- Discussion:
- spinal stensosis is a narrowing of the lumbar spinal canal and/or neural foramina;
- results in compression of the cauda equina and lumbar nerve roots, producing neural root ischemia and neurogenic claudication;
- compression of neural structures also compresses vascular supply of nerves so that symptoms are predominately those of neural ischemia;
- because both neural canal and the neural foramen are narrowed w/ spine in extension & opened in flexion, neural compression is most often temporary;
- pain induces patients to change position and relieve nerve pressure before permanent neurologic damage is done;
- although degenerative spondylolisthesis is common cause of stenosis, 10% of adults > 65 yrs may have this finding & many are asymptomatic;
- central stenosis:
- refers to narrowing and compression at the entrance and within the neural foramen formed by the cephalad and caudal pedicles,
facet joints dorsally and vertebral body and discs ventrally.
- contributing causes:
- achondroplasia
- references:
- The natural course of lumbar spinal stenosis.
rest and standing;
- patients are usually 50 years or older;
- radicular symptoms may be unilateral or bilateral with or without back pain
- pain occurs when the patient is upright and particularly when walking;
- standing and walking up inclines increase pain;
- sitting and lying on side with the hips and knees flexed relieve pain as does leaning over a shopping cart.
relieves pain
- patient seeks relief by sitting, leaning forward to "relieve pressure" putting his foot on a raised rest, or lying down;
- common denominator is changing the position of the spine from extension to flexion;
- dx of spinal stenosis is made by eliciting h/o of pseudoclaudocation, positive spinal Phalen test, and imaging confirming stenosis;
- patients may present with bizarre neurologic complaints
- EMG is helpful in evaluation the nerve roots affected and in ruling out other causes of neuropathy;
- Phalen test may be specific;
- this test attempts to reproduce symptoms of leg pain, weakness, or numbness by causing neural ischemia;
- w/ pt upright, bend the patient into extension for a full minute;
- this should accentuate the spinal stenosis;
- positive test will produce a crescendo of leg symptoms followed by rapid relief of these symptoms when the patient flexes forward,
places his hands on examination table, and places one foot on stool;
- Radiographs:
- AP and lateral radiographs including flexion and extension laterals are helpful.
- disk space narrowing is a poor predictor of symptoms;
- instability:
- normal anterior and posterior translation from L1 to L5 is about 8% of length of vertebral body or about 4 mm;
- note that the typical degenerative changes of osteophyte formation, decrease in disc height, and ligament calcification will serve to limit motion;
- Myelogram:
- myelogram with the patient in extension may offer the best information on location of stenotic areas;
- CT scan:
- coronal and sagittal CT reconstructions are quite helpful
- evaluate for lateral stenosis & central stenosis;
- cross-sectional dural areas of < 100 mm2 denote stenosis;
- clinical syndrome of lumbar stenosis correlates more closely w/ anteroposterior diameter of the dural sac;
- dural sac w/ AP diameter of < ten millimeters is consistent w/ clinical syndrome of lumbar stenosis;
- MRI:
- MRI delineates very accurately the compressive elements of LSS
- references:
- Role of computed tomography and myelography in the diagnosis of central spinal stenosis.
- Radiologic diagnosis of degenerative lumbar spinal instability.
- Non Operative Treatment:
- high percentage of patients will have little change in their symptoms without treatment;
- physical therapy and aquatic exercises which avoid extension may be helpful.
- image guided intralaminal epidural and transforaminal nerve root steroid injections may provide relief for variable periods of time.
- Operative Treatment:
- decompression by laminectomy and partial facetectomy is effective.
- indications for fusion:
- fusion with instrumentation in addition to decompression may be necessary in patients with degenerative spondylolisthesis,
degenerative scoliosis, post laminectomy, and those with adjacent segment stenosis following a fusion;
- w/ no segmental instability, arthrodesis may not be required, (assumming that posterior elements have not been destabilized);
- degenerative spondylolisthesis;
- positioning:
- be particularly certain that there is no pressure on abdomen which would compress the vertebral venous plexus;
- decompression:
- laminae are minimally trimmed for exposure;
- includes widening of lateral recess;
- removal of medial rim of facets;
- postero-lateral fusion:
- see: fusion of the spine
- references:
- Treatment of cervical spondylotic myelopathy by enlargement of the spinal canal anteriorly, followed by arthrodesis.
- Bone regrowth after surgical decompression for lumbar spinal stenosis.
- Lumbar foraminal stenosis: critical heights of the intervertebral discs and foramina. A cryomicrotome study in cadavera.
- Increase of motion between lumbar vertebrae after excision of the capsule and cartilage of the facets. A cadaver study.
- Laminectomy with and without spinal fusion.
- Postdecompression lumbar instability.
- Morbidity and mortality in association with operations on the lumbar spine. The influence of age, diagnosis, and procedure.
- Neurologic complications and lumbar laminectomy. A standardized approach to the multiply-operated lumbar spine.
- Repeat decompression of lumbar nerve roots. A prospective two-year evaluation.
- Degenerative lumbar spinal stenosis. Decompression with and without arthrodesis.
- The outcome of decompressive laminectomy for degenerative lumbar stenosis.
- A Comprehensive Study of Patients with Surgically Treated Lumbar Spinal Stenosis with Neurogenic Claudication.
- Perioperative Complications of Posterior Lumbar Decompression and Arthrodesis in Older Adults.
Review Papers: