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PubMedDate not supplied

The histaminergic innervation of the lateral geniculate complex in the cat.

The histaminergic innervation of the thalamic dorsal and ventral lateral geniculate nuclei and the perigeniculate nucleus of the cat was examined immunohistochemically by means of an antibody to histamine. We find histamine-immunoreactive neurons in the cat brain are concentrated in the ventrolateral portion of the posterior hypothalamus, confirming a previous report. However, this cell group also spreads into medial, dorsal, and extreme lateral regions of the posterior hypothalamus and extends as far rostral as the optic chiasm. Histamine-labeled fibers cover all regions of the lateral geniculate complex, but the density of labeling varies. The ventral lateral geniculate nucleus (vLGN) is most densely labeled, the A laminae of the dorsal lateral geniculate are sparsely labeled, and the geniculate C laminae and the perigeniculate nucleus show intermediate amounts of label. Thus, histaminergic fibers demonstrate a predilection for zones innervated by the W-cell system. Labeled fibers exhibit few branchings and numerous en passant swellings, lending a beaded appearance. The vLGN showed more instances of fibers with larger-sized swellings (up to 2 microns). Following injections of biotinylated tracers into the hypothalamus, we find labeled fibers throughout the lateral geniculate complex. The anterogradely labeled fibers resemble the histaminergic fibers in morphology, distribution, and relative bouton size. Thus, the hypothalamus appears to be the source of the histaminergic fibers in the lateral geniculate complex. Histamine-labeled fibers in the dorsal lateral geniculate nucleus (dLGN) exhibit uncommon ultrastructural morphology. Many extremely large, round, or elliptical vesicles fill the fiber swellings. Swellings are directly apposed to a variety of other dendritic and axonal profiles, but thus far no convincing synaptic contacts have been seen. The distribution and appearance of these histaminergic fibers resembles those reported for serotonergic fibers. Our results support the idea that histamine works nonsynaptically as a neuromodulator in the lateral geniculate complex, affecting the level of visual arousal.

Animals↗
PubMed1999

The influence of left lateral position on cardiac output changes after head up tilt measured by impedance cardiography.

BACKGROUND: The value of the impedance cardiography (IC) method for measuring cardiac output (CO) with the subject in the left lateral position has not yet been established. We compared the CO after a 30 degrees head-up tilt with the subjects in the supine and left lateral position. METHODS: Thirty healthy young volunteers were placed in the supine horizontal position. CO, stroke volume (SV) and heart rate (HR) were measured for five minutes using impedance cardiography (NCOMM3, BoMed Medical Manufacturing, Location). Then a 30 degrees head-up tilt was done and the measurements were continued for an additional five minutes. After that the subjects were placed in the left lateral horizontal position and the measuring procedure was repeated. RESULTS: After the tilt, SV and cardiac index (CI) decreased and HR increased statistically significantly in the supine and in the left lateral position. SV and CI also decreased statistically significantly but HR did not change after the shift from the supine to the left lateral position. Although CI was smaller in the left lateral position, the time course of CI change after the tilt was identical in the supine and in the left lateral position. CONCLUSION: When using the IC method of SV measurement, the absolute value of the CI changes when moving from the supine to lateral positions. It is not clear whether this change is physiologic or an artifact of the measurement technique. However, changes in CI in response to a 30 degree head up tilt are the same in either position. We conclude that changes in CI can be measured with the IC method in the lateral position.

Adult↗
PubMed1998

Comparison of umbilical artery Doppler velocimetry between maternal supine position and complete left lateral position in predicting obstetric complications.

The aim of this study was to compare the predictive value of umbilical artery Doppler velocimetry in women in the supine position with that in women in the complete left lateral position as a screening test for abnormal obstetric outcomes. Umbilical artery resistance index (RI) was measured at 27-29 weeks and 35-37 weeks in 202 pregnant women. The measurements were performed with the mother in the supine position in 100 cases (supine group), and in the complete left lateral position in 102 cases (lateral group). Predictive values of the tests for abnormal outcomes (small for gestational age, fetal distress, pregnancy-induced hypertension) were compared between both groups. When abnormal RIs were defined as being greater than the 90th centile in the supine group, the sensitivities for any of the abnormal outcomes at 27-29 weeks were 18% in the supine group and 6% in the lateral group; the positive predictive values were 30% and 25%, respectively. For measurement at 35-37 weeks, the sensitivity and positive predictive value were 29% and 45%, respectively in the supine group, and 0% in both cases in the lateral group. When abnormal RIs were defined as being greater than the 90th centile in the lateral group, the sensitivities at 27-29 weeks were 41% in the supine group and 6% in the lateral group; the positive predictive values were 44% and 8%, respectively. At 35-37 weeks, the sensitivity and positive predictive value were 53% and 43% in the supine group, and 6% and 8% in the lateral group. Umbilical artery Doppler velocimetry when the mother was in the complete left lateral position was of little value as a screening test. However, when the mother is in the supine position, it may serve as a kind of stress test and disclose latent obstetric abnormalities in certain cases.

Adult↗
PubMed1999

Tilted lateral radiographs in the evaluation of intra-articular distal radius fractures.

The anatomy of the distal radius confounds the assessment of fracture displacement of the lunate facet. Since reduction of the articular surface is paramount to obtaining good clinical results, this study was designed to evaluate whether a radiograph taken 22 degrees from true lateral (forearm held at a 22 degrees angle from the horizontal film cassette) would enhance the accuracy of measuring displacement. Fifteen lunate facet fractures of varying depression were produced in 7 fresh cadaveric wrists. Posteroanterior (PA), standard lateral, and 22 degrees tilted lateral radiographs were obtained of each fracture pattern. Four observers reviewed the films and measured the depression of the fragments from their anatomic position. Measurement error from actual depression averaged 1.1 mm when the evaluators evaluated the 22 degrees lateral and PA films, 1.5 mm for the standard lateral and PA views, and 0.8 mm for the standard lateral, 22 degrees lateral, and PA radiographs (combined group). The decrease in measurement error obtained from all 3 groups was statistically significant. The results of this study suggest that the 22 degrees tilted lateral, either in combination with the standard lateral radiograph or just with the PA view, may help the hand surgeon better understand the intra-articular depression of lunate facet fractures of the distal radius.

Cadaver↗
PubMed2000

Functional dissociation between medial and lateral prefrontal cortical spatiotemporal activation in negative and positive emotions: a combined fMRI/MEG study.

The orbitofrontal cortex has been cytoarchitectonically and connectionally subdivided into a medial and a lateral part which are assumed to subserve distinct functions in emotional processing. However the exact spatiotemporal mechanisms of negative and positive emotional processing in medial and lateral orbitofrontal cortex remain unclear. We therefore investigated spatiotemporal orbitofrontal and prefrontal cortical activation patterns during emotional stimulation in a combined fMRI/MEG study. We investigated 10 healthy subjects, 5 women and 5 men. Positive and negative pictures from the International Affective Picture system (IAPS) were used for emotional stimulation, whereas neutral and gray pictures were taken as control conditions. fMRI/MEG measurements covered the whole frontal lobe and a time window between -2000 and +200 ms around motor responses (right index finger extension) associated with each picture. Positively and negatively correlated activities were determined in various prefrontal/frontal cortical regions in fMRI. Isocontour maps and single dipoles in MEG were analyzed in 50 ms time windows ranging from -2000 to +200 ms. Dipoles and fMR images were mapped on three-dimensional anatomical MRI so that anatomical localization of single dipoles and regional fMRI activity could be compared. Both negative and positive emotional conditions differed from non-emotional control conditions by strong orbitofrontal and lateral prefrontal activation as well as by the presence of early magnetic fields (-1700 to +1100 ms). Negative emotional processing was characterized by strong medial orbitofrontal activation and earlier (-1700 ms), stronger and more medially oriented orbitofrontal dipoles. In contrast positive emotional processing showed a rather strong activation in lateral prefrontal cortex with later (-1500 ms), weaker and more laterally oriented orbito and prefrontal dipoles. Negative emotional processing can be characterized by strong and early medial orbitofrontal cortical activation, whereas positive emotional processing showed rather later and weaker activation in lateral orbitofrontal/prefrontal cortex. Such a functional dissociation between medial and lateral orbito-frontal/prefrontal cortex during negative and positive emotional processing lends further support to the assumption of a functional subdivision in the orbitofrontal cortex.

Adult↗
PubMed1993

Epidemiologic analysis of Kaposi's sarcoma as an early and later AIDS outcome in homosexual men.

The authors separately studied the epidemiology (risk and risk factors) of Kaposi's sarcoma occurring as an initial acquired immunodeficiency syndrome (AIDS) outcome (early Kaposi's sarcoma) and later after a different initial AIDS outcome (later Kaposi's sarcoma) in a cohort of 2,591 human immunodeficiency virus type 1-infected gay men of the Multicenter AIDS Cohort Study between 1984 and 1992. Among 844 AIDS cases, 202 presented with early Kaposi's sarcoma, 101 subsequently developed later Kaposi's sarcoma, and 541 were not diagnosed with Kaposi's sarcoma. Overall, 37.4% of AIDS cases were diagnosed with Kaposi's sarcoma prior to death. Kaposi's sarcoma diagnosed on the skin was significantly more common with early Kaposi's sarcoma (77.3%) than with later Kaposi's sarcoma (65.1%). Men presenting with an AIDS outcome other than Kaposi's sarcoma were at high risk for later Kaposi's sarcoma. Later Kaposi's sarcoma onset in men with a previous AIDS outcome was associated with the following characteristics: 1) lower immune status prior to AIDS and 2) longer post-AIDS survival. A Kaposi's sarcoma diagnosis in a man with a previous AIDS illness approximately doubled the risk (hazard) for death. Histories of urethral gonorrhea and scabies prior to study entry were more common in early Kaposi's sarcoma cases than in later Kaposi's sarcoma cases. However, self-reported sexual activity at study entry and prior to AIDS onset was highest in the later Kaposi's sarcoma group. In this cohort, cigarette smoking had a protective association against all Kaposi's sarcoma in univariate and multivariate models. Only 21.0% of the later Kaposi's sarcoma and 25.0% of the early Kaposi's sarcoma men smoked at least one-half pack of cigarettes daily at study entry compared with 33.8% of non-Kaposi's sarcoma and 35.5% of seroprevalent men still AIDS free. The reasons for this surprising association are unclear. However, other evidence which documents that habitual smoking alters the immune system (and possibly cytokine levels) in ways that could perhaps influence Kaposi's sarcoma pathogenesis should be considered.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Pulmonary blood flow does not redistribute in dogs with reposition from supine to left lateral position.

BACKGROUND: Recent studies have questioned the classical gravitational model of pulmonary perfusion. Because the lateral position is commonly used during surgery, the authors studied the redistribution of pulmonary blood flow in the left lateral decubitus position using a high spatial resolution technique. METHODS: Distributions of pulmonary blood flow were measured using intravenously injected 15-microm diameter radioactive-labeled microspheres in eight halothane-anesthetized dogs, which were studied in the supine and left lateral decubitus positions in random order. Lungs flushed free of blood were air-dried at total lung capacity and sectioned into 1,498-2,396 (1.7 cm3) pieces per animal. Radioactivity was measured by a gamma counter, and signals were corrected for piece weight and normalized to mean flow. RESULTS: Blood flow to the dependent left lung did not increase, and blood flow to the nondependent right lung did not decrease in the lateral position. The left lung received 39.3 +/-7.0% and 39.2+/-8.8% (mean +/- SD) of perfusion in the supine and left lateral positions, respectively. Detailed assessment of the spatial distributions of pulmonary blood flow revealed the lack of a gravitational gradient of blood flow in the lateral position. The distributions of blood flow did not differ in the supine and left lateral decubitus positions. CONCLUSIONS: Perfusion to each lung did not change with movement from the supine to the left lateral position. These findings contradict the prediction of increased dependent lung and decreased nondependent lung blood flow based on the gravitational model. It was concluded that the distribution of blood flow in the lateral position in dogs is dominated by pulmonary vascular structure.

Anesthetics, Inhalation↗
PubMed2000

Cervical transfacet versus lateral mass screws: a biomechanical comparison.

The authors directly the compared biomechanical pullout strength of screws placed in the cervical lateral masses to that of screws placed across the facet joints. Posterior cervical fixation with lateral mass plates is an accepted adjunctive technique for cervical spine fusions. Altered anatomy resulting from congenital malformation, tumor, trauma, infection, or failed lateral mass fixation may limit traditional screw placement options. Transfacet screw placement, which has been studied extensively in the lumbar spine, may offer an alternative when posterior cervical fusion is required. Ten fresh human cadaveric cervical spines (postmortem age range, 69 to 91 years) were harvested. On one side, transfacet screws were placed at the C3-4, C5-6, and C7-T1 levels. On the other side, lateral mass screws were placed at the C3, C5, and C7 levels. The screw insertion technique at each level was randomized for right or left. After screw placement, each set of vertebral bodies were dissected and mounted in a custom jig for axial pullout testing using a servohydraulic testing machine. The load-displacement curves were obtained for each screw pullout. The mean pullout strength for the screws placed across the facets was 467 N (range, 192 to 1,176 N). This compares with 360 N (range, 194 to 750 N) for the lateral mass screws (p = 0.008). At each level, transfacet screws exhibited greater pullout resistance compared with the lateral mass placement, but the difference was most pronounced at the C7-T1 level (lateral mass = 373 N, transfacet = 539 N, p = 0.042). Cervical transfacet screw placement provides pullout resistance that is comparable to, if not greater than, lateral mass placement. This type of placement, although technically difficult, may be an alternative to lateral mass screws in cases with unusual anatomy, stripped screws, or when additional intermediate points of fixation are desired.

Biomechanical Phenomena↗
PubMed1998

Prospective evaluation of lateral biopsies of the peripheral zone for prostate cancer detection.

PURPOSE: We evaluate the usefulness of adding 4 lateral biopsies of the peripheral zone to the routine sextant biopsy regimen for prostate cancer. MATERIALS AND METHODS: A total of 273 consecutive patients referred for abnormal digital rectal examination and/or prostate specific antigen 4 ng./ml. or greater underwent transrectal ultrasound and systematic biopsy. Lateral biopsies of the peripheral zone taken just medial to the lateral border of the prostate were added to the routine lesion directed and systematic sextant biopsy regimen. Comparisons between positive and negative biopsy groups as well as among various biopsy schemes were performed. RESULTS: Of the patients 44% had cancer on biopsy (121 of 273). While routine sextant biopsies detected 82% of cancers, 77% (17 of 22) of missed cancers were detected on lateral biopsies. Overall, lateral biopsies detected 70% of cancers, and tended to be positive in patients with small prostates and high grade tumors. A significant correlation was found between hypoechoic lesions on transrectal ultrasound and positive lateral biopsies (Fisher's exact test p = 0.0005). Cancer was found in 74 of 147 patients with lesions on transrectal ultrasound (50%). Routine sextant biopsies detected 76% of cancers (56 of 74 patients) while lateral biopsies detected 80% (59). Of these patients 15 (20%) had positive lateral and negative sextant biopsies. Routine sextant biopsies detected 91% of cancers in 121 patients without lesions on ultrasound (43 of 47). CONCLUSIONS: The addition of lateral peripheral zone biopsies increases the sensitivity for cancer detection while nearly eliminating the need for lesion directed biopsies.

Aged↗
PubMed2004

Regional wall motion and wall thickening visual scores from gated SPECT in anterior and infero-lateral myocardial infarctions.

BACKGROUND: The relationship between the visual scores for wall motion (WM) and wall thickening (WT) of different left ventricular regions in patients with anterior and infero-lateral myocardial infarctions was evaluated using gated SPECT. METHODS: Ninety consecutive patients (79 men and 11 women; mean age 56 +/- 9 years) with previous myocardial infarction (33 anterior and 57 infero-lateral) were included. Left ventricular volumes and ejection fractions (EFs) were calculated from quantitative rest gated SPECT 99mTc tetrofosmin images by using the QGS automatic algorithm. Global and regional (anterior, septal, inferior and lateral) wall motion and wall thickening scores were calculated by consensus of three experienced observers. RESULTS: The correlation between EFs and wall motion and wall thickening scores was better for WM scores in anterior (r=0.904, P<0.0001) than infero-lateral infarctions (r=0.674, P<0.0001). Correlation between wall motion and wall thickening scores was also better for anterior (r=0.898, P<0.0001) than for infero-lateral infarctions (r=0.750, P<0.0001). Except in septal regions, WT scores of the different regions were higher than WM scores (P<0.05) but the statistical significance was higher (P<0.001) in inferior and lateral regions of infero-lateral infarctions. CONCLUSION: Visual global wall motion and wall thickening scores obtained by gated SPECT showed good correlation between them and with the EF, but differences were observed between regional wall motion and wall thickening, especially in inferior and lateral regions of patients with infero-lateral infarctions.

Aged↗
PubMed1997

Evolution of the lateral canthoplasty: techniques and indications.

Lateral canthoplasty is a useful method to restore eyelid function and to protect the ocular surfaces. The success of the procedure depends on the proper analysis of periorbital anatomy as it relates to the specific indication for lateral canthoplasty. We report the experience with 1565 lateral canthoplasties with emphasis on the evaluation of newer techniques that better address anatomic and functional requirements. Between 1981 and 1994, 1565 lateral canthoplasties were performed in 684 patients. Of these, 1369 "reconstructive" lateral canthoplasties were performed in 586 patients and 196 "cosmetic" lateral canthoplasties were performed in 98 patients. All operations were performed by a single surgeon (Jelks), and follow-up ranged from 1 to 14 years. The evolution of the operative technique for lateral canthoplasty has been toward an operation that corresponds with the anatomy of the individual. Indications for the procedure include lateral canthal dystopia, horizontal lid laxity, ectropion, entropion, lid margin eversion, lid retraction with or without soft-tissue deficiency, and aesthetic improvement. The types of procedures performed will be reviewed in detail. The evaluation of the newer forms of lateral canthoplasty as unique reconstructive tools and as adjuncts to aesthetic surgery will be discussed.

Adult↗
PubMed2002

Treatment of lateral ray polydactyly of the foot: focusing on the selection of the toe to be excised.

The purposes of this study were to evaluate the results of the operative treatment of lateral ray polydactyly and to consider appropriate surgical procedures, especially focusing on the selection of the toe, lateral toe or medial toe, to be resected. Twenty-two patients with lateral ray polydactyly foot (25 individual feet) at an average of 71 months' follow-up were included in this study. Cases were classified morphologically into three types on the basis of Hirase's configuration. In addition, these types were divided into two subtypes, metatarsal and phalangeal, on the basis of radiographic evaluation of the level of duplication. The clinical evaluations of the reconstructed toe were performed, and these results were investigated according to their morphologic classification and excised toe group. The distinctive problem of medial toe excision is valgus deformity. Eight of 25 toes retained persistent valgus deformity, and all of these cases were in the medial toe excision group. On the other hand, a distinctive problem in lateral toe excision is postoperative pain. Two patients suffered from postoperative pain in phalangeal type cases in the lateral toe excision group, and the remaining medial toe had a medial protuberant middle phalanx. The pain occurred at that protuberant point. Based on their experiences, the authors created an algorithm for selection of the toe to be excised. In metatarsal type cases, from a functional perspective, the toe that has a radiographically dominant metatarsus should be retained. On the other hand, in phalangeal type cases, the authors give priority to shape rather than function, and they excise the morphologically smaller toe independent of the condition of the phalanx as viewed on radiography. If the medial toe and the lateral toe are approximately the same size, the authors excise the lateral toe to avoid valgus deformity. When the lateral toe has severe valgus deformity that seems unlikely to be correctable intraoperatively, the lateral toe should be considered for excision even if it is larger than the medial toe.

Adolescent↗
PubMed1995

Radiographic appearance of the odontoid lateral mass interspace in the occipitoatlantoaxial complex.

STUDY DESIGN: This is an anatomic study in which the odontoid lateral mass interspace is evaluated radiographically in various positions of upper cervical spine rotation. OBJECTIVES: The objectives are to determine whether odontoid lateral mass interspace asymmetry exists in the ligamentously intact cervical spine and to define odontoid lateral mass interspace behavior during atlantoaxial rotation. SUMMARY OF BACKGROUND DATA: Controversy exists regarding the behavior of the odontoid lateral mass interspace during atlantoaxial rotation. The meaning of interspace asymmetry varies depending on the author and the method of study. Atlas fractures account for 7% of cervical spine fractures and are frequently associated with other cervical fractures, so an understanding of the radiographic anatomy is crucial to the evaluation of these patients. METHODS: Ten human cadaveric cervical spines were dissected of all but ligamentous soft tissue and were mounted and prepared for radiographic study in neutral position and in varying degrees of right and left rotation. Radiographs were evaluated for odontoid lateral mass interspace asymmetry in neutral and in rotated positions, and data were analyzed. RESULTS: Measurable asymmetry could be shown when comparing neutral positions and when comparing rotated with neutral positions. A statistically significant difference could not be proven in this asymmetry, although clinical significance is suggested by the analysis of the data. CONCLUSION: Measurable asymmetry can be present in the neutrally positioned, ligamentously intact atlanto-axial complex and is not necessarily indicative of instability. This agrees with the concept of the "neutral zone" as described by White and Panjabi in Clinical Biomechanics of the Spine. There is a trend for increasing odontoid lateral mass interspace on the side to which the head is rotated, and this odontoid lateral mass interspace is measurably different from the contralateral odontoid lateral mass interspace, indicating that odontoid lateral mass interspace asymmetry is not a good indicator for cervical instability in the otherwise asymptomatic individual.

Adult↗
PubMed2003

Morphometric evaluation of screw fixation in atlas via posterior arch and lateral mass.

STUDY DESIGN: This study is a result of manual and radiologic measurements of 50 isolated anatomic specimens of C1 and five patients of atlantoaxial instability treated by screw fixation via posterior arch and lateral mass. OBJECTIVES: To investigate the feasibility of screw placement via posterior arch and lateral mass in atlas. SUMMARY OF BACKGROUND DATA: Several types of posterior approaches have been adopted for stabilization and fusion of atlantoaxial complex. Before this study, Gallie in 1939 gave a report on a posterior wiring technique that depended on a structural bone graft. Since then, double-looped wiring with two bone grafts and Halifax clamp technique had been introduced. A transarticular screw fixation technique was introduced by Magerl and Seeman in 1987, and a C1 lateral mass screw fixation technique was described by Harms in 2001. However, the feasibility of screw fixation in atlas via posterior arch and lateral mass has not been addressed until now. METHODS: Fifty dry samples of atlas were measured manually and radiologically with vernier calipers, protractors, and CT. The parameters of posterior arch, lateral mass, vertebral artery groove, axis length of screw path via posterior arch and lateral mass, the entry point, and screw direction were measured. Five patients of atlantoaxial instability were treated with this technique and the radiographs and CT scans were evaluated after surgery. RESULTS: The longest trajectory distance of the screw path was about 30 mm. The outer thickness at the thinnest part of groove was 4.58 mm, and it was found to be <4 mm in four cases (8%). The entry point is 18-20 mm lateral to the midline and 2 mm superior to the inferior border of posterior arch. The direction of screw placement is perpendicular to the coronal plane and about 5 degrees cephalad to the transverse plane. Ten screws via posterior arch and lateral mass were placed properly, without incidence of nerve or blood vessel injury in clinical practice. CONCLUSION: Atlas is capable for screw fixation via its posterior arch and lateral mass.

Adult↗
PubMed2003

Quantitative anatomy of the lateral mass of the atlas.

STUDY DESIGN: The lateral mass of the atlas was quantitatively measured. OBJECTIVES: To measure the ranges and external dimensions of the lateral mass of the atlas quantitatively, and to provide the anatomic basis for its posterior screw fixation. SUMMARY OF BACKGROUND DATA: Lateral mass screw fixation in cervical vertebra has been reported, but quantitative data regarding the anatomy of the lateral mass of the atlas are unknown. METHODS: Atlas specimens from 30 fresh cadavers were used for dissection to measure the width, thickness, and height of the lateral mass of the atlas, diameter of the atlantoaxial joint articular surface, and obliquity of the facet atlantoaxial joint in the coronary plane. RESULTS: According to measurements and statistics, the mean width of the lateral mass of the atlas is 15.47 mm, the mean thickness 17.21 mm, the mean height 14.09 mm, the mean transverse diameter of the atlantoaxial joint articular surface 17.90 mm, the mean longitudinal diameter of the atlantoaxial joint articular surface 15.63 mm, and the obliquity of the facet atlantoaxial joint in coronary plane 34.57 degrees. CONCLUSIONS: Very little information on the lateral mass of the atlas can be found. This study gives some parameters of the lateral mass of the atlas. On the basis of this study, it may be concluded that there is enough space for lateral mass screws in posterior up-cervical internal fixation.

Atlanto-Axial Joint↗
PubMed2004

Biomechanical comparison of anterolateral plate, lateral plate, and pedicle screws-rods for enhancing anterolateral lumbar interbody cage stabilization.

STUDY DESIGN: A repeated measures in vitro flexibility experiment was performed in calf spines. OBJECTIVES: To determine the biomechanical differences among three techniques for augmenting stability of an anterolateral lumbar threaded interbody cage. BACKGROUND: Stand-alone interbody cages are known to inadequately stabilize the spine. Surgeons often add supplementary instrumentation for a more stable construct. METHODS: Six L2-L5 calf spines (L3-L4 level instrumented) were tested: 1) intact; 2) with a single anterolateral interbody cage; 3) with cage plus anterolateral plating; 4) with cage plus lateral plating; and 5) with cage plus pedicle screw fixation. Specimens were loaded in each anatomic plane quasistatically (maximum 5.0 Nm). Angular motion was measured stereophotogrammetrically. RESULTS: The stand-alone interbody cage allowed significantly less range of motion than normal during all loading modes except axial rotation. Addition of pedicle screws-rods, anterolateral plate, or lateral plate significantly further reduced range of motion in all planes. Pedicle screws slightly outperformed the anterolateral plate during extension and lateral bending and slightly outperformed the lateral plate during flexion, extension, and left axial rotation (range of motion differences <0.65 degrees, P < 0.05). The anterolateral plate outperformed the lateral plate during flexion and extension, whereas the lateral plate outperformed the anterolateral plate during lateral bending (range of motion difference <0.57 degrees, P < 0.05). CONCLUSION: Anterolateral or lateral lumbar plating increases stability significantly compared to stand-alone interbody cage fixation. These findings support anterolateral or lateral plate fixation as a potential clinical alternative to pedicle screws-rods in this role and may obviate the need for combined anterior and posterior approaches when spinal instability exists.

Animals↗
PubMed2005

Anatomic changes in lateral spondylolisthesis associated with adult lumbar scoliosis.

STUDY DESIGN: Prospective consecutive series. OBJECTIVE: To analyze the anatomic changes in lateral spondylolisthesis. SUMMARY OF BACKGROUND DATA: Previous studies have focused on the correlation between lateral spondylolisthesis, and curve progression and pain. To our knowledge, there has not been any detailed report concerning anatomic changes in lateral spondylolisthesis. METHODS: We examined 24 consecutive patients (mean age 66 years), with lateral spondylolisthesis associated with lumbar scoliosis who had computerized tomography (CT) after myelography. Coronal reconstruction CT was used to measure the vertebral translation. Vertebral rotation was measured by the Aaro method using transaxial CT. RESULTS: The Cobb angle averaged 26 degrees (range 13 degrees-75 degrees). Lateral spondylolisthesis was found most commonly at the lower-end vertebra. The cephalad-slipped vertebra rotated toward the convex side of the main curve, whereas the caudal vertebra rotated toward the convex side of the lumbosacral hemi (or fractional) curve below. Mean lateral translation and vertebral rotation were 7 mm and 8 degrees, respectively. There was a significant correlation between lateral translation and vertebral rotation (r = 0.49; P = 0.018). The convex superior articular process of the caudal vertebra had compressed the nerve root laterally in 21 patients, of whom 10 had radicular pain. The concave, inferior articular process of the cephalad vertebra had compressed the dural sac posteriorly, and 2 patients had radicular pain. CONCLUSIONS: To our knowledge, this study has been the first attempt to analyze anatomic changes in lateral spondylolisthesis using CT. It may offer further insight into the pathogenesis of adult lumbar scoliosis.

Aged↗
PubMed2005

Focally increased activity in the lateral aspect of the mid cervical spine on bone scintigraphy is almost always benign in nature.

OBJECTIVES: Abnormal bone scan findings in the spine are often nonspecific. The confidence level for the differential diagnosis between metastases and benign or degenerative changes may vary depending on their appearance, location or intensity. The recognition of a specific pattern for certain benign conditions and its subcategorization will increase the credibility of bone scan interpretation while retaining a high level of sensitivity. We report one such finding, focally increased activity on the lateral side of the cervical spine on the posterior view, most common at the C3-C5 level ("mid-cervical-lateral-focus"). METHODS: Of 481 patients with various cancers who had at least 2 whole-body bone scans, 6 months or more apart, 41 patients were judged to show this characteristic "mid-cervical-lateral-focus" on at least one scan. Final diagnosis (metastasis vs. benign) for each "mid-cervical-lateral-focus" was made based on clinical grounds and serial bone scans. RESULTS: The bone scan showed definite multiple metastases in 15 patients, and the differential diagnosis for the "mid-cervical-lateral-focus" was already clinically irrelevant in these patients. Nevertheless, the "mid-cervical-lateral-focus" was finally judged to be benign in 14 of these 15 patients and in all remaining 26 patients without other obvious metastases. The only "mid-cervical-lateral-focus" judged to be a metastatic focus was not only clinically redundant, but also the most intense among all the "mid-cervical-lateral-foci." in this series (too intense to be interpreted as benign). CONCLUSION: The typical "mid-cervical-lateral-focus" pattern is extremely unlikely to represent metastases (virtually 0% in patients without other obvious metastases). This knowledge helps exclude metastases on bone scans.

Aged↗