc Herniation
• Juxtafacet cyst

Ganglion cyst Synovial cyst

• Arachnoiditis
• Intraspinal tumor
• Functional etiologies
• Diabetic neuritis

Differential Diagnosis

Associated Conditions

• Congenital

Achondroplasia Congenitally narrowed canal

• Acquired

Spondylolisthesis Acromegaly Post-traumatic Paget’s Disease Ankylosing spondylitis Ossification of the yellow ligament

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Radiographic Evaluation

Impingement on neural structures and loss of CSF signal on T2WI at severely stenotic

• levels. Good for seeing nerve impingement.

*Asymptomatic abnormalities are demonstrated in up to 33% of asymptomatic patients 50-70 yrs

• ld

MRI Lateral shows “washboard pattern” AP shows “wasp-waisting (narrowing of dye column. Myelogram Classically shows “trefoil” canal; also hypertrophied ligaments, facet arthropathy, and bulging discs; best for seeing bone CT scan May show spondylolisthesis, AP diameter of canal is narrowed but interpedicular distance is normal Lumbo-sacral spine x-rays

Lumbar Stenosis CT Scan

Lumbar Stenosis Myelogram

• Lateral myelogram of 60 yo

F complaints of both lower back and radiating leg pain > with activity. Segmental stenosis of severe degree from L-2 through L-5, with disc degeneration an posterior osteophyte formation

Lumbar Stenosis: Myelogram

• AP myelogram of an

83 yo F. At the level of L3-4 there is severe constriction with almost complete block, and at the L4-5 there is a mild narrowing on the left

• side. The nerve roots

also are affected at the L3-4 level

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Lumbar Stenosis: CT Scan Lumbar Stenosis: CT Scan Lumbar Stenosis MRI Scan Adjuncts to Radiographic Evaluation

EMG with NCV may show multiple nerve-root abnormalities bilaterally; or may be normal Vascular lab studies (Doppler) may assist in identifying vascular insufficiency Ratio of ankle to brachial blood pressure (A:B ratio: >1.0 is normal; mean of 0.59 in patients with intermittent claudication; 0.26 in patients with rest pain; <0,05 indicates impending gangrene “Bicycle test”: patients with NC can usually tolerate longer periods of exercise on a bicycle than patients with intermittent vascular claudication because the position in bicycling flexes the waist

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Lumbar Stenosis

Natural History and Treatment

Gary Rea, MD

• Radiographic stenosis-slowly progressive

with degeneration process

• Clinical symptoms-5 years back pain-leg

pain with intermittent deterioration

• Leg pain-progressively severe with

neurogenic claudication

• Paralysis-not an issue, even with severe

cases

Lumbar Stenosis Natural History

• Physical Therapy
• Flexion exercises-no extension
• Water aerobics
• Stationary bicycle, rowing, lifting weights

while sitting

• Other-Cane, Walker, Scooter

Lumbar Stenosis Treatment-Non Surgical Lumbar Stenosis Non-Treatments

• Traction with computerized

“decompression” apparatus

• $4000-insurance may not pay
• No randomized prospective studies to

show it is better than natural history or

• ther treatments

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Lumbar Stenosis Invasive Treatments

• Epidural Steroids
• May help in mild to moderate cases
• Rarely help in severe patients
• To be considered successful, must improve

pain for at least 3 months

Lumbar Stenosis Surgical Treatment

• X-Stop-Acts to flex spine and open canal
• Can be done under local
• Most useful in very elderly and poor health
• Long term effectiveness is not clear
• May have real problems with osteoporosis

Lumbar Stenosis Surgical Treatment

• Laminectomy alone-addresses the

stenosis, but does not address the instability inherent in the condition

• Best used in patients with normal

lordosis, males, older patients

• Still a good treatment option in

specific patients

Lumbar Stenosis Surgical Treatment

• Bilateral hemilaminectomy and fixation

with facet screws

• Not a common procedure, but addresses

the compression and the instability

• Less blood loss than fixation with pedicle

screws, but less strong

• Best in patients with single level problems

and in older patients

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Lumbar Stenosis Surgical Treatment

• Lumbar Laminectomy and fusion/fixation
• Addresses stenosis and instability
• No large randomized studies to show its

superiority

• BUT-many studies show the fusion/fixation

improves outcome in back pain and pain

• Has some increased risk because of length
• f surgery and blood loss
• Laminectomy and Fusion/Fixation with

Pedicle screws

• Problems-length of surgery, blood loss,
• steoporosis, problems at other levels,

complications

• Good News- 60-70% significant

improvement in symptoms-far greater than any other treatment in patients with neurogenic claudication

Lumbar Stenosis Surgical Treatment Summary-Treatment of Lumbar Stenosis

• Lumbar stenosis is a slowly progressive

degenerative problem-rarely emergency

• Non-invasive treatments focus on flexion

posture, sitting exercises, use of walking aids

• Decompressive therapy is unproven
• Steroid injections are reasonable, but often

not effective in severe cases

Summary-Treatment of Lumbar Stenosis

• Surgical Treatments

X-Stop-newer treatment puts vertebrae in flexion-less invasive-elderly population Laminectomy-effective, but doesn’t address instability-best in males without listhesis Bilateral hemilam with fixation with facet screws-smaller surgery, less strong, effective with single level disease

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Summary-Treatment of Lumbar Stenosis

• Surgical treatments
• Lumbar laminectomy and

fusion/fixation-addresses compression and instability > 60%success, but is big surgery in older population