A.G. Brusova, P.A. Manokhin, T.K.
Puznovskaya, T.A. Shyshkovetes.
Computer Nonlinear Diagnnostics (NLS) is a new highly informative method provided to examine the spine and the spinal morrow. The NLS advantages are noninvasiveness, scalability of the image field, a capability to obtain section of any orientation and virtual imagining of reticular canals and paravertebral zone. Undoubtedly the use of NLS in diagnostic of degenerative spine diseases has apparent prospects.
Subject and methods
The investigation was conducted by means of "Oberon 4009" metatron equipped with a 1.5 GHz digital trigger sensor. 1217 patient affected by degenerative changes in the lumbar region of the spine was investigated. The NLS of the spine and spinal marrow was performed for all patients, 112 patient had NLS and CT and myleography was performed for 10 patients.
Analysis of result
In 87% of cases in the examinee group we found disks affectes by degenerative changes. The elierst degenerative change in intervertebral disks (ID) was a hyoerchromous lesion (6p point on Flandler's scale) in zone between the pulpous nucleus and the fibrous annulus. Alonge with the degenerative changes NLS has detected an increased chromogenic density of the spinal from the bone marrow in the adjacent regions of the vertebral bodies (4-5 points according to Floander's scale). 3 degrees of the degenerative changes could be distinguished depending on the process intensity.
Degree1, a hyperchromous zone apprised at 4-5 on Flandler's scale, was detected in 90 patients. Conventional radiograph did not display any changes. Formation of fibrovascular tissue followed by its penetration into the bone marrow is believed to underline the changes. Some author relate these changes ro the lack of stability in the segment.
The histogram displayed a spectral similarity to the reference standard "intervertebral osteochondrosis" (D 0.396 to 0.425)
Degree 2, a hyperchromous response in the affected zone at 5-6 points in Flandler's scale was detected in 215 patients. Conventional radiograph did no showed any changes. According to some literary evidence, in this phase the histology detects a substitution of the fat bone marrow for the red bone marrow often accompanied by enlarged trabeculae. This phase generally precedes an osteochondrosis development which can be diagnosed a little while later by conventional radiographs.
The spectral similarity to the references standard "intervertebral osteochondrosis" was frank (D0.246 to 0.360)
Degree3, a frank hyperchromous response (6 points), which corresponds to a far advance vertebral body sclerosis, was detected in 312 patients. Some secondary symptoms, like local bulging and vertebral asteophytes, were detected with a far advance degenerative lesion of the disk and substantial similarity to the references standard "osteochondrosis" (D from 0.152 to 0.218). NLS allowed to differentiate between a protrusion and prolpse of the disk and existence of rupture of the fibrotic ring and condition of longitudinal and other ligaments.
A protrusion is defined as a bulging of disk tissue beyond the posterior out line of the vertebral body into the spinal canal. The fibrotic ring tissue endures through becomes very thin and NLS only revels zone of slight destructive changes in the structure (3-4 points0. With compression it gives an actually frank hyperchromous response(6 points).
Protrusion may be accompanied by slight caudal shift which is quiet often defined by means of the NLS-method at L5-S1 intervertebral disk level. NLS detected protrusion in 729 patients.
The rupture of the fibrotic ring fibers result in the prolapsed of the pulpous nucleus on a subligamentary level and the ligaments rupture results in the prolapsed inside the cerebrospinal canal. As can be seen from NLS, the longitudninal ligaments look well delimited and are represented as hyperchromous band-like structures (5-6 points) which adjoin the bones and fibrotic ring. The extraligamentary prolapsed can shift either in a caudal or cranial direction. The extraligamentary prolapses of the disk that lost contact with the host disk become sequesters. Occasionally, we observe some very small extraligamentary sequesters which shifted far into the cerebrospinal canal, which made it hard to detect them.
The NLS investigation detected prolapsed in 445 patients. In 685 of cases the hernias of intervertebral disk was combined with other degenerative dystrophic spinal changes on this level. The hernia of the intervertebral disk was detected at 1.4 -5 level in 83% and 1.3-4 level in 2% of cases. A lesion of several disk was found in 50 patients. 196 underwent surgery, among the 114 had lateral hernias, 76 patients had median lateral hernia and 6 had median hernia. 5 patient had surgery for hernia recurrence. The NLS diagnosed extraligamentary sequestrated hernia in 38 patients and intradural hernia was diagnosed in 3 patients. Multiple sequesters were detected in 5 patients.
The clinical symptomatology for the prolapsed of intervertebral disk was variable and did not always depend on their size. In some case we observed median protrusions which did not result in any clinical implication. The clinical symptomatology for small sequestrated hernia was no less then for large sequesters.
In evaluating the NLS data not only the size of hernia but also the reserve area of the cerebrospinal canal and their preposition should be taken in to account.
With a suspected hernia the NLS-investigation should be performed at least in two planes, sagittal and paraxial, i.e., parallel to the disk plane, and the sagittal investigation in T1w-SE can be combined with others sequences.
The median prolapses of intervertebral disks in sagittal shots could be seen quiet clearly. The signal content of the hernia predominantly corresponded to the NLS signal content of the pulpous nucleus. The external part of the fibrotic ring, posterior longitudinal ligament and the dura matter give a frank hyperchromous response and did not differentiate from one another. Thus,, the NLS method sometimes fails to present a direct proof of a rupture in the external and axial projections.
Sagittal shots have an advantage in deciding on the disk prolapsed, the size of intervebral foramina and the condition of the cerebrospinal canal and bones. These shots are not significant for detecting an intradural process with the cone especially poorly invisible in them. Frontal shots have drawbacks in determining the condition of the pulpous nucleus and fibrotic ring. To that and paraxial virtual models are used, for they allow to differentiate the process between the fibrotic ring rupture and protrusion free of the rupture. Thanks to virtual dimensional scaling sagittal shots allow to delimit the subarachnoid space.