Intradiscal Pressure Changes during Manual Cervical Distraction: A Cadaveric Study.

The objective of this study was to measure intradiscal pressure (IDP) changes in the lower cervical spine during a manual cervical distraction (MCD) procedure. Incisions were made anteriorly, and pressure transducers were inserted into each nucleus at lower cervical discs. Four skilled doctors of chiropractic (DCs) performed MCD procedure on nine specimens in prone position with contacts at C5 or at C6 vertebrae with the headpiece in different positions. IDP changes, traction forces, and manually applied posterior-to-anterior forces were analyzed using descriptive statistics. IDP decreases were observed during MCD procedure at all lower cervical levels C4-C5, C5-C6, and C6-C7. The mean IDP decreases were as high as 168.7 KPa. Mean traction forces were as high as 119.2 N. Posterior-to-anterior forces applied during manual traction were as high as 82.6 N. Intraclinician reliability for IDP decrease was high for all four DCs. While two DCs had high intraclinician reliability for applied traction force, the other two DCs demonstrated only moderate reliability. IDP decreases were greatest during moving flexion and traction. They were progressevely less pronouced with neutral traction, fixed flexion and traction, and generalized traction.

Primary and coupled motions after cervical total disc replacement using a compressible six-degree-of-freedom prosthesis.

This study tested the hypotheses that (1) cervical total disc replacement with a compressible, six-degree-of-freedom prosthesis would allow restoration of physiologic range and quality of motion, and (2) the kinematic response would not be adversely affected by variability in prosthesis position in the sagittal plane. Twelve human cadaveric cervical spines were tested. Prostheses were implanted at C5-C6. Range of motion (ROM) was measured in flexion-extension, lateral bending, and axial rotation under ± 1.5 Nm moments. Motion coupling between axial rotation and lateral bending was calculated. Stiffness in the high flexibility zone was evaluated in all three testing modes, while the center of rotation (COR) was calculated using digital video fluoroscopic images in flexion-extension. Implantation in the middle position increased ROM in flexion-extension from 13.5 ± 2.3 to 15.7 ± 3.0° (p < 0.05), decreased axial rotation from 9.9 ± 1.7 to 8.3 ± 1.6° (p < 0.05), and decreased lateral bending from 8.0 ± 2.1 to 4.5 ± 1.1° (p < 0.05). Coupled lateral bending decreased from 0.62 ± 0.16 to 0.39 ± 0.15° for each degree of axial rotation (p < 0.05). Flexion-extension stiffness of the reconstructed segment with the prosthesis in the middle position did not deviate significantly from intact controls, whereas the lateral bending and axial rotation stiffness values were significantly larger than intact. Implanting the prosthesis in the posterior position as compared to the middle position did not significantly affect the ROM, motion coupling, or stiffness of the reconstructed segment; however, the COR location better approximated intact controls with the prosthesis midline located within ± 1 mm of the disc-space midline. Overall, the kinematic response after reconstruction with the compressible, six-degree-of-freedom prosthesis within ± 1 mm of the disc-space midline approximated the intact response in flexion-extension. Clinical studies are needed to understand and interpret the effects of limited restoration of lateral bending and axial rotation motions and motion coupling on clinical outcome.

Restoration of spinal alignment and disk mechanics following polyetheretherketone wafer kyphoplasty with StaXx FX.

BACKGROUND AND PURPOSE: EPFs sustained during VCFs degrade the disk's ability to develop IDP under load. This inability to develop pressure in combination with residual kyphotic deformity increases the risk for adjacent vertebral fractures. We tested the hypothesis that StaXx FX reduces kyphosis and endplate deformity following vertebral compression fracture, restoring disk mechanics. MATERIALS AND METHODS: Eight thoracolumbar, 5-vertebrae segments were tested. A void was selectively created in the middle vertebra. The specimens were compressed until EPF and to a grade I-II VCF. PEEK wafer kyphoplasty was then performed. The specimens were then tested in flexion-extension (±6 Nm) under 400-N preload intact, after EPF, VCF, and kyphoplasty. Endplate deformity, kyphosis, and IDP adjacent to the fractured body were measured. RESULTS: Vertebral body height at the point of maximal endplate deformity decreased after EPF and VCF and was partially corrected after StaXx FX, remaining less than intact (P = .047). Anterior vertebral height decreased after VCF (P = .002) and was partially restored with StaXx FX, remaining less than intact (P = .015). Vertebral kyphosis increased after VCF (P < .001) and reduced after StaXx FX, remaining greater than intact (P = .03). EPF reduced IDP in the affected disk in compression-flexion loading (P < .001), which was restored after StaXx FX (P = 1.0). IDP in the unaffected disk did not change during testing (P > .3). CONCLUSIONS: StaXx FX reduced endplate deformity and kyphosis, and significantly increased anterior height following VCF. Although height and kyphosis were not fully corrected, the disk's ability to pressurize under load was restored.

[Comparative evaluation of diagnostic methods in thymus disease]. / Sravnitelnaia otsenka metodov diagnostiki porazhenii vilochkovoi zhelezy.

From analysis of the case records of 2,000 patients with the generalized form of myasthenia, who underwent operation at the surgical faculty clinic of the Moscow Medical Academy, the authors discuss in detail the results of using a wide spectrum of methods for examination of the thymus, including: pneumomediastinography (PMG), scintigraphy, phlebography, computed and magnetoresonance tomography (CT and MRT). Taking into account the sensitivity and specificity of each of these methods, the indications and contraindications, and the degree of invasiveness, the authors concluded that MR tomography is the method of choice for examination of the thymus. It yields the rechest information and is most simple and safe for the patient. They also noted that CT made it possible to locate the pathological process more exactly, and provided additional information on the degree of the invasion, the presence of implants, and the condition of the other mediastinal organs. The indications for phlebography of the thymus and PMG are limited because of their invasiveness, difficult techniques, high risk of complications, and relatively low informativeness. Scintigraphy of the thymus is the least informative examination method. In view of the high percentage of pseudopositive and pseudonegative results, it may be concluded that its use for detecting lesions of the thymus in patients with myasthenia is hardly expedient.

[Diagnosis, surgical treatment and prognosis in patients with generalized myasthenia]. / Diagnostika, khirurgicheskoe lechenie i ego prognoz u bolnykh generalizovannoi miasteniei.

The work deals with the clinical analysis of the richest experience in the surgical treatment of patients with generalized myasthenia in the country. The efficacy of various methods for the diagnosis of affection of the thymus is studied comparatively. It is shown that for more effective diagnosis of neoplastic lesions of the thymus wider use of computerized and magneto-resonance tomography is expedient and that they must replace the insufficiently informative and invasive examination methods used today (pneumonodiastinography, phlebography, scintigraphy, etc.) which still form the basis for the system of diagnostic research in patients with myasthenia. The authors determined the indications and contraindications for, the optimum terms for undertaking the surgical intervention and its volume in neoplastic and nonneoplastic diseases of the thymus in adults and children. Comparative evaluation of various means of preoperative management was conducted. It is shown that to improve the patient's condition and stabilize the myasthenic status on the possibly minimal doses of anticholesteremic agents glucocorticoid hormones should be included in the complex of preoperative management. The indications for hormonotherapy were determined. The efficacy of plasmapheresis, radiotherapy, and glomectomy with denervation of the sinocarotid zone was evaluated and their place in the complex treatment of patients was determined. From study of the late-term results of treatment of a large group of patients (children, adults with a thymus) the main causes of unsuccessful surgical treatment of generalized myasthenia were identified and the concrete means of improving the results of treatment were planned. Two types of changes in the clinico-immuno-morphological values were revealed in patients with generalized myasthenia, differing evidently in pathogenesis. New clinico-immuno-morphological correlations and prognostic factors were discovered, and a method for prognosticating the effect of thymectomy was suggested. It is shown that splenectomy has a favorable effect in the most severe category of patients in unsuccessful operative and nonoperative treatment. The tactics of management of patients accepted in the clinic led to a uncomplicated course of the postoperative period in the majority of patients in the last years.

[Magnetic resonance tomography in the diagnosis of surgical diseases]. / Magnitno-rezonansnaia tomografiia v diagnostike nekotorykh khirurgicheskikh zabolevanii.

The authors analyse the first experience in the use of magnetic resonance tomography (MP-tomography) in the diagnosis of some surgical diseases. MR-tomography of the mammary gland (257 patients), thymus (55 patients), adrenals (41 patients), and hypophysis (18 patients) was conducted. The results of the examination were compared with the findings of other diagnostic methods and verified intraoperatively and histologically. The authors claim that the high informativeness of MR-tomography, its noninvasiveness, the absence of a radiation load, and the possibility of repeating the examination many times in three mutually-perpendicular planes distinguish the method favorably and dictate the necessity of its further study in clinical medicine.

[Residual thymus gland in patients operated on for myasthenia]. / Ostatochnaia vilochkovaia zheleza u bol'nykh, operirovannykh po povodu miastenii.

The authors studied the causes of ineffective surgical treatment of myasthenia and found residual thymus to be one of them. From analysis of 21 cases in which part of the thymus was not removed (in 19 cases the diagnosis was verified histologically), they drew the conclusion that the causes of residual thymus may be technical errors due to inadequate choice of the surgical approach of the surgeons' insufficient experience, in removal of a thymoma failure to excise part of the thymus not involved in the tumor, incomplete knowledge of the role of the thymus in the pathogenesis of myasthenia and its incomplete removal in thymectomy in patients with generalized myasthenia. Uneventful postoperative course was noted in 11 patients, crises with respiratory disorders in 6 (prolonged artificial lung ventilation had to be resorted to in 4 of them), suppuration of the wound in 2, and pneumonia in 1 patient who was under artificial lung ventilation. The late--term results were studied in follow--up periods of 12 months to 15 years. The myasthenic status improved in all patients, the results were excellent and good in 15. In view of the difficulty in establishing the diagnosis and management, this grave category of patients must be treated at specialized centers.

[Cortical-cell thymomas with predominance of so-called nurse-cells in patients with myasthenia]. / Kortikal'nokletochnye timomy s preobladaniem kletok-"nianek" u bol'nykh miasteniei.

30 thymomas in patients with generalized myasthenia studied histologically and immunohistochemically are classified as cortico-cell thymomas (n-15), medullary-cell (n-1), mixed-cell (n-10) and cortical-cell thymomas consisting mainly of thymic "nurse"-cells. Pronounced histological features of thymomas with the predominance of "nurse"-cells allow one to consider them as a special variant of thymic tumours. Production of thymic hormones by tumour cells in combination with the loss of HLA-DR antigen expression may be of importance in the pathogenesis of autoimmunization in patients with myasthenia.

[Tactical and technical errors in surgical treatment of patients with generalized myasthenia gravis]. / Takticheskie i tekhnicheskie oshibki pri khirurgicheskom lechenii bol'nykh generalizovannoi miastenii.

From experience in surgical treatment of 1,800 patients with generalized myasthenia as well as from literature data, the authors analyse the main tactical and technical errors in the treatment of this category of patients. A complex approach and a program of improving the results of treatment of patients with myasthenia were elaborated. Compulsory examination of the mediastinum for revealing possible affection of the thymus is indicated in myasthenia. Median sternotomy with ++extra-fascial removal of the whole thymus is considered the optimal approach in thymectomy. Thymomthymectomy with extensive removal of the areolar tissue of the anterior mediastinum is believed to be the operation of ++choice in tumors of the thymus. Thymus tissue which is not removed during the operation is one of the causes of recurrent myasthenia, while unjustified extension of the volume of the operation in nonneoplastic affection of the thymus is also inadvisable. Preoperative radiotherapy is not recommended. The principles elaborated in the clinic enabled the authors to reduce the frequency of assisted ventilation sevenfold and the incidence of infectious complications, pneumonia among others, to 0.6%.