Mechanical and cellular processes driving cervical myelopathy.

Cervical myelopathy is a well-described clinical syndrome that may evolve from a combination of etiological mechanisms. It is traditionally classified by cervical spinal cord and/or nerve root compression which varies in severity and number of levels involved. The vast array of clinical manifestations of cervical myelopathy cannot fully be explained by the simple concept that a narrowed spinal canal causes compression of the cord, local tissue ischemia, injury and neurological impairment. Despite advances in surgical technology and treatment innovations, there are limited neuro-protective treatments for cervical myelopathy, which reflects an incomplete understanding of the pathophysiological processes involved in this disease. The aim of this review is to provide a comprehensive overview of the key pathophysiological processes at play in the development of cervical myelopathy.

Acute nontraumatic spinal intradural hematoma in a patient on warfarin.

BACKGROUND: Nontraumatic spinal intradural extramedullary hematomas are extremely rare. When they occur, they can rapidly lead to spinal cord or cauda equina compression and have devastating consequences. OBJECTIVE: The aim here was to report a case of this rare phenomenon and discuss the etiology, imaging, management, and outcome of intradural hematomas. CASE REPORT: We describe the case of a 76-year-old man on warfarin therapy who presented with severe lower back pain and flaccid paraparesis. Blood tests revealed an international normalized ratio of 6.0. A magnetic resonance imaging result suggested an intradural hematoma extending from L1 to L4 and compressing the spinal cord and cauda equina. Emergency surgical decompression revealed an extensive intradural extramedullary hematoma, which was evacuated. The patient showed only minor neurologic improvement 6 months postoperatively. CONCLUSIONS: Coagulopathy-induced spinal hemorrhage should be included in the differential diagnosis for patients presenting with signs of acute spinal cord compression.

Nonoperative modalities to treat symptomatic cervical spondylosis.

Cervical spondylosis is a common and disabling condition. It is generally felt that the initial management should be nonoperative, and these modalities include physiotherapy, analgesia and selective nerve root injections. Surgery should be reserved for moderate to severe myelopathy patients who have failed a period of conservative treatment and patients whose symptoms are not adequately controlled by nonoperative means. A review of the literature supporting various modalities of conservative management is presented, and it is concluded that although effective, nonoperative treatment is labour intensive, requiring regular review and careful selection of medications and physical therapy on a case by case basis.

The natural history and clinical syndromes of degenerative cervical spondylosis.

Cervical spondylosis is a broad term which describes the age related chronic disc degeneration, which can also affect the cervical vertebrae, the facet and other joints and their associated soft tissue supports. Evidence of spondylitic change is frequently found in many asymptomatic adults. Radiculopathy is a result of intervertebral foramina narrowing. Narrowing of the spinal canal can result in spinal cord compression, ultimately resulting in cervical spondylosis myelopathy. This review article examines the current literature in relation to the cervical spondylosis and describes the three clinical syndromes of axial neck pain, cervical radiculopathy and cervical myelopathy.

Risk analysis of blood transfusion requirements in emergency and elective spinal surgery.

Spinal surgery has long been considered to have an elevated risk of perioperative blood loss with significant associated blood transfusion requirements. However, a great variability exists in the blood loss and transfusion requirements of differing patients and differing procedures in the area of spinal surgery. We performed a retrospective study of all patients undergoing spinal surgery who required a transfusion≥1 U of red blood cells (RBC) at the National Spinal Injuries Unit (NSIU) at the Mater Misericordiae University Hospital over a 10-year period. The purpose of this study was to identify risk factors associated with significant perioperative transfusion allowing the early recognition of patients at greatest risk, and to improve existing transfusion practices allowing safer, more appropriate blood product allocation. 1,596 surgical procedures were performed at the NSIU over a 10-year period. 25.9% (414/1,596) of these cases required a blood transfusion (n=414). Surgical groups with a significant risk of requiring a transfusion>2 U RBC included deformity surgery (RR=3.351, 95% CI 1.123-10.006, p=0.03), tumor surgery (RR=3.298, 95% CI 1.078-10.089, p=0.036), and trauma surgery (RR=2.444, 95% CI 1.183-5.050, p=0.036). Multivariable logistic regression analysis identified multilevel surgery (>3 levels) as a significant risk of requiring a transfusion>2 U RBC (RR=4.682, 95% CI 2.654-8.261, p<0.0001). Several risk factors in the spinal surgery patient were identified as corresponding to significant transfusion requirements. A greater awareness of the risk factors associated with transfusion is required in order to optimize patient management.

Prevalence of Internet use amongst an elective spinal surgery outpatient population.

Nationally 62% of individuals in Ireland have internet access. Previous published work has suggested that internet use is higher among those with low back pain. We aimed to determine the levels of internet access and use amongst an elective spinal outpatient population and determine what characteristics influence these. We distributed a self-designed questionnaire to patients attending elective spinal outpatient clinics. Data including demographics, history of surgery, number of visits, level of satisfaction with previous consultations, access to the internet, possession of health insurance, and details regarding use of the internet to research one's spinal complaint were collected. 213 patients completed the questionnaire. 159 (75%) had access to the internet. Of this group 48 (23%) used the internet to research their spinal condition. Increasing age, higher education level, and possession of health insurance were all significantly associated with access to the internet (p < 0.05). A higher education level predicted greater internet use while possession of insurance weakly predicted non-use (p < 0.05). In our practice, internet access is consistent with national statistics and use is comparable to previous reports. Approximately, one quarter of outpatients will use the internet to research their spinal condition. Should we use this medium to disseminate information we need to be aware some groups may not have access.

The evaluation of the inverted supinator reflex in asymptomatic patients.

STUDY DESIGN: A prospective study was undertaken over a 6-month period to determine the incidence of the inverted supinator reflex in asymptomatic, neurologically normal individuals. OBJECTIVE: The objective of our study is to assess asymptomatic patients for the presence of the inverted radial reflex and to determine its clinical relevance. SUMMARY OF BACKGROUND DATA: The inverted radial reflex sign is commonly used in clinical practice to assess cervical myelopathy. It is unknown whether the sign correlates with the presence or severity of myelopathy, and no consensus exists regarding the significance of a positive sign in asymptomatic individuals. METHODS: Patients attending the Trauma Clinic at our institution were invited to participate. Each patient was examined neurologically and specifically for the presence or absence of the Babinski test, Hoffman's sign, the finger escape sign, static and dynamic Romberg's test, and the inverted supinator reflex. Patients were excluded if they had any history of neck pain, any history of neurosurgical procedure or spinal surgery, any known neurologic disorder or deficit, or if there was any outstanding medicolegal case. RESULTS: We examined 277 patients in 6-month period. The male to female ratio was 1.1:1. The mean age was 27 years (range, 16-78). The incidence of the inverted supinator reflex was 27.6% (75/271). Of the 75 positive patients, the inverted supinator reflex was present bilaterally in 39% (29/75). Nine of 75 patients (10%) had an associated positive Hoffman's sign but had no other signs suggestive of myelopathy. The proportion of patients with a positive inverted supinator reflex reduced with increasing age (Pearson correlation coefficient > 0.80). CONCLUSION: This study demonstrates that an isolated, inverted supinator reflex may be a variation of normal clinical examination. We believe that an isolated inverted supinator reflex, in the absence of other clinical findings, is not a reliable sign of cervical myelopathy; however, it must be interpreted with caution in the older patient.

Parathyroid hormone (1-34) augments spinal fusion, fusion mass volume, and fusion mass quality in a rabbit spinal fusion model.

STUDY DESIGN: The posterolateral rabbit spinal fusion model was used to assess the effect of intermittent parathyroid hormone on spinal fusion outcomes. OBJECTIVE: To test the hypothesis that intermittent parathyroid hormone (PTH) improves spinal fusion outcomes in the rabbit posterolateral spinal fusion model. SUMMARY OF BACKGROUND DATA: Spinal fusion is the definitive management for spinal deformity or instability, yet despite current technology, 5% to 40% of lumbar fusions result in pseudarthrosis. Animal studies have demonstrated enhanced fracture healing with the use of PTH, but the effect of PTH on spinal fusion is poorly described. METHODS: Forty-four male New Zealand white rabbits underwent bilateral posterolateral spine fusion (L5-L6 level). Twenty-two rabbits received daily subcutaneous injections of PTH (1-34) (10 microg/kg) and 22 received an injection of saline fluid. All were killed 6 weeks after surgery. L5-L6 vertebral segments were removed and analyzed with manual bending, faxitron radiography, microCT, and histomorphometry. RESULTS: Manual bending identified fusion in 30% (control) versus 81% (PTH) animals (P < 0.001). A radiographic scoring system ("0" = no bone formation, "5" = full fusion) resulted in an average score of 3.36 (control) versus 4.51 (PTH) (P < 0.001). MicroCT analysis demonstrated a median mass of 3.5 cc (control) (range, 2.25-5.40 cc) versus 6.03 cc (PTH) (range, 4.34-10.58 cc) (P < 0.001). Histology showed a median percentage bone area of 14.3% (control) (n = 12) versus 29.9% (PTH) (n = 15) (P < 0.001). The median percentage cartilage was 2.7% (control) (n = 5) versus 26.6% (PTH) (n = 5) (P < 0.01). Osteoclast quantification revealed median values of 140.5 (control) (n = 6) and 345.0 (PTH) (n = 8) (P < 0.001) respectively, and the percentage of osteoblasts revealed a median value of 31.4% (control) (n = 6) versus 64.4% (PTH) (n = 8) (P < 0.001). CONCLUSION: Intermittent PTH administration increased posterolateral fusion success in rabbits. Fusion bone mass and histologic determinants were also improved with PTH treatment. PTH has promise for use as an adjunctive agent to improve spinal fusion in clinical medicine.

Viscosupplementation in lumbar facet joint arthropathy: a pilot study.

BACKGROUND: Degeneration of the spine is a prevalent problem that generally advances with age, although its occurrence is not restricted to the elderly. Chronic low back pain is a common problem with several treatments, but rigorous evaluation of many interventions is still lacking. One of the most common methods of treating lumbar facet arthropathy is intra-articular injection of local anesthetic and steroid. However, in large joints, such as the knee, viscosupplementation has been shown to compare favorably to steroid in terms of symptom relief and duration of benefit. It is suggested that viscosupplementation may supersede steroid in treatment of symptomatic knee osteoarthritis. Hyaluronic acid (HA) therapy is still in its infancy in joints outside the knee, although some preliminary results are promising. OBJECTIVE: This was a pilot study to test the potential effectiveness of HA injection therapy in the treatment of lumbar facet joint arthritis. METHODS: Thirteen patients with symptomatic lumbar facet joint arthritis who met the inclusion criteria were prospectively recruited. Pretreatment evaluation of patients was by questionnaire, including the Visual Analog Score and Oswestry Disability Questionnaire. A single injection of HA into affected facet joints was then performed, with correct placement confirmed on fluoroscopy. The patients were similarly evaluated 6 weeks after treatment. RESULTS: Eighteen facets in 13 patients were injected with HA. At 6-week follow up, there was no significant improvement in pain when measured on the Visual Analog Score. There was also no significant improvement in the Oswestry Disability Questionnaire. CONCLUSIONS: Preliminary results from this pilot study do not demonstrate any benefit of viscosupplementation in the management of symptomatic lumbar facet arthropathy.

Thromboembolic disease after combined anterior/posterior reconstruction for adult spinal deformity: a prospective cohort study using magnetic resonance venography.

STUDY DESIGN: Thromboembolic disease (TED) after anterior/posterior spinal reconstructions was prospectively evaluated in 66 consecutive patients. OBJECTIVE: Determine the incidence of TED after anterior/posterior spinal reconstruction. SUMMARY OF BACKGROUND DATA: Few studies have examined the rate of TED after potentially high-risk combined anterior/posterior reconstructions. Magnetic resonance venography (MRV) is more effective at detecting pelvic deep venous thrombosis (DVT) than conventional screening, but has not been used in these patients. METHODS: We undertook a prospective cohort study of 66 consecutive adult patients (mean, 52.7 +/- 9.6 years) undergoing combined anterior/posterior spinal reconstructions for spinal deformity. All patients received only mechanical DVT prophylaxis. After surgery, MRV and bilateral lower extremity Doppler ultrasounds were obtained to screen for DVT, and contrast-enhanced spiral computed tomography scans were obtained for clinical suspicion of pulmonary embolism (PE). RESULTS: The total incidence of postoperative TED was 13.6% (9 patients). The overall rate of DVT was 9.1% (6 patients), one-third occurring in the pelvis. PE developed in 7.6% (5 patients). In 2 patients, PE developed less than 48 hours after positive dopplers. In 3 patients, PE developed despite negative screening studies. Right-sided thoracoabdominal approaches were associated with an increased risk of developing DVT (P = 0.03, Odds Ratio 9.8), PE (P = 0.01, Odds Ratio 20), and TED (P = 0.004, Odds Ratio 12). CONCLUSION: We report a high rate of TED after extensive anterior/posterior spinal reconstructions, for which a right-sided thoracoabdominal approach is an independent risk factor and screening ineffective at preventing PE. These patients should be considered at high risk for postoperative TED.

Analysis of meniscofemoral ligament tension during knee motion.

PURPOSE: The goal of this study was to show a functional role for the meniscofemoral ligaments (MFL) by analyzing MFL tension change through the full range of flexion and extension found at the human knee joint. METHODS: Ten fresh-frozen human knees containing both the anterior and posterior MFLs (aMFL and pMFL) were studied. An analysis of ligament tension during passive motion was undertaken using an isometric transducer. RESULTS: The MFLs functioned in a nonisometric and reciprocal manner. The aMFL developed tension with flexion and the pMFL tension with extension. The aMFL tension increased with tibial external rotation compared with internal rotation. Combined MFL tension was greater in flexion (P < .001) and increased as the tibia was externally rotated (P = .008). CONCLUSIONS: The MFL tension changes identified through knee flexion and extension support the theory that the MFLs have a functional role in knee stability and protection. This warrants their consideration in the clinical management of meniscal and PCL injuries. CLINICAL RELEVANCE: This cadaver study of the lateral MFLs indicates that the anterior and posterior portions work in a reciprocal manner with flexion and extension and supports the fact that these ligaments have a functional role in the human knee joint.

Discography-induced acute lumbar disc herniation: a report of five cases.

The reported complication rate of provocative lumbar discography is low, ranging from 0-2.5%. We report five cases of acute lumbar disc herniation precipitated by discography, a previously unreported complication. The cases reported comprise of four men and one woman with ages ranging from 23-45 years. All developed an acute exacerbation of radicular leg pain following multilevel provocative lumbar discography. One patient developed an acute foot drop. Comparison of lumbar MRI scans before and after discography demonstrated either a new herniated disc fragment or an increase in size of a preexisting herniation in all cases. On review of each discogram study and pre-discogram MRI an annular tear or small disc herniation was noted in all cases. In each case the patients' symptoms failed to resolve necessitating surgical intervention in all cases. In conclusion, annular deficiency is an obvious predisposing factor to discogram related disc herniation. New onset or a persistent exacerbation of radicular symptoms following provocative discography merits further investigation.

Kyphoplasty enhances function and structural alignment in multiple myeloma.

We prospectively evaluated 19 patients with multiple myeloma who had kyphoplasty for vertebral compression fractures. Functional status was assessed preoperatively and 3 months postoperatively using the Oswestry Disability Index. Restoration of anterior and midvertebral height was assessed using lateral radiographs. Meaningful improvement occurred in 16 of 19 patients, with a reduction of the average Oswestry Disability Index from 49 +/- 16.6 to 32.6 +/- 13.6. Partial restoration of anterior vertebral body height was achieved in 76% of levels with an average of 37.8% restoration of the defect. Partial restoration of midvertebral body height was achieved in 91% of levels with an average restoration of 53.4% of the defect. There were no significant complications. These results were compared with results of a cohort of 26 patients with osteoporotic compression fractures treated with kyphoplasty at 37 levels. There was no difference between the groups in terms of Oswestry Disability Index improvement and midvertebral height restoration after 3 months. Greater anterior vertebral height restoration was achieved in the osteoporotic group (51.2% versus 37.8%). Kyphoplasty is a safe treatment modality for myeloma-related vertebral compression fractures. Efficacy in terms of pain relief and functional outcome is comparable with the results in patients with osteoporosis.

Orthopedic management of vertebral and long bone fractures in patients with osteoporosis.

Because of the evolving demographics of the world's population, fracture surgeons must become experts in the treatment of fractures in osteoporotic bone. Toward this end, fracture surgeons are learning to modify the classic techniques of internal fixation to adapt them to the elderly population. Screws should be placed into the best quality of bone available, which, in most cases, is an opposing cortex. Screw fixation can be augmented using acrylic cement. When using plate fixation, stable bone contact at the fracture site is the most important factor in reducing strain in the plate. Shortening of the affected bone is advisable to achieve this contact in comminuted fractures. Plates should not be used to bridge areas of comminution in osteoporotic bone. Plates should generally be as long as is compatible with the affected bone, with screws placed as close to and as far away from the fracture site as possible. When confronted with diaphyseal fractures or fractures with metaphyseal-diaphyseal comminution, locked intramedullary nails can be used. Angled blade plates are applicable to osteoporotic metaphyseal fractures but should be used as tension band plates, which require stable load-sharing contact opposite the plate. Antiglide plating and use of tension band wires are also effective strategies for osteoporotic fractures. Finally, to reduce the morbidity of bone graft harvest and to ensure adequate volumes of graft, the use of bone graft substitutes is particularly applicable in elderly patients. All patients with evidence of osteoporosis should be started on a medical regimen to combat further bone loss that includes calcium supplementation with a prescription for antiresorptive agents, including bisphosphonates, calcitonin, or hormone replacement therapy.

Bovine thrombin induces an acquired coagulopathy in sensitized patients undergoing revision spinal surgery: a report of two cases.

STUDY DESIGN: A report of two cases is presented. OBJECTIVE: To raise awareness of bovine thrombin-induced factor V deficiency. SUMMARY OF BACKGROUND DATA: Bovine thrombin is a frequently used hemostatic agent in spinal surgery. Current preparations contain clotting factors in addition to thrombin, particularly factor V, which are immunogenic. Re-exposure of sensitized patients to bovine thrombin products during subsequent surgery may lead to the formation of antibodies that cross-react with human clotting factors, most commonly against factor V. Hemorrhagic complications have been reported in nonspinal patients due to a bovine thrombin-induced factor V deficiency. METHODS: Two spinal cases are reported, and the literature is reviewed. RESULTS: In the cases outlined, both patients underwent revision spinal surgery, with re-exposure to bovine thrombin. Both patients developed abnormal coagulation profiles, with an acquired factor V deficiency. No hemorrhagic complications occurred; however, second-stage surgery was delayed in one patient and not undertaken in the other. In both patients, the coagulopathy resolved spontaneously. CONCLUSIONS: Bovine thrombin-induced coagulopathy is well recognized in cardiac surgery but has not been reported in spinal surgical patients. Data available from cardiac surgical patients suggests that those who are sensitized to two or more bovine clotting factors are at greatest risk of hemorrhagic complications. The cases we present demonstrate that this phenomenon occurs in spinal surgical patients and serve to raise awareness of the potential danger of bovine thrombin in sensitized patients.

Treatment of multilevel cervical spondylotic myeloradiculopathy with posterior decompression and fusion with lateral mass plate fixation and local bone graft.

This is a retrospective review of 32 patients with multilevel cervical myelopathy treated by laminectomy and lateral mass plate fusion. The prognosis of surgically treated myelopathy is evaluated as well as prognostic factors for recovery of myelopathy. Diagnoses included cervical spondylosis or ossification of the posterior longitudinal ligament. Final follow-up was at 15.2 months (mean) postoperatively. Myelopathy was graded preoperatively and postoperatively by the system of Nurick. All patients had preoperative radiographs and magnetic resonance imaging (MRI). The presence of abnormal T2-weighted MRI signal (myelomalacia) was noted. Postoperative studies included flexion-extension radiographs to assess fusion and MRI to evaluate decompression of neural elements and resolution of myelomalacia. Severity of preoperative Nurick myelopathy, presence of myelomalacia, and age were evaluated as potential prognostic indicators for surgically treated myelopathy. Mean Nurick score improved from 2.6 (range 1-4) to 1.8 (range 0-3) postoperatively (p < 0.0001). Twenty-two patients (71%) had improvement in Nurick grade of at least one point, and nine showed no improvement. No patients had deterioration of Nurick grade. Preoperative myelomalacia was noted in 15 (47%) patients, and all 15 had residual myelomalacia postoperatively. Severe myelopathy, age, and myelomalacia had no prognostic value for improvement of myelopathy. Complications included pseudarthrosis (3%), wound infection (9%), and transient C5 palsy (6%). This study demonstrates excellent outcomes from laminectomy and fusion in multilevel cervical myelopathy. A high rate of improvement of myelopathy was observed, neurologic deterioration did not occur, and complication rates were low. Severe myelopathy and myelomalacia on preoperative MRI had no prognostic value.