NLS-Diagnosis Of Degenerative Changes In The Spine

A.G. Brusova, P.A. Manokhin,

T.K. Puzanovskaya, T.A. Shyshkovets

Computer Nonlinear Diagnosis (NLS) is a new highly informative method provided to examine

the spine and spinal marrow. The NLS advantages are non-invasiveness,

scalability of the image field, a capability to obtain sections of any orientation and virtual

imaging of radicular canals and paravertebral zone. Undoubtedly the use of NLS in

diagnosis of degenerative spine diseases has apparent prospects.

Subject and methods

The investigation was conducted by a 1.5 GHz NLS unit. 1217 patients affected by

degenerative changes in the lumbar region of the spine were investigated. NLS analysis of

the spine and spinal marrow was performed for all patients. 112 patients had NLS and CT,

and myelography was performed for 10 patients.

Analysis of results

In 87% of cases we found disks affected by degenerative changes. The earliest

degenerative change in inter-vertebral disks (ID) was a hyper-chromous lesion (6 points on

Flandler’s scale) in zone between the pulpous nucleus and the fibrous annulus. Along with

the degenerative changes NLS has detected an increased chromogenic density of the signal

from the bone marrow in the adjacent regions of the vertebral bodies (4-5 points according

to Flandler’s scale). 3 degrees of degenerative changes could be distinguished depending on

the process intensity.

Degree 1, a hyper-chromous zone appraised at 4-5 points on Flandler’s scale, was

detected in 90 patients. Conventional radiographs did not display any changes.

Formation of fibro-vascular tissue followed by its penetration into the bone marrow is

believed to underlie the changes. Some authors relate these changes to the lack of

stability in this segment.

The histograms displayed a spectral similarity to the reference standard “intervertebral

osteo-chondrosis” (D0.396 to 0.425).

Degree 2, a hyper-chromous response in the affected zone at 5-6 points on Flandler’s

scale was detected in 215 patients. Conventional radiographs did not show 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 osteo-chondrosis development which can be diagnosed a little

while later by conventional radiographs.

The spectral similarity was close to the reference standard “inter-vertebral

osteochondrosis” (D 0.246 to 0.360).

23Degree 3, a frank hyper-chromous response (6 points), which corresponds to a far

advanced vertebral body sclerosis, was detected in 312 patients. Some secondary

symptoms, like local bulging and vertebral asteophytes, were detected with far advanced

degenerative lesion of the disks and a substantial similarity to the reference stand

“osteochondrosis” (D from 0.152 to 0.218). NLS enables differentiation between a protrusion

and prolapse of the disk and existence of rupture of the fibrotic ring and the condition of

longitudinal and other ligaments.

A protrusion is defined as a bulging of the disk tissue beyond the posterior outline of the

vertebral body into the spinal canal. The fibrotic ring tissue endures though becomes

very thin and NLS only reveals a zone of slight destructive change in the structure (3-4

points). With compression it gives an acutely frank hyper-chromous response (6 points).

Protrusion may be accompanied by a slight caudal shift which is quite often defined by

means of the NLS-method at L5-81 inter-vertebral disk level. NLS detected protrusion in 729

patients.

The rupture of the fibriotic ring fibers results in the prolapse of the pulpous nucleus on a

subligamentary level and the ligament rupture results in the prolapse inside the

cerebrospinal canal. As can be seen from NLS, the longitudinal ligaments look well

delimited and are represented as hyper-chromous band-like structures (5-6 points) which

adjoin the bones and the fibrotic ring. The extra-ligamentary prolapse can shift either in a

caudal or a cranial direction. The extra-ligamentary prolapses of the disk that lost contact

with the host disk become sequesters. Occasionally, we observed some very small extra-

ligamentary sequesters which shifted far into the cerebrospinal canal, which made it hard

to detect them.

The NLS-investigation detected prolapse in 445 patients. In 68% of cases the hernia of

intervertebral disk was combined with other degenerative dystrophic spinal changes on

this level. The hernia of the intervertebral disk was detected at L4-5 level in 83%, and

L5-8 level in 15% and at L3-4 level in 2% of cases. A lesion of several disks was found

in 50 patients. 196 patients underwent surgery, among them 114 had lateral hernia, 76

patients had median lateral hernia and 6 had median hernia. 5 patients had surgery for

hernia recurrence. The NLS diagnosed extraligamentary sequestrated hernia in 38

patients, and intracural hernia was diagnosed in 3 persons. Multiple sequesters were

detected in 5 patients.

The clinical symptomatology for the prolapse of intervertebral disks was variable and did not

always depend on their size. In some cases we observed median protrusions which did not

result in any clinical implications. The clinical symptomology for small

sequestrated hernia was no less than 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 prepositions should be taken into account.

24With 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 other sequences.

The median prolapses of intervertebral disks in sagittal shots could be seen quite 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

ligaments and the dura matter give a frank hyperchromous response and do not

differentiate from one another. Thus, the NLS-method sometimes fails to present a direct

proof of a rupture in the external part of the fibrotic ring.

It is largely a lesion of the pulpous nucleus on the side of the back edge of the vertebral

body that speaks in favor of the protrusion in axial shots. Displacements and

compression of the spinal marrow can well be seen in both sagittal and axial projections.

Sagittal shots have an advantage in deciding on the disk prolapse, the size of

intervertebral foramina and the condition of the cerebrospinal canal and bones. These

shots are not significant for detecting an intra-dural process with the cone especially

poorly visible in them. Frontal shots have drawbacks in determining the condition of the

pulpus nucleus and fibrotic ring. To that end paraxial virtual models are used, allowing to

differentiate the process between the pulpus nucleus and the fibrotic ring and

sometimes make it possible to differentiate between the fibrotic ring rupture and the

protrusion free of the rupture. Thanks to virtual dimensional scaling sagittal shots allow to

well delimit the subarachnoid space.

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