Acute traumatic coagulopathy: pathophysiology and resuscitation.

Acute Traumatic Coagulopathy occurs immediately after massive trauma when shock, hypoperfusion, and vascular damage are present. Mechanisms for this acute coagulopathy include activation of protein C, endothelial glycocalyx disruption, depletion of fibrinogen, and platelet dysfunction. Hypothermia and acidaemia amplify the endogenous coagulopathy and often accompany trauma. These multifactorial processes lead to decreased clot strength, autoheparinization, and hyperfibrinolysis. Furthermore, the effects of aggressive crystalloid administration, haemodilution from inappropriate blood product transfusion, and prolonged surgical times may worsen clinical outcomes. We review normal coagulation using the cell-based model of haemostasis and the pathophysiology of acute traumatic coagulopathy. Developed trauma systems reduce mortality, highlighting critical goals for the trauma patient in different phases of care. Once patients reach a trauma hospital, certain triggers reliably indicate when they require massive transfusion and specialized trauma care. These triggers include base deficit, international normalized radio (INR), systolic arterial pressure, haemoglobin concentration, and temperature. Early identification for massive transfusion is critically important, as exsanguination in the first few hours of trauma is a leading cause of death. To combat derangements caused by massive haemorrhage, damage control resuscitation is a technique that addresses each antagonist to normal haemostasis. Components of damage control resuscitation include damage control surgery, permissive hypotension, limited crystalloid administration, haemostatic resuscitation, and correction of hyperfibrinolysis.

Type 2 diabetes is associated with vertebral fractures in a sample of clinic- and hospital-based Latinos.

Latinos are the fastest growing ethnic population in the United States and type 2 diabetes is a major health burden in this population, but little effort has been made to study the prevalence of diabetic vertebral fragility in Latinos. We performed a cross-sectional study to determine vertebral fracture prevalence in a hospital-based population of South Texas residents (N = 296). We defined fractures in X-rays as a >20% reduction in vertebral body height. Numerous variables were recorded, including age, body mass index, indicators of diabetes management and others. 71% of the sample (N = 296) was Latino. The prevalence of vertebral fracture was increased in diabetic subjects relative to non-diabetic subjects (diabetic 27.9%, non-diabetic 13.8%) and, regardless of sex and diabetics status, decreased in Latinos relative to non-Latinos (Latino 16.7%, non-Latino 26.4%). These data suggest that vertebral fractures may be a growing concern for diabetic Latinos as well as diabetics of any racial/ethnic background.

Plaster of Paris as bone substitute in spinal surgery.

In order to assess the effectiveness of calcium sulphate (plaster of Paris; POP) as a substitute for autologous bone graft, we performed lumbar intervertebral fusion in mature sheep using POP and a variety of other graft materials, and reviewed the literature. The osteoconductivity of the POP grafts was compared to that of grafts carried out with autogenous iliac crest, frozen allogeneic bone, and ProOsteon 500 coralline bone. We also compared the osteogenicity of POP to admixtures of autogenous iliac crest bone with POP and coralline bone, and to an osteoinductive demineralized sheep bone preparation (DBM). The substrates were loaded into tubular titanium mesh, implanted into excavated disc spaces and recovered after a period of 4 months. Fusion mass segments tested in flexion and tension showed that POP was equal to autogenous bone and most other substrates. The POP fusions were significantly tougher than the DBM fusions, even though histomorphometry failed to reveal differences in the amount of trabecular bone. We conclude that POP can be used to achieve a biomechanically stable interbody lumbar vertebral fusion. In addition, our literature review indicated that POP can be used as a vehicle for local delivery of antibiotics in bone infections.

Jejunal manometry predicts tube feeding intolerance in the postoperative period.

Postoperative nutrition is best provided enterally; however, patients often develop intolerance to enteral feedings. Our aim was to prospectively identify abdominal examination and jejunal pressure activity associated with postoperative intolerance of enteral feedings. Twenty-nine patients underwent abdominal operation and needle catheter jejunostomy placement. Elemental tube feedings were started on the day after surgery and advanced to the caloric goal rate over three days. Patients whose feedings were slowed at the attending surgeon's discretion were defined as intolerant. Jejunal manometry and a standardized abdominal exam were performed on postoperative days 1, 3, and 5. Fifteen patients (52%) were intolerant of tube feedings and had decreased jejunal motor activity but more active bowel sounds prior to feedings. After feedings, intolerant patients developed abdominal distension, but other abdominal findings were inconsistent. A marked decrease in phase II of the migrating motility complex (MMC) and the lack of a fed response were present in both groups. The overall jejunal motility present on day 1 following surgery identifies patients that will not tolerate enteral feedings. The abdominal examination, MMC parameters, and motor response to feeding did not predict feeding intolerance.

Chemonucleolysis: the state of the art.

This review presents the history of chemonucleolysis, the techniques, indications, contraindications, and complications. Presenting an historical overview and comparison of success rates with surgical discectomy may provide a fresh understanding of the controversy surrounding chemonucleolysis and establish its efficacy in relation to more invasive treatments. A review of the literature from 1973 through 1998 for chemonucleolysis, open discectomy, and microdiscectomy provided published success rates for these procedures, and a mean rate with standard deviation was determined. In the experience and opinion of the authors, chemonucleolysis remains a viable alternative for patients who have exhausted all conservative means of treatment. Proper patient selection leads to success rates comparable to open discectomy and microdiscectomy.

Plaster of Paris as an osteoconductive material for interbody vertebral fusion in mature sheep.

STUDY DESIGN: In adult female sheep, histologic and biomechanical criteria were used to determine whether the osteoconductive performance of plaster of paris would promote the incorporation of the tubular titanium mesh implants used for interbody vertebral fusions. OBJECTIVES: To compare the osteogenicity of plaster of paris with that of autogenous iliac crest bone and bone marrow 6 months after they were loaded into tubular titanium mesh cages and implanted as L3-L5 bridges after L4 corpectomies. SUMMARY OF BACKGROUND DATA: One of the aims of surgery for vertebral pathology is to stabilize the spine by interbody fusions. The morbidity associated with the use of iliac crest autograft bone for fusion grafts prompted trials using plaster of paris as an osteoconductive substrate. METHODS: The total volume of bone that invested the L3-L5 mesh cages after 6 months was quantitated by computed tomography scans. All specimens subsequently were cut into fusion mass segments for biomechanical testing in flexion, extension, compression, and torsion, and then embedded in plastic for sectioning and histomorphometry to determine the trabecular bone volume within the titanium mesh. RESULTS: In each experimental model, implants of plaster of paris were the osteoconductive equal of autogenous iliac crest bone/marrow preparations. The volumes of bone formed around and within the titanium mesh were identical, and the tissues were biomechanically indistinguishable. A partial mechanism was determined by modifying the system for midshaft femoral defects. CONCLUSIONS: In the sheep, a tubular titanium mesh packed with plaster of paris forms an osteoconductive conduit to achieve a biomechanically stable interbody lumbar vertebral fusion.

Pathomechanics and clinical relevance of disc degeneration and annular tear: a point-of-view review.

Annular tear is a major cause of intervertebral disc degeneration that results in disabling back pain. Many of the stresses resulting in this type of lesion are common in the workplace: compression, torsion, compression combined with flexion, and vibration. Age-related disc degeneration begins early in adulthood, and progresses thereafter, altering disc morphology and mechanical properties in ways that predispose to disc herniation, and should not be misconstrued as "old age." Acute trauma may produce disc herniation whether or not there are predisposing factors, such as age-related degeneration, but disc herniation in the absence of acute injury requires the presence of preexisting degenerative changes.

Intraoperative somatosensory evoked potential findings in acute and chronic spinal canal compromise.

STUDY DESIGN: Early and long-term postoperative outcome were analyzed by retrospective record review and compared with results of intraoperative somatosensory evoked potential (SEP) findings in 70 patients with chronic lumbar stenosis. SUMMARY OF BACKGROUND DATA: Adverse SEP changes occur in up to 2% of patients during scoliosis surgery and may reverse with intraoperative intervention. Little is known about the short- or long-term results of intraoperative intervention based on adverse SEP changes in patients with chronic lumbar stenosis during lumbar decompression and fusion. OBJECTIVE: To compare intraoperative SEP changes with immediate and long-term neurologic outcome in patients undergoing lumbar decompression, instrumentation and fusion for chronic lumbar stenosis and to determine whether the early correlation between intraoperative SEP deterioration and clinical outcome persisted. METHODS: Monitoring SEPs using an alternating arm and leg stimulation paradigm allowed rapid identification of intraoperative changes. Retrospective record review was conducted without knowledge of intraoperative SEP findings. Clinical and SEP findings were then compared, to determine whether the strong association between intraoperative SEP results and early clinical outcome persisted. RESULTS: Nine of 12 patients who had unilateral intraoperative SEP deterioration that resolved with intervention had no adverse sequelae; the remaining three had new ipsilateral weakness that persisted during a 9-24-month follow-up. Intraoperative SEPs deteriorated in 15% of patients with normal and abnormal baseline SEPs. Intraoperative SEP deterioration could not be predicted by preoperative radicular pain, focal symptomatology or baseline SEP findings. 80% of patients with normal SEPs but only 54% with abnormal SEPs had immediate and sustained pain relief. SEP deterioration that reversed with surgical intervention or high-dose steroids resulted in no adverse neurologic outcome. CONCLUSIONS: Acute, unilateral, unresolved intraoperative SEP deterioration was associated with long-term ipsilateral weakness not predicted by clinical or neurologic findings before surgery. Clinical improvement persisted in 92% of patients, 4% were unchanged, and 4% had persistent neurologic changes during an average 12-month follow-up period. The findings underscore the need for monitoring SEPs during surgery in all patients undergoing invasive lumbar surgery and for rapid identification and intervention should a unilateral SEP change persist.

A prospective study of 342 patients using transpedicular fixation instrumentation for lumbosacral spine arthrodesis.

The objective of this research was to determine the efficacy and safety of an experimental instrumentation device designed for transpedicular spinal fixation by evaluating fusion rates and clinical pain and function scores; to determine complication rates associated with the device; and to compare the obtained data with that previously published in the literature. Four hundred forty-two consecutive patients were enrolled in this 4-year, Food and Drug Administration-monitored investigational device exemption trial to undergo surgery for implantation of the device. Eighteen surgeons at 11 nationwide medical centers performed the operations and subsequent evaluations. The study population was derived from three diagnostic categories: degenerative disc disease, multioperated back, and vertebral fracture. The data source consisted of radiographs, clinical examination, and structured forms and questionnaires. Patients were evaluated preoperatively, intraoperatively, and postoperatively at 3, 6, 12, and 24 months. By the 24-month postoperative interval, attrition had reduced the study population to 342 patients, among whom bony fusion was obtained in 91.5%. Pain scores demonstrated a statistically significant improvement in clinical outcome. Intraoperative complications occurred in 21.9% of patients. Of the 442 study patients, 2.9% experienced device-related complications. Moreover, a total of 2,304 screws and bolts were implanted in this patient population. Of these, 0.39% were reported to have fractured. Among the 342 study patients observed during 24 months, the breakage rate of device components (bolt or screw) was 2.63%. These data compare favorably to existing reports of spinal arthrodesis effected with other types of instrumentation and without device implantation. In a 4-year trial, the experimental transpedicular fixation instrumentation produced successful spinal fusion in the majority of our study population, with acceptable complication rates.

Torsional injury resulting in disc degeneration: I. An in vivo rabbit model.

Torsional injuries may be a precursor to intervertebral disc degeneration, but published rabbit models indicate a latent time of 6 months. We describe a rabbit model in which instability and disc degeneration appear within 3 months. Sixty-five male New Zealand rabbits underwent presurgical irradiation to inhibit heterotopic bone formation. Control animals then underwent either a soft-tissue release or facetectomy and capsulotomy, whereas experimental animals received surgery and an acute 30 degrees torsional lumbar injury. Capsulotomy, as well as facetectomy without torsion, failed to effect disc degeneration. However, the rabbits that received torsion exhibited clear indications of degenerative disc changes (thinning, increased PLA2 levels, and decreased nucleus pulposus volume) within 60-90 days. The observations associate disc degeneration with a destabilizing acute torsional injury.

Torsional injury resulting in disc degeneration in the rabbit: II. Associative changes in dorsal root ganglion and spinal cord neurotransmitter production.

The mechanism mediating the chronic pain associated with lumbar disc degeneration may involve neurotransmitters elaborated by dorsal root ganglion (DRG). This hypothesis has been tested in an applicable rabbit model of disc degeneration. Twenty control male rabbits underwent a soft-tissue release; 20 experimental rabbits sustained a facetectomy and capsulotomy and received an acute torsional lumbar injury. The levels of calcitonin gene-related peptide, vasoactive intestinal peptide, and substance P were measured in the DRG, spinal cord, and disc at 10, 30, 60, and 90 days postoperatively. Torsional injury was associated with a statistically significant increase in most DRG and spinal cord neurotransmitter values after 60-90 days. These points in time marked the periods of maximum biomechanical instability and disc narrowing. Such data support concepts about the association between chronic lumbar spinal instability, disc degeneration, and pain.

Correlation of bone equivalent mineral density to pull-out resistance of triangulated pedicle screw construct.

Thirty single-pedicle and triangulated pedicle screws were subjected to pull-out tests until complete dislodgment was achieved. Peak load, displacement curves, angle of triangulation, and equivalent mineral density were recorded. Dual pedicle screw triangulation produced a 154.4% increase in peak pull-out strength compared with that of the single pedicle screw. Salvage triangulation (replacing failed screws with a triangulation construct) produced a 127.4% increase in peak strength over that of the single screw. Positive correlation was found between individual screw peak strength, bone mineral density, and displacement at peak load. Primary and salvage triangulation produced higher resistance to pull-out than a single pedicle screw, which reflects the potential, beneficial effect of using this technique. Triangulation, therefore, can be used as primary (prophylactic) technique to enhance pedicular screw pull-out during forceful vertebral manipulation.

The prolapsed intervertebral disc. The high-intensity zone with discography correlation.

STUDY DESIGN: The study compared the presence of the high-intensity zone on magnetic resonance imaging with the results of awake discography. OBJECTIVES: To see if there was a correlation between the results of awake discography and the presence of a high-intensity zone on magnetic resonance imaging. SUMMARY OF BACKGROUND DATA: The evaluation of discogenic pain has proved to be somewhat elusive. Recent studies have indicated the high-intensity zone as being highly sensitive in the diagnosis of the painful discogenic segment. The present study was designed to investigate whether the presence of a high-intensity zone is associated with a concordant pain response on awake discography. METHODS: Magnetic resonance images were obtained in 29 patients with low back pain with and without radiculopathy. Consecutive patients were considered for surgical intervention after falling to respond to conservative treatment. The presence of a high-intensity zone was specifically looked for within the posterior anulus. Each patient subsequently underwent awake discography with computed tomography. Computed tomography was classified according to the Dallas Discogram Scale and the presence of a concordant pain response. Chi-square analysis was used to calculate the presence of a high-intensity zone versus disc disruption and the correlation of high-intensity zone and concordant pain response. RESULTS: There was no statistically significant correlation between the presence of a high-intensity zone and a concordant pain response at any level. The high-intensity zone was, however, never seen in a morphologically normal disc. CONCLUSIONS: Although the high-intensity zone is present within the posterior anulus of some abnormal discs, it is not necessarily associated with a concordant pain response.

Identification and spectral characterization of the external aldimine of the O-acetylserine sulfhydrylase reaction.

The O-acetylserine sulfhydrylase (OASS) reaction has been studied using a number of spectral probes including UV--visible, fluorescence, circular dichroism, and 31P NMR spectroscopy. The addition of L-cysteine, L-alanine, and glycine to OASS results in a shift in lambda max of 412 nm for the internal Schiff base to 418 nm resulting from the formation of the external Schiff base. The addition of L-serine or O-methyl-D,L-serine gives decreases of the absorbance of unliganded enzyme at 412 nm of about 50% and 20%, respectively, concomitant with an increase in the absorbance at 320 nm and a shift in the lambda max of the remaining visible absorbance to 418 nm. The spectral shifts observed in the presence of L-serine are suggestive of establishing an equilibrium between different forms of external Schiff base. The concentration dependence of the changes at 440 (L-cysteine) and 320 nm (L-serine) provides an estimate of the dissociation constant for the external aldimine. The pH dependence of the dissociation constant suggests the alpha-amine of the amino acid must be unprotonated for nucleophilic attack at C4' of PLP, and an enzyme side chain must be unprotonated to hydrogen-bond the thiol or hydroxyl side chain of the amino acid. When L-cysteine is the amino acid, the thiol side chain must be protonated to hydrogen-bond to the unprotonated enzyme side chain. The 31P NMR chemical shift is increased from 5.2 ppm for unliganded enzyme to 5.3 ppm in the presence of L-cysteine, signaling a tighter interaction at the 5'-phosphate upon formation of the external Schiff base.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-base chemical mechanism of O-acetylserine sulfhydrylases-A and -B from pH studies.

The pH dependence of kinetic parameters using natural and alternative reactants was determined in order to obtain information on the chemical mechanisms of the A and B isozymes of O-acetylserine sulfhydrylase (OASS) from Salmonella typhimurium. A general mechanism is proposed for OASS in which OAS binds with its alpha-amine unprotonated to carry out a nucleophilic attack on C4' of the protonated Schiff base and with the acetyl carbonyl hydrogen-bonded to a protonated enzyme group (or a water molecule), which aids in the beta-elimination of acetate. The enzyme lysine that was in Schiff base linkage with the active site pyridoxal 5'-phosphate deprotonates the alpha-carbon in the beta-elimination reaction, and a proton is likely released with the acetate product. Sulfide likely binds as HS- to undergo nucleophilic attack on the alpha-aminoacrylate intermediate, followed by protonation of the alpha-carbon by the enzyme lysine. In OASS-A, HS- is hydrogen-bonded to the enzyme group that assists in the beta-elimination of acetate, but this is not the case for OASS-B. The pH independent equilibrium constant for the first half-reaction of OASS-A is 1.6 x 10(-3), while the second half-reaction is practically irreversible.

Painful lumbosacral sensory distribution patterns: embryogenesis to adulthood.

When the dorsal root ganglion is irritated by any of a variety of mechanisms, pain is referred to the various structures innervated by that root. In many circumstances, this pain is specific and may be used as a diagnostic aid. Unfortunately, emphasis is placed on defining a dermatomal distribution; the existence of a myotomal or sclerotomal origin of referred pain is often overlooked. This review presents the embryologic, anatomic, and neurophysiologic etiology of referred pain from the lumbar spine.

Intradiscal steroids. A prospective double-blind clinical trial.

A prospective, randomized, double-blind study was performed to evaluate the clinical efficacy of intradiscal steroid injections. Criteria for entrance were one-level internal disc disruption or nonsequestered nuclear prolapse with or without sciatica and a positive pain response on awake discography. Exclusion criteria were multilevel disease, central or lateral stenosis, prior lumbar surgery, or medical disease requiring systemic steroids. A total of 25 patients were randomly assigned to Treatment Group A (methylprednisolone, Depo-Medrol 80 mg/ml, The Upjohn Co., Kalamazoo, Michigan) or Treatment Group B (bupivacaine, Marcaine .5% 1.5 ml, Sanofi Winthrop Pharmaceuticals, New York, New York). Fourteen patients received Depo-Medrol, with 21% showing subjective improvement and 79% no improvement; 0% were clinically worse. Eleven patients received intradiscal Marcaine, with 9% showing clinical improvement and 91% no improvement; 0% were clinically worse. To quantify clinical response, a pain diagram grid score, a visual analog scale, and the Oswestry Pain Questionnaire were used before injection and 10-14 days after injection. No statistically significant benefit was identified in the use of intradiscal steroids.

Awake discography. A comparison study with magnetic resonance imaging.

This study was undertaken to determine the correlation between awake discography findings and magnetic resonance imaging in the evaluation of symptomatic lumbar disc disease. The study included 164 consecutive patients who underwent evaluation with discography and magnetic resonance imaging for lumbar disc disease from August 1987 to September 1989. Chronic low-back pain, with or without radicular symptoms, was the presenting complaint in each case. Each patient had previously failed conservative treatment. The average age was 36 (range, 19-66 years). Magnetic resonance images were performed before discography in each case. Discography was performed with patients minimally sedated and under local anesthesia. A lateral approach was used. Magnetic resonance imaging and discography correlated in 90 cases (55%) and differed in 74 (45%). Considering disc levels, discography and magnetic resonance imaging correlated in 371 discs (80%). There were 172 normal discs and 199 abnormal discs. Of the abnormal discs, 151 (76%) reproduced symptoms. In 60 discs (13%), magnetic resonance images showed abnormal findings and the discogram normal findings. Discs levels classified as abnormal on magnetic resonance imaging demonstrated that 108 discs (37%) were asymptomatic. Magnetic resonance imaging showed normal findings and the discogram abnormal findings in 34 discs (7%), of which 21 (5%) recreated exact symptoms and 13 (2%) caused no pain. Magnetic resonance imaging is a static test and discography the only available dynamic test for disc evaluation. Awake discography is a diagnostic study that can determine which abnormal discs are symptomatic via the pain response.

Intravenous colchicine for low-back pain: a double-blind study.

Colchicine, a drug used for centuries in the treatment of gout, has been reported to be effective for low-back pain due to disc disorders. A prospective, randomized, double-blind study evaluating the therapeutic effect of intravenous colchicine was conducted in a group of patients with low-back pain with symptoms originating less than 6 months previously. Each patient completed a questionnaire and a pain drawing. Laboratory studies including uric acid and sedimentation rate were performed, as was a detailed physical examination and lumbar thermography. All treatment parameters (including physical therapy, anti-inflammatory medications, and instructions) were constant except that each patient received either intravenous colchicine or intravenous saline. Results indicate a significant difference between the two groups, the intravenous colchicine group showing improvement in symptoms for a few hours or days over a 3-week course of treatment. However, the relief was often of short duration.

A reassessment of Holt's data on: "The question of lumbar discography".

This paper is a detailed critique of Holt's study entitled "The Question of Lumbar Discography." His finding of a 37% false positive rate in asymptomatic volunteers has been used to discredit lumbar discography as a valid diagnostic study in the investigation of low back pain patients with nonprolapsing disc disease of the lumbar spine. The authors show why Holt's paper should no longer be used as scientific and authoritative evidence against the use of discography by today's standards.