Lumbar Stenosis • Pathophysiology Lumbar Spinal Stenosis � Decreased volume of the spinal canal due to osteoarthritis of the disc and facet joints � Less space available for the neural elements � Mechanical irritation can incite a local inflammatory Carole A. Miller, MD, FACS response � Vascular and conduction changes of neural elements Professor, Department of Neurosurgery are thought to be responsible for the symptoms Director Neurosurgery Residency Training Program � Chronic neural compression leads to edema, demyelization and wallerian degeneration of the Director, Ohio State Comprehensive Spine Center 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 Lumbar Stenosis • Pathophysiology • In the lumbar spine developmental, acquired, or a combined disease may lead to lumbar spinal stenosis with significant neurological sequelae. • Central Stenosis � Ligamentum flavum buckling or hypertrophy • Developmental stenosis in the lumbar region may � Superior facet process hypertrophy or osteophyte involve an isolated segment, causing a ring like formation constriction of the region or it may involve � Intervertebral disc protrusion or osteophyte formation multiple levels of the entire lumbar segment. • Later recess stenosis • However, developmental stenosis in and of itself � Entrance zone: hypertrophy of the superior articular rarely causes symptoms. process � Mid zone: Fibrocartilage overgrowth of the pars • Combined stenosis is the most common form of interarticularis defect lumbar spinal stenosis giving rise to clinical � Foraminal stenosis: Pedicular kinking from scoliosis, disease, and it is more common in the lumbar foraminal disc herniations, or foraminal collapse spine than in the thoracic or cervical spine. secondary to collapse of disc space 1
Lumbar Stenosis Lumbar Stenosis • Key points in Lumbar Stenosis: • Central canal stenosis: � Caused by hypertrophy of the facets and ligamentum � Narrowing of the AP flavum, may be exacerbated by disc bulging or dimension of the spinal spondylolisthesis, may be superimposed on congenital canal. The reduction in narrowing canal size may cause � Most common at L4-5 and then L3-4 local neural compression and/or compromise of the � Symptomatic stenosis produces gradually progressive blood supply to the cauda back and leg pain with standing walking that is relieved equina by sitting or lying (neurogenic claudication) � Generally occurs in patients with congenitally shallow • Foraminal stenosis: lumbar canal with superimposed acquired degeneration � Narrowing of the neural � Symptoms differentiated from vascular claudication foramen which is usually relieved at rest regardless of position Lateral recess stenosis • � Usually responds to surgery; fusion may be an adjunct Lumbar Stenosis Lumbar Stenosis • The transverse diameter can be determined on conventional x-rays • Central Canal Stenosis sagittal diameter required myelography, CT or MRI � Congenital as in achondroplastic dwarf • 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 � 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. 2
Differential Diagnosis Lumbar Spinal Stenosis • Vascular insufficiency • Trochanteric bursitis • Often presents as neurogenic claudication (NC) aka pseudoclaudication. • Lumbar or Thoracic Disc Herniation � Ischemia of LS nerve roots and increased • Juxtafacet cyst metabolic demand from exercise together with � Ganglion cyst vascular compromise of the nerve root due to pressure from surrounding structures � Synovial cyst • Arachnoiditis • Must be differentiated from vascular claudication aka intermittent claudication, resulting form • Intraspinal tumor ischemia of exercising muscles • Functional etiologies • Diabetic neuritis Clinical features distinguishing Associated Conditions neurogenic from vascular claudication • Congenital Feature Neurogenic claudication Vascular claudication � Achondroplasia pain dermotomal Muscular group (sclerotomal) � Congenitally narrowed canal Sensory loss Dermatomal Stocking distribution Inciting factors Exercise with maintenance of a Reliably reproduced with • Acquired given posture (65% have pain fixed amount of exercise; rare with standing at rest); coughing at rest produces pain (38%) � Spondylolisthesis Relief with rest Slow often > 30 min; usually Almost immediate not positional; *standing and resting dependent on posture (relief � Acromegaly usually not sufficient of walking induced symptoms with standing is a key � Post-traumatic differentiating feature Claudicating distance Varies day to day in 62% Constant day to day in 88% � Paget’s Disease Peripheral pulses Normal Decreased or absent Discomfort on lifting or Common (67%) Infrequent (15%) � Ankylosing spondylitis bending Foot pallor on elevation None marked � Ossification of the yellow ligament Skin temp feet Normal decreased 3
Radiographic Evaluation Lumbar Stenosis Myelogram Lumbo-sacral May show spondylolisthesis, AP diameter of spine canal is narrowed but interpedicular distance is normal x-rays • Lateral myelogram of 60 yo CT scan Classically shows “trefoil” canal; also F complaints of both lower hypertrophied ligaments, facet arthropathy, back and radiating leg pain and bulging discs; best for seeing bone > with activity. Segmental stenosis of severe degree Myelogram Lateral shows “washboard pattern” from L-2 through L-5, with AP shows “wasp-waisting (narrowing of dye column. disc degeneration an posterior osteophyte MRI Impingement on neural structures and loss of CSF signal on T2WI at severely stenotic formation levels. Good for seeing nerve impingement. *Asymptomatic abnormalities are demonstrated in up to 33% of asymptomatic patients 50-70 yrs old Lumbar Stenosis: Lumbar Stenosis CT Scan 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 4
Lumbar Stenosis MRI Scan Lumbar Stenosis: CT Scan Adjuncts to Radiographic Lumbar Stenosis: CT Scan Evaluation “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 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 Vascular lab studies (Doppler) may assist in identifying vascular insufficiency EMG with NCV may show multiple nerve-root abnormalities bilaterally; or may be normal 5
Lumbar Stenosis Treatment-Non Surgical Lumbar Stenosis • Physical Therapy Natural History and Treatment • Flexion exercises-no extension • Water aerobics Gary Rea, MD • Stationary bicycle, rowing, lifting weights while sitting • Other-Cane, Walker, Scooter Lumbar Stenosis Lumbar Stenosis Natural History Non-Treatments • Radiographic stenosis-slowly progressive with degeneration process • Traction with computerized “decompression” apparatus • Clinical symptoms-5 years back pain-leg pain with intermittent deterioration • $4000-insurance may not pay • Leg pain-progressively severe with • No randomized prospective studies to show it is better than natural history or neurogenic claudication other treatments • Paralysis-not an issue, even with severe cases 6
Lumbar Stenosis Lumbar Stenosis Invasive Treatments Surgical Treatment • Laminectomy alone-addresses the • Epidural Steroids stenosis, but does not address the instability inherent in the condition • May help in mild to moderate cases • Rarely help in severe patients • Best used in patients with normal lordosis, males, older patients • To be considered successful, must improve pain for at least 3 months • Still a good treatment option in specific patients Lumbar Stenosis Lumbar Stenosis Surgical Treatment Surgical Treatment • Bilateral hemilaminectomy and fixation • X-Stop-Acts to flex spine and open canal with facet screws • Can be done under local • Not a common procedure, but addresses the compression and the instability • Most useful in very elderly and poor health • Less blood loss than fixation with pedicle • Long term effectiveness is not clear screws, but less strong • May have real problems with osteoporosis • Best in patients with single level problems and in older patients 7
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