Neuropathies of the lumbar plexus trunks, in particular those of the femoral nerve, are the most common complications of lateral interbody spondylodesis of the lumbar spine. Modeling of this surgical intervention in normal animals experimentally makes it possible to assess the degree of its trauma to the nervous structures, and to understand what is the reason for the persistence or aggravation of neurological symptoms iatrogenic injuries or the existing pathology progression. Purpose of the Study. To study histological and morphometric changes in the femoral nerve in the long-term periods after modeling of the lateral interbody spondylodesis of the canine lumbar spine. Design of the Study. An experimental prospective continuous uncontrolled study. Material and Methods. Discectomy via lateral approach was performed in 18 mongrel dogs (aged 2-3 years, mass 13.2-17.6 kg) at the level of L4-5 и L5-6, interbody titanium implants were mounted, the lumbar spine was stabilized with a wire device for external fixation within 30 days. Clinical-and-neurological evaluation was performed, as well as histological investigation of the femoral nerves from the side of surgical approach. Results. In the early postoperative period a temporary decrease in the femoral nerve function was observed, which was manifested by the disorder of the support function and muscle weakness of the pelvic limbs, decrease in the knee reflex, the foot support shift to the metatarsal pad. Later, until the end of the study (18 months), the general condition of all animals was satisfactory, there were no disorders of the limb support function and motor reflexes. After six months, in the femoral nerve there was 4-fold decrease in the proportion of large fast-conducting myelin fibers D 10 m and 3-fold increase in that of the small ones. The mean axon diameter and myelin thickness were 62% and 53% of the norm. After 12-18 months, the dimensional characteristics of myelin fibers were restored. During the entire experiment, 4-6% of myelin fibers were reactively-and-destructively altered. Conclusions. The modeling of the lateral interbody spondylodesis of the lumbar spine in normal animals experimentally demonstrated the absence of neurological symptoms after 6-18 months, which indicated low invasiveness of the surgical intervention. Nevertheless, the subclinical reactive-and-destructive changes in the myelin fibers of the femoral nerve revealed 6 months after the surgery indicated the need for preventive anti-neurotic therapy.
ВACKGROUND: For the treatment of degenerative diseases of the spine, various deformities, a minimally invasive technique of lateral lumbar interbody fusion is used, which minimizes the risks of spinal cord injury. In the development of these pathologies, the most important role is assigned to the paraspinal muscles, the histological features of which are insufficiently elucidated in the relevant literature when modeling spondylodesis.
АIM: To investigate the effect of lateral interbody vertebral fusion (spondylodesis) when introducing titanium implants on the histostructure of the psoas minor muscle.
МATERIALS AND METHODS: Experiments were performed in 14 mongrel dogs, 3 individuals the control group (norm). The аnimals underwent discectomy at the level of L45, L56 vertebrae through the lateral approach on the right, and interbody titanium implants were installed. The lumbar spine was stabilized with an external fixator for 30 days. Paraffin muscle sections were stained with hematoxylin-eosin, according to Masson.
RESULTS: During the experiment, an increased variety of myosymplast diameters, loss of polygonality of their profiles, fibrosis of the interstitial space, and sclerotization of the vascular membranes were observed in the psoas minor muscle. The volume density of endomysium in both muscles increased 1.5 times relative to the norm after 6 months Other parameters decreased: the volume of myosymplasts was 95%, that of microvessels 73% on the left, 83% on the right. On the other hand, the degree of fatty infiltration increased, amounting to 276% on the left and 394% on the right of the normal parameters. After 18 months, the bulk density of muscle fibers on the left was restored to the value in the control, on the right it was only 95%. The degree of sclerotization in the muscle on the left is 133%, on the right 161% of the norm; the index of fatty infiltration was 146% on the left and 339% on the right of the normal parameter.
CONCLUSION: pathohistological changes in the psoas minor during lateral interbody fusion are more pronounced on the side of the operative approach, which necessitates minimizing trauma to the paravertebral muscles during operations in order to prevent sclerotization and fatty involution of muscle tissue.
Abstract:We consider one type of convergence of multiple trigonometric Fourier series intermediate between the convergence over cubes and the λ-convergence for λ > 1. The well-known result on the almost everywhere convergence over cubes of Fourier series of functions from the class L(lnhas been generalized to the case of the Λ-convergence for some sequences Λ.
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