Terms in this set (108)
Is there high quality evidence to date regarding the timing of surgical decompression in spinal cord injury?
No. Retrospective data might suggest benefit to earlier decompression, bt equivocal to date.
What pharmacologic therapies have been tried for spinal cord injury?
methylprednisolone, GM1 ganglioside, TRH, gacyclidine, naloxone, and nimodipine.
What was the initial NASCIS trial?
The authors assumed that methylprednisolone was beneficial and omitted a placebo group, testing high dose vs. low dose methylprednisolone and finding no difference in neurologic outcome, but a much increased risk of medical complications with the high dose arm.
What were the methods of the NASCIS 2 trial?
Methylprednisolone was given to 162 patients as a bolus of 30 mg per kilogram of body weight, followed by infusion at 5.4 mg per kilogram per hour for 23 hours. Naloxone was given to 154 patients as a bolus of 5.4 mg per kilogram, followed by infusion at 4.0 mg per kilogram per hour for 23 hours. Placebos were given to 171 patients by bolus and infusion.
What were the results of the NASCIS 2 trial?
Primary analysis demonstrated no benefit; post hoc analysis showed modest motor and sensory improvements.
What was the design of the NASCIS 3 trial?
1991-1995. 500 patients, 3 arms: 24h methylprednisolone, 48h methylprednisolone, and tirilizad (a steroid with antioxidant but no glucocorticoid effects); importantly, functional outcome measures were used.
What complications were noted with a 48 hour regimen of methylprednisolone?
Twofold higher rate of severe pneumonia, fourfold incidence of severe sepsis compared to the 24 hour group.
What were the results of NASCIS 3?
There were statistically significant, but not clinically important differences in the Functional Independence measure. The FIM scale ranges from 18 to 126 (independent, and completely dependent, respectively.
Median FIM was 99 vs 103 in the tirilizad vs 48h MP group.
What tracts do SSEPs monitor?
What is the sensitivity/specificity of SSEPs?
SSEPs are highly (95%) specific for neurologic compromise, but not sensitive (30%), with a high false negative rate. Thus the rationale behind multimodality monitoring.
What are SSEPs?
Subdermal needle electrodes excite repetitive action potentials that propagate from peripheral nerves through the dorsal columns to the sensory cortex.
What SSEP changes are deemed significant to alert the surgeon?
Generally, a 50% decrease in amplitude combined with a 10% increase in latency compared to baseline prompts an alert.
What nonsurgical variables may cause SSEP changes?
Depth of anesthesia, patient temperature, and MAP.
What are MEPs?
Motor evoked potentials involve electrical or magnetic stimulation of the motor cortex, which cause muscle activation. These are intermittent, and loss of MEPs are the phenomenon of interest.
What is the value of EMG?
EMG, either as continuous free-running or triggered, can be sensitive to surgical manipulation, root irritation, such as in pedicle screw placement or tethered cord release. Typically L2-S2 for lumbosacral surgeries.
What constitutes "significant" EMG feedback?
Sustained (>2 sec) activity prompts an alert. (What to do?) Continuous EMG has high sensitivity (100%) but low specificity (25%).
What anesthetic agents should be minimized with use of neuromonitoring?
Halogenated agents and nitrous oxide affect SSEP amplitude and latency. MEPs require TIVA (total intravenous anesthesia) without neuromuscular blockade.
What is the major component of the nucleus pulposus?
Aggrecan, a very hydrophilic proteoglycan rich in keratan and chondroitin sulfates. Interspersed thin collagen fibers.
How is the disc innervated?
The posterior annulus receives fibers from the sinuvertebral nerve and the anterior and lateral annulus receive direct branches from the ventral rami and gray rami comunicantes.
What types of collagen are predominant in discs?
Types 1 and 2.
What is currently believed to be the dominant factor affecting disc degeneration?
Heredity, as demonstrated by multiple twin studies showing that most disc degeneration is heritable.
What are the major hormonal regulators of bone metabolism?
PTH, Vitamin D, Calcitonin, Gonadal hormones.
What is the effect of PTH on bone and calcium homeostasis?
Hypocalcemia stimulates PTH production. PTH stimulates increased calcium reabsorption in the kidney, and via Vit D, in the gut. In the bone, at high doses, it activates osteoclasts; at low intermittent doses it stimulates osteoblasts.
What is the effect of Vitamin D?
Vitamin D also serves to increase circulating calcium.
What is the role of calcitonin?
Calcitonin prevents bone resorption by binding directly to osteoclasts.
What is the effect of the gonadal hormones on bone?
Both estrogen and testosterone increase bone formation.
What are the definitions of osteopenia and osteoporosis?
Bone mineral densities of 1-2.5 SD below, and greater than 2.5 SD below age-/gender-matched means, respectively.
What is the treatment of an osteoporotic vertebral fracture?
Ca (1200mg/d) and Vit D (600IU/d) supplementation.
Strength and aerobic exercise training.
Calcitonin (intranasal) improves acute pain.
Bisphosphonates (50% reduction in fracture incidence)
What is the risk of future compression fracture after vertebroplasty or kyphoplasty?
Approximately 4-5x higher, nearly 20% in 1 year
What is the evidence basis for vertebroplasty at present?
There are three randomized controlled trials. Two showed no evidence of benefit; the other showed moderate improvement in pain.
What are the "seronegative spondylarthropathies"?
Those not associated with serum rheumatoid factor; ie ankylosing spondylitis, reactive arthritis, psoriatic and enteropathic arthropathies.
How is ankylosing spondylitis diagnosed?
>3months LBP, limited lumbar ROM, limited chest expansion, Sacroiliitis on MRI or plain film, HLA B-27 (90% of AS pts are HLA B27 positive; 1-2% of HLA B27 population develops AS).
What is the treatment of ankylosing spondylitis?
NSAIDs and anti-TNF agents.
What is reactive arthritis?
Arthritis that occurs following an infection, formerly "Reiter's Syndrome" Also associated with B-27 and high frequency of GU and ophthalmic symptoms.
What MRI characteristics differentiate a liquid epidural abscess from the more common epidural phlegmon?
A collection that enhances only peripherally, has a central nonenhancing part, and is T2-hyperintense is very likely to be fluid and esaily drainable.
A collection that enhances homogeneously and is hypo or isointense on T2 is likely a phlegmon, ie granulation tissue.
For what use is rhBMP-2 approved?
Single level L4/5 or L5/S1 ALIF.
Is electromagnetic bone stimulation beneficial for fusion?
Yes; it does appear to promote fusion.
What is the normal sagittal cervical canal diameter?
17 to 18mm. Stenosis is generally defined as less than 13mm, and a median diameter of 8mm is typical in series of symptomatic myelopathy.
What evidence is there for various forms of nonoperative treatment of cervical radiculopathy?
One Belgian RCT demonstrated symptomatic improvement in acute cervical radiculopathy for a c-collar and for PT compared to no active treatment at 6 weeks, but no difference at 6 months, with near-complete resolution of pain. Two RCTs showed no difference for the treatment of chronic radiculopathy.
Is there evidence to favor surgery over nonoperative management of cervical myelopathy?
No. The only randomized controlled trial, Kadanka et al from Czech Republic, followed patients for 10 years and found no significant differences in functional outcomes between patients randomized to operative decompression versus nonoperative management.
What is the natural history of cervical myelopathy?
It is generally stable; a minority of patients show improvement or deterioration over a ten year time period.
Is there any evidence to favor surgery over nonoperative management of cervical radiculopathy?
The only RCT, Persson et al 1997, from Sweden, showed a possible early benefit of ACDF in pain and muscle strength,but no significant difference at 1 year. This study was had methodologic issues w/crossover and outcome measures.
What advantages does a posterior foraminotomy offer over ACDF for radiculopathy?
Direct visualization of the root, preservation of the disk/motion segment, avoidance of laryngeal n, dysphagia, possibly reduced degenerative adjacent level changes.
What evidence exists regarding cervical disc arthroplasty compared to ACDF?
Several RCTs have shown equivalent outcomes with cervical arthroplasty compared to ACDF. None have shown improvements that meet minimally clinically importance differences in outcome scores.
What approach is preferred for cases of OPLL?
A posterior approach is generally preferable to avoid dural tear resulting from the frequent ventral dural adhesions with this disease.
What are the fixation options for C2?
Pedicle screws, pars screws and translaminar screws.
How are C2 pars screws different from pedicle screws in terms of length, entry points and trajectories?
Pars screw entry point is more caudal and medial, and the trajectory is more straight ahead, and screws tend to be shorter (typically 16mm).
Describe the entry point, trajectory and length of a C2 pars screw.
Pars screw is started 2-3mm rostral and lateral to the junction of the caudal lamina and inferior facet, trajectory is slightly less rostrally directed than a C1-2 transarticular screw, and typically a 16mm long screw is adequate.
What C2 screw technique completely avoids risk to the vertebral artery?
Translaminar, described by Wright in 2004.
Describe the entry point, trajectory and length of cervical lateral mass screws.
The Magerl technique describes a starting point slightly medial and caudal to the geometric center of the lateral mass, which is marked with a burr, drilled at an angle approximately 20-30 degrees medial to lateral, and parallel to the facet joints. Hole is drilled until the ventral cortex is breached, at 12-16mm.
What nerve root most commonly shows painless weakness after cervical decompressive operations?
C5, as a deltoid or biceps weakness.
What percent of axial rotation occurs at the atlantoaxial joints?
Where does the most flexion-extension movement occur in the cervical spine?
O-C2 provides 30-50%.
What is Spurling's maneuver?
Slight extension with lateral bending toward the symptomatic side and axial compression, which can exacerbate radicular symptoms along a compromised nerve root.
What two surface landmarks can be used to plan anterior cervical surgery?
The cricothyroid membrane identifies the C6 level; the thyroid cartilage corresponds to C3-4.
Is there evience to support the addition of fusion or instrumentation to anterior cervical discectomy?
No. Several RCTs have show no benefit in patient outcome for addition of fusion to simple discectomy. Avoidance of kyphosis is commonly cited reason for bone graft/fusion, however no relationship between kyphosis and symptoms have been shown. Instrumentation is used to purportedly reduce pseudarthrosis, however it has not been shown to improve outcome and is also associated with higher rate of revision surgery.
What is the suspected etiology of OPLL?
There is a genetic predisposition, with HLA and collagen genes associated.
What is the natural history of OPLL?
One Japanese study found that with 30 year follow-up, the chances of being free from myelopathy was 70% for patients who were initially asymptomatic.
What is the most common objective measure of myelopathy?
The Japanese Orthopedic Association (JOA) score.
UE function--ability to eat with spoon or chopsticks
LE function--walking unassisted, with cane, or with walker
UE/LE/trunk sensory loss
What were the SPORT trials?
Concurrent observational cohort study and (attempted) randomized controlled trial comparing surgical to nonoperative therapy for lumbar disc herniation, lumbar stenosis, and lumbar spondylolisthesis.
What was the primary issue complicating interpretation of the SPORT results?
Crossover; ie patients randomized to nonoperative care undergoing surgery, or vice versa, undermining the randomization process and making the "intention-to-treat" analysis almost useless.
Were there any significant differences in outcome in SPORT patients with disc herniation, stenosis, or spondylolisthesis between operative and nonoperative cohorts?
In the intention-to-treat analysis, no (due to crossover/nonadherence). However, on an as-treated basis, there were clinically important improvements in all primary outcome measures for surgery in all three pathologies.
What diseases can confound the diagnosis and worsen the outcome of decompression for lumbar stenosis?
Diabetic neuropathy and peripheral vascular disease.
What lumbar interspace is most commonly stenotic?
Do spondylolysis or spondylolisthesis have any association with low back pain?
Multiple population based studies have shown no association between either condition and low back pain. Up to 20% of the adult population has a spondylolisthesis. (Calling into question the disease and treatment)
What gender is more affected by spondylolysis, and what is the prevalence in the general population?
Spondylolysis is more common in males (3:1) and occurs in roughly 5% of people. It is almost entirely at L5.
What is the significance of a negative rhematoid factor?
It does not exclude the diagnosis of rheumatoid arthritis, which is defined on clinical criteria of morning stiffness, pain and swelling of multiple joints, subq nodules and x-ray changes.
What are the most common effects of RA in the cervical spine?
AA dislocation, cranial settling, rheumatoid granulation tissue.
What new class of medications has revolutionized RA treatment and reduced incidence of spine manifestations?
Anti-TNF-a and anti-IL-1 agents.
How is ventral cervicomedullary compression managed in RA/basilar invagination?
If reducible, traction followed by posterior OC fixation is performed. If irreducible, ventral (transoral) resection of odontoid is performed.
What is the major risk factor for for spinal dysraphism?
Maternal diabetes mellitus.
What do the vertebral bodies, cartilaginous tissue disks and meninges arise from?
Mesoderm forms somites, of which the ventral portion becomes the sclerotomes that become all these structures. The intermediate portions are the myotoms that become the striated muscles and the dorsal portions are the dermatomes.
What varieties of sacral agenesis exist?
Total sacral agenesis with missing lumbar vertebra, total sacral agenesis only, subtotal sacral angenesis, hemisacrum, agenesis of the coccyx.
What nerve is at risk with ASIS bone graft harvest?
Lateral femoral cutaneous nerve; start incision 4cm lateral to ASIS
What nerves are at risk woth posterior iliac crest bone graft harvest?
Cluneal nerves. If accessed through a separate incision, should be at least 8cm off midline.
What is the rationale behind variable angle screws in anterior cervical instrumentation?
The variable trajectory screw is designed to maintain axial loading despite graft subsidence. Permits load sharing by minimizing the presence of stress shielding and promotes fusion.
What is the range of catalogue prices of available US anterior cervical plating systems?
The minimum construct costs range from $1000-2000. (Data is from Youmans-circa 2000)
What side thoracotomy is preferred for access to the anterior thoracic spine?
A left-sided retropleural approach is preferred, at the rib two levels above the vertebral level to be operated (ie 6th rib for T8 lesion)
Which sympathetic ganglia are transected for the treatment of palmar and axillary hyperhidrosis, respectively?
T2 sympathetic ganglia for palmar and T3 and T4 for axillary via thoracoscopy.
What operative approaches may be considered for clival chordomas?
Transsphenoidal/transethmoidal, transoral/transpharyngeal, transmaxillary, infratemporal fossa, lateral extrapharyngeal, transcondylar, transfacial, transbasal.
What is the role of radiation therapy in skull base chordomas?
The best results to date have been published with high-dose (80 Gy) fractionated proton beam therapy. Some authors reoperate on recurrent disease prior to radiation.
What is the difference between plasmacytoma and multiple myeloma?
They are both B-cell lymphoproliferative diseases; prognosis is dramatically different: solitary plasmacytoma 5yr survival is 60% vs. 20% w/multiple myeloma.
What treatment is advised in eosinophilic granulomas?
Biopsy to exclude other causes of vertebra plana in children (eg TB, osteomyelitis) and low dose radiation. Chemotherapy only for multiple/systemic forms (Letterer-Siwe and Hand-Schuller-Christian dz).
How may pseudogout or calcium pyrophosphate deposition present?
As a painful retro-odontoid mass in geriatric patients. Resection is an option.
What is the treatment of osteoid osteomas and osteoblastomas?
Symptomatic for osteoid osteomas, curettage and bone grafting for for larger/symptomatic lesions.
What bony spine lesion can present in association with other lesions such as giant cell tumor, osteoblastoma, fibrous dysplasia or osteosarcoma?
Aneurysmal bone cyst. May also present as primary lesions.
What approach is most commonly used for meningiomas of the foramen magnum?
Posterior suboccipital, retrocondylar approach. Vertebral artery often encased by tumor.
What are the most common extramedullary spinal tumors in adults?
Nerve sheath tumors and meningiomas. More rarely, filum ependymomas.
What are the most common intramedullary spinal cord tumors in adults?
Ependymoma and astrocytoma. More rarely hemangioblastoma.
What are the most common intramedullary cord tumors in children?
How do intramedullary ependymomas appear on MRI?
Homogenously enhancing, symmetric location.
What is the most common primary malignant vertebral column tumor?
What spinal tumor is characterized by heterogenous appearance with fluid-fluid levels?
Aneurysmal bone cyst.
What spine mass can be embolized as sole therapy?
What is the primary treatment of painful hemangiomas?
What is the second most comon primary vertebral column tumor?
After lymphoproliferative tumors, chondrosarcoma accounts for 12% of cases.
What is the standard treatment of plasmacytoma and multiple myeloma?
Radiation therapy. Chemo and bone marrow transplant for advanced disease. Steroids for symptomatic patients.
What malignancies have the highest risk of developing symptomatic metastatic epidural cord compression?
Breast 22%. Lung 15%. Prostate 10%.
In the 10% of patients with no known history of cancer and a newly diagnosed spinal metastasis, what is the most common ultimate diagnosis?
Lung ca in over 50%.
What evidence supports surgical management of compressive spinal metastases?
Patchell et al, 2005, randomized decompressive surgery+XRT vs. XRT alone, 50 pts per group. Surgical pts were more likely to walk and retain or regain ambulatory function.
What is the standard XRT for spinal metastases?
30-40Gy in 10-20 fractions. Short course radiotherapy for patients w/<6 months survival.
What is the optimal patient for radiosurgery for spinal metastasis?
Well circumscribed tumor with pain but no severe cord compression and already undergone conventional XRT.
What are the 2002 recommendations for cervical spine injury screening of asymptomatic trauma patients?
Imaging of the cervical spine after trauma is not recommended in asymptomatic patients (ie neurologically normal, not intoxicated, without neck pain, without distracting significant injuries).
Is MRI required prior to closed reduction of cervical dislocation?
No, it is not required. The risk of permanent neurologic morbidity with closed reduction is approximately 1% in awake patients.
What are contraindications to odontoid screw placement?
Fracture displacement, transverse ligament rupture, chronic fracture, osteopenia.
What are the considerations of a left- vs. right-sided anterior approach to the cervicothoracic junction?
A left sided approach gives a lower risk of injury to the recurrent laryngeal nerve but a higher risk to the thoracic duct.
How many fused vertebra is the sacrum derived from?
What is Denis' classification of sacral fractures?
Zone I (alar region-lowest rate of neuro deficit, possibly L5 root)
Zone II (foraminal region)
Zone III (central sacral canal region-50% neuro deficits, often bowel or bladder)
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