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Biomedical subjects

Daniel K Resnick

Publications and source records attributed to Daniel K Resnick.

At least 19 recordsLinked to original sources
PubMed2007

Use of ventral plates for cervical arthrodesis.

OBJECTIVE: Ventral cervical plates are used to increase the immediate postoperative rigidity of the spine after decompressive and reconstructive procedures. The evidence supporting this practice is reviewed. METHODS: A computerized literature search of the database of the National Library of Medicine was conducted using PubMed. All relevant articles were reviewed and a critique was performed to explore the utility of ventral cervical plating. RESULTS: Several randomized controlled trials of ventral cervical discectomy versus ventral cervical discectomy and fusion were identified. Three randomized controlled trials that included a differentiation between anterior cervical decompression and fusion, with and without plating, were identified. Many retrospective series, technical reports, and topical reviews were also identified. CONCLUSION: There is little support in the literature for the medical usefulness of ventral cervical plates after single-level cervical fusion. There may, however, be a cost-benefit advantage to the use of such devices. In multilevel procedures and in the setting of traumatic instability, there seems to be an advantage to the use of cervical plates.

Arthrodesis↗
PubMed2006

Thiazolidinedione class of peroxisome proliferator-activated receptor gamma agonists prevents neuronal damage, motor dysfunction, myelin loss, neuropathic pain, and inflammation after spinal cord injury in adult rats.

Thiazolidinediones (TZDs) are potent synthetic agonists of the ligand-activated transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma). TZDs were shown to induce neuroprotection after cerebral ischemia by blocking inflammation. As spinal cord injury (SCI) induces massive inflammation that precipitates secondary neuronal death, we currently analyzed the therapeutic efficacy of TZDs pioglitazone and rosiglitazone after SCI in adult rats. Both pioglitazone and rosiglitazone (1.5 mg/kg i.p.; four doses at 5 min and 12, 24, and 48 h) significantly decreased the lesion size (by 57 to 68%, p < 0.05), motor neuron loss (by 3- to 10-fold, p < 0.05), myelin loss (by 66 to 75%, p < 0.05), astrogliosis (by 46 to 61%, p < 0.05), and microglial activation (by 59 to 78%, p < 0.05) after SCI. TZDs significantly enhanced the motor function recovery (at 7 days after SCI, the motor scores were 37 to 45% higher in the TZD groups over the vehicle group; p < 0.05), but the treatment was effective only when the first injection was given by 2 h after SCI. At 28 days after SCI, chronic thermal hyperalgesia was decreased significantly (by 31 to 39%; p < 0.05) in the pioglitazone group compared with the vehicle group. At 6 h after SCI, the pioglitazone group showed significantly less induction of inflammatory genes [interleukin (IL)-6 by 83%, IL-1beta by 87%, monocyte chemoattractant protein-1 by 75%, intracellular adhesion molecule-1 by 84%, and early growth response-1 by 67%] compared with the vehicle group (p < 0.05 in all cases). Pioglitazone also significantly enhanced the post-SCI induction of neuroprotective heat shock proteins and antioxidant enzymes. Pretreatment with a PPARgamma antagonist, 2-chloro-5-nitro-N-phenyl-benzamide (GW9662), prevented the neuroprotection induced by pioglitazone.

Animals↗
PubMed2006

B1 and TRPV-1 receptor genes and their relationship to hyperalgesia following spinal cord injury.

STUDY DESIGN: Laboratory investigation of pain behavior following spinal cord injury. OBJECTIVE: To explore changes in the spinal cord expression of nociceptive genes following spinal cord injury (SCI) as they relate to the manifestation of pain behavior in rats. SUMMARY OF BACKGROUND DATA: Neuropathic pain following SCI is common, disabling, and largely untreatable. In peripheral nerve injury models, bradykinin B1 and vanilloid 1 (TRPV-1) receptor activity is associated with neuropathic pain behavior. We sought to examine the role of these gene products in SCI-mediated pain. METHODS: Rats were subjected to SCI using the MASCIS impactor. Animals were tested preinjury and at regular intervals postinjury for the appearance of thermal hyperalgesia using a hind limb withdrawal latency test. The expression of B1 and TRPV-1 genes was assessed using real-time polymerase chain reaction. Immunohistochemistry was used to localize the B1 and TRPV-1 receptors within the spinal cord. RESULTS: Greater than twofold increases in the expression of the B1 and TRPV-1 genes were detected in the injured region of the spinal cord in animals exhibiting hyperalgesia compared with animals with SCI that did not display hyperalgesia. Immunohistochemical staining revealed that both receptor types were largely localized to the dorsal horn. Staining for TRPV-1 receptors decreased while that for B1 receptors increased in all of the injured animals when compared with sham-operated controls. CONCLUSION: B1 and TRPV-1 receptor genes are overexpressed in the injured spinal cord of animals manifesting thermal hyperalgesia following SCI compared with similarly injured animals without hyperalgesia. This finding is consistent with past work regarding the role of these receptors in nociception and indicates that ongoing modifiable processes are occurring in the spinal cord that lead to clinical pain syndromes.

Animals↗
PubMed2006

Changes in spinal cord injury-induced gene expression in rat are strain-dependent.

BACKGROUND AND CONTEXT: The functional recovery of animals subject to experimental spinal cord injury (SCI) is dependent on the injury model as well as the species and strain of animal used. Previous studies have shown differences in rates and degree of recovery between rats of different strains. PURPOSE: We sought to explore the hypothesis that differences in gene expression are associated with differences in functional recovery. STUDY DESIGN/SETTING: Laboratory study involving cohorts of three different strains of rat. METHODS: We used the Impactor device to produce identical spinal cord contusion injuries in groups of Long Evans, Sprague-Dawley, and Lewis rats (10 each). The functional recovery of animals was assessed using the Basso, Beattie, and Bresnahan rating scale. Six weeks after injury, rats were killed and the spinal cords were harvested for deoxyribonucleic acid microarray analysis. Changes in gene expression compared with intraspecies controls (3 each) were assessed at the region of injury and at a rostral segment of the spinal cord. Selected genes were also studied with real-time polymerase chain reaction. RESULTS: We found that different strains tended to exhibit different patterns of functional recovery. There were differences between the strains in terms of gene expression. CONCLUSIONS: These results emphasize the importance of testing novel therapies for SCI in a variety of animal species before introduction into human trials. Further research into the influence of several gene products on functional recovery is needed.

Animals↗
PubMed2006

Evidence-based guidelines in lumbar spine surgery.

Lumbar fusion is a commonly performed procedure for the treatment of painful instability of the spine, usually manifest as chronic low back pain. The safety, efficacy, and cost of these procedures have been questioned in the professional and lay press. Recently, evidence based medicine techniques have been used to investigate the role of lumbar fusion for the treatment of a variety of spinal disorders. This chapter describes the general principles and procedures used for the development of evidence based guidelines for the performance of lumbar fusion.

Bone Screws↗
PubMed2006

Biomechanical comparison of four C1 to C2 rigid fixative techniques: anterior transarticular, posterior transarticular, C1 to C2 pedicle, and C1 to C2 intralaminar screws.

OBJECTIVE: We performed a biomechanical comparison of several C1 to C2 fixation techniques including crossed laminar (intralaminar) screw fixation, anterior C1 to C2 transarticular screw fixation, C1 to 2 pedicle screw fixation, and posterior C1 to C2 transarticular screw fixation. METHODS: Eight cadaveric cervical spines were tested intact and after dens fracture. Four different C1 to C2 screw fixation techniques were tested. Posterior transarticular and pedicle screw constructs were tested twice, once with supplemental sublaminar cables and once without cables. The specimens were tested in three modes of loading: flexion-extension, lateral bending, and axial rotation. All tests were performed in load and torque control. Pure bending moments of 2 nm were applied in flexion-extension and lateral bending, whereas a 1 nm moment was applied in axial rotation. Linear displacements were recorded from extensometers rigidly affixed to the C1 and C2 vertebrae. Linear displacements were reduced to angular displacements using trigonometry. RESULTS: Adding cable fixation results in a stiffer construct for posterior transarticular screws. The addition of cables did not affect the stiffness of C1 to C2 pedicle screw constructs. There were no significant differences in stiffness between anterior and posterior transarticular screw techniques, unless cable fixation was added to the posterior construct. All three posterior screw constructs with supplemental cable fixation provide equal stiffness with regard to flexion-extension and axial rotation. C1 lateral mass-C2 intralaminar screw fixation restored resistance to lateral bending but not to the same degree as the other screw fixation techniques. CONCLUSION: All four screw fixation techniques limit motion at the C1 to 2 articulation. The addition of cable fixation improves resistance to flexion and extension for posterior transarticular screw fixation.

Aged↗
PubMed2005

A blinded assessment of radiographic criteria for atlanto-occipital dislocation.

STUDY DESIGN: Blinded comparison of 5 methods to diagnose atlanto-occipital dislocation (AOD) on plain radiographs and computerized tomography (CT) of the cervical spine. OBJECTIVE: To determine the best method to diagnose AOD. SUMMARY OF BACKGROUND DATA: Several methods are proposed for the diagnosis of AOD, including the Power's ratio, X-line method, basion-dens interval, condylar gap, and Harris method. No blinded comparison of the results of these methods has been compared to patient outcome, and there is no information available regarding the accuracy of these methods applied to CT scans. METHODS: Plain lateral radiographs and CTs of the cervical spine were reviewed in 104 patients, including 6 with AOD. Images underwent a blinded review by a board certified neurosurgeon (D.K.R.), orthopedist (P.A.A.), radiologist (J.C.), and emergency physician (D.B.B.). Each diagnostic method for AOD was applied for determination of sensitivity, specificity, and positive and negative predictive values. The ability to identify relevant anatomic landmarks was also tabulated. RESULTS: Average values for sensitivities, specificities, positive and negative predictive values for each method applied to plain radiographs are: 0.4625-1.0, 0.8933-0.9725, 0.2775-0.45, and 0.975-1.0, respectively. These values for each method applied to CT scans are: 0.7075-1.0, 0.8725-0.9775, 0.3175-1, and 0.98-1.0, respectively. Identification of relevant anatomic landmarks occurred 99.75% of the time when these methods were applied to CT scans compared to 39% to 84% of the time on plain radiographs. CONCLUSIONS: Sensitivity, specificity, positive and negative predictive values of these methods improve when applied to CT scans because of better visualization of anatomic landmarks. This result suggests CT scans of the cervical spine may be warranted in all trauma patients suspected of having cervical spine injury.

Atlanto-Occipital Joint↗
PubMed2005

Minimally incisional stabilization of unstable L5 burst fracture.

BACKGROUND: Burst fractures of the L5 vertebral body are uncommon. Treatment options described include prolonged immobilization and surgical stabilization, most commonly with an instrumented fusion from L4 to the sacrum. METHODS: We describe the use of a minimally incisional technique to provide temporary internal fixation in a patient with an L5 burst fracture who was not a candidate for prolonged immobilization. RESULTS: This technique resulted in an excellent outcome without the requirement for a fusion. CONCLUSION: Minimally incisional fixation procedures are a treatment option for select patients with L5 burst fractures.

Adult↗
PubMed2005

Reconstruction of anterior iliac crest after bone graft harvest decreases pain: a randomized, controlled clinical trial.

OBJECTIVE: A substantial number of patients report persistent pain after graft harvest from the anterior iliac crest. There have been several retrospective case series published that suggest that iliac crest reconstruction using a variety of techniques may decrease graft site pain. This study, a randomized, controlled clinical trial at a university hospital, tested the hypothesis that reconstruction of the iliac crest will reduce graft harvest site pain. METHODS: A randomized, controlled clinical trial using the McGill Pain Inventory as the primary outcome measure was performed to evaluate the effect of anterior iliac crest reconstruction after graft harvest. Thirty patients who were treated with anterior cervical discectomy and fusion or cervical corpectomy and fusion with autologous iliac crest graft were randomized to one of two groups. Patients in Group 1 were treated with reconstruction of the iliac crest with commercially available tricalcium phosphate bone void filler after graft harvest. Patients in Group 2 were treated without graft site reconstruction. Graft site pain was assessed immediately after surgery, 6 weeks after surgery, and 3 months after surgery. RESULTS: Treatment groups were well matched with regard to patient age, sex, and smoking history. Although patients in each group reported persistent pain 6 weeks and 3 months after graft harvest, patients in the reconstruction group reported significantly less severe pain at 6 weeks and tended to have less pain at 3 months after surgery. CONCLUSION: Reconstruction of the iliac crest with tricalcium phosphate bone void filler significantly decreases the severity of postoperative pain 6 weeks after surgery.

Adult↗
PubMed2005

Linear accelerator radiosurgery for trigeminal neuralgia.

OBJECTIVE: To report the clinical outcomes following treatment of trigeminal neuralgia with linear accelerator-based radiosurgery. METHODS: Twenty-eight patients with medication refractory idiopathic trigeminal neuralgia were treated with a single fraction of 80 Gy to the trigeminal nerve root. For treatment delivery, a 4-mm collimator and a 7-arc technique were delivered using a stereotactic floor stand system with an isocenter stability of 0.2 +/- 0.1 mm to minimize dose to the brainstem. Treatment delivery time was approximately 55 minutes. RESULTS: With a median follow-up of 12 months (range, 1-40 mo), 57% of patients achieved complete pain relief and 75% (exact 95% confidence interval, 55 to 89%) had their pain reduced to 3 or less on a 10-point pain scale. Median time to pain relief was 1 month. Four patients did not respond to treatment. The actuarial mean time to pain recurrence in responders was 14 months, and the actuarial mean response duration in major to complete responders was 16 months. Women had significantly longer mean time to pain recurrence than men (16 versus 7 months; P = 0.05). Three patients reported new mild facial numbness after radiosurgery and one patient developed neurotrophic keratopathy. CONCLUSION: Linear accelerator-based radiosurgery for medication refractory trigeminal neuralgia provides effective pain relief with a low complication rate.

Aged↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 2: assessment of functional outcome.

Functional disability secondary to acute low-back pain, chronic low-back pain, lumbar stenosis, and lumbar disc disease may be reliably and validly assessed using functional outcome surveys that are valid, reliable, and responsive. Outcome instruments supported by Class I and Class II medical evidence for the evaluation of low-back pain include the Spinal Stenosis Survey of Stucki, Waddell-Main, RMDQ, DPQ, QPDS, SIP, Million Scale, LBPR Scale, ODI, and CBSQ. Many of these outcome measures have been applied to patients who have been treated with lumbar fusion for degenerative lumbar disease and have proven to be valid and responsive; however, the reliability of these instruments has never been specifically assessed in the lumbar fusion patient population. Patient satisfaction surveys have been used to measure outcome following lumbar fusion. Their usefulness resides in their insight into patient attitudes toward the treatment experience but is limited because of their inability to measure responsiveness and the lack of information on their reliability.

Humans↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 3: assessment of economic outcome.

Lumbar fusion may be associated with a high short-term cost, especially if instrumentation is placed; however, there appear to be long-term economic benefits associated with lumbar fusion including resumption of employment. To describe the economic impact of lumbar fusion for degenerative disease adequately, it is important to define the patient population treated with fusion and to compare efficacy as well as the costs of other treatment alternatives. Any such analysis should include both short- and long-term costs and benefits.

Humans↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 4: radiographic assessment of fusion.

The assessment of fusion status with static plain radiography is accurate in approximately two thirds of patients treated with lumbar fusion when the radiographic results are compared with surgical exploration findings. Therefore, static plain radiography is not recommended as a stand-alone modality following lumbar fusion procedures. The addition of lateral flexion-extension radiography may improve accuracy because the lack of motion between fused lumbar segments on lateral views is highly suggestive of a solid fusion. Some degree of motion between segments may be present even when the spine has fused. The amount of motion allowable across fused segments is not clear, and the role of internal fixation in limiting motion has also not been adequately addressed. The addition of multiplanar CT scanning results in the detection of pseudarthrosis in some patients in whom fusion has been deemed successful based on plain radiographic criteria. Therefore, CT scanning may be more accurate in the determination of fusion status than plain radiography; however, a rigorous comparison of modern CT scanning and surgical exploration has not been performed. It appears that RSA is exquisitely sensitive for the detection of motion between vertebral bodies, and the loss of motion between treated vertebral segments does appear to indicate the presence of fusion. The modality, however, is invasive and not widely available. Furthermore, the only

Humans↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 5: correlation between radiographic and functional outcome.

At the present time, there is no Class I or II medical evidence to indicate that the appearance of a radiographic fusion is significantly associated with improved functional outcomes. The majority of Class III medical evidence does suggest that successful radiographic fusion is associated with improved clinical outcomes. It is widely acknowledged that this relationship is not perfect.

Humans↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 6: magnetic resonance imaging and discography for patient selection for lumbar fusion.

Discography is an exquisitely sensitive but not specific diagnostic test for the diagnosis of discogenic low-back pain. The restriction of the definition of a positive discographic study to one that elicits concordant pain from a morphologically abnormal disc improves the definition's accuracy. Fusion surgery based on discography alone, however, is not reliably associated with clinical success. Therefore, discography is not recommended as a standalone test for treatment decisions in patients with low-back pain. Magnetic resonance imaging is a sensitive and noninvasive test for the presence of degenerative disc disease. Discography should not be attempted in patients with normal lumbar MR images. Discography appears to have a role in the evaluation of patients with low-back pain, but it is best limited to the evaluation of abnormal interspaces identified on MR imaging, the investigation of adjacent-level disc disease, and as a means to rule out cases of nonorganic pain from surgical consideration.

Humans↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 7: intractable low-back pain without stenosis or spondylolisthesis.

Class I medical evidence exists in support of the use of lumbar fusion as a treatment standard for carefully selected patients with low-back pain intractable to the best medical management. There is Class III medical evidence that suggests that a course of intensive cognitive and physical therapy may be an efficacious treatment option for the treatment of patients with chronic disabling low-back pain.

Humans↗
PubMed2005

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 8: lumbar fusion for disc herniation and radiculopathy.

There is no convincing medical evidence to support the routine use of lumbar fusion at the time of a primary lumbar disc excision. There is conflicting Class III medical evidence regarding the potential benefit of the addition of fusion in this circumstance. Therefore, the definite increase in cost and complications associated with the use of fusion are not justified. Patients with preoperative lumbar instability may benefit from fusion at the time of lumbar discectomy; however, the incidence of such instability appears to be very low (< 5%) in the general lumbar disc herniation population. Patients who suffer from chronic low-back pain, or are heavy laborers or athletes with axial low-back pain, in addition to radicular symptoms may also be candidates for fusion at the time of lumbar disc excision. Patients with a recurrent disc herniation have been treated successfully with both reoperative discectomy and reoperative discectomy combined with fusion. In patients with a recurrent lumbar disc herniation with associated spinal deformity, instability, or associated chronic low-back pain, consideration of fusion in addition to reoperative discectomy is recommended.

Humans↗