Type 1 neurofibromatosis is a serious hereditary disease in which mainly skin, nervous, muscular, and bone systems are damaged. In bone systems the most common deformities are thoracic kyphosis and scoliosis. Data for morphological changes in the structural components of spine in neurofibromatosis are scarce. Thus our study aimed to investigate morphological changes in structural components of the spine in NF1 neurofibromatosis. Growth plates, intervertebral discs, and fragments of vertebral bodies from deformed and adjacent segments of the spine were obtained from 15 patients aged 10–14 years with scoliosis (Cobb angle 90–120°) caused by neurofibromatosis. Preoperative examination included MRI study of the spine and brain to exclude intracanal masses, and radiographic study of the spine. Patients did not present any neurological symptoms. All children underwent anterior release and interbody fusion. Structural spinal components from children aged 12–14 years collected at forensic autopsy were used as controls. Tissues were investigated by conventional histochemical and ultrastructural methods. The levels of aggrecan and Introduction
Methods
diagnosis of AIS King type II and III, younger than 21 years, not operated before. A total of 247 patients met the inclusion criteria and they were divided in two groups:
thoracic curve less than 90° and more than 90°. In the group (A) there were 168 patients (male/female – 11/157, mean age 15.3 years), in the group (B) – 79 patients (male/female – 8/71, mean age 15.5 years). Coronal curve flexibility was assessed on supine side-bending AP radiographs. According the type of surgical technique the patients were divided in four groups:
I - CDI correction II - CDI + skeletal traction III - anterior apical release with interbody fusion and CDI IV - anterior apical release, skeletal traction and CDI. All the operations in the groups III and IV were performed in one session.
So, CDI adds only 9.1° to side-bending correction (Gr. I) and skeletal traction gives 5.8° more (Gr. II). Anterior release with CDI improves preoperative correction by 14.7° (Gr. III) and the same procedure with skeletal traction – by 30.0° (Gr. IV). Consequently the part of the skeletal traction varies from 5.8° to 6.2°. Anterior release in its turn gives 14.7° of additional correction per se and 20.9° with skeletal traction. In the group (B) mean thoracic curve before surgery was 109°, on the side-bending films 90.6° and after surgery 54°. The corresponding data according the type of surgery are presented in Table 2. So, CDI adds 26.3° to side-bending correction (Gr.I) and skeletal traction gives only 1.9° more (Gr.II). Anterior release with CDI improves preoperative correction by 25.9° (Gr.III) and the same procedure with skeletal traction – by 40.6° (Gr.IV). Consequently the part of the skeletal traction varies from 1.9° to 14.7°. Anterior release in its turn does not give additional correction per se and 12.2° – with skeletal traction.
Idiopathic scoliosis has been studied through centuries, but problems of its aetiology and pathogenesis up till now are the subjects of considerable discussion. Pathogenetic mechanism of the spine deformity development in idiopathic scoliosis (IS) was established on the basis of in-depth morphological and biochemical investigations of structural components of the spine in patients with IS (surgical material) (Zaidman A.M., et al. 2001). It was shown that IS develops on the basis of disturbance of proteoglycans (PG) synthesis and formation in vertebral growth plates. Decrease of chondroitin sulphate component of PG and increase of keratan sulphate one, as well as decrease in degree of sulphating of glycosaminoglycan (GAG) chains and increase of non-acetilated sugars – all this evidences for conformational changes in proteoglycans. The found keratan sulphate-related fraction is likely a marker of genetic changes in PGs in idiopathic scoliosis. Structural changes in PGs in combination with reduce of quantity of diffuse molecules which perform trophic and informational function, and disorders of receptor function of chondroblast membranes (ultra structural and histochemical findings) are the factors of disorders in regulation mechanisms of vertebral growth plate cells and matrix differentiation and reproduction. Long-term studies (Zaidman A.M., et al., 1999–2003) demonstrated a major-gene effect in Idiopathic Scoliosis. The next stage was major gene localization by the method for candidate gene testing. The aggrecan gene with known polymorphism of the number of tandem repeats in exon G3 was considered to be one of these candidate genes. Various alleles of this gene provide attachment of different number of chondroitin sulfate chains to a proteoglycan core protein, thereby changing functional properties of cartilage. The aggrecan gene AGC1 coding a core protein of aggrecan molecule has been localised to region 15q2b. In anald families nine alleles of aggrecan gene have been identified, among them three alleles with tandem repeats numbers of 25, 26, and 27 prevailed. We did not reveal preferable transmission of any of these alleles to the proband The absence of reliable association of IS with polymorphism of exon G3 can not be interpreted as a non-linkage of the whole aggrecan gene to IS development determination. As the linkage of other proteoglycans to IS development has not been excluded, we perform the RT-PCR and immunoblot analyses of the expression of main PG genes and their protein products in cultivated chondroblasts isolated from vertebral growth plates in 15 patients with III–IV grade IS (surgical material). The study has shown that aggrecan gene expression is significantly decreased in cultivated chondroblasts from patients with IS, what correlates with a decrease of synthesed protein product, both in cells (chondrocytes) isolated from IS patients and in cultural media. The presence of keratan sulphate-related fraction and keratan sulphate increase are associated with luminicene increase. In present we perform a sequencing of aggrecan genome.
Since the first pathography of Idiopathic Scoliosis (IS) and Scheuermann’s disease (SD) clinicians consider these two pathologies as separate nosological entities. The reason for this is different clinical implications of diseases. SD is known to be more common in boys, while IS is a sad privilege of girls. Kyphotic spinal deformity is typical for patients with Scheuermann’s disease while scoliotic one for patients with idiopathic scoliosis. Schmorl’s nodes are found more frequently in SD. Both deformities are attributed to the growth asymmetry, anterior growth plates are affected in SD and lateral ones – in IS. Despite different clinical presentations, these two nosologies have the same pathogenetic mechanism and semiology. To our regret, there are no reports on comparative morphological and biochemical investigations of SD and IS. Long-term studies have given rise to the question of a single nature of scoliotic and kyphotic spine deformities.
The potency for synthesis and structural organization of chondroblasts isolated from vertebral body growth plates of patients with IS and SD were subjects of morphological, biochemical, and ultrastructural analyses. Qualitative and quantitative composition of growth plates was investigated in culture mediums.
Morpho-histochemical study of the spine structural elements has revealed the same changes in patients with IS and patients with SD:
Disturbance of structural and chondral organization of cells and matrix in vertebral body growth plate. Decrease of chondroitin sulfate content and increase of keratan sulfate content. Lower response to oxidation-reduction enzymes in cytoplasm of chondroblasts. Change of the ultrastructural organization of cells: Golgi complex with flat vacuoles and enlarged cisterns of endoplasmic reticulum. Extracellular matrix with fragmented collagen fibrils and small fragments of proteoglycans.
